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15 October 2010, Volume 31 Issue 19
Invited Papers
Signaling Pathways of Dietary Phytochemicals for Health
PANG Guang-chang,CHEN Qing-sen,HU Zhi-he,XIE Jun-bo
2010, 31(19 ):  1-24.  doi:10.7506/spkx1002-6630-201019001
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Natural phytochemicals (Phc) derived from dietary sources or medicinal plants have gained extensive recognition in potential protection and clinical applications for human health. Fruits and vegetables are abundant sources of highly effective phytochemicals for functional foods, which exert anti-cancer functions by inhibiting the process of carcinogenesis through the upregulation of cytoprotective genes encoding carcinogen-detoxifying enzymes, antioxidant enzymes, cytokines and regulation networks of immunity. Plenty of studies have proved that the mechanisms include the induction of cell cycle arrest and apoptosis, or the inhibition of signal transduction pathways such as mitogen-activated protein kinase (MAPK), protein kinase C (PKC), phosphoinositide 3-kinase (PI3K), Toll-like receptors (TLRs), abnormal cyclooxygenase-2 (COX-2), activator protein-1 (AP-1), and nuclear factor-kappa B (NF-κB). Effectiveness of chemopreventive agents can reflect their capability to counteract certain upstream signals that result in genotoxic damage, redox imbalance and cellular stress. NF- κ B and AP-1 provide mechanistic links among inflammation, immunity regulation and cancer. Thus, the complexity is due to cell signaling cascades and their cross-talks. Abnormality in MAPK pathway and/or related downstream transcription factors might cause the replication of uncontrolled cells and the transformation of malignant cells. Therefore, the inhibition of these pathways will provide an effective strategy for the prevention and treatment of cancer.

Basic Research
Effect of Ice-structuring Protein on the Stability of Frozen Hydrated Gluten
LI Ling-ling1,JIA Chun-li1,HUANG Wei-ning1,*,KIM Yangsoo1,RAYAS-DUARTE Patricia2
2010, 31(19):  25-28.  doi:10.7506/spkx1002-6630-201019002
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To understand the effect of ice-structuring protein (ISP) from winter wheat on the stability of frozen hydrated gluten, the freezable water content, rheological properties and microstructure of hydrated gluten with and without added ISP frozen for 1, 2, 4, 7 weeks and 9 weeks were determined by differential scanning calorimetry (DSC), rheometer and scanning electron microscopy (SEM), respectively. The results showed that: 1) the amount of freezable water in hydrated gluten increased with increasing frozen time, while the addition of ISP could prevent the increase in freezable water content that; 2) both the G' and G'' of hydrated gluten decreased with increasing frozen storage time, while hydrated gluten containing ISP always had higher G' and G'' than its blank counterpart at the same frozen storage time points; and 3) less damage of gluten network caused by ice growth and recrystallization was observed for hydrated gluten containing ISP compared with control one at the same frozen storage time points. These results indicate that ISP can prevent hydrated gluten network from ice crystal damage.

Effect of Wheat Starch on the Sensory Quality of Fried Instant Noodles
CHEN Xu1,YIN Jing-yuan1,ZHAO Lei2,HOU Guo-you3,MI Jun-feng3,GAO Hai-yan1,*
2010, 31(19):  29-32.  doi:10.7506/spkx1002-6630-201019003
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To investigate the effect of wheat starch on the sensory quality of instant noodle, some indexes such as the total starch content, amylose content, sedimentation volume, and pasting properties of special purpose flour (twenty batches of five product varieties from one manufacture) for the production of instant noodles and the texture profile analysis (TPA) experimental indicators and sensory quality of corresponding processed instant noodles, and the correlations between flour and instant noodle properties were analyzed. Sedimentation volume and amylose content were both highly positively correlated with initial pasting temperature, but highly negatively correlated with peak viscosity and instant noodle sensory evaluation indexes, and total starch content was highly positively correlated with instant noodle sensory evaluation indexes. Therefore, lower amylose content and sedimentation volume and higher total starch content of flour are all beneficial to the improvement of sensory quality of instant noodles.

Distribution of Polyphenols in Rapeseed Shell and Kernel and Effect of Oil Extraction Methods on Their Content in Rapeseed Meal
LIU Qin,WU Li,SHI Jia-yi,JU Xing-rong*
2010, 31(19):  33-37.  doi:10.7506/spkx1002-6630-201019004
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Six binary solvent systems were used to extract industrial high-temperature rapeseed meal (a byproduct of rapeseed oil extraction at a temperature ranging from 110 to 115 ℃ after steaming at 115 ℃), and a mixture of ethanol and 1 mol/L HCl (7:3, V/V) was the selected solvent system for further studies in view of higher extraction efficiency, DPPH radical scavenging activity and ferric reducing antioxidant power (FRAP) as well as environmental friendship. The following studies included comparisons on total polyphenol content, DPPH radical scavenging activity and FRAP value among the extracts from the residues left after oil extraction from rapeseed shell and kernel, solvent extraction-derived rapeseed meal and industrial hightemperature rapeseed meal, HPLC-MS/MS identification of major components of the extract from solvent extraction-derived rapeseed meal and quantification of sinapine and sinapic acid in it. The total polyphenol content, DPPH radical scavenging activity and FRAP value of the extract from the residue left after oil extraction from rapeseed kernel were all approximately 2-fold higher than those of the extract from rapeseed shell with oil extraction and the contents of sinapic acid and sinapine exhibited approximately 2.5- and 1.5-fold increases, respectively. The comparison between solvent extraction-derived rapeseed meal and industrial high-temperature rapeseed meal indicated that during high-temperature oil extraction, total polyphenol content, DPPH radical scavenging activity, FRAP value and the contents of sinapic acid and sinapine decreased by 12.06%, 10.0%, 5.6%, 5.6% and 21.12%, respectively.

