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Table of Content

15 August 2011, Volume 32 Issue 15
Basic Research
Synthesis and Characterization of Pyrrolyl Alanine and Its Hyperchromic Effect on Laba Garlic Pigments
WANG Dan,HU Xiao-song,ZHAO Guang-hua
2011, 32(15):  1-4.  doi:10.7506/spkx1002-6630-201115001
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Pyrrolyl alanine, which can increase the shelf life of Laba garlic and maintain its green color, was synthesized by Paal-Knorr method and characterized by mass spectroscopy, infrared spectroscopy and 1H NMR spectroscopy. The hyperchromic effect of pyrrolyl alanine on Laba garlic pigments was also explored. The results showed that the addition of pyrrolyl alanine at the dose of 5.0 mmol/L prolonged the formation of green pigments in Laba garlic and as a result, the commodity character of Laba garlic could be maintained for 45 days at least. Moreover, the formation of green pigments still exhibited an upward trend after 45-day storage. Therefore, pyrrolyl alanine has an obvious hyperchromic effect on Laba garlic pigments.
Antioxidant Activity and Stability of Litchi Polyphenols
FENG Wei-hua,YU Li-mei,QIN Yan,CHEN Si-si,BAI Wei-dong
2011, 32(15):  5-9.  doi:10.7506/spkx1002-6630-201115002
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In this study, fresh litchi pulp was extracted with 70% aqueous ethanol twice by shaking for 6 h each time; afterward, the resulting extracts were pooled, condensed by rotary evaporation, defatted with n-hexane and reextracted with ethyl acetate/ethyl ether mixture (1:1, V/V); and finally, an organic phase and an aqueous phase both containing polyphenols were obtained. The antioxidant activity of litchi polyphenols in the two phases was evaluated by DPPH radical scavenging and ferric reducing antioxidant power (FRAP) assays. Meanwhile, the relationship between total phenol content (TPC) and antioxidant activity of the two phases were explored. The stability and antioxidant activity of litchi polyphenols showed a downward trend with increasing temperature (25-70 ℃), and prolonged exposure to sunlight (12-96 h) could also result in a gradual decrease in the stability and antioxidant activity of litchi polyphenols. TPC and antioxidant activities of both polyphenolic extracts were kept stable in the pH range of 8-9. Meanwhile, an obvious correlation between TPC and antioxidant activity was observed for both polyphenolic extracts (P<0.05). Therefore, lower temperature and light-free environments are benefit for TPC and antioxidant activity of litchi polyphenols during storage and processing.
Emulsifying Properties of Pigskin Collagen Peptides with Different Molecular Weights
YU Dong-hua ,XU Zhi-hong ,WEI Zhen-cheng,ZHANG Ye-hui,ZHOU Ling-ling,WANG Chong
2011, 32(15):  10-13.  doi:10.7506/spkx1002-6630-201115003
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Ultra-filtration was used to separate pigskin collagen hydrolysate prepared by sequential hydrolysis with alcalase followed by papain and three peptide fractions including PCH1, PCH2 and PCH3 were obtained. Colorimetry was used to determinate the emulsifying capacity and emulsion stability of PCH1, PCH2 and PCH3 under various conditions of pH, soluble protein concentration and oil amount. The results showed that the emulsifying capacity and emulsion stability of PCH1, PCH2 and PCH3 could be greatly affected by pH, soluble protein concentration and oil amount (P<0.05). Soluble protein concentration was found to be the most obvious affecting factor. In addition, PCH2 and PCH3 had stronger emulsifying capacity than PCH1 (P<0.05). PCH peptide having better emulsifying properties was determined to have a lower molecular weight.
Investigation Based on Viscosity of the Association Behavior of Ethanol and Water in Fen-flavor Liquor
QIAO Hua,MA Yan-hong,ZHAO Zhen-wu,ZHANG Sheng-wan
2011, 32(15):  14-19.  doi:10.7506/spkx1002-6630-201115004
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Aqueous ethanol solutions at different concentrations were used as the model liquors to explore the effects of alcohol concentration, storage time and major trace flavor components on the viscosity of Fen-flavor liquor and the association behavior between alcohol and water with the aim of providing a theoretical reference for further exploring aging mechanisms of Chinese liquor. Results indicated that trace elements in Fen-flavor liquor had certain impacts on the strength of ethanol-water association, but the major affecting factor was ethanol concentration.
Effects of Acid Treatment and Enzymatic Treatment on the Content and Properties of Resistant Starch in Boiled Rice
WANG Tseng-hsing,CHEN Ming-fen,LU Shin
2011, 32(15):  20-24.  doi:10.7506/spkx1002-6630-201115005
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Resistant starch is difficult to digest due to its physical characteristics, which can play important roles in blood glucose regulation, body weight control, cancer prevention and other physiological activities. Resistant starch has been classified into four categories depending on resistance causes. Type III resistant starch (RSIII) is a retrograded and non-granular starch that can be generated by various types of processing. In this study, the formation of RSIII in boiled rice was explored based on acid treatment and pullulanase treatment. Both treatments could increase the content of resistant starch in boiled rice. Differential scanning calorimetry analysis revealed increased initial pasting temperature, phase transition peak temperature and phase transition enthalpy of starch in boiled rice due to the increased content of resistant starch. X-ray diffraction showed that crystal structure of resistant starch in boiled rice converted into Type V from Type A . Moreover, the resistant starch achieved by these treatments revealed excellent thermal stability.
Separation and Antioxidant Activity of Polyphenols with Different Polarities from Hovenia acerba Fruit
XIANG Jin-le,LI Zhi-xi, LI-Huan, WU Qing-hua,ZHENG Shu-yan
2011, 32(15):  25-29.  doi:10.7506/spkx1002-6630-201115006
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Different polyphenol extracts (crude methanol extract and its fractions soluble in ethyl acetate, chloroform, n-butanol and water) obtained from Hovenia acerba fruit stalks using organic solvents with different polarity were tested for their UV absorption characteristics in the range of 200-700 nm and polyphenol contents, and their antioxidant activity was assessed based on the ability to scavenge DPPH and ABTS free radicals and reduce ferric ions in vitro. The results indicated that liquid-liquid extraction was a successful method for separating polyphenols with different polarities. The crude extract and its different fractions had different spectral characteristics. A significant difference in total polyphenol content and antioxidant activity was observed among the crude extract and its different fractions. Four different fractions of the crude extract could be ranked in the following order: water-soluble fraction > n-butanol-soluble fraction > ethyl acetate-soluble fraction > chloroform-soluble fraction. Therefore, polar polyphenols were dominant in Hovenia acerba fruit stalks.
Pasting Properties of Carboxymethylated Product from Mechanically Activated Cassava Starch (Ⅱ)
TAN Yi-qiu,HUANG Zu-qiang,NONG Ke-liang
2011, 32(15):  30-33.  doi:10.7506/spkx1002-6630-201115007
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Cassava starch was subjected to mechanical activation for 60 min on a stirring-type ball mill. Carboxymethyl starch (CMS) was prepared by using activated cassava starch as the raw material, NaOH as the catalyst and ClCH2COOH as the etherification agent. The effects of temperature, CMS concentration, pH, electrolyte, storage time and shear stress on the viscosity of CMS paste were investigated. The results showed that the viscosity of CMS paste was relatively stable between 25 ℃ and 40 ℃, and revealed a gradual decrease at temperatures over 40 ℃. Meanwhile, the viscosity of CMS paste was increased with increasing CMS concentration. CMS paste revealed weak resistance to acid, alkali and salts, the highest viscosity in neutral medium and high sensitivity to NaCl, but was not steady at normal or low temperatures and close to Newtonian liquid.
Physico-chemical Properties and Thermal Oxidation Stability of Akebia trifoliata var. australis Seed Oil
JIANG Yan,DU Yan-xue,XIONG Hua,BAI Chun-qing,ZHANG Zhong,LI Jie
2011, 32(15):  34-38.  doi:10.7506/spkx1002-6630-201115008
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The physico-chemical properties and thermal oxidation stability of Akebia trifoliata var. australis seed oil extracted by hexane was evaluated in this paper. The results showed that the contents of crude fat and protein in the seeds of Akebia trifoliata var. australis were 39.33% and 17.97%, respectively. The acid value, peroxide value, p-anisidine value, iodine value and saponification value of the extracted oil were 1.28 mgKOH/g, 0.57 mmol/kg, 4.15, 74.12 gI2/100 g and 198.6 mg KOH/g, respectively. Gas chromatographic analysis indicated that the seed oil was rich in palmitinic acid, oleinic acid and linoleic acid, which altogether accounted for 93.73% of total fatty acids. In addition, the extracted oil revealed an absorption maximum at 212 nm and excellent thermal oxidation stability below 220 ℃.
Antioxidant Activity of Different Solvent Extracts from Rabdosia serra (Maxim.) Hara Roots
DONG Yi,LIN Lian-zhu,ZHAO Mou-ming
2011, 32(15):  39-42.  doi:10.7506/spkx1002-6630-201115009
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The extraction efficiency of soluble components from Rabdosia serra (Maxim.) Hara roots using seven kinds of solvents such as distilled water, 60% ethanol, aqueous ethanol, methanol, butanol, chloroform and ethyl acetate was explored. Meanwhile, total phenol contents and the abilities to scavenge DPPH and ABTS free radicals and to chelate Fe2+ of seven different extracts were also evaluated. The results showed that water and 60% ethanol extracts had better effectiveness in extracting soluble components from R. serra (Maxim.) Hara roots. In addition, the highest content of total phenols was detected in 60% ethanol extract. Moreover, 60% ethanol extract also revealed the best DPPH racial scavenging capacity (better than rosemary extract, bamboo extract and ascorbyl palmitate), the best ABTS+ · scavenging capacity (better than rosemary extract), and the best Fe2+ chelating capacity (better than rosemary extract, bamboo extract and rutin).
