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15 November 2010, Volume 31 Issue 21
Invited Papers
Wireless Communication Networks between Food and Human Body
PANG Guang-chang,CHEN Qing-sen,HU Zhi-he,XIE Jun-bo
2010, 31(21 ):  1-9.  doi:10.7506/spkx1002-6630-201021001
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A new hypothesis of cellular wireless communication networks was proposed on the basis of current research achievements in the field of immunology, which were summarized from gastrointestinal mucous receptor pathways of foods. In this hypothesis, cytokine network was a signal transduction system during cell communications. The cells especially for leukocytes can communicate with each other in networks by a manner of paracrine or autocrine. In addition, the cells can also execute long-distance whole communication through the autocrine mode. A coordinated communication network between wireless and wire communications was established through cellular communication between gastrointestinal mucous and neuroendocrine system. In this communication network, cells accepted gene expression and quantitative regulation of cellular signal amplification through receptors, signal transduction and cascade system. However, the cytokine and chemokine can accomplish the signal transduction through circulatory system among cells without mutual interference even at the condition of lowconcentration. Functional foods can change the complex communication networks to realize their biological functions. Therefore, the establishment of this theory and research method will have the potential to alter functional foods.

Basic Research
Rheological Properties of Rabbit Skeletal Myosin under Different Conditions
XU Ke,WU Ye,XU Xing-lian*,ZHOU Guang-hong
2010, 31(21):  10-14.  doi:10.7506/spkx1002-6630-201021002
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An investigation of rheological properties of myosin from two rabbit muscle types (Pasoas major, PM and Semimembranosus proprius, SMp) was carried out under different levels of protein concentration, temperature, pH value and KCl concentration. K (viscosity coefficient), n (flow index) and Ea (activation energy) were calculated following the power law or the Arrhenius equation, and from the results of calculation, it can be concluded that myosin is a pseudoplastic fluid under different conditions, and that the relationship between sheer stress (τ) and sheer rate (δ) is a power law function. K and n were influenced by protein concentration, temperature, pH and KCl concentration, and myosins from both rabbit muscle types had identical changes in the two parameters. The relationship between viscosity coefficient and protein concentration complied with a polynomial equation, and the Arrhenius equation could describe the influence of temperature on the flow behavior of rabbit skeletal myosin well.

Effects of Freeze Drying and Storage of Oat Sourdough Starter on Volatile Flavor Compounds of Bread
LIU Ruo-shi1,WAN Jing-jing1,ZHANG Kun1,HUANG Wei-ning1,*,RAYAS-DUARTE Patricia2
2010, 31(21):  15-19.  doi:10.7506/spkx1002-6630-201021003
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Oat breads made with non-freeze-dried L.sanfranscensis containing sourdough starter and freeze-dried ones stored at 4 ℃ for 0 and 30 days were analyzed for their volatile compound composition by solid phase micro-extraction/gas chromatography-mass spectrometry (SPME/GC-MS) in order to explore the effects of freeze drying and storage of sourdough starter on volatile flavor compounds of bread. A total of 87 compounds were identified in the three oat breads and acids, alcohols, aldehydes, aromatic and heterocyclic compounds were of most importance in the volatile profile. The most abundant volatile compound category in all samples was acids, followed by alcohols, aromatic and heterocyclic compounds and aldehydes. Through freeze-drying and subsequent storage, aldehydes and alcohols contents first increased and then decreased; while acid, esters, ketones and aliphatic compounds experienced an opposite process, and the concentration of aromatic and heterocyclic compounds rose up. Breads made with both freeze-dried starters were also rich in volatile flavor compounds. Acetic acid and ethanol contents showed opposite changes due to the competition between L.sanfranscensis and yeast. The relative abundance of furfural increased in both cases. However, hexanal content significantly decreased after freeze-drying and was not detected in bread made with 30-day stored freeze-dried starter.

Sterilization and Biological Window Effects of Pulsed Magnetic Field on Staphylococcus aureus and Its Inactivation Dynamics
XU Shen-shi1,MA Hai-le1,2,*
2010, 31(21):  20-23.  doi:10.7506/spkx1002-6630-201021004
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The sterilization effect of pulsed magnetic field treatment on Staphylococcus aureus was examined under different levels of field intensity, pulse number and bacterial suspension temperature. As field intensity increased, the residual survival rate of Staphylococcus aureus generally tended to decrease and the best sterilization effect was observed at a filed intensity of 3.5 T. The effect of pulse number on the residual survival rate of this strain was similar to that of field intensity, and the residual survival rate of this strain reached its minimum after 20 pulses were completed, and then tended to be unchanged with increasing pulse number. Additionally, environmental temperature had a synergistic promoting effect on the inactivation of Staphylococcus aureus. The above results demonstrate that the optimal levels of field intensity, pulse number and bacterial suspension temperature for sterilizing Staphylococcus aureus were 3.5 T, 20 and 30℃, respectively. The percentage of residual viable cells was 7.29% under these conditions. The sterilization of pulsed magnetic field on Staphylococcus aureus displayed a biological window effect. The window value of field intensity under 20 pulse number and 20 window value of pulse number accorded with the following recurrence formula: IW(n) = n(9-n)/4-1 (n is appearing sequence of the window value of field intensity, n = 1, 2 and 3). The comparative analysis of correlation coefficients (R2) of the Gelow, the Weibull and the Hulsheger models indicates that the Gelow model is the best model describing the dynamic change of percentage of residual viable Staphylococcus aureus cells during pulsed magnetic field treatment.

Effects of Physico-chemical Factors on Complexation of Cetyltrimethyl Ammol/Lonium Bromide with Whey Protein
LIU Wei,LI Xing-min*,ZHENG Hai-tao,LIU Yi
2010, 31(21):  24-28.  doi:10.7506/spkx1002-6630-201021005
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Today, understanding physico-chemical factors affecting the complexation between coagulant and protein granules for protein separation is of great interest to the finding of novel coagulants and the reasonable utilization of whey protein. The effects of different factors such as final cetyltrimethyl ammol/lonium bromide (CTAB) concentration, pH, temperature, whey protein concentration and ionic intensity on the complexation between CTAB and whey protein were dealt with for finding the best complexation conditions. Final CTAB concentration was found to be the most important factor. pH had no significant effect on CTAB/whey protein complexation. At different pH values, the complexation was significantly affected by temperature. In a range of 0 to 200 mmol/L, higher ionic intensity resulted in a decrease of CTAB/whey protein complexation. However, increasing whey protein concentration affected the complexation in a positive way, resulting in an increase of protein recovery.

Optimization of Enzymatic Hydrolysis of Loach Muscle for Production of Antioxidant Peptides and Measurement of Their Molecular Weights
YAO Dong-rui1,WANG Shu-jun1,LI Yuan-yuan1,PAN Sai-kun1,YANG Fan1,2
2010, 31(21):  29-33.  doi:10.7506/spkx1002-6630-201021006
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In order to obtain bioactive peptides having better ability to scavenge hydroxyl free radicals generated in Fenton system, the muscle of loach (Misgurnus anguillicaudatus) was hydrolyzed separately with flavourzyme, protamex, trypsin and pepsin and bromelain, and bromelain was the selected protease for the hydrolysis of loach muscle. The subsequent investigations involved optimization of the hydrolysis of loach muscle by response surface methodology for achieving maximum hydroxyl free radical scavenging rate and Sephadex G-15 gel column chromatographic determination of relative molecular mass distribution of the hydrolysate obtained under optimized hydrolysis conditions. The optimal conditions for bromelain-catalyzed hydrolysis of loach muscle were determined as follows: solid/liquid ratio, 1:4; enzyme dose, 0.2%; pH, 6.47; hydrolysis temperature, 54.48 ℃; and hydrolysis duration, 59.97 ℃. The hydrolysate obtained under these conditions displayed a free radical scavenging rate of 99.03% and an IC50 value of 0.57 mg/mL, and contained peptides having a relative molecular mass varying from 1129 to 2344.

Photocatalytic Degradation of Propranolol with MWCNTs-TiO2 Composite
CHEN Hai-bo1,DAI Ke2,CHEN Hao1,*
2010, 31(21):  34-38.  doi:10.7506/spkx1002-6630-201021007
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Residual propranolol in the aquatic environment would cause harm to aquatic products safety, and even threaten human health through the food chain, so it is necessary to take effective measures to remove propranolol. The photocatalytic degradation of propranolol in aqueous heterogeneous solution containing nanosized multi-walled carbon nanotubes (MWCNTs)-TiO2 composite as a photocatalyst was investigated under ultraviolet (UV) illumination, and the optimal experimental conditions for the photocatalytic degradation of propranolol such as propranolol concentration, initial pH, catalyst dose, light illumination time and mixing ratio for MWCNTs and TiO2 were determined. After 180-min UV illumination under optimized experimental conditions, the degradation rate of propranolol was as high as 95%. Meanwhile, a preliminary exploration on the degradation mechanism of propranolol was carried out, and the results showed that the degradation of propranolol was mainly attributed to the oxidation of hydroxyl free radicals.

Characterization and Correlation Analysis of Physico-chemical Properties of Starch from Different Potato Cultivars
WANG Lan1,REN Si-chen2,DU Xin1,WANG Jun1,CHENG Wei1,SUN Zhi-da2,XIONG Guang-quan1,*
2010, 31(21):  39-44.  doi:10.7506/spkx1002-6630-201021008
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Potato starch has some special properties, which contribute to its versatile utilization and application potential. Starches from different sources have different physico-chemical and functional properties. In this work, eight potato cultivars were extracted to obtain starch, and the extracted starches were subjected to characterization and correlation analysis of physicochemical properties such as chemical composition, swelling power, solubility and thermal and rheological properties. Potato starch crystallinity was negatively correlation with temperature at storage modulus peak and swelling power, respectively. The contents of amylose and phosphorus were both positively correlated with temperature at storage modulus peak, storage modulus peak, transition temperature (onset, To; peak, Tp; and conclusion, Tc) but negatively correlated with crystallinity. Furthermore, a negative correlation between amylase content and gelatinization enthalpy was also observed.

Functional Properties of Rapeseed Peptides Derived from Solid-state Fermentation
JU Xing-rong1,HE Hai-yan1,HE Rong2,WANG Li-feng1,2,YUAN Jian1
2010, 31(21):  45-49.  doi:10.7506/spkx1002-6630-201021009
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The functional properties of rapeseed peptides (RSP) derived from solid-state fermentation were studied and compared with those of rapeseed protein (RP) in this work. The results showed that in comparison with RP, RSP had a better solubility and could keep a high NSI over 85% at a wide range of pH 2.0 to 12.0, while RP had a worse solubility when the value of pH was lower than 8.0. Neither the water-binding nor oil-binding capacities of RP had an obvious change at a varying temperature between 20℃ and 80 ℃, while those of RPS decreased as temperature increased. RSP also showed better emulsifying capacity in a large concentration range (2 to 5 g/100mL) when compared with RP. At the same time, RSP had better foaming capactiy and foam stability but had worse gel properties. Besides, RSP had the ability to scavenge DPPH free radicals, which was positively linearly correlated with concentration over a range from 0 to 500μg/mL (R2 = 0.9912), and the IC50 was 328μg/mL.

Comparison of Cheese Samples with Different Hardness in Texture and Rheological Properties
YANG Shu,GAO Xin*,XU Jia-chao,FU Xiao-ting,ZHANG Zhao-hui
2010, 31(21):  50-53.  doi:10.7506/spkx1002-6630-201021010
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Cheese samples with different hardnesses (hard, semi-hard and soft) were subjected to chemical composition analysis, texture profile analysis (TPA), sensory evaluation and characterization of rheological properties in this study. The TPA analysis was performed on a texture analyzer. The hardness of cheese had a significant effect on its texture characteristic parameters and rheological properties. Moreover, hard cheese showed larger breaking strength and elasticity, and lower cohesiveness, while soft cheese showed smaller breaking strength and elasticity, and higher cohesiveness. The results of rheological properties analyzed by dynamic method showed that storage modulus (G′), loss modulus (G″) and dynamic viscosity (η′) decreased with decreasing hardness over the entire frequency sweep.

Antimicrobial Effect of Polyphosphate Additives in Fishery Product
SHEN Biao1,HU Xing-juan1,XU Jun-hui1,BEI Wen-lian1,WU Zu-fang2
2010, 31(21):  54-57.  doi:10.7506/spkx1002-6630-201021011
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Objective: To find out which ones of four polyphosphates are antimicrobial molecules and to determine their critical antimicrobial concentrations. Methods: Liquid agars at different pH values (6.0, 7.2 and 8.0) were used to test the inhibitory effects of orthophosphate, tripolyphosphate, pyrophosphate and trimetaphosphate on Bacillus subtilis and Micrococcus luteus. Results: Two of the four polyphosphates were an antimicrobial, including tripolyphosphate and pyrophosphate. Their critical concentrations causing antimicrobial positivity were 0.2 g/100mL and 0.3 g/100 mL (1157.56 mg/kg and 1601.43 mg/kg, calculated as P2O5), respectively. A two-factor, three-level orthogonal array design was employed to evaluate the synergistic antimicrobial effect of tripolyphosphate and pyrophosphate, and the results revealed that as long as one of the two polyphosphates simultaneously added had a concentration in their mixed solution equalling or exceeding its own critical concentration, a positive antimicrobial result (inhibition zone equalling or exceeding 2 mm) could be observed. Conclusion: The risk of antimicrobial positivity caused by polyphosphates can be reduced by controlling the amounts of added tripolyphosphate and pyrophosphate.