Quality Evaluation of Whole Wheat Flour Prepared from Hashi,, Black Wheat
QU Min
2011, 32(15):  43-45.  doi:10.7506/spkx1002-6630-201115010
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Black wheat is rich in proteins, minerals, vitamin B and antioxidant activity. It has attracted more and more attention due to its special nutritional values in recent years. In this paper, the 1000-grain weight and milling of Hashi black wheat were analyzed. The physiochemical indexes, gluten content, gluten properties, rheological characteristics of whole wheat flour prepared from Hashi black wheat were studied. The results showed the 1000-grain weight was 30.11 g and the yield of flour was 75%. The contents of protein and dry and wet gluten was 18.56%, 28.79% and 64.55%, respectively, all of which were much higher than those of ordinary wheat flour. However, general gluten elasticity was observed. The dough water absorption rate, formation time, stability time, softening degree and silty value were 67.6%, 3.0 min, 2.1 min, 119 FU and 40, respectively. Moreover, the rheological characteristics of whole-wheat flour were weaker than those of ordinary wheat flour. Based on comprehensive judgment, Hashi,, black wheat was suitable for producing noodles. This investigation will provide a theoretical basis for the development and exploitation of black wheat in food processing.
Stability and Thermal Degradation Kinetics of Polyphenols from the Whole plant of Geum japonicum Thunb variant
OUYANG Yu-zhu,LI Yong,WU Dao-hong,GUO Hong-bin
2011, 32(15):  46-48.  doi:10.7506/spkx1002-6630-201115011
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In this paper, the effects of pH and temperature on the stability and thermal degradation kinetic characteristics of polyphenols from the whole plant of Geum japonicum Thunb variant were explored. Results indicated that the concentration of polyphenols was increased with increasing pH but decreased with increasing temperature. The thermal degradation of polyphenols from G.japonicum was a first-order kinetic model with an excellent linear relationship. The rate constants of thermal degradation reaction at 30, 40, 50, 60 ℃ and 70 ℃ were 0.0096, 0.0115, 0.0153, 0.0175 h-1 and 0.02 h-1, respectively. Its apparent activation energy was 15.6952 kJ/mol.
Effect of NaCl on Texture and Functional Characteristics of Mature Mozzarella Cheese
ZHANG Gang,REN Fa-zheng,TAN Feng,ZHANG Xiao-ying
2011, 32(15):  49-53.  doi:10.7506/spkx1002-6630-201115012
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In this study, the texture and functional characteristics of mature Mozzarella cheese prepared based on NaCl treatment performed at different process steps (before, at and after stretching in hot water) were evaluated. Results indicated that mixing of chopped curds with 6% NaCl before stretching in in hot water provided better functional properties. Based on the analysis of rheological properties, NaCl treatment at different process steps and NaCl amount were the possible causes of differences in texture and functional characteristics of Mozzarella cheese through changing casein structural strength.
Effect of Ultra High Pressure Treatment on Pectin Methylestrase and Perdoxidase in Orange Juice
CHEN He-qing,PAN Si-yi,WANG Ke-xing
2011, 32(15):  54-57.  doi:10.7506/spkx1002-6630-201115013
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In order to promote the industrialization of not from concentrated orange juice (NFCOJ), ultra-high pressure (UHP) sterilization was used for the inactivation of pectin methylesterase (PME) and peroxidase (POD) in orange juice. UHP treatment for fresh juice was performed at ambient temperature and pressures ranging from 200 to 600 MPa. The remaining activity of PME (pectin methylesterase) and POD (peroxide dismutase) in processed juice was measured by titration and UV-visible spectroscopy, respectively. The results showed both enzymes were slightly activated after 10-min treatment at 200 MPa. An obvious inactivation of PME and POD were observed when the pressure was higher than 300 MPa up to 600 MPa and the treatment time was prolonged, and the inactivation in the pressure range from 300 to 600 MPa was fitted well to the first-order kinetic model. Moreover, PME was more sensitive to pressure than POD.
Chemical Modification and in vitro Antioxidant Activity of Polysaccharides from Cordyceps militaris
QU Jin-yu,REN Da-ming
2011, 32(15):  58-61.  doi:10.7506/spkx1002-6630-201115014
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Crude Cordyceps militaris polysaccharides obtained by ethanol precipitation were purified by sequential column chromatographies on DEAE-cellulose 52 and Sephadex G-100. Further, purified Cordyceps militaris polysaccharides were successfully modified by either sulfation, carboxymethylation or acetylation and their antioxidant activity and that of their modification products were comparatively assessed based on the ability to in vitro scavenge superoxide anion, hydroxyl and alkyl free radicals. Carboxymethylation showed the largest degree of substitution for Cordyceps militaris polysaccharides, followed by acetylation and sulfation. Three different modification products revealed different antioxidant activities. Sulfation and carboxymethylation could obviously increase the antioxidant activity of Cordyceps militaris polysaccharides and result in the highest increase of respectively 95.19% and 73.58% in the scavenging rate against alkyl radical, followed by hydroxyl and superoxide anion radicals. A decrease in the ability to scavenge superoxide anion, hydroxyl and alkyl free radical, however, was observed after acetylation. Therefore, the antioxidant activity of polysaccharides from Cordyceps militaris can be improved remarkably through appropriate chemical modifications.
Mass Spectral Analysis of Phosphorylated Peptides Formed under Dry Heating Conditions
TU Zong-cai,WANG Hui,CHEN Gang,LIU Cheng-mei,LIU Guang-xian,XIAO Hui
2011, 32(15):  62-65.  doi:10.7506/spkx1002-6630-201115015
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Two peptide models such as peptide A and peptide B containing serine (S), threonine (T) and tyrosine (Y) were built. The phosphorylation of both peptides was carried out under dry heating conditions. The phosphorylation sites were determined using FT-ICR MS and LTQ-ETD MS/MS. FT-ICR analysis revealed one phosphorlyated site in either peptide under dry heating conditions. In addition, LTQ-ETD MS/MS analysis revealed obvious characteristic peaks of phosphorylated S and Y in peptide A. It was difficult to determine the phosporlyation of T due to the overlapped characteristic peaks of phosphorylated Y and T. However, the LTQ-ETD MS/MS spectrum of peptide B only revealed the phosphorylation of S without the phosphorylation of T. In summary, S and Y were easier to be phosphorylated than T in the same peptide under dry heating conditions.
Effect of Zinc on Antioxidant Activity of Lycium Extract
JIN Li-e,WANG Xiao-juan,YAN Guo-lan
2011, 32(15):  66-69.  doi:10.7506/spkx1002-6630-201115016
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In order to solve the problem that the antioxidant activities of natural extracts are weaker than those of synthetic antioxidants, the effect of zinc ions on the antioxidant activity of lycium extract was explored. The antioxidant activity of ethanol extract from lycium in the presence of zinc chloride, zinc gluconate or zinc acetate was evaluated by lipid oxidation, β-carotene bleaching, DPPH radical scavenging capacity and superoxide anion radical scavenging capacity. Due to different antioxidant mechanisms, the antioxidant activity of ethanol extract from lycium could be affected by zinc ions. The complex between zinc acetate and lycium extract revealed the strongest scavenging capacity against DPPH and superoxide anion free radicals, with a scavenging rate of 85% and 20%, respectively when the complex concentration was 800 mg/L. The complex between zinc gluconate and lycium extract showed the strongest inhibitory effect against lipid oxidation. In contrast, the complex between zinc chloride and lycium extract was the strongest in inhibiting β-carotene oxidation. Different new absorption peaks in UV-visible spectra of these complexes were observed, suggesting that new substances were generated.
Antioxidant Effect of Total Flavonoids from Zanthoxylum bungeanum Seeds
ZHANG Yu-si,GONG Zhu-nan,SHI Xue-ping
2011, 32(15):  70-73.  doi:10.7506/spkx1002-6630-201115017
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The antioxidant effect of crude total flavonoid extract from Zanthoxylum bungeanum seeds obtained by extraction with 60% ethanol aqueous solution and its purified counterpart obtained by adsorption on type AB-8 macroporous resin was evaluated by DPPH radical scavenging, total reducing power, total antioxidant capacity and anti-lipoperoxidation assays. The results showed that purified total flavonoids from Zanthoxylum bungeanum seeds had stronger antioxidant effect than BHT at the same concentrations. Crude and purified total flavonoids from Zanthoxylum bungeanum seeds indicated a noticeable increase with increasing concentration and a positive correlation between their total antioxidant activity and concentration. Crude and purified total flavonoids from Zanthoxylum bungeanum seeds could inhibit lecithin phospholipid liposome peroxidation induced by Fe2+ in a concentration-dependent fashion. In addition, crude total flavonoid extract from Zanthoxylum bungeanum seeds showed higher antioxidant effect than its purified counterpart.
Morphological Analysis of Common Edible Starch Granules by Scanning Electron Microscopy
WANG Shao-qing,WANG Lin-lin,FAN Wen-hao,CAO Hong,CAO Bao-sen
2011, 32(15):  74-79.  doi:10.7506/spkx1002-6630-201115018
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The ultrastructural morphology of common edible starch granules was analyzed by scanning electron microscopy (SEM). Starch granules under investigation were observed to have different shapes such as tube-like, stick-like, ball, flat-disk-like, complex type, polyhedron with smooth or pointed edges and corners and kidney-like and were classified according to these shapes. Meanwhile, a detail analysis was performed on the morphological characteristics of each type of starch granule in this study. Accordingly, the development rules for different starch granule shapes were summarized for further research on the morphology of starch granules. The gallery for the microscopic morphology of edible starch granules presented in this study is a reliable reference for the product quality supervision of domestic starch.
Mathematical Modeling of Thin-layer Drying of Red Dates (Ziziphus jujuba Mill)
LIU Kun,LU Zhou-min,BAO Rong,ZHAO Jia-qi,JIAO Wen-yue
2011, 32(15):  80-83.  doi:10.7506/spkx1002-6630-201115019
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In order to explore the drying regularity of red dates and provide a theoretical foundation for the drying of red dates, the drying characteristics of red dates were evaluated in a laboratory scale dryer. The drying experiments were carried out at 50, 60 ℃ and 70 ℃ at a constant air velocity. Seven commonly used thin-layer drying mathematical models were selected and used to fit the experimental data using non-linear regression analysis for establishing a suitable mathematical model that describes the drying of red dates. The results indicated that the drying process involved two stages, acceleration phase and deceleration phase, without a constant-rate phase. The performance of different drying models was investigated by comparing their coefficients (R2), chi-square values (χ2) and root mean square errors (RMSE). Among these models, the Page model was the most suitable model for describing the drying curve of red dates with a R2 of 0.99921, χ2 of 0.0088687 and RMSE of 0.0082514. The effect of drying air temperature on the rate constant and coefficient of the Page model was also explored. Therefore, this model can adequately describe the change regulation of water content according to the comparison of experimental values and predicted values.
Purification and Antioxidant Activity in vitro of Polysaccharide from Apostichopus japonicus Longitudinal Muscle
ZHANG Jian,WANG Mao-jian,GENG Yue,CHEN Tao,ZHAO Yun-ping,LIU Jing-xi,GAO Ji-qing
2011, 32(15):  84-87.  doi:10.7506/spkx1002-6630-201115020
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Objective: To separate and purify an antioxidant polysaccharide fraction from Apostichopus japonicus longitudinal muscle and to measure the abilities of the fraction and its sulfated counterpart to scavenge hydroxyl and superoxide anion free radicals. Methods: The separation and purification procedure was made up of papain hydrolysis, deprotenization with trichloroacetic acid, and Sephacryl S-400 gel filtration chromatography. The resulting fraction with higher free radical scavenging activity was selected for further studies including infrared spectral analysis and determination of molecular weight and sulfate content. Meanwhile, the fraction was sulfated, and its free radical scavenging activity was compared with that of its sulfated counterpart. Results: The obtained polysaccharide revealed an acidic glycosaminoglycan structure, whose relative molecular weight, sulfate content and substitution degree were 676 kD, 10.98% and 0.285, respectively. Its sulfated counterpart had a sulfate content of 17.43% and a substitution degree of 0.360. Both of them had certain antioxidant activity to scavenge hydroxyl and superoxide anion free radicals, and the antioxidant activity of the sulfated polysaccharide was stronger. Conclusion: Sulfation can result in an increase in the sulfate content, substitution degree and antioxidant activity of the polysaccharide fraction with higher from Apostichopus japonicus longitudinal muscle.
Antibacterial Mechanisms of Fructus mume Extract against Listeria innocua
GENG Fei,WANG Wei,ZHOU Tao
2011, 32(15):  88-93.  doi:10.7506/spkx1002-6630-201115021
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The antibacterial mechanisms of ethanol extract from Fructus mume (prepared by reflux extraction with 95% ethanol and subsequent rotary evaporation until a concentration of 1 g/mL, namely raw material weight/condensed extract volume ratio = 1:1) against Listeria innocua were assayed by flow cytometry. The minimum inhibitory concentration (MIC) of the extract against L. innocua was 0.625 mg/mL. In the presence of the extract at different concentrations such as 1, 2 and 4 MICs, the changes of forward scatter (FSC) light, DNA content, membrane potential, cell cycle, Ca2+ and Annexin V-FITC/PI double staining of L. innocua were analyzed by flow cytometry. The results showed that the extract could inhibit L. innocua by destroying cell membrane system and blocking DNA synthesis.
Prebiotic Function of Alpha-Galactooligosaccharides from Chickpea Seeds
HE Jin-yan,ZHANG Yun,LI Wei,SUN Yi,ZENG Xiao-xiong
2011, 32(15):  94-98.  doi:10.7506/spkx1002-6630-201115022
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Crude chickpea extract was obtained from chickpea seeds by extraction with 50% ethanol aqueous solution by shaking and purified by medium-pressure activated carbon-diatomite column chromatography to obtain chickpea α-galactooligosacchardies (α-GOS) with different purities. The prebiotic function of α-GOS was evaluated by anaerobic fermentation method in vitro against human fecal bacteria and fluorescence in situ hybridization (FISH). The results demonstrated that α-GOS in chickpea was an efficient proliferation factor to beneficial bacteria such as Bifidobacterium spp. and Lactobacillus-Enterococcus spp., and an inhibitory factor to harmful bacteria such as Bacteroides prevotella group and Clostridium histolyticum group. During the anaerobic fermentation in vitro, the bacterial composition was affected by the addition of chickpea α-GOS. However, total bacterial number had no difference. In addition, the sample with the highest content of α-GOS (>90%) showed the highest prebiotic index (PI, 2.00). The PI of samples containingα-GOS at the content of 70%-80% and 80%-90% and crude chickpea extract were 1.39, 1.73 and 0.89, respectively, while the PI of the control sample without saccharide addition was -0.29. Therefore, α-GOS in chickpea had an excellent prebiotic function.
Application of Ultra-high Pressure Treatment to Extend the Shelf-life of Smoked Ham
HAN Yan-qing,SUN Xin-sheng,LIU Deng-yong,XU Xing-lian,ZHOU Guang-hong
2011, 32(15):  99-102.  doi:10.7506/spkx1002-6630-201115023
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In order to understand the effect of ultra-high pressure (UHP) treatment on the shelf-life, quality and nutritional index of low-temperature smoked ham, the slices of vacuum-packaged smoked ham were subjected to UHP (400 and 600 MPa) treatments at 22 ℃ for 10 min prior to storage at 4 ℃. Total counts of spoilage microorganisms in UHP-treated and control hams were determined after 0, 1, 30 days and 90 days of storage. In addition, TBARS and free fatty acids were assayed and sensory analysis was performed. The results indicated that UHP treatment could effectively inactivate Enterobacteriaceae, Brochothrix thermosphacta, Pseudomonads, moulds and yeasts in smoked ham. Some lactic acid bacteria were the final dominant spoilage bacteria in smoked ham and revealed strong resistance to high-pressure treatment. The content of saturated fatty acids slightly increased, but the content of unsaturated fatty acids slightly decreased after UHP treatments. The changes of saturated and unsaturated fatty acids are pressure-dependent. At the beginning of cold storage, no change of TBARS value in smoked ham with and without high-pressure treatment was observed. However, at the late storage period, UHP-treated ham revealed increased TBSRS value. Therefore, UHP treatment can effectively extend the shelf-life of low-temperature smoked ham, and will not result in obvious changes of free fatty acids, color and lipid oxidation in smoked ham during storage 4 ℃, thereby better maintaining free fatty acid composition as well as original product quality and taste.
Comparative Analysis of Antioxidant Activity in vitro and in vivo of Health Foods by ORAC Assasy
ZHAO Jian,SONG Liang-nan, LIU Wei,WEN Jing
2011, 32(15):  103-108.  doi:10.7506/spkx1002-6630-201115024
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Objective: To explore the antioxidant activity of health foods in vivo and in vitro by ORAC (oxygen radical absorbance capacity) fluorometric assay and to carry out correlation analysis. Methods: The antioxidant activities of vitamin C and 3 health foods were evaluated in trolox equivalent antioxidant capacity. Results: A correlation between the in vivo and in vitro antioxidant activities of health foods was observed. The antioxidant activity of samples whose in vitro antioxidant activity was larger than the gavage dose of 25μmol Trolox/kg body weight for mice was determined as positive in mice after oral administration for 30 consecutive days. Conclusion: Under certain conditions, a correlation between the in vivo and in vitro antioxidant activities of health foods determined by ORAC exists, which can be used for speculating the antioxidant activity in vivo of heath foods by ORAC determination in vitro.
Quantitative Structure-Activity Relationship Studies on Relative Sweetness of Aniline Derivatives
ZHU Li-lan
2011, 32(15):  109-112.  doi:10.7506/spkx1002-6630-201115025
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In this article, a novel connectivity index (mLtv) was established by extending Kier,s connectivity index (mXtv). The quantitative structure-activity relationship (QSSR) between the relative sweetness (RS/B) of 20nitroaniline and cyanoaniline derivatives and mLtv was explored using multivariate statistical regression. Based on leaps-and-bounds regression analysis, an optimal binary QSAR model was set up. The traditional correlation coefficient (R) and cross-validation correlation coefficient (Q2) of leave-one-out (LOO) were 0.943 and 0.844, respectively. These results demonstrated that the model is highly reliable and has good prediction capability. Meanwhile, it was better than that of Kier,s connectivity index. Moreover, the model can be explained by the AH-B-W sweetness theory of Shallenberger and Kier.
Preparation of Antioxidant Peptides from Naked Oat Globulin by Alkaline Protease Hydrolysis
ZHANG Mei-li,LIN Rui,GUAN Wen-di,MASARINA
2011, 32(15):  113-116.  doi:10.7506/spkx1002-6630-201115026
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Naked oat globulin was prepared by Osborne,s method and hydrolyzed by alkaline protease. The antioxidant peptides in the hydrolysate were purified by Sephadex G-25 gel filtration chromatography and their molecular weights were determined. The scavenging capacity of each purified fraction against hydroxyl, superoxide anion and DPPH free radicals was also determined. The results indicated that two fractions were obtained from hydrolyzed naked oat globulin and named as fraction I and fraction II. The molecular weight ranges of fraction I and fraction II were 10738-133929 and 114-861 D, respectively. In addition, fraction II had higher scavenging effect against hydroxyl radicals (IC50 = 0.589 mg/mL), superoxide anion radicals (IC50 = 1.783 mg/mL) and DPPH radicals (IC50 = 0.095 mg/mL) than fraction I and the hydrolysate.
Correlation and Applicability of Different Methods for Determining Protein Hydrophobicity
ZENG Mao-mao,WANG Xiao,CHEN Jie
2011, 32(15):  117-120.  doi:10.7506/spkx1002-6630-201115027
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Proteins regularly used in foods such as soy protein isolate (SPI) and whey protein as well as their hydrolysates were selected as the experimental subjects to explore the correlation and applicability of different methods for determining protein hydrophobicity. The results indicated that ANS (1-anilinonaphthalene-8-sulfonic acid) fluorescent probe method was an appropriate method for measuring the hydrophobicity of various kinds of proteins and their hydrolysates (DH <23); CPA (cis-parinaric) fluorescent probe method was not suitable for determining proteins with relatively weak hydrophobicity; reverse-phase high performance liquid chromatography method was a good method for proteins with relatively moderate and strong hydrophobicity; the linearity of surface tension method had shortcomings when the hydrophobicity was characterized by gas-liquid interface parameters. All of these investigations provided a theoretical basis for determining hydrophobicity in food protein systems.