Determination of Antioxidant Activity of Extracts from Ligustrum lucidum Fruit
LIU Xiao-geng,LI Feng-yue,ZHANG Shao-qing,PAN Jian-feng
2010, 31(21):  58-61.  doi:10.7506/spkx1002-6630-201021012
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The DPPH radical scavenging effects of different solvent extracts from different parts of Ligustrum lucidum fruit growing in Nanjing were comparatively investigated. Moreover, the effects of sunlight illumination and growth period on the DPPH free radical scavenging activity of ethanol extract from whole Ligustrum lucidum fruit were examined, and the lyophilized ethanol extract from whole Ligustrum lucidum fruit was subjected to sensory evaluation and comparison with VC and tea ployphenols in free radical scavenging capacity. Polar and non-polar solvents were employed to extract Ligustrum lucidum fruit, and the extracts derived from polar solvent extraction showed stronger DPPH free radical scavenging capacity. Solvents and fruit parts both made a difference to DPPH free radical scavenging capacity. The same solvent extracts from different fruit parts obtained with methanol, ethanol or water were ranked in the following order starting with the strongest: peel > whole fruit >shell > kernel. For acetone, ethyl acetate and ethanol extracts, the order was peel > whole fruit > kernel > shell. All five solvent extracts from whole fruit showed a positive correlation between DPPH free radical scavenging activity and concentration in the lower concentration range, and the slopes were much higher than those in the higher concentration range. However, the concentration-effect relationship in the higher concentration range was complicated and closely associated with solvent type. The highest DPPH free radical scavenging activity of Ligustrum lucidum fruit was observed at the early ripening stage, followed by different decreases at the middle and post ripening stages. The ethanol extract from Ligustrum lucidum fruit exposed to sunlight revealed significantly higher DPPH free radical scavenging activity than that from Ligustrum lucidum fruit unexposed to sunlight. The lyophilized ethanol extract from whole Ligustrum lucidum fruit had a DPPH free radical scavenging capacity (IC50= 5.38-10.46) equivalent to that (IC50 = 8.59) of VC but lower than that (IC50 = 1.70) of tea polyphenols. The solid water-soluble ethanol extract in dark brown is a potential effective antioxidant.

Analysis of Fatty Acid Composition of Yak Meat and Its Relationship with Myoglobin Oxidation
SUN Ye-kun,WANG Miao,YANG Hu,ZHANG Chi,WEN Wen-ting,SUN Qun*
2010, 31(21):  62-64.  doi:10.7506/spkx1002-6630-201021013
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A comparative investigation on the fatty acid composition of skeletal muscles of Maiya yak and common yellow cattle and an analysis on the relationship between fatty acid composition and myoglobin oxidation were conducted. The daily oxidation rates of myoglobin for Maiya yak and common yellow cattle were 1.54% and 5.03%, respectively, and the daily lipid oxidation rates (TBARS) of skeletal muscle were 0.088/d and 0.049/d. These data indicate that the oxidation rates of myoglobin and lipid in yellow cattle skeletal muscle were both significantly faster than those in Maiya yak skeletal muscle (P< 0.5). The analysis of fatty acid composition showed that the relative content of saturated fatty acids in Maiya yak skeletal muscle was 45.94%, significantly higher than that in yellow cattle skeletal muscle of 38.01% (P < 0.5), while yellow cattle skeletal muscle displayed significantly higher content of polyunsaturated fatty acids than Maiya yak skeletal muscle (P < 0.5). The difference in fatty acid composition might be one of the main reasons causing the difference in myoglobin oxidation between both beef skeletal muscles.

Synergistic Antimicrobial Effect of Ethanol Extracts from Clove and Licorice
ZHANG Yan-nan1,NING Zhi-liang1,CHEN Chang-wu1,WANG Da-wei2,*
2010, 31(21):  65-67.  doi:10.7506/spkx1002-6630-201021014
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The inhibitory effects of ethanol extracts from six commonly used spices on five species of microorganisms were measured and compared in order to screen spices with higher antimicrobial activity, and the optimal mixing ratio for screened spices resulting in the best synergistic antimicrobial effect was determined. Clove and licorice were the selected spices based on the results from the comparison of antimicrobial activity, and the best mixing ratio for the ethanol extracts from them was 5:3(V/V), which gave a synergistic antimicrobial effect better than single uses of them. The mixture presented minimum inhibitory concentrations (MIC) of 3.125 mg/mL for bacteria and 6.25 mg/mL for mold and could show better antimicrobial effect at a low concentration.

Using TLC-bioautography to Screen Active Compounds in Rape Bee Pollen
SUN Li-ping1,2,DU Xia1,XU Xiang1,2,DONG Jie1,2,AN Zhong-yao1,YANG Jia-lin1
2010, 31(21):  69-71.  doi:10.7506/spkx1002-6630-201021015
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TLC-bioautography was used to screen the DPPH radical scavengers and the antibacterial ingredients in rape bee pollen. The experimental results indicated the flavonoids as DPPH radical scavengers mainly existed in form of glycosides in rape bee pollen, and the acidicly hydrolyzed ethanol extract from rape bee pollen contained a variety of antioxidant compounds including quercetin and kaempferol. There were two small molecules with Rf values of 0.29 and 0.86 found to have antibacterial activity in the water extract from rape bee pollen. According to the results of color development reaction, the types of antibacterial components were polyphenols, tannin, flavonoids or saponins, etc.

Chemical Composition and Functional Properties of Rapeseed Protein Hydrolysates Left after Aqueous Enzymatic Extraction of Oil
WANG Ying-yao,WEI Cui-ping,LUAN Xia,ZHANG Shuang-yu,DU Chuan-lin
2010, 31(21):  72-75.  doi:10.7506/spkx1002-6630-201021016
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The chemical composition, physico-chemical properties and in vitro functional properties of the rapeseed protein hydrolysates (RPHs) left after aqueous enzymatic extraction of oil were studied. The hydrolysates mostly consisted of protein, carbohydrate and ash, and the contents were 54.95%, 28.83% and 14.82%, respectively. The hydrophobic amino acid content was 37.21 g/100 g protein. The hydrolysates had an excellent solubility and lower viscosity at high concentration. Their reducing power and abilities to scavenge DPPH and hydroxyl free radicals were all obvious, indicating good antioxidant effect in vitro.

Optimization of Conditions for Controlled Oxidation of Lard and Analysis of Volatile Oxidation Products
XU Yong-xia,ZHANG Ruo-jie,XU Jing-yi,CHEN Qing-chan,WANG Ke-xing,PAN Si-yi*
2010, 31(21):  76-80.  doi:10.7506/spkx1002-6630-201021017
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The process conditions for the controlled oxidation of lard before the production of pork flavor via thermal reaction were optimized using orthogonal array design based on single factor and experiments. Peroxide value (POV), thiobarbituric acid (TBA) and acid value (AV) were used to evaluate oxidation status. The optimal controlled oxidation conditions of lard were found to be: reaction temperature, 120 ℃; reaction duration, 2 h; and oxygen flow rate, 0.025 m3/h. The volatile oxidation products obtained under these optimal conditions were analyzed by headspace solid phase micro-extraction (HS-SPME) combined with GC-MS. A total of 32 compounds were identified in oxidized lard. Aldehydes were the most abundant volatile components, which accounted for 52.52% of the total volatile oxidation compounds.

Sequential Extraction of Protein Fractions from Chinese Soft-shelled Turtle (Pelodiscus sinensis) and Their Antioxidant Activities
LIU Yan1,LIU Cheng-chu1,*,YANG Jing-ya1,LIU Qi-gen2,LI Ying-sen2,LI Jia-le2,3
2010, 31(21):  81-84.  doi:10.7506/spkx1002-6630-201021018
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Protein fractions were separated and purifies from wild Chinese soft-shelled turtles using sequential extraction procedures and their antioxidant activities were investigated by DPPH free radical scavenging and reducing power assays. It was found that the glycoprotein and water-soluble protein fractions had higher antioxidant effect in a positive concentrationdependent fashion, with half maximal inhibitory concentrations (IC50) of 0.21 mg/mL and 1.94 mg/mL, respectively. These results suggest that the protein fractions from Chinese soft-shelled turtle possess strong antioxidant activities and have a great potential to be developed as a healthcare food or a nutriceutical.

Optimization of Enzymatic Preparation of Antioxidant Black Sesame Protein Hydrolysate
CHEN Xiao-gang,LIU Ai-wen,CHEN Xin,LAN Jian-jun
2010, 31(21):  85-88.  doi:10.7506/spkx1002-6630-201021019
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Black sesame protein was prepared by alkaline extraction and acid precipitation, and then subjected to single enzymatic hydrolysis with neutral proteinase, papain and alkaline protease. Neutral protease was screened out of the three proteases for preparing black sesame protein with higher free radical scavenging activity. Additionaly, the optimization of respective conditions for neutral protease hydrolysis for achieving maximum scavenging rates for hydroxyl, superoxide anion and peroxyl free radicals was carried out using orthogonal array design, and the results showed that the maximum scavenging rates for the above three species of radicals were up to 94.84%, 74.78% and 43.63%, respectively, under optimized hydrolysis conditions.

Effect of Rinsing Mode on Modori of Silver Carp Surimi
LIU Ru1,2,QIAN Man1,2,LEI Yue-lei1,2,XIONG Shan-bai1,2,*
2010, 31(21):  89-93.  doi:10.7506/spkx1002-6630-201021020
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The effect of four rinsing modes (with saline, acid, alkaline or plain waters) on the modori and endogenous protease activity of silver carp surimi was investigated in this work. Modori depended on rinsing solution type. Rinsing with salt water could remove effectively endogenous protease and inhibit modori. Acidic water was not an ideal rinsing solution for the removal of endogenous protease. Rinsing with acidic water resulted in the poorest gel properties due to acidic denaturation of some proteins among these four rinsing modes and therefore, was unsuitable for processing silver carp surimi. In conclusion, modori is closely related to endogenous protease and protein denaturation before heating would augment modori.

Antioxidant Properties of Ferulic Acid Sugar Esters in vitro
ZHAO Bing1,ZHANG Ke2,WANG Jing1,*,SUN Bao-guo1,CAO Yan-ping1
2010, 31(21 ):  94-97.  doi:10.7506/spkx1002-6630-201021021
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The ferulic acid sugar esters prepared from wheat bran hydrolyzed by endo-xylanase were characterized for their antioxidant properties in vitro reflected by the abilities to scavenge hydrogen peroxide as well as hydroxyl and DPPH free radicals and to chelate metals using two synthetic antioxidants, BHT and VC, as the controls. The sugar esters were found to have strong antioxidant properties, which were better than those of free ferulic acid.

Antimicrobial Activity and Stability of Ethanol Extract from Propolis
MENG Liang-yu,LAN Tao-fang,LU Jia-kun,ZHANG Yi-fan,CHU Ying-ying
2010, 31(21):  98-100.  doi:10.7506/spkx1002-6630-201021022
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The ethanol extract from propolis obtained by hot reflux extraction was assayed for its antimicrobial activity, and its stability was also studied with Bacillus cereus as the indicator strain. The results showed that the extract had very strong antimicrobial activity and was very stable to temperature, pH value, ultraviolet and metal ions. After thermal treatment at 121℃ or alkaline treatment at pH 10, the antimicrobial activity of the extract showed a notable descent.

Change in Isoflavone Composition in Sufu during Post-fermentation Process
ZHOU Ying,PAN Si-yi*
2010, 31(21):  101-104.  doi:10.7506/spkx1002-6630-201021023
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In this study, the changes in type and amount of isoflavone in sufu (fermented bean curd) during post-fermentation process were measured. The results indicated that the total content of isoflavones in sufu exhibited a gradual decrease during post-fermentation process. A rapid degradation of isoflavone glucosides such as daidzin and genistin was observed under low salt conditions, which were completely transformed into isoflavone aglycones including daidzein and genistein during post-fermentation process. Therefore, post-fermentation might be beneficial to enhance the physiological function of sufu.

Antioxidant and Free Radical-scavenging Activities Bean Peptides (KBP)
REN Hai-wei1,ZHU Dong-mei2,WANG Yu-li1,YUAN Ya-lan1,GAO Yu-jing1,SU Xue-yan1
2010, 31(21):  105-109.  doi:10.7506/spkx1002-6630-201021024
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Kidney bean peptides (KBP) were fractionated by gel filtration on SephadexG-50.The antioxidant and free radicalscavenging activities of three KBP fractions (Fra-A, Fra-B, Fra-C) were investigated using reducing power and 1,1-diphenyl- 2-pycrylhydrazyl (DPPH)/superoxide/hydroxyl radical-scavenging assay. The reducing power activity of Fra-C (RP50 2.263 mg/mL) was lower than that of ascorbic acid (RP50 0.828 mg/mL). Fra-C showed the strongest scavenging activity against DPPH, superoxideanion and hydroxyl radicals. The radical-scavenging effect was in a dose-dependent manner and the EC50 values for DPPH, superoxide and hydroxyl radicals were found to be 2.301, 2.553 mg/mL and 1.386 mg/mL, respectively. The amino acid analysis showed that Fra-C had a hydrophobic amino acid content of 36.78% and a hydrophobicity of 364.73 kcal/mol.The molecular weight distribution of Fra-C was found to mainly vary from 100 to 1000. The antioxidant activity of Fra-C is clearly related to the amino acid composition, the content of THAA and the molecular mass.

Effect of Gels on the Stability of Peanut Milk Using Turbiscan Technology
HANG Zhi-qi,XU Jing-song,HAN Qing-bo,TONG Li-feng
2010, 31(21):  110-113.  doi:10.7506/spkx1002-6630-201021025
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The effect of gels on the stability of formulated peanut milk was studied. The distribution of particle size of UHT pure milk and peanut milk was determined by light scattering techniques with a Malvern Mastersizer Hydro2000 Mu and the stabilities of the samples suspended by gellan gum and microcrystalline cellulose respectively were measured by Turbiscan Lab. The results indicated that the particle size distribution of milled peanut mainly ranged from 20 to 500μm, higher than that of pure milk ranged from 0.03 to10 μm. The SI value of control peanut milk without gel was 0.88, while those of peanut milkssuspended by MCC or HM-B gellan were 0.45 and 0.17, respectively. There was no significant difference among the creaming velocities of all samples, however the sediment amount of peanut milks were significantly reduced by MCC and gellan. Moreover, participating was lower in peanut milk stabilized by gellan than by MCC. Therefore, the suspending capability of gellan gum is greater than MCC, indicating that gellan gum is more suitable for stabilizing formulated peanut milk.