Comparative Studies on Rheological Properties of Mayonnaise Samples
YANG Shu,GAO Xin,YU Tian,XU Jia-chao,FU Xiao-ting
2011, 32(15):  121-125.  doi:10.7506/spkx1002-6630-201115028
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Four kinds of mayonnaise samples were tested for their basic chemical composition, rheological properties and sensory characteristics. Static and dynamic rheological tests showed that all investigated mayonnaise samples were thixotropic and pseudoplastic and had weak gel-like properties. According to these results, kewpie mayonnaise had the best rheological and sensory properties followed by kewpie mayonnaise (2005), kewpie sweet mayonnaise and kewpie thousand island mayonnaise.
Antioxidant Activity of Eucommia ulmoides Oliv. Leaves Grown in Three Areas
ZHANG Qiang,SU Yin-quan,LI Xiu-hong
2011, 32(15):  126-129.  doi:10.7506/spkx1002-6630-201115029
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The antioxidant activities of aqueous extracts from Eucommia ulmoides Oliv. leaves grown in Xinjiang, Sichuan and Shaanxi were assayed based on DPPH radical scavenging capacity, hydroxyl radical scavenging capacity, anti-lipid peroxidation activity, metal ion chelating capacity and reducing power with BHT, vitamin C and vitamin E as the positive controls. Their total phenol contents were also determined. Eucommia ulmoides Oliv. leaves grown in Sichuan and Shaanxi had higher total phenol content than those grown in Xinjiang. Meanwhile, the DPPH radical scavenging activity, hydroxyl radical scavenging capacity, metal ion chelating capacity and reducing power of the aqueous extracts from Eucommia ulmoides Oliv. leaves from Sichuan and Shaanxi were higher than those of the aqueous extract from Eucommia ulmoides Oliv. leaves from Xinjiang. However, the aqueous extract from Eucommia ulmoides Oliv. leaves from Xinjiang revealed higher anti-lipid peroxidation activity. E. ulmoides Oliv. leaves from Sichuan and Shaanxi showed a similarity in their antioxidant activity in vitro, but were different from E. ulmoides Oliv. leaves from Xinjiang.
Properties of Acetylated Mung Bean Starch with Low Substitution Degree
CHU Li-jun, XIONG Liu,SUN Qing-jie
2011, 32(15):  130-134.  doi:10.7506/spkx1002-6630-201115030
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Acetylated mung bean starches with low substitution degree were prepared by esterification with glacial acetic acid, and their properties such as transparency, retrogradation, solubility, swelling power, viscosity and texture properties were studied. The results showed that the transparency, swelling power, solubility, trough viscosity and final viscosity of acetylated mung bean starch were increased and the gelatinization temperature, peak viscosity and breakdown were decreased when compared with native mung bean starch. Moreover, the gel properties of mung bean starch were improved after acetylation.
Antioxidant Activities of Resveratrol, Oxyresveratrol, Esveratrol, Mulberroside A from Cortex mori
WANG Yuan-cheng,WU Chun,CHEN Hu,ZHENG Ying,XU Li,HUANG Xian-zhi
2011, 32(15):  135-138.  doi:10.7506/spkx1002-6630-201115031
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Stilbene compounds can protect foods from oxidation and inhibit tyrosinase activity. Using arbutin, vitamin C (VC) and vitamin E (VE) as the reference substances, the antioxidant activities and radical scavenging capacities of 3 kinds of stilbene compounds such as resveratrol, oxyresveratrol and mulberroside A from Cortex mori were investigated. The results showed that the six investigated antioxidant substances ranked in the following order: VC > resveratrol > oxyresveratrol > VE > arbutin > mulberroside A in terms of their reducing power, VC > VE > oxyresveratrol > resveratrol > arbutin > mulberroside A in terms of their DPPH radical scavenging capacity, and resveratrol > oxyresveratrol > arbutin > mulberroside A > VC > VE in terms of their ABTS+ · scavenging capacity. These results will promote their application in food additives.
Antioxidant Stability and Functional Properties of Egg White Peptides
NIU Hui-hui, MA Mei-hu, YANG Kun
2011, 32(15):  139-143.  doi:10.7506/spkx1002-6630-201115032
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The antioxidant stability and functional properties (emulsifying capacity, water absorbing capacity and oil absorbing capacity) of egg white peptides (EWP) obtained from lyophilized egg white by pepsin hydrolysis were measured with respect to temperature and pH. The results showed that the scavenging capacities of EWP against hydroxyl, superoxide anion and DPPH free radicals were all increased with increasing EWP concentration. Meanwhile, temperature and pH had a great impact on the antioxidant activity of EWP. The storage of EWP at pH 12.0 for 4 h could result in the loss of antioxidant activity. Moreover, EWP also revealed excellent emulsifying properties, water absorbing capacity and oil absorbing capacity. All of these investigations are benefit for its application in the food and cosmetic industries.
Gelation Characteristics and Rheological Behavior of Semen Euryale Protein Isolate
ZHOU Xiang-yun,CHENG Qi,LI Chun-yun,WANG Li-mei,QI Bin
2011, 32(15):  144-147.  doi:10.7506/spkx1002-6630-201115033
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Semen Euryale protein isolate (SEPI) was prepared to explore its gelation characteristics and rheological behavior. The protein concentration for the lowest gelation endpoint (LGE) was determined to be 5 g/100mL. Meanwhile, the effects of SEPI concentration and pH on gel formation were investigated and the effects of standing time and sucrose amount on the rheological behavior of SEPI solution were also explored. The results indicated that prolonged standing time could result in weak hydration of SEPI solution, enhanced protein-protein interactions and increased apparent viscosity of SEPI solution. In addition, the addition of sucrose also could lead to the increase of apparent viscosity and the decrease of mobility, thereby improving the stability of SEPI solution.
Bioengineering
Catalytic Activity Improvement of Acid-stable Alpha-Amylase from Hyperthermophilic Thermococcus siculi HJ21 by Site-directed Mutagenesis
YAO Ting,LI Hua-zhong,FANG Yao-wei,LU Zhao-xin,WANG Shu-jun,JIAO Yu-liang,LIU Shu
2011, 32(15):  148-152.  doi:10.7506/spkx1002-6630-201115034
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Based on the analysis of hyperthermophilic acid-stable α-amylase gene from Thermococcus siculi HJ21 (TSA), site-directed mutagenesis of six amino acid residues could improve the catalytic activity of α-amylase. Five mutants with higher catalytic activity were identified as K98R, A109V, Y121S, V125L and Y184H, respectively. Subsequent recombination of the mutants produced a mutant enzyme named as TSAM-23. Compared with TSA, the catalytic activity of TSAM-23 was enhanced significantly. The catalytic activity and thermal stability of TSAM-23 at 90 ℃were increased by 3.75 times and 2.4%, respectively. TSAM-23 had an optimal pH of 5.0, which revealed a decrease of 0.5 when compared with TSA.
A Bacillus spp. Strain against Penicillium expansum: Screening, Identification, Phylogenetic Analysis and Activity of Extracellular Antibacterial Substances from It
KONG Wei-jia,WANG Yang,SHANG Nan,ZHANG Bao,LI Ping-lan
2011, 32(15):  153-157.  doi:10.7506/spkx1002-6630-201115035
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In order to obtain a Bacillus spp. that can protect post-harvest fruits from blue mould and patulin, plate confrontation test and double layer agar diffusion method were used for strain screening in this study. The Bacillus strain LPL-T12 isolated from oolong tea exhibited the best antibacterial effect, whose fermentation supernatant had an inhibitory zone diameter of (22.74 ± 0.44) mm against Penicillium expansum 3.3703. In addition, LPL-T12 was identified as Bacillus amyloliquefaciens through morphological observation, physiological and biochemical experiments, 16S rDNA sequence analysis and specific PCR amplification. After the fermentation supernatant of the strain was subjected to ammonium sulfate precipitation and dialysis against several different pore-size membranes, a thermosensitive protein with molecular weight of more than 8000 D was obtained based on antibacterial activity analysis, protease hydrolysis and heating treatment.
Predictive Modeling of Staphylococcus aureus Growth in Raw Milk
LI Bo,MAN Chao-xin,ZHAO Feng,YANG Shi-qin,LANG You,JIANG Ya-nan,JIANG Yu-jun
2011, 32(15):  158-162.  doi:10.7506/spkx1002-6630-201115036
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In this paper, the growth of S. aureus in raw milk at 15, 25 ℃ and 37 ℃ in winter, spring and summer was studied. The Logistic and Gompertz models were used to establish a model predict describing the growth of S. aureus in raw milk. The root mean square errors (RMSE) of the Gompertz model in winter, spring and summer were 0.0936, 0.1057 and 0.1032, respectively. The RMSE values of the Logistic model were 0.1498, 0.1926 and 0.1857 in three seasons. These results indicated that the Gompertz model can predict the growth rate of S. aureus more accurately than the Logistic model. Meanwhile, a square root model has been developed predicting the growth rate of S. aureus in raw milk as a function of temperature.
Effect of Initial pH on Mycelial Growth and Intracellular Nucleoside Production of Paecilomyces tenuipes in a 30 L Fermentor
GUI Lin,GE Fei,ZHOU Xiao-nan,ZHOU Quan
2011, 32(15):  163-166.  doi:10.7506/spkx1002-6630-201115037
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Effect of initial pH on the mycelial growth and intracellular nucleoside production of Paecilomyces tenuipes was studied in a 30 L fermentor during submerged fermentation. The results showed that the optimal initial pH was 6.5. The maximal biomass reached up to 28.7 g/L and the maximal nucleoside production was up to 5.94 mg/g. The maximal biomasses corresponding to different initial pH values such as 7, 6, 5.5, 5 and 4.5 were 26.4, 27.3, 23.6, 21.2 mg/g and 18.5 mg/g, respectively, which were achieved on the 9th, 10th, 11th, 11th days and 13th days of fermentation and the corresponding maximal nucleoside production was 5.27, 5.51, 4.89, 4.29 mg/g and 4.05 mg/g, respectively, which was observed on the 11th, 11th, 11th, 13th days and 13th days. Therefore, the best mycelial growth intracellular nucleoside production could be achieved by initial pH adjustment.
Fermentation Conditions and Sugar Metabolism of High-sugar Cane Juice
LI Dan,YU Shu-juan,LIU Dong-mei
2011, 32(15):  167-172.  doi:10.7506/spkx1002-6630-201115038
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In this study, the fermentation conditions of high-sugar (> 25 °BX) cane juice with a yeast strain having good resistance to alcohol and sugar were optimized by one-factor-at-a-time and orthogonal array design methods for maximizing alcohol production. The results indicate that the alcohol content in fermentation broth at the end of fermentation was up to 19.02% under the following optimal conditions: initial brix of fermentation liquor of 30 °BX, fermentation pH of 4.5, fermentation temperature of 30 ℃ and inoculation amount of 10%, which was much higher than that obtained by ordinary fermentation (10%-15%). Sugar utilization was also investigated at different brix levels during the fermentation process. When the brix was 30°BX, sugars could be fully utilized. However, fructose could not be utilized at the brix level of 35°BX. Moreover, neither fructose nor glucose could be utilized at the brix level of 40°BX. In fermentation broth, the osmotic pressure of sugars had a negative linear relationship with fermentation time and a negative linear relationship between sugar consumption rate and initial brix level was also observed.
Culture Conditions for SOD Production by Streptococcus thermophilus
WANG Xing-hua,CHEN Yue
2011, 32(15):  173-176.  doi:10.7506/spkx1002-6630-201115039
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The effects of temperature, culture time and plant extract, an aqueous extract obtained from mixed Lycium barbarum and Eleutherococcus senticosus at a ratio of 1:1 (m/m) and concentrated by rotary evaporation until a concentration of 1. 0 g/mL (total material weight/concentrated extract solution volume ratio) on the production of superoxide dismutase (SOD) by liquid shake-flask fermentation of Streptococcus thermophilus were studied using completely randomized design. Experimental data processing was carried out using analysis of variance (ANOVA) and regression analysis. The ANOVA results showed that: 1). The effect of culture temperature on SOD production was highly significant (P<0.01); when the culture temperature was 41 ℃, the highest SOD yield was 901.667 U/g wet cells. 2). The effect of culture time on SOD production was also highly significant (P<0.01); when the culture time was 48 h, the highest yield of SOD was 932.6667 U/g wet cells. 3). The effect of plant extracts on SOD production was significant (P<0.01); when plant extract addition was at 8%, the highest SOD yield was 1347.0000 U/g wet cells. Therefore, the optimal culture conditions that can maximize SOD yield and result in a higher input-to-output ratio were culture temperature at 41 ℃, fermentation duration of 24 h, and 8% plant extract. The regression analysis showed no significant correlation between SOD production and culture temperature (P>0.05). SOD production (Y) showed a highly significant linear relationship with plant extract amount or culture time, and the corresponding regression equations were Y = 865.033 + 52.383X (P<0.01) and Y = 238.757 + 17.346X (P<0.01), respectively.
Isolation and Identification of Limonin-degrading Strains Isolated from Fermented Grains during Vinegar Fermentation
JI Xue-fang,SHI Jun-ling,ZHANG Jin-hua
2011, 32(15):  177-181.  doi:10.7506/spkx1002-6630-201115040
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Five strains with stronger limonin-degrading ability named as CS1, CS2, CS3, CS4 and CS5 were isolated from fresh fermented grains of vinegar. Among them, strain CS4 exhibited the highest limonin degradation rate of (58.86 ± 2.81)% and the highest enzyme activity of (120.09 ± 1.32) U/mL in fermentation broth. On the basis of their morphological, physiological and biochemical characteristics and 16S rDNA gene sequence, all of the 5 strains were identified as Bacillus genus, including 2 Bacillus siamensis strains, 1 Bacillus amyloliquefaciens strain, 1 Bacillus pumilus strain and 1 Bacillus tequilensis strain that had the highest limonin-degrading capability (strain CS4).
Effect of Disulfide Bond on Anti-Listeria innocua LIN3 Activity of Enterocin A
ZHAO Ai-zhen,XU Xing-ran,HAN Wen-yu
2011, 32(15):  182-185.  doi:10.7506/spkx1002-6630-201115041
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Based on the amino acid sequence of Enterocin A, two cysteine substitution mutants, Enterocin A (C14S) and Enterocin A (C47W) were designed and obtained in E. coli expression systems. The agar diffusion assay was used to test the anti-Listeria innocua LIN3 activity of the mutants, recombinant Enterocin A and β-mercaptoethanol-reduced recombinant Enterocin A. Recombinant Enterocin A with His-tag at N-terminus revealed stronger antibacterial activity, while GST-Enterocin A revealed a significant decrease in antibacterial activity. The two mutants andβ-mercaptoethanol-reduced recombinant Enterocin A with destroyed disulfide bonds exhibit no detectable antibacterial activity. Therefore, disulfide bonds are essential for the antibacterial activity of Enterocin A.
Non-alcoholic Beer Production by Saccharomycodes ludwigii
LIU Yang,LI Hong,DU Jin-hua
2011, 32(15):  186-190.  doi:10.7506/spkx1002-6630-201115042
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In this study, the colonies of Saccharomycodes ludwigii were observed to have a cream-colored, translucent, glossy, humid and smooth surface with middle bulge and regular fringe, and the cells were large and lemon-shaped with budding at both ends. Saccharomycodes ludwigii could ferment 89.9% fructose and 91.9% glucose and its rate of sucrose utilization was 100%, but it could ferment neither maltose nor maltotriose. Saccharomycodes ludwigii was used for producing non-alcoholic beer. We determined the main physicochemical indices and main flavor compounds in final the fermentation broth. The results indicated that Saccharomycodes ludwigii fermented wort produced a lower alcohol content, which was approximately 6 times less than that of common brewer s yeast fermentation under the same conditions. When the original wort concentration was lower than 8 °P, the alcohol content of prepared beer was lower than 0.5% (V/V). The main flavor compounds were identical to those in common beers. Compared with the non-alcoholic beer available in markets, the obtained non-alcoholic beer had fewer esters, no obvious difference in high-grade alcohol and similar taste.
Dominant Microflora Analysis of Tibetan Kefir Strain TK3 from Henan
GAO Jie,ZHANG Jia-jia,GU Feng-ying,ZHANG Xiao-yan,SU Zhong-rui,RUAN Hui,HE Guo-qing
2011, 32(15):  191-195.  doi:10.7506/spkx1002-6630-201115043
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Microflora analysis of Tibetan kefir strain TK3 from Henan was conducted in this paper. The microstructure was observed under a scanning electron microscope. The strain TK3 was composed of Lactobacillus and yeast, and attached to the matrix. Physiological and biochemical tests, and partial 16S rDNA (bacteria) and 26S rDNA (yeast) sequence identification revealed that the dominant microbial species in TK3 were Leuconostoc lactis, Lactococcus lactis, Lactobacillus plantarum, Kazachstania unispora, Kluyveromyces marxianus, and Kazachstania exigua, which presented in fermented milk in the order of magnitude of 107, 107, 107, 106, 106 CFU/mL and 107 CFU/mL, respectively. Moreover, the numbers of these microbial species remained stable after 7 days of storage at 4 ℃.
Isolation and Identification of Culturable Microorganisms in a 10-Year-Old Fermented Pu-erh Tea
PENG Xi-chun,YU Miao
2011, 32(15):  196-199.  doi:10.7506/spkx1002-6630-201115044
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It has been known that microbial species and quantity have a great influence on the quality of Pu-erh tea during its storage. In this study, four types of selective media were used to culture microorganisms in a 10-year-old fermented Pu-erh tea. The colonies of microorganisms than can grow in each medium were counted. Then, microbial isolation and morphological identification under a microscope were performed. 16S rRNA sequence analysis was used for further identification. The results showed that the total bacterial count in the 10-year-old fermented Puer tea was approximately 4.3 × 103 CFU/g and the mold count was roughly20 CFU/g. Neither yeast nor actinomycete was observed. Seven bacterial strains were isolated and identified as gram-positive bacteria belonging to five species, namely Bacillus subtilis (2 strains), B. amyloliquefaciens (1 strain), B. licheniformis (2 strains), B. sporothermodurans (1 strain) and B. shackletonii (1 strain). Only two mold species such as Aspergillus niger and Penicillium chrysogenum were isolated and identified through microscopic observations.
Construction and Identification of an Anti-clenbuterol Single-chain Fv Library for Ribosome Display
LIU Xi-xia,SUN Yuan-ming,DONG Jie-xian,YANG Wu-ying,XIE Xi,WANG Hong
2011, 32(15):  200-204.  doi:10.7506/spkx1002-6630-201115045
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In order to construct a high-capacity ribosome display anti-clenbuterol single chain Fv (CBLscFv) library for the selection of high affinity scFv antibody, CBL-BSA immunogen was immunized to Balb/c mice. Spleen cells were isolated and total RNA was extracted by the Trizol method for cloning heavy chain and light chain gene by RT-PCR. VH and VL were rearranged randomly by SOEing (splicing by overlap extension). Finally, the elements T7 promoter, 3' stem loop structure, ribosome binding sites, spacers and 5' stem loop structure were screened in vitro. The constructed library was verified by blue/white screening and further sequencing. The results showed that the titer of antiserum from immunized mice for library construction was 1:128000. The heavy and light chain variable region genes were successfully amplified to be approximately 360 bp and 330 bp, respectively. The fragment of the constructed ribosome display library was approximately 1200 bp with a capacity of 1.75 × 1013. Meanwhile, sequence analysis was carried out using IMGT/V-QUEST database. The results showed that the heavy chain and light chain variable region genes were rearranged by mouse IG set, and the homology rates were more than 84%. Amino acid sequence alignment revealed a homology rate of 37.82% for heavy chain amino acid sequences and 39.09% for light chain amino acid sequences. The diversity was observed in VH-CDR3, VL-CDR1, VL-CDR2 and VL-CDR3. Therefore, a high-capacity ribosome display library with the function for antibody screening was successfully constructed.