Dynamic Changes of Physico-chemical Properties and Chemical Composition of Donkey Colostrums during Different Lactation Periods
LU Yue-wen,YANG Jie*,JIANG Xin-yue
2010, 31(21):  114-118.  doi:10.7506/spkx1002-6630-201021026
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In this work, we investigated the physico-chemical properties and chemical composition of donkey colostrums during different lactation periods. The results indicated that the relative density, refractive index, conductivity and acidity of donkey colostrums were all higher than those of common milk; whereas, pH was lower than that of common milk. The contents of protein, ash and fat in donkey colostrums exhibited a decrease trend with the extension of lactation period. The content of lactose was the lowest at 6 h post partum and then the lactose content exhibited a gradual increase with increasing lactation period. In addition, the content of IgG in donkey colostrums was determined by a high-performance affinity chromatography (HPAC) to reveal a decrease trend due to the prolonged lactation period.

Analysis of Bioactive DPPH Free Radical Scavenging Components in Date Honey
MU Xue-feng1,2,SUN Li-ping1,*,XU Xiang1,PANG Jie2
2010, 31(21):  119-122.  doi:10.7506/spkx1002-6630-201021027
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The bioactive components in date honey having the ability to scavenge DPPH free radicals were quanlitatively and quantitatively analyzed by HPLC-DPPH. In total, 12 DPPH free radical scavenging components were found in date honey, and 4 of them were identified as caffeic acid, p-coumaric acid, naringenin and kaempferol. The contents of these components were in the range of 48.8 to 741.3 μg/100 g honey. The scavenging capacities of these bioactive components exhibited an obvious difference, which was highly correlated with the molecular structures of bioactive components.

Antioxidant Activity and Molecular Weight Distribution of in vitro Gastrointestinal Digestive Hydrolysate from Flying Squid (Ommastrephes batramii) Skin-gelatin
CHEN Xiao-e,XIE Ning-ning,FANG Xu-bo,YU Hui,JIANG Ya-mei,LI Zhen-da
2010, 31(21):  123-130.  doi:10.7506/spkx1002-6630-201021028
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In order to evaluate the antioxidant activity and molecular weight distribution of in vitro digestion product of flying squid (Ommastrephes batramii) skin-gelatin, the preparation of flying squid skin-gelatin hydrolysate derived from in vitro gastrointestinal (GI) digestion (SHGD) was performed using a simulated model and SHGD was analyzed for its amino acid composition, antioxidant effects (reducing power, inhibitory effect on lipid autooxidation and free radical scavenging capacity) and molecular weight distribution. SHGD was rich in antioxidant amino acids including tyrosine, histidine, proline, alanine and leucine, and their total content was 32.78%. The content of total hydrophobic amino acids (THAA) (37.48%) was comparatively higher than that of skin-gelatin. With increasing concentration from 20 mg/mL to 25 mg/mL, the reducing power of SHGD presented no obvious change, and was similar to that of butylated hydroxyanisole (BHA). At concentrations of 16 mg/mL and 12 mg/mL, SHGD showed better ability to scavenge DPPH free radicals than BHA and α-tocopherol, respectively. The scavenging rates of SHGD at 25 mg/mL against hydroxyl and superoxide anion free radicals were (81.93±2.02)% and (72.26± 2.12)%, respectively. Meanwhile, SHGD was a stronger inhibitor against lipid peroxidation when compared to BHA. At the same concentration conditions, flying squid skin-gelatin was remarkably inferior to SHGD in antioxidant effect. Furthermore, based on our experimental results, it is deduced that the fractions of SHGD having a molecular weight varying from 383 to 1492 u might be responsible for its antioxidant activity.

Inhibitory Effect of Extract from Salicornia herbacea on Tyrosinase Activity
YU Xiao-hong,SHEN Yu-xiang,CHEN Hong-xing,SHAO Rong*,XU Wei
2010, 31(21):  131-133.  doi:10.7506/spkx1002-6630-201021029
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In this paper, the inhibitory effect of extract from Salicornia herbacea on tyrosinase activity was investigated. Four extracts including water extract, ethanol extract, ultrasound-assisted water extract and ultrasound-assisted ethanol extract were used as the materials to explore the inhibitory effect on tyrosinase activity. The results indicated that the extraction rate did not exhibit an obvious difference after distillation evaporation and rotary evaporation. However, the inhibition effect on tyrosinase had a significant difference among four extracts using tyrosine as the substrate. The inhibition rates on tyrosinase were 32.48% for water extract, 62.37% for ethanol extract, 43.56% for ultrasound-assisted water extract and 75.81% for ultrasound-assisted ethanol extract, respectively. Moreover, the ultrasound-assisted ethanol extract was the strongest enzyme inhibitor among them.

Antibacterial Activity of Passion Fruit Juice
YANG Feng1,HE Ren1,2,REN Xian-e1,LIANG Yi1,HUANG Yong-chun1
2010, 31(21):  134-136.  doi:10.7506/spkx1002-6630-201021030
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A preliminary antibacterial evaluation of passion fruit juice was performed in this paper. Passion fruit juice had strong inhibitory effect on Escherichia coli, Staphylococcus aureus, Candida tropicalis and Aspergillus niger. The ethanol-acetone (1:1, V/V) extract from the juice also had inhibitory effect on E. coli, S. aureus, C. tropicalis and A. niger with minimum inhibitory concentrations (MICs) of 125, 250, 500 mg/mL and 500 mg/mL, respectively. The cyclohexane extract from the juice had inhibitory effect on E. coli, S. aureus with a MIC of 250 mg/mL but no inhibitory effect on C. tropicalis and A. niger.

Effect of Enzymatic Modification on Solubility of High-temperature Denatured Soybean Meal
REN Wei-cong1,CHENG Jian-jun1,*,ZHANG Zhi-yu1,ZHAO Wei-hua1,JIANG Lian-zhou1,2
2010, 31(21):  137-141.  doi:10.7506/spkx1002-6630-201021031
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The effect of alkaline portease modification on the nitrogen solubility index (NSI) of high-temperature denatured soybean meal was investigated. The optimal conditions for the enzymatic hydrolysis of high-temperature denatured soybean meal were explored by single factor method and response surface analysis. The optimal enzymatic hydrolysis conditions were found to be: substrate concentration, 8.56 g/100mL; enzyme loading, 13004.69 U/g pro; hydrolysis pH 9.0, hydrolysis temperature, 59.10 ℃; and hydrolysis time, 20.47 min. The degree of hydrolysis (DH) was 15.86% under the optimal hydrolysis conditions, and the NSI was 92.58%, much higher than that before the hydrolysis of 21.24%.

Effects of Maturity Degree and Drying Methods on Anthocyanin and Toxins Contents in Purple Corn
XIAO Li-xia1,WANG Fen1,YU Hong-tao1,ZHAO Xiao-yan2,*,HU Xiao-song3
2010, 31(21):  142-146.  doi:10.7506/spkx1002-6630-201021032
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In order to explore the optimal harvesting season and drying method, the content changes of fumonisin B1 and aflatoxin B1, B2, G1 and G2 in husk, cob and grain of purple corn during mature period and different drying methods were determined by high performance liquid chromatography. Results indicated that the best time for harvesting purple corn was its plantation after 10 weeks; the husk of purple corn exhibited the highest content of anthocyanin and was easy to be dried at this harvesting time point. Microwave drying had strong detoxification capability, however, it also resulted in the loss of anthocyanin. Thus, microwave drying was not suitable for industrialized production. Airflow drying was suitable for kernels. The loss of anthocyanin in husk and cob of purple corn was less during sunlight drying. In addition, sunlight drying method could degrade 50% toxins. Therefore, sunlight drying is an economic drying method and suitable for industrialized production.

Effects of Deformation Rate and Degree of Compression on Texture Profile Analysis of Hard-boiled Egg
YU Xiu-fang1,MA Mei-hu1,*,YANG Fang1,LIU Li-li1,2,DU Xin-wu3
2010, 31(21):  147-151.  doi:10.7506/spkx1002-6630-201021033
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Three deformation rates (0.5, 1.0 mm/s and 2.0 mm/s) and seven degree of compression (10%, 20% through 70%) were selected for the texture profile analysis (TPA) of hard-boiled egg in order to explore the effects of the two parameters on the measurement of texture characteristics of hard-boiled egg. It was found that degree of compression was a more significant affecting parameter than deformation rate. Fitting of linear, quadratic polynomial and logarithmic models predicting texture characteristics in one experimental condition range was conducted, the results showed that the quadratic polynomial model best fitted the hardness, cohesiveness and resilience of egg white and yolk, and had statistical significance. In conclusion, it is suggested that the optimal parameters for the TPA analysis of cooked egg products were as follows: degree of compression, 60% for egg white and 30% for egg yolk; and deformation rate, 1.0 mm/s.

Physico-chemical Properties of Extract from Alisma orientalis by Supercritical Carbon Dioxide Extraction
YI Xing1,2, JIAO Shuang2,XIAO Xiao-nian1,ZHONG Qiu-chen2,YIN Hong-mei2
2010, 31(21):  152-154.  doi:10.7506/spkx1002-6630-201021034
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Some physico-chemical properties such as acid value, saponification value, peroxide value and emulsification property of the extract from Alisma orientalis by supercritical carbon dioxide (SC-CO2) extraction were determined. The effects of storage time and temperature as well as illumination time on oxidative stability of the extract were also investigated. The optimal emulsification conditions of the extract were grinding time of 3 min, emulsification temperature of 25 ℃, and hydrophilic and lipophilic balance (HLB) value of emulsifier ranged from 15.2 to 15.6. During the storage at room temperature, SC-CO2 extract could result in rancidification. Meanwhile, the oxidation of the extract could be accelerated by temperature and illumination. Moreover, the saponification value exhibited an increase trend with the increase of storage time, temperature and illumination time. The illumination intensity had the strongest effect on saponification value.

Correlation between Antioxidant Activity and Carotenoid Content in Bee Pollen Oil
XU Xiang1,2,HE Wei3,SUN Li-ping1,2,*,DONG Jie1,2,LI Tian-jiao1
2010, 31(21):  155-158.  doi:10.7506/spkx1002-6630-201021035
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The contents of carotenoids and antioxidant activity of the oils extracted from eight kinds of common bee pollen were determined to analyze the correlation between the two parameters. Results indicated that all the eight bee pollen oils had scavenging effect on DPPH free radicals, but displayed a significant difference (P<0.05) and their IC50 values for scavenging DPPH free radicals ranged from 0.212 to 7.110 mg/mL. Carotenoids was abundantly contained in bee pollen oil and the content of carotenoids was linearly correlated (R2 = 0.8645) with antioxidant activity. These results indicate that carotenoids might be one kind of the predominant antioxidants in bee pollen oil.

Solubility and Physico-chemical Properties of Lac Resin and Its Sodium Salt
LI Kai1,2,ZHOU Mei-cun1,ZHANG Hong1,*,ZHENG Hua1
2010, 31(21):  159-164.  doi:10.7506/spkx1002-6630-201021036
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The dissolution of lac resin in sodium carbonate, a necessary processing before the production, modification and application of lac resin, was done. The change of solubility, pH and total dissolved solids (TDS) of lac resin in sodium carbonate with different concentrations and temperatures were determined to establish a solubility curve of lac resin for exploring its dissolving principle and dynamic model. Meanwhile, the physiochemical properties of lac resin and its sodium salt were determined and compared to test the possibility of being used as a single material. Results indicated that the dissolving process of lac resin in sodium carbonate was an acid-base reaction in a zero grade mode. Sodium salt of lac resin based film with exhibited better thermostability, hardness, wettability, and excellent solubility in mimic gastric liquid (pH 1.0) or mimic intestinal liquid (pH 6.8) when compared to lac resin based film.

Effect of Sudan Red III on Fluorescence Quenching of Myoglobin and Molecular Modeling of Their Interaction
ZHU Shao-ping1,CAI Bing-feng2,MAO Hui2,ZHAO Bo2,*
2010, 31(21):  165-168.  doi:10.7506/spkx1002-6630-201021037
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The molecular interaction mechanism between Sudan red III and myoglobin (Mb) was investigated by fluorescence spectrum combined with molecular modeling under the mimic physiological conditions. Results showed that the fluorescence of Mb was quenched by Sudan red III due to the complex formation between them. This kind of fluorescence quenching was a static quenching. Molecular modeling revealed that Sudan red III could bind to the Site 1 of Mb. Hydrophobic interaction and hydrogen bond formation contribute to the binding of Sudan red III. The hydrophobic interaction and hydrophilic interaction between Sudan red III and Trp, Tyr, Phe residues in Mb resulted in static fluorescence quenching of Mb and disordered displacement of maximum emission peak. These interactions were focused on the residues of Phe33, Phe43 and Phe138 in Mb.

Antioxidant Activity, Moisture-absorbing and Moisture-retention Properties of Collagen Peptides from Different Sources
JIA Jian-ping,LU Jian-zhang,ZHOU Yan-gang,CHENG Min,YE Xiao-di,ZHENG Gao-li*
2010, 31(21):  169-172.  doi:10.7506/spkx1002-6630-201021038
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Objective: To explore the antioxidant activity, moisture-absorbing and moisture-retention properties of collagen peptides from different sources. Methods: The antioxidant activities of collagen peptides from different sources were evaluated by determining their scavenging activities on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis-2-ethybenz-thiazoline-6-sulfonic acid (ABTS+) free radicals and their reducing power. Results: The collagen peptide from donkey revealed the strongest scavenging activity on DPPH free radicals with IC50 of 0.63 mg/mL. The collagen peptide from Alaska pollack skin exhibited stronger scavenging activity on ABTS+ free radicals with an IC50 of 0.12 mg/mL. Meanwhile, the collagen peptide from donkey also exhibited the strongest reducing power, which was 0.61 at the concentration of 10 mg/mL. The moisture-absorbing and moisture-retention rates of collagen peptide from donkey were 10.17% and 98.90% under the relative humidity of 43%. Conclusion: The collagen peptide from donkey can be used as a good additive in functional food and cosmetics.