Dynamic Changes in Main Enzyme Activities and pH during Pepper (Piper nigrum L.) Decortication by Bacillus licheniformis Fermentation
XIONG Hai-bo,HOU Yuan-yuan,LIU Si-xin,MIAO Zi-jian,LI Cong-fa
2011, 32(15):  205-208.  doi:10.7506/spkx1002-6630-201115046
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Static liquid-state Bacillus licheniformis fermentation was used for pepper decortication and compared with traditional water retting. Meanwhile, the dynamic changes of pectinases, xylanase, cellulase and pH during pepper decortication by the two methods were explored. The results showed that the changes of polygalacturonase (PG) and pectin lyase (PL) revealed a similar pattern with two activity peaks during both decortication processes. However, cellulase activity was low and the pectin esterase (PE) activity remained high. Similar pH changes were observed during both decortication processes pH was between 5 and 5.5 at the end of decortication. Xylanase activity showed two peaks in traditional water retting method and a gradual increase in the late stage of Bacillus licheniformis fermentation. Therefore, pectinase might play an important role during pepper decortication. In the early stage of decortication, PG and PL first acted on pectin substances and damaged the pectin complex structure, and then PE hydrolyzed pectin molecules to form pectic acid accompanied with pH decrease. Further, xylanase activity increased gradually in the late stage of decortication and as a result, hemicellulose was rapidly depolymerized. Therefore, pepper decortication was completed under the synergistic action of multiple enzymes.
Expression of Ampullarium crossean Cellulase Gene in Corprinus cinereus Driven by gpd Promoter from Flammulina velutipes
YANG Pei-zhou,GUO Li-qiong,LIN Jun-fang
2011, 32(15):  209-213.  doi:10.7506/spkx1002-6630-201115047
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In order to investigate the expression of multifunctional cellulase gene of Ampullarium crossean (mfc) in large filamentous fungi driven by glyceradehyde-3-phosphate dehydrogenase (gpd) promoter (Fvl) of Flammulina velutipes, a new eukaryotic expression vector containing F. velutipes gpd promoter (Fvl) and A. crossean cellulase gene (mfc) was constructed. The expression vector was inserted into the chromosome of tryptophan auxotrophic Corprinus cinereus by polyethylene glycol(PEG) mediation. The transformants were selected by PCR and Southern blotting. The transcription of mfc was confirmed by RT-PCR and the expression of mfc was further determined by measuring the activities of filter paper enzyme , carboxymethylcellulase and xylanase. The results showed that mfc driven by F. velutipes gpd promoter exhibited highly effective expression in engineered C. cinereus, and the strain with the highest cellulase activity was Cfvlm9, in which the filter paper enzyme, carboxymethylcellulase and xylanase activities were 21.5, 44 U/mL and 235 U/mL, respectively with 1.79, 1.6 and 2.97 fold increase as compared to the control strain.
Regulatory Effect of Probiotics on Intestinal Flora Disorder Evaluated by FISH-FC
WANG Jin,YANG Li-jie
2011, 32(15):  214-219.  doi:10.7506/spkx1002-6630-201115048
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Objective: To explore the effect of mixed Lactobacillus acidophilus and Lactobacillus plantarum cultures (1:1, V/V) on intestinal flora disorder in mice by fluorescence in situ hybridization combined with flow cytometry (FISH-FC) and to elucidate the regulation mechanisms. Methods: The inhibitory activity of the mixture on pathogenic bacteria was determined in vitro. Antibiotic-associated diarrhea mouse model was established by giving specific-pathogen-free (SPF) mice drinking water containing clindamycin hydrochloride at the dose of 2.8 mg/mL for 7 days. Predominant bacteria such as Enterobacteriaceae, C. coccoides-E.rectale and Bacteroides-Prevotella were quantified by FISH-FC method. After diarrhea was successfully induced, the model mice were administered with the mixture of Lactobacillus acidophilus and Lactobacillus plantarum at different amounts of 107, 108, 109 CFU/mL by gavage. Sterile saline was used as the control. Results: Compared with the control, the administration of the mixture containing Lactobacillus acidophilus and Lactobacillus plantarum could result in the fast recovery of disordered intestinal flora (P <0.01). The effective dose was 107 CFU/mL. Conclusion: Direct antimicrobial effect may be one of the mechanisms for regulating intestinal flora disorder.
Identification and Phylogenetic Analysis Based on gyrB and luxA of Photobacterium PB-P3.9
ZHOU Ming-xia,CHEN Yong-zhe,WANG Hui,CHEN Zhi,DENG Le
2011, 32(15):  220-224.  doi:10.7506/spkx1002-6630-201115049
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Photobacterium strain named PB-P3.9 was isolated from pork by streak plate method. Phylogenetic analysis based on the gyrB and luxA genes was performed. This strain was identified as Photobacterium phosphoreum according to its biological properties and sequence analysis. The gyrB and luxA genes revealed 99% and 98% homology when compared with standard strains. Phylogenetic tree construction based on the standard gyrB and luxA gene sequences published in GenBank was carried out using MEGA4.1 software package by neighbor-joining method. The results showed that this strain had the highest similarity with the standard strain NCIMB1279. Based on their similarities in phylogenetic tree and the growth conditions, it is possible that the isolated strain comes from a marine deep-sea fish such as NCIMB1279, NCIMB1275, NCIMB7 or ATCC11040T, or a middle-level seawater plankton.
Effects of Additives on Bromelain Activity
ZHAO Li-chao,WANG Yan,HE Feng-lin,CHEN Jie-lan,LIU Xin
2011, 32(15):  225-229.  doi:10.7506/spkx1002-6630-201115050
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Bromelain is easy to lose its activity during processing and storage. The effects of additives on bromelain activity were studied based on its relative enzyme activity and thermal inactivation kinetics. Meanwhile, different protective strategies for keeping the stability of bromelain during processing and storage were also discussed. The results showed that glucose, fructose and soluble starch could affect the stability of bromelain and fructose was the most powerful affecting factor followed by glucose and soluble starch. The protective mechanisms of metal ion chelators such as EDTA-2Na and sodium polyphosphate, preservatives such as sodium benzoate and reductants such as metabisulfite and β-mercaptoethanol on the activity of bromelain were different, but their application at appropriate amounts could increase bromelain activity. Metabisulfite revealed the best activation effect on bromelain. When the concentration of metabisulfite was 0.05%, the activity of bromelain could significantly improve and the relative activity of bromelain was 3.68. Moreover, the activity of metabisulfite-treated bromelain did not reduce to the original level until 3 days of storage.
Nutrition & Hygiene
Effect of Bovine Casein Glycomacropeptide on MUC2 Expression in Mice with Ulcerative Colitis
JIA Yu-chen,CHEN Qing-sen,FENG Yi-nan,XU Yi-jun,LI Yang
2011, 32(15):  230-233.  doi:10.7506/spkx1002-6630-201115051
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Objective: The effect of bovine casein glycomacropeptide (CGMP) on MUC2 expression in mice with ulcerative colitis (UC) was investigated to explore the therapeutic efficacy of CGMP for UC. Methods: Mice were randomly divided into four groups including normal control group, model control group, CGMP group and sulfasalazine (SASP) group. UC model establishment was carried out by enema administration of oxazolone. The mice in the model control and normal control groups were given regular feed, and the mice in the CGMP group and SASP group were administered with CGMP at the dose of 50 mg/(kg ·d) and SASP at the dose of 40 mg/(kg ·d) after for 5 consecutive days, respectively. The changes in body weights and disease activity index (DAI) were recorded every day. The colon was separated to conduct HE staining and MUC2 immunohistochemical staining and record visible lesion score. Results: CGMP could effectively alleviate ulcerative colitis and reduce visible lesions in the mouse colon. HE staining revealed integrated epithelial cells in the colon of CGMP-treated mice. Meanwhile, IHC staining confirmed that CGMP could promote the secretion of MUC2 in the mouse colon. Conclusion: CGMP can alleviate colon inflammation by promoting the secretion of MUC2 in the mouse colon to enhance the barrier protection of intestinal mucosa.
Sub-chronic Toxicity Evaluation of Sodium Selenite in Rats
HU Bin,CHEN Yi-zi
2011, 32(15):  234-238.  doi:10.7506/spkx1002-6630-201115052
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Objective: The aim of this study is to explore the sub-chronic toxicity of sodium selenite. Methods: Wistar rats were randomly divided into three groups and administered with sodium selenite at the doses of 0.470, 0.235 mg/kg and 0.118 mg/kg (1/25-1/100 LD50) for 12 consecutive weeks. Each rat was subjected to recovery observation for another 2 weeks after stopping administration of sodium selenite. The blood and major organs were harvested at the end of 12th and 14th week to investigate the effect of sodium selenite on the growth, histopathological change, blood routine index and blood biochemical index of rats. Results: Sodium selentie at the dose of 0.235 mg/kg revealed an obvious inhibitory effect on the growth of rats. Meanwhile, it also exhibited different influences on major organs, blood routine indexes and blood biochemical indexes. Histopathological examination indicated that the major organs including heart, liver, spleen, lung, kidney and intestine were damaged. Conclusion: Sodium selenite has sub-chronic toxicity to rats. The lowest adverse effect level of sodium selenite can be observed at the level of 0.235 mg/kg, and no adverse effect level of sodium selenite occurs at the level of 0.118 mg/kg. The damage to rats can result in partly reversible effect without any delayed toxicity in a short term.
Amino Acid Composition and Nutritional Evaluation of Semen Euryales from Different Regions
CHEN Rong,WU Qi-nan,SHEN Bei
2011, 32(15):  239-244.  doi:10.7506/spkx1002-6630-201115053
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The amino acid composition and nutritional evaluation of Semen Euryales harvested from 15 regions were analyzed using an automatic amino acid analyzer. The results showed the average content of total amino acids in 15 samples of Semen Euryales investigated was 103.33 mg/g, and of free amino acids 0.98 mg/g. All of these samples contained all kinds of essential amino acids in a balanced proportion, which was close to the recommended level by WHO/FAO. Among the essential amino acids found in Semen Euryales, the first limited amino acid was Lys. In addition, Glu and Leu were the principal amino acids. However, 15 different geographic origins differed obviously in the contents of Glu and Leu and could therefore be grouped into 5 categories. Further, the nutritional value of southern Euryale ferox grown in the Taihu Lake region of Jiangsu Province, China was not superior to northern Euryale ferox grown in Hongzehu Lake region of the same province in terms of the amino acid composition.
Effect of Feeding Diets Containing Different Oils to Broilers on Meat Quality and Fatty Acid Composition in Breast and Thigh Muscles
AN Wen-jun,ZHANG Li,ZHUANG Su,WANG Tian
2011, 32(15):  245-250.  doi:10.7506/spkx1002-6630-201115054
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The purpose of this study was to investigate the effect of adding different vegetable oils or fat to basal diet on the meat quality, cholesterol content and fatty acid composition of breast and thigh muscles of Arbor Acre (AA) broilers. Totally 648 one-day-old chickens were randomly divided into 6 groups: CON (fed basal diet mainly consisting of corn meal and soybean meal as normal control), SO (fed basal diet added with soybean oil as positive control), LO (fed basal diet added with lard as negative control), COP (fed basal diet added with commercial complex vegetable oil sample mainly containing palm oil), COC (fed basal diet added with commercial complex vegetable oil sample mainly containing coconut oil) and COV (fed basal diet added with commercial complex vegetable oil sample containing multiple vegetable oils). Each chicken was fed for 42 days. The results showed that: (1) Drip loss (24 h postmortem) of breast muscle in COP group was significantly increased (P < 0.05) and cooking loss of thigh muscle in COC group was significantly decreased (P < 0.05). (2) Breast ratio of unsaturated to saturated fatty acids in LO group was improved (P < 0.05); more n-3 PUFAs were determined in SO, LO, COP and COC groups (P < 0.05); compared with CON group, the contents of n-6 PUFAs in SO and COC groups were higher (P < 0.05) and the ratio of n-6 to n-3 PUFAs in the other four groups except COV group was lower (P < 0.05). (3) The content of cholesterol in breast muscle from SO group was lower than that in the other four groups except LO group (P < 0.05). These results indicated that the feeding vegetables oils and lard to broilers could increase PUFA content in the breast muscle and have no adverse effect on meat quality. Soybean oil could change the proportion of fatty acids in the breast muscle and reduce cholesterol level.
Protective Effect of Acid-insoluble Protein from Millet against CCl4-induced Liver Injury in Mice
XU Jie,WANG Chang-qing,ZHAO Chen-yong,FAN Ying,WANG Fei
2011, 32(15):  251-254.  doi:10.7506/spkx1002-6630-201115055
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In this paper, the protective effect of acid-insoluble protein from millet against CCl4-induced liver injury in mice was explored. The results indicated that serum ALT and AST levels and hepatic MDA content in mice treated with acid-insoluble protein from millet were significantly lower than those in mice from the liver damage model group (P <0.05). Meanwhile, abnormal morphology of mouse liver surface, necrosis of liver cells, steatosis and inflammatory cells infiltration were reduced by dietary administration with acid-insoluble protein from millet in a dose-dependent manner. Therefore, millet acid insoluble protein can protect mice from acute liver injury induced by CCl4.
Suppressive Effect of Cordyceps militaris on the Development of Nephropathy in Diabetic Rats
LI Bing, WANG Jing-feng,YANG Yan-cun, LI Xiao-lin, YANG Yu-hong, TENG Lai-bin, XUE Chang-hu
2011, 32(15):  255-259.  doi:10.7506/spkx1002-6630-201115056
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Objective: To explore the inhibitory function of Cordyceps militaris on the development of nephropathy in diabetic rats. Methods: Diabetic rat model was established by intraperitoneally injecting streptozotocin at the dose of 60 mg/kg. After the diabetic rats were administered with Cordyceps militaris at the dose of 400 mg/kg for 8 consecutive weeks, fasting blood glucose level, kidney index, the contents of microalbumin (mAlb) and β-N acetyl glucosaminidase (NAG) in urine, and the contents of blood urea nitrogen (BUN), creatinine (Cr) and uric acid (UA) in serum were determined. The mRNA expression of transforming growth factor-β1 (TGF-β1), transforming growth factor beta-receptor II (TGFβR II) and connective tissue growth factor (CTGF) in the kidney were evaluated by semi-quantitative RT-PCR. The expression of collagen IV and TGF-β1 protein in the kidney was determined by immunohistochemistry and Western blot analysis. Results: C. militaris could significantly reduce fasting blood glucose (P<0.05), kidney index (P<0.01), 24-h urine collection (P<0.01), the excretion of mAlb (P<0.01) and NAG (P<0.01) in urine, and serum BUN, Cr and UA levels (P<0.05) of diabetic rats. C. militaris administration resulted in a remarkably down-regulation of TGF-β1, TGFβR II and CTGF mRNA expression in the kidney of diabetic rats (P<0.01). Western blot and immunohistochemistry analyses revealed a reduction in the expression of TGF-β1 and collagen IV protein due to C. militaris administration. Conclusion: C. militaris has anti-hyperglycemic function and can improve kidney filtration function. The mechanisms of these functions may be due to the inhibited expression of TGF-β1, TGFβR II and CTGF as well as the reduced accumulation of collagen in the mouse kidney.
Synergistic Hypoglycemic Effect of Bioactive Components from Mulberry Leaves in Combination with Metformin in Diabetic Mice
XUAN Guang-shan,PAN Shi-jia,NAN Ji
2011, 32(15):  260-264.  doi:10.7506/spkx1002-6630-201115057
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Objective: To investigate the effects of respective combinations of three bioactive components from mulberry leaves including polysaccharides, flavonoids and alkaloids with metformin on the levels of blood glucose, glycogen, glucose tolerance in diabetic mice. Methods: A mouse model of experimental diabetes was established by intraperitoneal injection of streptozocin. Metformin alone or in combination with polysaccharides, flavonoids and alkaloids from mulberry leaves was intragastrically administered at a dosage of 100 mg/(kg ·d) once a day for 12 days to observe their effects on body weight and the levels of blood glucose and glycogen in diabetic mice. Results: Each of the three components from mulberry leaves could enhance the blood glucose-lowering effect of metformin in diabetic mice. Metformin plus mulberry leaf alkaloids exhibited the most powerful hypoglycemic effect, resulting in a 39.41% reduction in blood glucose level, which was increased by 5.13% when compared with metformin alone.
Effects of Ethanol and n-Butanol-soluble Extract from Herba Portulacae on Learning and Memory Performance in D-Galactose-induced Senile Mice
JIN Ying-zi,LI Ying-jun,ZHANG Hong-ying
2011, 32(15):  265-268.  doi:10.7506/spkx1002-6630-201115058
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Objective: To study the effects and mechanisms of ethanol extract and its n-butanol-soluble fraction from Herba Portulacae on learning and memory performance in senile mice induced by D-galactose. Method: Mice were randomly divided into 6 groups: control group, model group and n-butanol-soluble fraction treatment (0.5 g/(kg ·d) and 0.25 g/(kg ·d)) groups and ethanol extract treatment groups (1 g/(kg ·d) and 0.5 g/(kg ·d)) groups. Normal saline was given to control group once daily for 42 consecutive days by subcutaneous injection in the neck back, and 1 g/(kg ·d) D-galactose to the other 5 groups using the same administration route before intragastric administration of the same volume of distilled water and corresponding drugs (in aqueous solution) every afternoon during the administration period. Mouse learning and memory performance were tested by step-through test and water maze test, and MDA content and SOD and GSH-Px activities in the brain of senile mice were assayed. Results: Both dosages of n-butanol-soluble fraction could significantly improve mouse learning and memory performance (P <0.01), and the dosage of 0.5 g/(kg ·d) resulted in a significant increase in the activities of SOD and GSH-Px in the brain (P <0.05, P <0.01), and the other dosage significantly decreased MDA content in the brain (P <0.05). Meanwhile, ethanol extract from Herba Portulacae had a highly significant improving effect on mouse learning and memory performance (P <0.01) and significantly reduced MDA content in the brain (P <0.05). Conclusion: From these results, we concluded that ethanol extract and its n-butanol-soluble fraction from Herba Portulacae are capable of significantly improving senile mouse learning and memory performance. The possible mechanisms may be through increasing SOD and GSH-Px activities and decreasing MDA content in the brain. Furthermore, ethanol extract from Herba Portulacae is superior to its n-butanol-soluble fraction.
Effect of Royal Jelly on Learning and Memory Performance of Aged Rats
PENG You-rui,ZHONG Fang-xu,YANG Bo,GAO Rong-jing,SU Feng
2011, 32(15):  269-272.  doi:10.7506/spkx1002-6630-201115059
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Adult SD rats were used as experimental subjects to establish a subacute aging model by intraperitoneally injecting D-galactose. After the aging model was successfully established, the aged rats were administered intragastrically with royal jelly. The learning and memory of the rats in each group were evaluated by Morris water maze. The contents of monoamine transmitters such as norepinephrine (NE) and dopamine (DA) in the brain tissue were determined in a fluorescence spectrophotometer. Meanwhile, cerebral SOD activity and DNA content in the rats were also determined. The results showed that the learning and memory of aged rats revealed a significant decrease when compared with those of normal rats. The average latency of the rats from the model group exhibited an obvious extension, which was prolonged from 15.52 s to 21.62 s. Meanwhile, the number of traversing original platform was dropped obviously, which was dropped from 7.5 to 4.25 (P < 0.05). Moreover, the swimming track of the rats from the model group also exhibited a remarkable change. The contents of NE and DA, and the activity of SOD in the brain tissue of aged rats were significantly decreased; in contrast, the content of MDA was increased greatly (P < 0.05). On the other hand, the learning and memory of the rats from the royal jelly group were improved significantly when compared with that of aged rats from the model group. The average latency was shortened from 21.62 s to 14.34 s (P < 0.05), the contents of NE and DA in the brain and the activity of SOD were enhanced, but the content of MDA was dropped obviously. These results indicated that royal jelly can improve spatial learning and memory performance of aged rats and the contents of monoamine neurotransmitters as well as SOD activity, and reduce MDA content. Therefore, royal jelly can regulate the metabolism of monoamine transmitters to result in its anti-aging function and improve learning and memory capability.