Antioxidant Effects of Extract from Different Parts of Five Natural Plants: A Comparative Study
XIE Juan-ping,JIANG Xiong-bo
2010, 31(21):  173-175.  doi:10.7506/spkx1002-6630-201021039
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Objective: The antioxidant activities of extracts from different parts of Viola japonica Langsd., Phytolacca acinosa Roxb, Plantagoasiatica L., Premna microphylla Turcz. and Epimedium sagittatum were determined to screen natural antioxidant resources and effective parts. Methods: Different parts of these plants were extracted with methanol under the assistance of ultrasound wave treatment. The antioxidant activities of these plants were assayed by evaluating the scavenging effects on DPPH free radicals. Results: All the extracts from these plants had significant antioxidant activity. The strongest DPPH free radical scavenger was the extract from leaves of Premna microphylla Turcz., followed by extracts from leaves of Viola japonica Langsd., leaves of Plantagoasiatica L., roots of Plantagoasiatica L., leaves of Epimedium sagittatum, leaves of Phytolacca acinosa Roxb, roots of Phytolacca acinosa Roxb, and roots of Viola japonica Langsd.. Conclusion: There is a close relationship between antioxidant activity and the type and part of these plants and the extracts from different parts of these plants shows an antioxidant effect positively dependent on dose.

Physico-chemical and Microbiological Properties of Steamed and Steam-baked Bread during Storage
LENG Jin-song1,DAI Yuan2,LIU Chang-hong3
2010, 31(21):  176-181.  doi:10.7506/spkx1002-6630-201021040
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Physico-chemical (hardness, water activity, fragmentation ratio and swelling degree, crystallinity, TPA structural properties) and microbiological properties of steamed and steam-baked bread stored at 25 ℃ during storage were compared to explore the effect of processing method on the quality of products and the retrogradation mechanism. Steam-baked bread had more excellent function in delaying retrogradation, attenuating aging, preventing from microbial invasion and extending storage period.

Isolation, Purification and Monosaccharide Composition Analysis of Polysaccharide from Diaphragma of Juglans regia L.
GAO Li1,WANG Qiang2,PATIGUL Mahmut1
2010, 31(21):  182-185.  doi:10.7506/spkx1002-6630-201021041
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The purpose of this work was to isolate and purify polysaccharide from diaphragma of Juglans regia L (PDJL) and analyze its monosaccharide composition. A water-soluble crude polysaccharide was obtained by water extraction, ethanol precipitation and freeze-drying. The crude polysaccharide was purified to obtain a fraction of PDJL-A11 on DEAE-cellulose52 column and SephadexG-100 column. The purity of PDJL-A11 was analyzed by UV spectrophotometer. The monosaccharide composition and molecular ratio of PDJL-A11 were analyzed by gas chromatography. The monosaccharide composition of PDJLA11 was composed of arabinose, fructose, mannose, rhamnose and glucose with a molar ratio of 2.11: 6.52: 8.81: 12.59: 15.58.

Comparative Physico-chemical Properties of Starches from Three Kinds of Legumes
YANG Hong-dan,DU Shuang-kui*,ZHOU Li-qing,ZHAO Jia
2010, 31(21):  186-190.  doi:10.7506/spkx1002-6630-201021042
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Starches were extracted from blackeye pea (Vigna unguiculata (L.) Walp), black bean (Phaseolus vulgaris L.) and lentil (Lens culinaris M.) by wet-grinding method, and were comparatively characterized for their physico-chemical properties with sweet potato and corn starches as the controls. Most of legume starch granules were kidney-shaped, while others were spherical. Obvious birefringence was also observed. The contents of apparent amylose in blackeye pea, black bean and lentil starches were 34.98%, 45.35% and 37.24%, respectively. The swelling capability and solubility of legume starch displayed an increase at a higher temperature. The three legume starches displayed a pasting temperature ranging from 72.9 to 77.0 ℃. Black bean starch exhibited the highest pasting temperature as well as the lowest peak viscosity, breakdown value, final viscosity and retrogradation value. The pasting property of blackeye pea starch was opposite to that of black bean starch. The To , Tp and Tc of the three legume starches revealed a significant difference. However, no significant difference was observed in their enthalpy. The order of starch enthalpy from strong to weak was lentil starch, blackeye pea starch and black bean starch.

Types and Digestion-resistant Properties of Carbohydrate in Chestnut
QIN Hai-bing1,2,MO Kai-ju1,2,*,WANG Xing-ping1,2
2010, 31(21):  191-194.  doi:10.7506/spkx1002-6630-201021043
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HPLC-RI and routine chemical methods were used to investigate the relationship between the types of carbohydrate and the digestion-resistant properties in chestnut in this paper. Results showed that chestnut was composed of 35.77% starch and 30.16% amylase. Fresh chestnut had 27.44% resistant starch, accounting for 68.93% of total starch; however, ripe chestnut had 5.46% resistant starch, accounting for 13.36% of total starch. The content of resistant starch in ripe chestnut exhibited an increase trend. The content of resistant starch was increased from 14.66% to 20.15% within 48 h. The soluble sugar in chestnut mainly included sucrose, rhamnose, glucose, fructose, maltose and raffinose, while raffinose could not be digested and absorbed in human body. Therefore, the resistant starch and raffinose with high content is the major reason why fresh chestnut is difficult to digest and ripe chestnut is easy to induce flatulence.

Bioengineering
Optimization of Fermentation Conditions for Producing Conjugated Linoleic Acid in Lactobacillus plantarum lp15-2-1 by Response Surface Analysis
ZHOU Qian,LIU Pei,MA Liu-liu,RUAN Hui,HE Guo-qing*
2010, 31(21):  195-199.  doi:10.7506/spkx1002-6630-201021044
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In this work, the fermentation conditions for converting linoleic acid into conjugated linoleic acid (CLA) by Lactobacillus plantarum lp15-2-1 were studied. Single factor experiments were done to understand the effects of inoculum amount, incubation temperature, pH, incubation time and initial level of linoleic acid on CLA production. Using response surface Box-Benhnken design, a quadratic polynomial regression model was established. The results indicated that the optimal levels of incubation temperature, initial level of linoleic acid and pH were30 ℃, 0.21 mg/mL and 6.3, respectively. Under these optimal fermentation conditions, the yield and conversion rate of CLA were 44.77μg/mL and 21.32 %, which were higher than the predicted values of 45.326μg/mL and 7.78 %, respectively.

Expression of Enhanced Green Fluorescent Protein in DH5α E. coli
WANG Xiao-hui
2010, 31(21):  200-203.  doi:10.7506/spkx1002-6630-201021045
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To construct a recombinant plasmid (pGT-EGFP), the fragment of EGFP (enhanced green fluorescent protein) gene was amplified by PCR from the cloning vector pEGFPpA-CAN, and then inserted into the pGEM-T easy vector. The expression of EGFP was regulated by the SP6 promoter in pGEM-T easy. Compared with the culture of DH5α E. coli, the culture of DH5α E. coli with pGT-EGFP was a little greener in color. Through fluorescence microscope, the morphological features of DH5α E. coli with green fluorescence could be clearly observed. Moreover, the extraction of total protein from the lysate of DH5α E. coli with pGT-EGFP derived from ultrasonic treatment was done. The SDS-PAGE analysis showed that EGFP was a soluble protein, with a molecular weight of approximately 30 kD, which was identical to the theoretical size.

Effects of Storage Temperature and Milk-based Media on Survival of Enteropathogenic Escherichia coli EPEC O114:K90
JIANG Bo,MENG Xiang-chen*,ZHANG Hong-yu
2010, 31(21):  204-207.  doi:10.7506/spkx1002-6630-201021046
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In this study, the survival situation of enteropathogenic Escherichia coli EPEC O114:K90 in different milk-based products stored at different temperatures was explored. Sterile milk, yoghurt and sour milk bacteria beverage were artificially contaminated by different initial concentrations of EPEC O114:K90 and subsequently stored at different temperatures. The survival rate of EPEC O114:K90 was periodically measured by plate count method during storage. Both low temperature and low acid environment could alleviate the growth of EPEC O114:K90. Water bath treatment at 72 ℃ for 15 min completely inactivated EPEC O114:K90 in the above three milk-based products. This strain was sensitive to regular processing conditions.

Screening and Identification of a Bacillus amyloliquefaciens Strain Producing Antimicrobial Substances
YANG Sheng-yuan1,WEI Jin2,LI Yun1,YAO Hong1,HUANG Yue-dan1
2010, 31(21):  208-212.  doi:10.7506/spkx1002-6630-201021047
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A strain producing broad-spectrum antimicrobial substances, named K6, was isolated and screened from the soil of a local vegetable garden in Xiangqiao district, Chaozhou city, which presented an inhibition effect on the growth of Mirococcus luteus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Bacillus cereus, Bacillus megaterium, Bacillus thuringiensis, Saccharomyces cerevisiae, Rhizopus stolonifer and Candida albicans. The strongest inhibition effect on gram-positive bacteria was observed. Base on the morphological, 16S rDNA sequence and phylogenic analysis, the strain K6 was classified as Bacillus amyloliquefaciens.

Mathematical Modeling for the Growth of Specific Spoilage Organisms in MAP Chilled Beef
HU Jie-yun1,OU Jie1,*,LI Bai-lin1,YAN Wei-ling2,LIN Lu2
2010, 31(21):  213-217.  doi:10.7506/spkx1002-6630-201021048
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In this study, the growth models of Pseudomonas, one of the specific spoilage organisms, in chilled beef during storage at different temperatures in modified atmosphere packaging (MAP) environment were developed by Matlab7.0 to obtain Gompertz model parameters. A secondary model describing the growth of this specific spoilage organism and a kinetic growth model with temperature as the independent variable following the response surface and the square root equations, respectively, were constructed so as to validate the kinetic growth model at low temperatures ranging from 0 to 10 ℃. All the constructed Gompertz model displayed a correlation coefficient exceeding 0.99. The bias factor and accuracy of the secondary model were both between 0.90 and 1.05. These data demonstrate that the constructed primary and secondary models can both effectively predict the growth situation of Pseudomonas in chilled beef during storage in MAP environment at a temperature varying from 0 to 10 ℃.

Screening and Identification of a Pseudomonas lutea Strain Capable of Degrading Caffeine
LI Na1,JI Bao-ping1,*,LI Bo1,WU Wei2
2010, 31(21):  218-221.  doi:10.7506/spkx1002-6630-201021049
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Objective: The aim of this work was to find strains capable of degrading caffeine so as to develop a biological approach for caffeine detoxicification. Method: The preliminary screening of target strains was performed using caffeine as both carbon and nitrogen sources, and then the ten screened strains were further screened by evaluating their abilities to degrade caffeine in liquid medium after culture. As a result, a strain with the strongest ability to degrade caffeine was obtained and named HZ-1. After 48 h culture of HZ-1, caffeine in liquid medium was completely degraded. Based on the morphological, physiological and biochemical properties and 16 rDNA gene sequence, this strain was identified as Pseudomonas lutea. To the best of our knowledge, this is the first report on the biological degradation of caffeine at home.

Optimization of Amounts of Added Natural Growth-promoting Factors for Fermentation of Cattle Bone Meal by Probiotics for Calcium Conversion
WU Min1,LUO Ai-ping2,*,YIN Yan-yang2,LIU Zhi-ze2
2010, 31(21):  222-225.  doi:10.7506/spkx1002-6630-201021050
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Natural growth-promoting factors were added to probiotic fermentation of fresh cattle bone meal for exploring the synergistic effect on the conversion rate of calcium. Single factor experiments were used to select probiotics. Meanwhile, orthogonal experiments were used to explore the optimal combination of growth factors on the basis of conversion rate of free calcium. Results indicated that corn juice, tomato juice, bean sprout juice, cabbage juice, carrot juice and milk have obvious growth-promoting effect on probiotics. Except for corn juice, the lower pH at the end of fermentation could result in the greater number of viable cells and the higher conversion rate of calcium. In addition, the optimal addition amount of cabbage juice, tomato juice, bean sprout juice and milk was 15%, whereas 20% for carrot juice and 5% for corn juice. Potato juice exhibited an inhibitory effect on the fermentation of Lactobacillus rhamnosus, Lactobacillus acidophilus, and their combinatorial fermentation. Orthogonal experimental results showed that the optimal combinatorial formula of four growth-promoting factors were 18.0% cabbage juices, 15.0% bean sprout juice, 12.0% tomato juice and 20.0% carrot juice. The conversion rate of calcium was up to 38.8% at the condition of this optimal combinatorial formula.

Optimization of Liquid-state Fermentation Conditions for Preparing Rapeseed Angiotensin I-converting Enzyme Inhibitory Peptides
WANG Li-feng1,2,JIN Jing1,YUAN Jian1,HE Rong1,2,JU Xing-rong1
2010, 31(21):  226-231.  doi:10.7506/spkx1002-6630-201021051
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Rapeseed meal was used to prepare angiotensin I-converting enzyme (ACE) inhibitory peptide through liquidstate fermentation by Bacillus subtilis. The optimal fermentation conditions were explored by single factor and response surface experiments through evaluating the yield of peptide and ACE inhibitory rate. The optimal fermentation conditions were 0.45 g/100mL potassium dihydrogen phosphate, 0.8 g/100mL glucose, material/liquid ratio of 1: 23 and initial pH 7.0. The ACE inhibitory rate reached up to 69.79% under these optimal fermentation conditions.

Screening and Identification of L-lysine-producing Probiotics
LUO Chao-chao,GAO Xue-jun*,WANG Qing-zhu,YU Wei,LIU Xiao-fei,LU Zhi-yong,QIAO Bin
2010, 31(21):  232-235.  doi:10.7506/spkx1002-6630-201021052
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The present study aimed to expand the utilization of L-lysine-producing strains in food and animal feeds and raise the security of L-lysine production by microbial fermentation. In total, 66 strains having the ability to produce L-lysine were isolated from commercially available doughs for the making of bread, fried dough twists, steamed bread, steamed cake and Russian style bread and kojis for the making of rice wine and distilled liquor. These strains were cultured, and the quantitation of L-lysine content in medium at the end of culture was carried out using HPLC. Two of the 66 isolated strains were found to produce higher amount of L-lysine and the contents of L-lysine in the resultant fermentation broths were 52.33 g/L and 46.09 g/L respectively. Using 16S rDNA sequence and Blast analyses and specific primer PCR technique, they were identified as Leuconostoc mesenteroides ATCC 8293 and Lactobacillus delbrueckii subsp. bulgaricus ATCC BAA-365.

Sequence Analysis of Shiga Toxin Gene from Non-O157 Escherichia coli Strain Isolated from Foods
LI Rui1,DAI Shi-jiao1,DAI Kai1,DU De-long1,ZHU Ting-heng2,*
2010, 31(21):  236-238.  doi:10.7506/spkx1002-6630-201021053
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A non-O157 E. coli strain (named EC6) which produces Shiga toxin type 1 was isolated from beef and the sequence of its Shiga toxin gene was analyzed. The full length of stx1 gene from strain EC6 was amplified by PCR, cloned into the pGEM-T Easy vector and sequenced. The results showed that the stx1 gene of EC6 had up to 99% similarity with the stx1 sequences deposited in GenBank database, indicating the occurrence of mutation. Furthermore, a phylogenetic tree was constructed by neighborjoining method, and according to it the stx1 gene of EC6 was stx1 genotype.

Optimization of Cell Suspension Culture of Carpesium macrocephalum for Flavonoid Production
LI Yu-ping1,2,GONG Ning3,WANG Yong-hong1,FENG Jun-tao1,ZHANG Xing1,*
2010, 31(21):  239-243.  doi:10.7506/spkx1002-6630-201021054
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The goal of the present study was to optimize the culture conditions for the establishment of suspension cell lines from Carpesium macrocephalum callus. The effects of medium type, concentrations of sucrose, VB1, NAA and 6-BA, initial pH value, inoculum quantity and culture time on cell biomass and flavonoid production were examined. The optimal conditions for culture in NT liquid medium conducive to both cell growth and flavonoid production were as follows: initial pH, 5.5, inoculum quantity, 40 g/L; NAA concentration, 1.0 mg/L; and 6-BA concentration, 0.2 mg/L. Cell browning was inhibited by adding 1.0-4.0 mg/L of VB1. Both the growth of Carpesium macrocephalum cells and the synthesis of flavonoids trended to first ascend and then descent with prolonged culture time. A cell biomass ranging from 23.54 to 24.51 g/L was achieved at 15-20 d post-inoculation, and the yield of flavonoids was between 1.19% and 1.23%.

Full-length cDNA Cloning of Glycosyltransferase Family from Rhodiola sachalinensis
YU Han-song1,ZHANG Ji-xing2,LI Yan-fang3,MA Lan-qing4,*,HU Yao-hui1,*
2010, 31(21):  244-247.  doi:10.7506/spkx1002-6630-201021055
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In order to obtain the critical enzyme for the synthesis of Rhodiola sachalinensis glycoside, two putative UDPglycosyltransferase (UGT) cDNAs (GenBank accession number, EF508689和EU567325) were isolated from R. sachalinensi. The primers were designed for 3'-rapid amplification of cDNA ends (RACE) based on the consensus hybrid oligonucleotide primers (CODEHOP) strategy by the Block Maker program. A full-length cDNA sequence (Genbank accession numbers: EF508689 and EU567325) was obtained through the amplification using a SMARTerTM RACE cDNA Amplification Kit (TaKaRa, Dalian, China), whereas the sequence obtained using a 5'-RACE system (version 2.0, InvitrogenTM Life Technologies) contained no full-open reading frame.The cloning efficient of two 5'-RACE systems was investigated. Results exhibited that TaKaRa SMARTerTM RACE cDNA Amplification Kit was more efficient in complete cDNA sequence cloning, compared with the InvitrogenTM 5'-RACE system.

Breeding of High-yield L-Lactic Acid Strains for Co-fermentation of Glucose and Xylose by N+ Implantation
PANG Rui,PAN Li-jun*,JIANG Shao-tong,WU Xue-feng
2010, 31(21):  248-253.  doi:10.7506/spkx1002-6630-201021056
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In order to increase the production of L-lactic acid by co-fermentation of glucose and xylose, Rhizopus oryzae As3.819 was mutated by low energy N+ implantation. The results showed that the survival rate curve was a typical saddle shape with a high positive mutation rate at a dose of 50×2.5×1013 ions/cm2. Under this implantation dose, strain N50-7 was obtained with high yield and stability. L-lactic acid yield by N50-7 was 79.42 g/L, 17.75% higher than the original strain. The optimal composition of fermentation medium for N50-7 were as follows: glucose 100 g/L, xylose 50 g/L, (NH4)2SO4 3 g/L, KH2PO4 0.3 g/L, MgSO4·7H2O 0.3 g/L and ZnSO4·7H2O 0.4 g/L. The final concentration of L-lactic acid was 103.81g/L after 72 h fermentation, which was 30.71% higher than that before breeding.

Cloning of Extracellular Protease Gene from Lactobacillus and Expression in Escherichia coli
YANG Gui-lian,QIN Shou-tao,LIU Qiong,WANG Chun-feng*
2010, 31(21):  254-257.  doi:10.7506/spkx1002-6630-201021057
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Objective: To construct a recombinant plasmid carrying extracellular protease gene from Lactobacillus. Methods: The extracellular protease gene was cloned from genomic DNA of L. helveticus and inserted into the expression vector pW425et. Then the recombination plasmid was transformed into the competence thyA gene-mutant E. coli X13. The expressed protein was analyzed by SDS-PAGE. Results: The recombinant shuttle plasmid pW425et-R was constructed successfully and the Lactobacillus extracellular proteinase gene was expressed in E. coli X13. Conclusion: Our research idea is feasible for the successful expression of Lactobacillus extracellular protease gene in E. coli X13, which will provide a basis for further preparation of recombinant Lactobacillus with anti-hypertensive function.

Production of 2-Keto-D-Gluconic Acid Using Immobilized Pseudomonas fluorescens AR4
CHEN Ping1,MIAO Xiao-yan1, ZHANG Xiao-mei1,ZHOU Qiang2,SUN Wen-jing2,3,*
2010, 31(21):  258-261.  doi:10.7506/spkx1002-6630-201021058
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The cells of Pseudomonas fluorescens AR4 were immobilized by sodium alginate, and the optimization of fermentation conditions for producing 2-keto-D-gluconic acid by immobilized cells were investigated. The results showed that 5.0% of sodium alginate was the optimal carrier for immobilizing Pseudomonas fluorescens AR4 to give a high yield, and the immobilized cells could be reused for 7 times. The optimal concentration of corn steep liquor in fermentation medium was 0.75g/100 mL, and fermentation temperature was between 30 ℃ and 36 ℃. Under the optimal conditions, immobilized cells and free cells could give similar yield and conversion rate of 13.5 g/100 mL and 90.0%, respectively.

Effect of Precursors on Mycelium Growth and Polysaccharide Biosynthesis in Medicinal Mushroom Phellinus igniarius
ZOU Xiang1,GUO Xia1,2,SUN Min2
2010, 31(21):  262-265.  doi:10.7506/spkx1002-6630-201021059
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To promote mycelium growth and polysaccharide biosynthesis in Phellinus igniarius, different groups (sugar and plant oil) of precursors were added to synthetic complete medium and the effects of the kind and amount of separately added sugars and plant oils on Phellinus igniarius mycelium growth and polysaccharide biosynthesis were dealt with. A two-factor, threelevel full combination design was used to optimize the conditions for lactose supplement, and the results showed that a maximum mycelium biomass of up to 13.18 g/L and a maximum polysaccharide production of up to 1.21 g/L were achieved after 168 h fermentation in a 3 L fermentor with an initial lactose concentration of 30 g/L, and the increment percent of polysaccharide production was 25% in comparison with the control. Among oils from three plants, including soybean, olive and rapeseed, rapeseed oil most obviously promoted the growth of Phellinus igniarius mycelia, and the maximum mycelium biomass was up to 23.77 g/L after fermentation for 144 h in a 7 L fermentor, 207.1% higher than that obtained from the control, while polysaccharide biosynthesis was inhibited by adding rapeseed oil.

Effect of Fermentation Strains on Volatile Flavor Components in Dry-cured Pork
YU Hai,LI Xiang,GE Qing-feng,JIANG Yun-sheng,WANG Zhi-jun*
2010, 31(21):  266-270.  doi:10.7506/spkx1002-6630-201021060
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Pork was used as the material to prepare into dry-cured pork with Staphylococcus epidermidis, Staphylococcus xylosus and Staphylococcus auricularis according to the technological processing of Rugao ham. Solid-phase micro-extraction and gas chromatography-mass spectrometer were used to determine the relative contents of volatile flavor components and identify the species in dry-cured pork. Meanwhile, the effect of microorganism fermentation strain on volatile flavor compounds in drycured pork was explored. Totally 149 compounds including 17 aldehydes, 32 alcohols, 44 hydrocarbons, 28 esters, 10 ketones, 10 acids, 5 heterocyclics, 1 phenol and 1 ether were identified in four samples. Different microorganism fermentation strains had significant impacts on the species and relative contents of flavor compounds in dry-cured pork. Compared with the control group, hydrocarbons in dry-cured pork exhibited a higher content. Whereas, heterocyclics exhibited a higher content in Staphylococcus xylosus group; aldehydes were more in Staphylococcus xylosus group and esters were more in Staphylococcus auricularis group.

Construction of Disulfide-Stablized Single Chain Variable Fragment Directed against Chloramphenicol
LI Huang-jin,CHEN Wei,ZHAO Lin,CHAI Wei-jia,TANG Wei
2010, 31(21):  271-274.  doi:10.7506/spkx1002-6630-201021061
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To construct a disulfide-stablized single chain variable fragment directed against chloramphenicol ( sdsFvCAP), both cloned V genes were introduced a cystine code by site-specific mutagenesis, then assembled into sdsFvCAP gene by overlap extension PCR. Under the control of strong promoter T7, the sdsFvCAP gene was failed to be individually expressed in Escherichia coli, but over-expressed as inclusion when GC content in the terminal 5 sequence was decreased by synonymous mutation. The inclusion protein was refolded with β -cyclodextrin companion system, and showed affinity similar to its parent monoclonal antibody (MAb). The sdsFvCAP prepared in this study could be potentially used instead of conventional antisera or MAb for development of a rapid and affordable immunoassay for the detection of residual CAP in foods.

Enzymatic Properties of Polyphenol Oxidase from Kuerle Pear
ZHU Lu-ying1,WU Wei-wei1,2,SUN Jie1,DU Ting-ting1
2010, 31(21):  275-278.  doi:10.7506/spkx1002-6630-201021062
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Enzymological characterization of the polyphenol oxidase (PPO) from Kuerle pear towards catechol as a substrate was conducted using spectrophotometry method. The results showed that the optimal pH and temperature for this enzyme was 5.7 and 42 ℃. High temperature treatment could inhibit PPO activity. The kinetics of PPO reaction was in accord with the Michaelis-Menten equation, with Km and Vmax values of 0.152 mol/L and 169.49 U/min, respectively. Ascorbic acid exhibited stronger inhibition effect on PPO activity than citric acid, NaCl and EDTA-2Na.

Screening and Identification of a Strain Degrading L-Malic Acid and Critic Acid
WANG Li-fang,ZHANG Wei,WEN Lian-kui*
2010, 31(21):  279-282.  doi:10.7506/spkx1002-6630-201021063
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A strain (named S8) degrading both L-malic acid and critic acid was isolated from the soil of the wineyard in Jilin Agricultural University. The abilities of this strain to degrading 12 g/L L-malic acid and critic acid solutions were measured, and deacidification rate was 93.17% for L-malic acid and 92.08% for critic acid. Based on the morphological, physiological and biochemical identification and the rDNA-ITS (internal transcribed spacer) sequence analysis, this stain was classified as Issatchenkia terricola. The investigation of its biological characteristics showed that the optimal temperature and pH for its growth were 30 ℃ and 2.0-5.5, respectively. After passaging of 10 generations, the acid-degrading ability and growth characteristics of this strain were still stable.

Sterilization Effects of Four Kinds of Sterilization Agents on Cobia Fillets
WANG Ping1,2,WU Yan-yan1,*,LI Lai-hao1,YANG Xian-qing1,GONG Xiao-jing1,2,
2010, 31(21):  283-288.  doi:10.7506/spkx1002-6630-201021064
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Objective: To compare the sterilization effects of four kinds of processing agents on cobia fillets. Methods: The effects of food grade chitosan, solid chlorine dioxide (ClO2), ozone (O3) water and sodium hypochloride (NaClO) as the sterilization agents on cobia fillets were explored to screen the optimal sterilization agent and treatment conditions through the determination of total colonies, sensory evaluation and color difference. Results: The optimal sterilization conditions for individual application were 2 g/L chitosan for 8 min immersion, 200 mg/L ClO2 for 10 min treatment, 6 mg/L ozone water for 10 min sterilization and 100 mg/L sodium hypochloride treatment for 5 min. Through further comparing the effects of four sterilization agents on sensory quality of cobia fillets, chitosan, ClO2 and NaClO could result in a significantly negative effect on the sensory quality of cobia fillets; in contrast, ozone water treatment revealed an obvious sterilization effect without reducing the sensory quality of cobia fillets. Thus, ozone water was the best sterilization agent for cobia fillets. Conclusion: The optimal sterilization condition on cobia fillets is the treatment with 6 mg/L ozone water for 10 min. These investigations will provide a theoretical guidance for developing effective and safe sterilization agents for cobia fillet processing.