Antarctic Krill Oil Improves Learning and Memory of Rats
LIU Yun,WANG Ya-en,LI Li-de,XU Kai,TIAN Dan,JIANG Guo-liang
2011, 32(15):  273-276.  doi:10.7506/spkx1002-6630-201115060
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Objective: To observe the effect of Antarctic krill oil on the improvement of learning and memory of rats. Methods: The effect of Antarctic krill oil and deep sea fish oil on learning and memory of rats was evaluated by Morris-water maze and Y-shaped maze methods. Results: Antarctic krill oil could significantly reduce the latency of escaping onto the platform, and increase the frequency of crossing the platform and the proportion of swimming time of rats in the target area of Morris-water maze. Y-shaped maze results indicated that Antarctic krill oil could significantly reduce the number required for achieving the goal and improve the correct response rate after 48 h. Conclusion: Antarctic krill oil can improve learning and memory of rats and the effectiveness is better than that of deep sea fish oil.
trans C18:1-induced HUVEC Endotheliocyte Damage by NOS-NO System
QIU Bin,LIU Rong,DENG Ze-yuan,FAN Ya-wei,LI Jing,HU Jiang-ning,LI Yu
2011, 32(15):  277-280.  doi:10.7506/spkx1002-6630-201115061
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In order to explore the mechanism of trans C18:1-induced endotheliocyte damage by NOS-NO system, the viability of human umbilical vein endothelial cells (HUVECs) subjected to trans C18:1 treatments at the concentrations of 50, 100, 200μmol/L and 400μmol/L for 24 or 48 h was determined by MTT assay. Meanwhile, the content of NO and the activity of NOS in HUVECs treated with trans C18:1 at the dose of 200μmol/L for 24 h were also determined using a commercial kit. Moreover, the viability of HUVECs subjected to treatments of trans C18:1 coupled with nitric oxide synthase inhibitor L-arginine methyl nitrite (LNAME) and/or nitric oxide donor (SNP) were also determined. The results indicated that trans C18:1 could decrease the viability of HUVECs in a dose- and time-dependent manner. The viability of HUVECs could be decreased by the combinatorial treatment of LNAME and trans C18:1 but increased by the combinatorial treatment of SNP and trans C18:1. trans C18:1 treatment could induce the secretion of NO and significantly decrease the activity of eNOS, but had no obvious effect on the activity of iNOS in HUVECs. Therefore, trans C18:1 treatment can reduce the secretion of NO through inhibiting eNOS activity, which suggests that the involvement of NOS-NO system is one of the important mechanisms of trans C18:1-induced HUVEC damage.
Effects of Several Kinds of Maillard Reaction Products on the Proliferation of Human Umbilical Vein Endothelial Cells
ZHOU Xiao-li,ZHANG Xiao-jing,TANG Wen,ZHOU Yi-ming
2011, 32(15):  281-284.  doi:10.7506/spkx1002-6630-201115062
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Several kinds of Maillard reaction products with the flavor of braised or roasted beef, chicken and pork. The effects of these Maillard reaction products on the proliferation of human umbilical vein endothelial cells (HUVEC) were evaluated by MTT assay. The results showed that all the investigated Maillard reaction products had an obvious inhibitory effect on the proliferation of HUVECs. Meanwhile, the Maillard reaction product with roasted flavor revealed the strongest inhibitory effect.
Effect ofα-Linolenic Acid from Silkworm pupa Oil on Experimental hyperlipidemia in Rats
WU Xiao-xia,LI Jian-ke,LIU Ying-li
2011, 32(15):  285-288.  doi:10.7506/spkx1002-6630-201115063
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Objective: To investigate the preventive and therapeutic effects of α-linolenic acid from silkworm pupa oil in hyperlipidemic rats. Methods: Hyperlipidemia in SD rats was induced by feeding high-fat diet. α-Linolenic acid from silkworm pupa oil was also fed to the model rats. The contents of serum triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and apolipoprotein AI (Apo A-I) were determined, and the activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were analyzed. Results: α-Linolenic acid from silkworm pupa oil could result in a significant decrease in the contents of TC and TG, and an increase in the contents of HDL-C and Apo A-I and the activities of LPL and HL in hyperlipidemia rat serum. Conclusion: α-Linolenic acid from silkworm pupa oil has significantly preventive and therapeutic effects in hyperlipidemia rats.
Reviews
Research Progress in Bioactivities of Carotenoid Metabolites
HE Qiang-qiang,HUI Bo-di,GONG Ping,LIN Kong-liang
2011, 32(15):  289-295.  doi:10.7506/spkx1002-6630-201115064
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Carotenoids have strong bioactivities in vivo. However, carotenoids can be finally decomposed into fragments to form metabolites in vivo. The bioactivities, metabolism and chemical conversion of those fragments have gained extensive attention. In the last two decades, many investigations have demonstrated that the decomposed fragments of carotenoids reveal strong bioactivities and effect on human health. Therefore, it is important to explore the bioactivities of carotenoids from foodstuffs. In this article, bioactivity studies on pro-vitamin A and non-pro-vitamin A carotenoids, such as β-carotene and lycopene, are reviewed with the aim of providing a reference for nutrition and food science.
Simulated Moving Bed Chromatography and Its Application Prospects in the Separation of Functional Components in Tea
HUANG Yong-dong,JIANG Yong-wen,JIANG He-yuan,WANG Bin
2011, 32(15):  296-302.  doi:10.7506/spkx1002-6630-201115065
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Simulated moving bed chromatography, developed in the 1960s, is a kind of continuous preparative chromatography with multiple advantages, such as improving product purity and recovery rate, increasing separation efficiency and reducing costs. This technology has been extensively used in the petrochemical, food and pharmaceutical industries, but has not yet been applied to separate functional components of tea. Current studies have demonstrated the successful separation of catechin by using simulated moving bed chromatography. In this paper, separation principles and application progress at home and abroad of simulated moving bed chromatography are summarized. Meanwhile, its application prospects in the separation of functional components from tea are also discussed. Therefore, simulated moving bed chromatography will become a major research direction for the preparation of catechin and theaflavin.
Research Progress in Prebiotic Properties of Edible Mushroom
ZHOU Bei-li,LIANG Qiang,ZOU Yan,MING Jian,ZHAO Guo-hua,
2011, 32(15):  303-307.  doi:10.7506/spkx1002-6630-201115066
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The balance of intestinal flora plays an important role in human health and disease prevention. Prebiotics are the most promising health foods because they can regulate the structure and number of intestinal flora. Mushroom extract can significantly modify intestinal flora composition, which reveals the promotion roles in the metabolism and proliferation of beneficial microorganisms such as Lactobacilli and Bifidobacteria, as well as the inhibitory effect on pathogenic bacteria such as E. coli, Clostridium and Salmonella. The major components with prebiotic function in mushroom are non-digestible polysaccharides.
Recent Advances in Studies on Molecular Biology Methods for Detecting Bacteria in Viable but Nonculturable State
LI Zheng-yi,JIA Jun-tao,ZHU Su-zhen,JIANG Ying-hui,FANG Bao-hai,LEI Zhi-wen
2011, 32(15):  308-311.  doi:10.7506/spkx1002-6630-201115067
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A number of bacteria have been reported to have the capability to enter a viable but nonculturable (VBNC) state as a response to environmental stress. Cell culture techniques often fail to detect bacterial cells in the VBNC state; however, molecular biology methods can improve the detection efficiency for VBNC cells. Among molecular biology methods for detecting bacterial cells in the VBNC state, the detection of specific DNA or mRNA is a common method and a gfp gene encoding green fluorescent protein has been used as an effective marker to examine VBNC state. Recently, a combinatorial method, designated as ethidium monoazide (EMA)-PCR method, has also been established to detect live/dead cells due to the selective penetration of EMA/PMA into dead cells in the presence of live cells. This detection method combined with the selectivity of EMA/PMA and the specificity of PCR is sufficient to detect viable cells and VBNC cells.
Research Progress of Lysinoalanine, a Harmful Substance in Food Processing
DONG Pan,ZHAO Yan,YANG You-xian,LI Jian-ke,TU Yong-gang
2011, 32(15):  312-316.  doi:10.7506/spkx1002-6630-201115068
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The generation of harmful substances during food processing is one of research focuses for food safety in recent years. Lysine can readily crosslink with cystine, serine, phosphoserine or dehydroalanine to form lysinoalanine when protein-containing foods are processed at high temperature or by alkali treatment. In this article, the formation conditions and mechanisms of lysinoalanine and its harmfulness on experimental animals and human body are summarized. The future research direction of lysinoalanine is also prospected.
Recent Advances in Research on Preparation Technologies and Applications of Tea Polyphenol Nanoparticles
HE Jin-lan,LUO Li-yong,ZENG Liang,
2011, 32(15):  317-322.  doi:10.7506/spkx1002-6630-201115069
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Tea polyphenols have multiple health benefits including antioxidant and antibacterial activities, cancer prevention, anti-radiation and immune enhancement. However, the application of tea polyphenols is often limited due to weak fat-soluble property, poor stability to oxidation, and reduced activity in alkaline solution. Tea polyphenol nanoparticles have greater advantages in size, fat solubility, stability, oxidation resistance, transdermal activity and other aspects than the ordinary tea polyphenol samples. Currently, tea polyphenol nanoparticles have been widely applied in the food, medicine and daily chemical industries. In this paper, the current preparation technologies and applications of tea polyphenol nanoparticales are reviewed and the future development trend is also proposed.
Market Status and Prospects of Chilled and Frozen Prepared Foods
LIU Xing-yan,CHEN An-jun,PU Biao
2011, 32(15):  323-328.  doi:10.7506/spkx1002-6630-201115070
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Due to the changes of living tempo, family size and economic conditions, the importance of prepared foods in food system is increasing. In this article, the domestic and international status of chilled and frozen prepared foods is summarized. The objective reasons of rapid development for chilled and frozen prepared foods are analyzed. The brilliant prospects of chilled and frozen prepared foods in China are proposed.