Inhibitory Effects of Natural Edible Components on Vibrio parahaemolyticus
WU Wei-hua1,LIU Cheng-chu1,*,SHEN Xiao-sheng2,ZHAO Yong1,LI Ying-sen3,LI Jia-le3,4
2010, 31(21):  289-292.  doi:10.7506/spkx1002-6630-201021065
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Vibrio parahaemolyticus is the most prevalent foodborne pathogen in China, especially in the coastal cities. In this work, the effects of three natural edible components including acetic acid, alcohol and tea polyphenol on the survival rate of Vibrio parahaemolyticus in cultural broth were explored through single factor and orthogonal array experiments. Vibrio parahaemolyticus was completely inactivated after treatment with 50% alcohol or 0.5 mg/mL tea polyphenol solution for 5 min on the basis of single factor experiments. In addition, bacterial population was reduced by 4.79 lg(CFU/mL) when Vibrio parahaemolyticus cells were treated with acetic acid solution (pH 2) for 0.5 min. The orthogonal array optimization showed that the combined treatment of alcohol, organic acid and tea polyphenol could result in a synergistic inhibitory effect on Vibrio parahaemolyticus. Vibrio parahaemolyticus could be effectively inhibited after treatment with acetic acid solution (pH 2.8) containing 20% alcohol and 0.125 mg/mL tea polyphenol, or acetic acid solution (pH 2.4) containing 12% alcohol and 0.125 mg/mL teapolyphenol. These results suggest that the combined use of alcohol, organic acid and tea polyphenol can offer a compound antibacterial agent for reducing the risk of Vibrio parahaemolyticus infection during seafood consumption.

Microbial Population and Antibacterial Activity in Fuzhuan Brick Tea
ZHANG Hao1,2,LI Hua3,*,MO Hai-zhen2
2010, 31(21):  293-297.  doi:10.7506/spkx1002-6630-201021066
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In this study, the microbial ecology and antimicrobial activity of Fuzhuan brick tea were investigated. The microbial separation and identification showed that Eurotium spp., Aspergillus spp. and Penicillium spp. were mainly responsible for the natural fermentation of Fuzhuan brick tea, and among them, Eurotium spp. was the dominant fungus. The water extract from Fuzhuan brick tea was found to have inhibitory effect on many food-borne pathogenic bacteria, especially on Bacillus cereus, Bacillus subtilis, Clostridium perfringens and Clostridium sporogenes, which displayed an ascent as the fermentation time was prolonged. This suggests the generation of metabolites able to inhibit food-borne pathogenic bacteria and spoilage bacteria during the fugal fermentation of Fuzhuan brick tea.

Fermentation Conditions for the Production of Low-temperature Alkaline Protease by Pseudoalteromonas flavipulchra HH407 and Its Enzymatic Properties
LU Ming-sheng1,3,WANG Shu-jun1,3,*,LI Hua-zhong2,LI Dan1,2,CHEN Li3,FANG Yao-wei1,3
2010, 31(21):  298-303.  doi:10.7506/spkx1002-6630-201021067
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The optimal fermentation conditions for producing low-temperature alkaline protease by a marine bacterium (Pseudoalteromonas flavipulchra HH407) from Lianyungang sea area and some enzymatic properties of this enzyme are reported in this article. The highest enzyme production was achieved at the conditions of fermentation temperature of 20 ℃, pH 8.0, NaCl concentration of 20 g/L, inoculum amount of 2.5% and medium volume in fermentation tank of 20%. Meanwhile, enzyme production was improved by adding mannitol, fructose, lactose, sucrose, maltose, fishmeal and yeast extract. The optimal reaction temperature for this protease was 35 ℃. The relative enzyme activity was 21.7% at 0 ℃ and 80% after incubation at 45 ℃ for 60 min. The optimal pH for this protease was pH 10.0. A high level of relative activity could be remained in the pH range of 7.0 to 11.0. This protease was stable in the range of pH 8.0 to 11.0. Therefore, it is a low-temperature alkaline protease. Moreover, its activity was stimulated in the presence of Mn2+, Cu2+ and Ca2+, and inhibited in the presence of Hg2+ and PMSF, but was not affected by EDTA. These investigations suggest that this protease might be a serine protease.

Isolation, Purification and Characterization of Recombinantα-Galactosidase from Rice
LI Su-hong1,ZHU Min-peng1,LI Tuo-ping2,*
2010, 31(21):  304-307.  doi:10.7506/spkx1002-6630-201021068
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A crude enzyme solution rich in recombinant riceα-galactosidase from the engineering strain E. coli pET-32a (+)- Gal/ Origami DE obtained from our laboratory was prepared and purified on a Ni-Sepharose affinity column. The purifiedα- galactosidase showed a single protein band in SDS-PAGE with a molecular mass of 59 kD. This enzyme exhibited the highest activity at the conditions of pH 5.0 and 45 ℃. Meanwhile, it showed the best stability at pH 4.0-7.0 and 0-20 ℃. The kinetic parameters Km and Vmax were 0.78 mmol/L and 10.16 mmol/(mg·min), respectively. Most of metal and organic ions did not affect the activity of this enzyme. However, Ag+, Hg2+ and pCMB (p-chloromercuribenzoic acid) significantly decreased its activity by 84%, 87% and 92%, respectively.

Screening and Identification of Erythritol-producing Strains
LIU Peng,WANG Ze-nan*,SU Ya,LI Ying,ZHANG Qiu-zi,WU Hong-yin
2010, 31(21):  308-311.  doi:10.7506/spkx1002-6630-201021069
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Osmophilic yeasts were isolated from honey, pollen and soil by using the medium containing 30% glucose. Two strains producing erythritol but not producing glycerol were identified by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Strain E54 with high ability to produce erythritol was selected by periodic acid oxidation method. The productivity and conversion rate of erythritol were 41.1 g/L and 22.8% after fermentation for 90 h using strain E54 in the medium containing 20% glucose and 0.5% yeast extract. This strain was identified as Moniliella acetoabutans through the analyses of morphological, physiological and biochemical characteristics, 5.8S rDNA sequence and the established phylogenetic tree.

Isolation, Identification and Fermentation Analysis of a Cellulose-degrading Bacterium from Arctium lappa L. Rhizosphere
HOU Jin-hui,CAI Kan,ZHENG Bao-gang,CAO Yu-peng,YE Jun
2010, 31(21):  312-315.  doi:10.7506/spkx1002-6630-201021070
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In this study, a cellulose-degrading bacterium, NP10, was isolated from burdock (Arctium lappa L.) rhizosphere. NP10 was identified to belong to the family of Bacillus sp. and its 16S rDNA Genbank accession number was FJ908093. Meanwhile, NP10 was identified as an alkaline cellulose-degrading strain through batch fermentation. A maximum filter paper activity of 18.2 U/mL was obtained after 48 h fermentation under the conditions of 32 ℃ and initial pH 8, and the optimal fermentation temperature and duration as well as initial pH were 32 ℃, 36 h and 7, respectively, for achieving a maximum carboxymethyl cellulose activity of 8.1 U/mL.

Enzymatic Characterization and Inactivation of Polyphenol Oxidase from Stachys floridana Schuttl.ex Benth
GUO Xiang-feng
2010, 31(21):  316-319.  doi:10.7506/spkx1002-6630-201021071
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The enzymatic properties of polyphenol oxidase (PPO) extracted from Stachys floridana Schuttl.ex Benth were characterized. Meanwhile, the inactivation of this enzyme by thermal treatment or adding chemical inhibitors was investigated, and a compound inhibitor composed of three selected chemical inhibitors (citric acid, vitamin C and L-cysteine) was developed and its formulation was optimized. The optimal reaction pH, time and temperature conditions for PPO activity were 5.0, 2.0 min and 30 ℃, respectively. Color preserving agents such as ascorbic acid, L-cystenine, citric acid, NaHSO3, Na2SO3 had a significant inhibitory effect on PPO activity. The optimal combinatorial formula was composed of 0.05 g/100mL citric acid, 0.05 g/100mL vitamin C and 0.05 g/100mL L-cysteine, and the resultant enzyme inhibition rate reached up to 93.5%.

Chemical Modification of Zinger Protease
LIU En-qi,ZHANG Jian-ping,HE Ju-ping,LIU Quan-de,GAO Ming-xia
2010, 31(21):  320-323.  doi:10.7506/spkx1002-6630-201021072
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Zinger protease was modified separately with monomethoxypolyethylene glycol (mPEG) and dextran to promote its activity and stability. Dextran and mPEG were activated by sodium periodate and by cyanuric chloride, respectively. The activated mPEG and dextran were solely added into sodium tetraborate buffer solution with 2.0 mg/mL zinger protease and then the mixed solutions were incubated at 40 ℃ for 1 h. The optimal mass ratio between modifying agent and zinger protease, and reaction pH were measured. When the ratio between mPEG and zinger protease was 17.5:1.0 and pH was 9.0, the modification rate of zinger protease modified with mPEG was 52.6% and the relative enzyme activity (activity of modified enzyme/activity of natural enzyme) was 54.0%. The modification rate of zinger protease modified with dextran was 51.6% and the relative enzyme activity was 3.3 at the conditions of dextran/zinger protease ratio of 42:1 and pH 6. The thermal stability of both modified enzymes was higher than that of natural enzymes; meanwhile, the thermal stability of zinger protease modified with dextran was higher than that of zinger protease modified with mPEG. Therefore, dextran has a better modification effect on zinger protease than mPEG. Dextran is more suitable for the chemical modification of proteases and the development and utilization of novel enzymes.

Nutrition & Hygiene
Protective Effect of Bilberry Anthocyanin Extract (BAE) against Photo-oxidative Damage of Human Retinal Pigment Epithelial Cells
SONG Xue,HAN Yong,JI Bao-ping*,LIU Yi-xiang,LU Ye-chun
2010, 31(21):  324-328.  doi:10.7506/spkx1002-6630-201021073
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Objective: To establish a photo-oxidative damage model of human retinal pigment epithelium (hRPE) cells for evaluating the protective effect of bilberry anthocyanin extract (BAE). Methods: Illumination intensity, exposure time and incubation time were selected as the factors to establish the model through evaluating cell variability and LDH activity. Meanwhile, the precaution group, stress group and repairing group were designed to administrate three different concentrations in each group. Cell viability and vascular endothelial growth factor (VEGF) expression level were used to evaluate the preventive effect of BAE. Results: Illumination for 24 h at an intensity of 2500 lx and subsequent incubation time for 24 h were the optimal conditions for the model establishment. The damage rate of hPRE cells was up to 20%. No significant cell damage was observed for the precaution and the stress groups (P < 0.01), while the repairing group did not exhibit preventive effect. All the groups inhibited VEGF expression level in a dose-dependent manner. Conclusion: RPE cells can be damaged by visible light and the damage degree is correlated with illumination intensity and illumination duration. BAE can protect cells from light damage and inhibit VEGF level secreted from damaged cells. Therefore, people can intake bilberry to keep eye healthy and prevent the diseases of eyes.

Effect of Superfine Dietary Fiber from Soybean Bran on Blood Glucose Tolerance in Diabetic Mice
XIAO An-hong1,2,LU Shi-guang1,2
2010, 31(21):  329-331.  doi:10.7506/spkx1002-6630-201021074
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Purpose: To explore the effect of superfine dietary fiber from soybean bran on glucose tolerance in diabetic mice. Methods: Glucose tolerance was determined in common and alloxan-induced diabetic mice fed different granular sizes of superfine dietary fiber (140-200 mesh and more than 200 mesh) at a dosage of 5 g/kg bw each day. Results: Compared with the model group, the areas under the blood sugar curve in common mice treated with superfine dietary fiber at two dosages decreased by 14.94% and 15.48% (P < 0.05), and blood sugar peaks in common mice after meal at two dosages decreased by 12.38% and 12.51%. Similarly, compared with the model group, the areas under the blood sugar curve in diabetic mice treated with superfine dietary fiber at two dosages decreased by 24.05% and 29.68% (P < 0.01), and blood sugar peaks in diabetic mice after meal at two dosages decreased by 38.71% and 39.26%. Conclusion: The blood sugar tolerance in common and diabetic mice treated with superfine dietary fiber has an obvious improvement, and blood sugar peaks and blood sugar levels in common and diabetic mice after meal are significantly decreased. However, the granular size of superfine dietary fiber does not exhibit obvious improving effect on blood sugar tolerance and decrease in blood sugar level.

Effects of Casein Phosphopeptides, High-calcium Diet and Their Combination on Hyperuricemic Rats
ZHANG Rui1,YAO Fang-fang1,HE Wei2,*
2010, 31(21):  332-334.  doi:10.7506/spkx1002-6630-201021075
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Objective: To study the effects of casein phosphopeptides (CPPs), high-calcium diet and their combination on uric acid (UA), total cholesterol (TC), xanthine oxidase (XOD) and adenosine deaminase (ADA) in the serum and XOD and ADA in the liver of hyperuricemic rats. Methods: Hyperuricemic model rats were induced by intragastric administration with adenine (100 mg/(kg bw·d)) and ethambutol (250 mg/(kg bw·d)) for 3 weeks. The model rats were then treated with foods containing CPPs, high-calcium diet and their combination for 28 days. After intervention for 28 days, UA, TC, XOD and ADA in serum and XOD and ADA in liver were determined. Results: Serum uric acid level of rats induced by intragastric administration was significantly higher than that in the control group before intervention. Compared with the model rats, each intervention group exhibited an obvious decrease in UA and TC levels. The XOD activities in all the intervention groups were all lower than those in the liver of the model group, and the ADA activities in all the intervention groups were lower than those in both the serum and liver of the model groups, especially in high-calcium diet and their combination intervention groups (P < 0.05). Conclusion: CPPs and high-calcium diet exhibit a high potential to decrease uric acid level.

Inhibitory Effect of Different Polarity Fractions of Ethanol Extract from Oat on Vascular Smooth Muscle Cell Proliferation
HUANG Chen,JI Bao-ping*,YANG Pei-ying,ZHOU Feng,WU Wei,CAI Sheng-bao
2010, 31(21):  335-339.  doi:10.7506/spkx1002-6630-201021076
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The ethanol extract from oat was fractionated with different polarity solvents (n-hexane, ethyl acetate, 1-butanol and water), and the four fractions obtained were assessed for their abilities to scavenge DPPH free radicals, inhibit the proliferation of vascular smooth muscle cells (VSMC) and promote the release of NO from VSMC in vitro. Among these four fractions, the ethyl acetate soluble fraction had the most prominent DPPH free radical scavenging ability, with an EC50 of (2.5 ± 0.4)mg/mL. Meanwhile, this fraction could remarkably inhibit the proliferation of VSMC and elevate the NO producing ability. The preliminary HPLC analysis indicated that this fraction mainly contained three kinds of avenanthramide, Bc, Bp and Bf.

Hematopoiesis Activity of Bioactive Peptides from Taihe Black-bone Silky Fowls
WANG Yong,LIU Jian-hua,TIAN Ying-gang,ZHU Sheng,XIE Ming-yong*
2010, 31(21):  340-343.  doi:10.7506/spkx1002-6630-201021077
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Objective: To investigate the hematopoiesis activity of bioactive peptides from Taihe Black-bone Silky Fowls (TBSF). Methods: Blood loss combined with myelosuppression drug (Fluorouracil, 5-FU) was used to establish a blood deficiency mouse model. Red blood cells (RBC) and hemoglobin (HGB) levels were measured to evaluate the hematopoiesis effects of bioactive peptides from TBSF and isolated bioactive peptide fraction A. Results: Compared with the blood deficiency group, the RBC level of bioactive peptides group has a significant difference on the 12th day administration (P< 0.05); During the period of 6 to 12 days, RBC and HGB levels of bioactive peptides group exhibited a significant faster than the Ejiao group (P<0.05). On the 18th day, HGB level of bioactive peptides group was higher than other groups, and also significantly higher than the normal control group (P < 0.05). The RBC level in bioactive peptide fraction A group was higher than the blood deficiency group at each time point although no significant difference was observed (P> 0.05), while the blood deficiency group and the Ejiao group exhibited a significant difference (P< 0.01), compared with the normal control group. On the 20th day, there was no significant difference in HGB level (P> 0.05) between the bioactive peptide fraction A group and the normal control group, while the blood deficiency group and the Ejiao group revealed a significant difference from the normal control group (P< 0.01). Conclusion: Bioactive peptides from TBSF exhibit hematopoiesis activity by elevating RBC and HGB levels to some extent.

Effect of Ethanol Extract of Propolis on Proliferation and Apoptosis of Human Liver Carinoma Hep G2 Cells
WU Zheng-shuang1,2,DONG Jie2,ZHANG Hong-cheng2,GAO Wen-hong1,*
2010, 31(21):  344-348.  doi:10.7506/spkx1002-6630-201021078
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In order to investigate the effect of propolis on cell proliferation and apoptosis, the ethanol extract of propolis was used to treat human liver carcinoma Hep G2 cells. The inhibitory rate of ethanol extract from propolis on the proliferation of human liver carcinoma Hep G2 cells was determined by MTT assay and the apoptosis of human liver carcinoma Hep G2 cells was examined by using inverted fluorescence microscope and flow cytometry analysis. Results indicated that 12.5-200 μg/mL ethanol extract of propolis exhibited an obvious inhibition effect on the proliferation of Hep G2 cells after 24 h and 48 h treatment in a time- and dose-dependent manner. The apoptosis of Hep G2 cells was obviously observed after treatment and apoptosis rate was in the range of 6.36% to 21.9% in a dose-dependent manner. These results confirm that propolis can significantly inhibit the proliferation and induce apoptosis of Hep G2 cells.

Antihyperglycemic Function of Momordica charantia L. Bleeding sap in STZ-Induced Diabetic Mice
DONG Ying1,ZHU Jing-ying1,CHEN Jun2
2010, 31(21):  349-352.  doi:10.7506/spkx1002-6630-201021079
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The present study was aimed at studying the antihyperglycemic effect and its mechanism of Momordica charantia L.bleeding sap (MBS) on streptozotocin-induced diabetic mice. Ten mice were selected randomly as control, while another 50 mice were injected with STZ 170 mgkg bw after fasting for 17–18 h to induce diabetes. The diabetic mice were divided into 3 groups: model group, metformin group (200 mg/(kg bw·d)) and MBS group (200 mg/(kg bw·d)). After 30 days of gavage administration, the levels of fasting blood glucose and blood-fat, serum insulin and hepatic glycogen content were examined. The paraffin sections of pancreas, stained with HE, were made into pathological sections for observation. The results showed that MBS could significantly reduce the levels of fasting blood glucose and blood-fat in diabetic mice, with an increase in hepatic glycogen and insulin content. The pathological sections showed that MBS improved the function of pancreas islet tissues, accelerate the renovation of pancreatic β cells in diabetic mice. The above results indicate that MBS can accelerate the repair of pancreatic inlet β cells injured by streptozotocin, stimulate the secretion of insulin, increase the synthesis of hepatic glycogen and regulate blood lipid metabolism so as to reduce blood glucose level of diabetic mice.

Inhibition Effect of Okra Polysaccharides on Proliferation of Human Cancer Cell Lines
REN Dan-dan,CHEN Gu*
2010, 31(21):  353-356.  doi:10.7506/spkx1002-6630-201021080
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The anticancer bioactivity of polysaccharide has gained more and more attention in recent years. Herein, the inhibitory effect of polysaccharides extracted from okra, Abelmoschus esculentus (L.) Moench, was investigated on different human cancer cell lines, OVCAR-3, MCF-7, Hela and MCG-803 cells. Raw polysaccharide (RPS) was extracted from fresh okra fruit by ethanol precipitation and further purified by DEAE anion exchange chromatography to obtain fractions E1, E2 and E3. These cancer cells were treated with different concentrations of okra polysaccharides for 72 h and their proliferation were analyzed by MTT assay. RPS and E1 had a significant inhibition effect on the proliferation of OVCAR-3 cells in a dose-dependent manner, and the lowest survival rates were 72.30% and 52.31%, respectively. E3 had an obvious inhibition effect on MCF-7, Hela and MCG-803 cells with the lowest survival rates of 63.90%, 63.51% and 67.71%, respectively. Therefore, these investigations are significance of exploring and developing okra as functional foods.

Antioxidant Effect of Raspberry Glycoprotein
TIAN Tian,DUAN Yu-feng*,NIU Fu-ge
2010, 31(21):  357-360.  doi:10.7506/spkx1002-6630-201021081
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Objective: To investigate the antioxidant activity of raspberry glycoprotein (RGP) in vitro and in vivo. Methods: The antioxidant activity of raspberry glycoprotein in vitro was evaluated by determining its reducing power and scavenging capacities against hydroxyl, superoxide anion and DPPH free radicals. The activities of CAT, SOD and GSH-PX in serum, liver and brain tissues of mice were determined to evaluate the antioxidant activity of raspberry glycoprotein in vivo. Results: Raspberry glycoprotein significantly increased the activities of CAT, SOD and GSH-PX in serum, liver and brain tissues of mice, revealed strong reducing power, and effectively eliminated hydroxyl, superoxide anion and DPPH free radicals. Conclusion: Raspberry glycoprotein has obvious antioxidant effect.

Effect of Purple Potato Homogenate and Its Separated Fractions on Blood Pressure of SHR
HU Zhi-he1, ZHANG Ran-xi1, FENG Yong-qiang2, ZHU Li-min2
2010, 31(21):  361-364.  doi:10.7506/spkx1002-6630-201021082
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Purple potato homogenate was filtrated through multiple layers of gauze, and both the filtrate and residue were harvested. After a period of time of sedimentation, the filtrate was separated into two layers, namely water-soluble upper layer and starch-rich lower layer. The effects of purple potato homogenate, its filtration residue and the water soluble and starch-rich factions of its filtrate on blood pressure of spontaneously hypertensive rats (SHR) was investigated by using 12-week-old male SHR and Wistar rats as the trial animals with different gavage administration doses (0.1, 1 g/kg bw and 5 g/kg bw). The results showed that none of the above four materials had an obvious effect on the blood pressure of normal Wister rats in the given dose range. Except the starch-rich fraction, all the others had a significant effect on decreasing blood pressure of SHR. The water-soluble fraction was the most effective antihyperglycemic factor with 20.83 mmHg drop at 1 hour after administration at 0.1 g/kg bw, 23.50 mmHg at 2 hours after administration at 1 g/kg bw, 24.48 mmHg at 4 hours after administration at 5 g/kg bw. These drops were followed by a slow rebound up to the pre-administration level at 8 hours. From these results, it can be concluded that all the byproducts of purple potato starch extraction have a notable antihyperglycemic effect.

Improvement of Oxazolone-induced Ulcerative Colitis in Mice by Bovine Casein Glycomacropeptide
JIA Yu-chen, CHEN Qing-sen*
2010, 31(21):  365-368.  doi:10.7506/spkx1002-6630-201021083
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In order to explore the effect of casein glycomacropeptide (CGMP) on xazolone-induced ulcerative colitis in mice, the control group was fed regular diet, while the model group and three treatment groups were administered CGMP at three doses of 5, 50 mg/(kg bw·d) and 500 mg/(kg bw·d) by oral gavage for 5 days after oxazolone challenge. The change of body weight was daily recorded and diamine oxidase (DAO) activity in serum, myeloperoxidase (MPO) activity, malonaldehyde (MDA) content in colon, and histological change of colon were determined after the last administration. Treatments with the three doses of CGMP showed improvement on oxazolone-induced ulcerative colitis, while the dose of 50 mg/(kg bw·d) CGMP seemed to be better. In conclusion, CGMP holds promising potential to be applied in a nutritional therapy for the treatment of ulcerative colitis.

Effect of Heavy Metal Content in Soil from Luoyang Vegetable Base on Vegetable Safety
WANG Hui1, WANG Yi-juan1,LI Xing-hui2,*,XU Ren-kou3
2010, 31(21):  369-372.  doi:10.7506/spkx1002-6630-201021084
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Soil and vegetables from Luoyang vegetable base were used as the subjects to determine the contents of heavy metal ions such as Cr, Pb, Cd and Hg by atomic absorption spectrometry. The pollution status of soil and the quality of vegetables were evaluated by single factor pollution index and comprehensive pollution index. Results showed that the contents of Cr and Pb did not exceed the second-level limit of“ Standard of Soil Environment” (GB 15618—1995). However, Luolong and Yichuan vegetables base were polluted by heavy metals according to the national vegetable food criteria. The key pollution factor was Pb with an exceeding rate of 36.3%. The highest content of lead was determined in leafy vegetables such as leaf lettuce. The lower pollution of lead was determined in root and stem vegetables, which was remained at the safe level.

Combined Effect of Bovine Colostrumson and Selenium-enriched Rhodopseudomonas palustris G3 on Immune Function in Mice
YANG Qi-yin1,2,3,WANG Jia-fang1,JIA Bing-sheng1,GUAN Hai-hua1,LIU Qing1
2010, 31(21):  373-377.  doi:10.7506/spkx1002-6630-201021085
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In order to investigate the effect of selenium-enriched bovine colostrumson on immune function of immunodepressed mice induced by cyclophosphamide, selenium-enriched Rhodopseudomonas palustris G3 (hereinafter called selenium-enriched G3) was mixed with bovine colostrumson to prepare selenium-enriched bovine colostrumson. The immunodepressed mice were treated with selenium-enriched G3, bovine colostrumson and selenium-enriched bovine colostrumson, respectively. The administration was carried out once a day for 47 successive days after 3 days of adaptive feeding, and organ index, white blood cell number, T-cell population, the contents of SOD and GSH-Px in blood, and feed/gain ratio of mice were determined at the end of the administration. Results indicated that selenium-enriched G3, bovine colostrumson and selenium-enriched bovine colostrumson could increase the utilization efficiency of diet, enhance the activities of SOD and GSH-Px in blood, and improve mouse immune function. Compared with the control group, the selenium-enriched bovine colostrumson exhibited best improved immune at the high dosage.

Effects of Peptides Derived from Spirulina Protein on Mucosal Immune System in Rabbits
LIU Xiao-juan1,PANG Guang-chang1,*,WANG Lian-fen1,2
2010, 31(21):  378-383.  doi:10.7506/spkx1002-6630-201021086
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Objective: To explore the effects of peptides derived from Spirulina protein hydrolyzed by alkali protease on mucosal immune system in rabbits. Methods: Protein was extracted from Spirulina by salting out method, and then hydrolyzed with alkaline protease. The rabbits were treated with the hydrolysate by intragastric administration, intraperitoneal injection and ear vein injection, respectively. At 3, 2 and 2 h after administration, ELISA kit was used to determine the concentration changes of IL-1β, IL-6, IL-12, IFN-γ, TNF-α, IL-1Ra, IL-4, IL-10 and TGF-β in rabbit serum. Results: Compared with the control group treated with physiological saline, all the three administration route groups showed a notable decrease in the concentration of IL-12 but an increase in both the concentrations of IFN-γ and IL-10. However, on the basis of the comparison among the three administration routes, intraperitoneal injection revealed the most remarkable change in cytokines; in contrast, the two others had no obvious change. In the intraperitoneal injection group, the concentrations of IL-1 β, IL-6, IL-12 and TNF-α revealed a significant decrease, while those of IL-1Ra and IL-4 exhibited a dramatic increase, which suggests that the peptides derived from Spirulina protein hydrolyzed by alkali protease have strong immune activity. Conclusion: The immune signaling transduction of Spirulina peptides in mucosal immune system is completed by inhibiting NF-κB and PKC/p38/MAPK pathways in mucosal epithelium, endothelial cell, monocytes/macrophages and lymphocytes, which is similar to the phytochemical mechanism for inhibiting NF-κB and inflammatory reaction.

Tolerability of Yogurt Strains to Mimic Gastric Acid and Bile Salt as Analyzed by Flow Cytometry
WANG Qing-mei,CHEN Qing-sen*
2010, 31(21):  384-389.  doi:10.7506/spkx1002-6630-201021087
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Studies on the tolerability of traditional yogurt strains to gastric acid and bile salt are very important to evaluate probiotic strains in yogurt. The Streptococcus thermophilus and Lactobacillus bulgaricus in yogurt were evaluated for their  olerance to different pH and different concentrations of bile salt in mimic gastrointestinal environment using flow cytometry (FCM) combined with double-fluorescence dye staining by 5(6)-cFDA and PI. The cell viability was very small, and the percentage of labeled viable cells was only 41.8% at an exposure pH of 2.0 and became higher and higher as the exposure pH increased from 3.0 to 7.0 (3.0, 4.0 through 7.0), and the inhibitory effect on viable cells showed a progressive reduction. The percentage of labeled viable cells exposed to 1 g/100mL deconjugated bile salt (DBS) was 48.7%, and those of labeled viable cells exposed to 0.5 g/100mL, 0.25 g/100mL, 0.1 g/100mL and 0.05 g/100mL DBS displayed an increasing pattern. Flow cytometry and plate counts were comparatively used to determine cell viability. The above two species of strains exhibited strong tolerance at the conditions of pH 5.0-7.0 gastric acid and 0.05-0.5 g/100mL deconjugated bile salt. Flow cytometry count was superior to plate count.

Potential Risks of Heavy Metals (Hg, Cd and Pb) from Seafood to Health
LI Yu,FENG Zhi-hua,LI Gu-qi,YAN Bin-lun
2010, 31(21):  390-393.  doi:10.7506/spkx1002-6630-201021088
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The contents of heavy metals including Hg, Cd and Pb in edible marine products such as molluscs, crustaceans, and fish from a local market in Lianyungang were determined to evaluate the potential risks to health on the basis of target hazard quotients (THQs). Results indicated that mercury had the highest concentration in molluscs (0.06-1.23 mg/kg), followed by fish (0.024-1.03 mg/kg), and crustaceans (less than 0.25 mg/kg). Cadmium level in molluscs was in the range of 0.18 to 4.02 mg/kg, which was higher than that in crustaceans (less than 0.05 mg/kg) and fish (less than 0.07 mg/kg). However, Pb level was generally low, which was between 0.04 mg/kg and 0.23 mg/kg in molluscs, less than 0.03 mg/kg in crustaceans, and less than 0.07 mg/kg in fish. According to the THQ values of Cd and Pb, there is no risk to health after consuming these seafoods from this market. In contrast, according to the THQ values of mercury, one kind of fish (Platycephalus indicus) has the risk to health during consumption.

Reviews
Research Progress in Postharvest Physiology and Storage Technology of Pomelo Fruit
LIU Shun-zhi1,JIANG Yue-ling1,LI Xiao-mei1,ZHANG Zhao-qi2,HU Wei-rong1,*
2010, 31(21):  394-399.  doi:10.7506/spkx1002-6630-201021089
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In China, the production of pomelo occupies 12.9% of citrus fruits. The production, quality and export of this species of fruit show great potential. This article reviews recent progress in postharvest physiology and storage technology of pomelo involving storage characteristics, the effect of harvesting period on fruit quality, physiological and metabolic changes during storage, physiological disorders, postharvest handling, fresh-cutting and fresh-keeping, fresh-keeping on the plant, and so on.

Designing of Post-Olympic Food Supply Chain Traceability Framework
GAO Jian1,WU Lin-hai2,*,XU Ling-ling1
2010, 31(21):  400-404.  doi:10.7506/spkx1002-6630-201021090
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With the technological development of coding, information and communication, traceability system has gradually been applied to the management of food supply chain, in order to ensure food safety and improve information management and logistics, which is actually a good information management platform of the whole supply chain. In this study, a general food traceability framework was presented for providing an integrated analytical method for the implementation and promotion of food traceability system in supply chain in the post-Beijing Olympic period.

Prevention and Control of Foodborne Viruses
SUN Yue-e1,2,SUN Yuan1
2010, 31(21):  405-408.  doi:10.7506/spkx1002-6630-201021091
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During the last decade, an increasing infection incidence of foodborne viruses worldwide was observed to affect food safety. Because serious food safety issue can be resulted from viruses in very low dosage, the fresh, convenient and safe foods are highly desired by consumers. Thus, the novel food-processing technologies and preservation methods have attracted a tremendous amount of attention. In this paper, the types, characteristics, transmission pathways as well as prevention and control strategies of foodborne viruses are reviewed. Moreover, current research progress of preservation methods to reduce virus level in foods is also discussed.

Current Research and Trend of Safety Evaluation of Food Flavorings
CHENG Lei,SUN Bao-guo,SONG Huan-lu,CHEN Hai-tao,XU Hong*
2010, 31(21):  409-412.  doi:10.7506/spkx1002-6630-201021092
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Food flavoring substances always play an important role in the manufacturing and consumption of foods, while the present research on their safety is still not satisfactory due to a variety of reasons. With the improvement of living standards and increasing emphasis on food safety, the importance of safety evaluation on food flavorings is increasingly prominent. This paper reviews the features of food flavorings, their safety issues, and the current research on their safety evaluation in China and abroad. The main problems on safety evaluation faced now as well as the prospects to the future study are drawn finally.

Advances in Inoculated Fermented Vegetables
WANG Wei-dong1,2,CHEN An-hui1,YANG Wan-gen1,LI Chao1
2010, 31(21):  413-416.  doi:10.7506/spkx1002-6630-201021093
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Fermented vegetables are important products. In this article, microorganism types and their functions during the fermentation process of vegetables are summarized. Based on the current research achievements of inoculated fermented vegetables, the advantages and disadvantages of inoculated fermentation are discussed and compared with the natural fermentation.

Research Advance in Detection Technologies for Allergen in Food
ZHENG Yi-cheng1,2,HUA Ping3,YANG An-shu1,2,*,LIU Bo1,4,CHEN Hong-bing1,2
2010, 31(21):  417-421.  doi:10.7506/spkx1002-6630-201021094
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Food allergy has become one of the global food safety problems, and the diseases originated from food allergy reaction is seriously affecting human life, so it is especially important to detect the allergen in food. In this paper, the commonly used technologies for the detection of allergen in food are reviewed briefly. Meanwhile, the future development is also discussed.

Research Process on the Effects of Food-derived Bioactive Substances on Aberrant DNA Methylation Associated with Colorectal Cancer
LIANG Yun,CHEN Qing-sen*
2010, 31(21):  422-426.  doi:10.7506/spkx1002-6630-201021095
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Aberrant DNA methylation, as a vital epigenetic change, has been shown to be closely associated with the occurrence and development of colorectal cancer. This paper reviews recent progress in the mechanism of arrant DNA methylation and its importance as well as the relationship between arrant DNA methylation and colorectal cancer at home and abroad. Besides, the regulatory mechanisms of food-derived bioactive substances on DNA methylation by controlling the metabolism of methyl groups and the activity of DNA methyltransferases so as to influence the occurrence and development of colorectal cancer are herein summarized.

Research Progress in Preservative Effect of Plant Essential Oil on Fruits and Vegetables
ZHOU Xiao-wei,WANG Jing,GU Nie,ZHENG Yong-hua*
2010, 31(21):  427-430.  doi:10.7506/spkx1002-6630-201021096
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The decay caused by microorganism invasion is the major loss of postharvest fruits and vegetables, which brings huge economic loss. Plant essential oils containing a variety of chemical components are the secondary metabolites extracted from plants. The antibacterial activity and the capability to maintain quality of fruits and vegetables have gained extensive interests. The application of natural plant essential oils in the preservation of fruits and vegetables has become the research focus in recent years. In this paper, antibacterial activity, the effects and possible mechanisms of plant essential oils involved in the preservation of fruits and vegetables are discussed, which is expected to provide a theoretical reference for the development of natural food preservatives for fruits and vegetables.

Research Progress in Secoiridoid Compounds
LUO Yu-yan1,LU Cheng-ying1,2,*,CHEN Gong-xi1,GUI Ke-yin2
2010, 31(21):  431-436.  doi:10.7506/spkx1002-6630-201021097
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Secoiridoid compounds have drawn more attention due to their various biological activities in recent years. The natural secoiridoid compounds newly found in different plants at home and abroad between 2002 and 2009 are introduced in this paper. Furthermore, the current situation of research on separation, extraction, detection and biological characterization of secoiridoid compounds is summarized, and the food and medical application prospects are also predicted.

Recent Advances in Extraction and Analysis of Volatile Flavor Compounds in Chinese Liquor
LIU Yu-ping,HUANG Ming-quan,ZHENG Fu-ping,CHEN Hai-tao,SUN Bao-guo*
2010, 31(21):  437-441.  doi:10.7506/spkx1002-6630-201021098
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Volatile flavor compounds play an important role for the type and style of Chinese liquor. This paper summarizes the applications of gas chromatography-mass spectrometry (GC-MS) without sample pretreatment and with solvent extraction or solid-phase microextraction to analyze the volatile components in Chinese liquor reported in the recent decade. Moreover, the sources, roles and affecting factors of volatile components in Chinese liquor are summed up briefly. In conclusion, solid-phase microextraction coupled with GC-MS is comparatively more simple and effective method for the analysis of volatile composition of Chinese liquor.

Research Advances in the Influence of Actomyosin Dissociation on Postharvest Meat Tenderness
LI Sheng-jie,XU Xing-lian*,ZHOU Guang-hong
2010, 31(21):  442-445.  doi:10.7506/spkx1002-6630-201021099
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The dissociation of actomyosin may be one of the causal factors that make meat become tender during postmortem aging. This article introduces the formation of actomyosin during rigor mortis postmortem, detailedly discusses the potential effects of the dissociation of actomyosin on meat tenderization. Meanwhile, the factors that may cause the dissociation of actomyosin during postmortem aging are summarized.

Microalgal Docosahexaenoic Acid: A New Functional Food Additive
WEN Xue-xin1, LI Jian-ping1, HOU Wen-wei2, PENG Xiao-fang1,MA Jin-yu3
2010, 31(21):  446-450.  doi:10.7506/spkx1002-6630-201021100
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Docosahexaenoic acid (DHA) is a necessary element during the growth of infants and children, and also a necessary supplement benefiting for the health of adults. Because DHA cannot be synthesized in human body and daily intake from dietary sources is insufficient, it is essential to consume special DHA supplemental products. Based on diet habits of Chinese people and recommendations for Dietary Reference Intake (DRI) of DHA from international authorities, DRI of DHA for Chinese people is suggested in this paper. As a natural, safe, environment-friend functional food additive, microalgal DHA has drawn extensive attention and been applied widely in some countries. Meanwhile, it will be developed as a popular healthcare product and applied in food industry in China. However, technical problems in the application of microalgal DHA still need to be further investigated. As a new functional food additive, microalgal DHA will become a development tend of healthcare and food industries.

Research Progress of Ellagic Acid as a Functional Factor of Health Products
LU Jing-jing1,DING Ke2,YANG Da-jin1,*
2010, 31(21):  451-454.  doi:10.7506/spkx1002-6630-201021101
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Ellagic acid has spiked extensive attention at home and abroad as a functional factor of health products. In this paper, current preparation processing of ellagic acid is reviewed and the toxicity of ellagic acid is evaluated. Its functions and mechanisms of antioxidation and anticancer are also discussed.

Current Research and Development of Animal Blood Extract Activity
DENG Li1,LIU Zhang-wu1,*,DU Jin-ping2
2010, 31(21):  455-458.  doi:10.7506/spkx1002-6630-201021102
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Animal blood with a reputation of "liquid meat" is rich in protein. Its extracts are newly developed animal resources with a wide range of application values. In this paper, bioactive components in animal blood are introduced. Furthermore, the advantages and disadvantages of different extraction methods for immunoglobulin, superoxide dismutase and heme are compared. The development and utilization status, and future research directions of animal blood extracts are also proposed.

Advances in Ultrasound-assisted Extraction of Bioactive Compounds from Plants
MA Ya-qin1,2,3,YE Xing-qian4,WU Hou-jiu1,3,ZHOU Zhi-qin1,2,WANG Hua1,3,SUN Zhi-gao1,3
2010, 31(21):  459-463.  doi:10.7506/spkx1002-6630-201021103
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In this paper, the mechanisms of ultrasound-assisted extraction are briefly introduced. Current research progress and future development trends related to ultrasound-assisted extraction of bioactive compounds from plants are reviewed. Application potential of ultrasound-assisted extraction technology in food processing is analyzed. Problems existing in the realization of industrial control of ultrasound-assisted extraction at present and future research direction are critically discussed.

Research Progress in Molecular Mechanism of Tea Polyphenol for Protecting Cardiovascular System
LIU Dong-ying,WANG Yin*
2010, 31(21):  464-468.  doi:10.7506/spkx1002-6630-201021104
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Tea polyphenols have attracted considerable attention in the prevention of cancer and cardiovascular diseases. The molecular mechanisms of tea polyphenols involved in antioxidant, anti-inflammatory, antithrombotic, anti-angiongenic and protective effects on endothelial functions are reviewed in this paper. Meanwhile, the molecular targets of tea polyphenols are also discussed to explore the correlation between functional effects and signaling transduction pathways.