Enzymatic Elimination of Allergens in Litopenaeus vannamei
WU Hai-ming,HU Zhi-he*
2010, 31(19):  38-41.  doi:10.7506/spkx1002-6630-201019005
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To eliminate the allergens in Litopenaeus vannamei, the meat of this shrimp was hydrolyzed separately with trypsin and papain, and their respective hydrolysis conditions were optimized for achieving minimum optical density at 492 nm (OD492 nm) in the indirect ELISA determination of allergen elimination. The optimal conditions for trypsin hydrolysis were determined as follows: pH 8.0; enzyme/substrate mass ratio 1:100; hydrolysis temperature 45 ℃; substrate concentration 5 g/100 mL; and hydrolysis duration 3 h, and the resultant OD492 nm value was 0.085. pH of 6.5, enzyme/substrate mass ratio of 1:100, hydrolysis temperature of 60 ℃, substrate concentration of 5 g/100 mL and hydrolysis duration of 3 h were found optimal for papain hydrolysis, and the minimum OD492 nm value under these conditions was as low as 0.049.

Quantitative Structure-retention Relationship Studies of Chemical Constituents in Volatile Oil from Rhoeo spathacea (Sw.) Stearn Flowers
FENG Chang-jun,SHI Chun-ling,LI Ming-jian
2010, 31(19):  42-44.  doi:10.7506/spkx1002-6630-201019006
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On the basis of Kier s molecular connectivity index (mXtV) and electronegativity distance vector (Md), the retention time of 20 organic components in volatile oil from Rhoeo spathacea (Sw.) Stearn flowers was determined and a four-variable model (QSRR) of gas chromatographic retention time (tR/min) for 20 chemical components was established from mXtV, Md by leaps-andbounds regression (LBR). Traditional correlation coefficient (R) and cross-validation correlation coefficient (Q) of leave-one-out (LOO) were 0.963 and 0.832, respectively. The model was highly reliable and had favorable prediction capability. The dominant factors for retention time were molecular size and spatial shape of organic molecules. The Kier s converse indices and electronegativity distance vector exhibited a good rationality and efficiency in characterizing retention time of organic compounds. This model could elucidate the change trend of retention indices for organic components.

Antioxidant Activity Assessment of Extracts from Different Parts of Sonchus oleraceus L.
HAN Yang-yang1,WANG Tian-xiao2,ZHU Hai-fang1,WANG Wei1,WANG Jian-hua1,*
2010, 31(19):  45-48.  doi:10.7506/spkx1002-6630-201019007
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Four different parts of Sonchus oleraceus L. (root, stem, leaf and flower) were extracted separately with water and different concentrations of ethanol (25%, 50%, 75% and 100%) under room temperature. The calculation of extraction efficiency was performed, and the resultant extracts were tested for their DPPH radical scavenging capacity (EC50, half maximal effective concentration) and the contents of total flavonoids. Fifty percent ethanol gave the highest extraction efficiency of ethanol soluble substances from each of these four parts of Sonchus oleraceus L. Different extracts from different parts of Sonchus oleraceus L. all had significantly dosage-dependent antioxidant activity, which was related to the contents of total flavonoids and total polyphenols. The order of antioxidant activity for these four parts was: flower > leaf > stem > root.

Assessment of in vitro Antioxidant Activity of a Triterpenoidal Saponin from Ganoderma lucidum Fruit Bodies
CUI Yue-hua1,ZHANG Ke-chang2
2010, 31(19):  49-53.  doi:10.7506/spkx1002-6630-201019008
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To assess the in vitro antioxidant activity of a triterpenoidal saponin from Ganoderma lucidum, named GCTL1, GCTL1 was tested for its abilities to scavenge superoxide anion, hydroxyl, DPPH and hydroxyl peroxide free radicals, reducing power and ferric-chelating capacity and was compared with BHT and vitamin C, synthetic antioxidants. GCTL1 had interesting antioxidant effect. The IC50 values for scavenging superoxide anion, hydroxyl, DPPH and hydroxyl peroxide were (0.247 ±0.05), (0.197 ± 0.002), (0.09 ± 0.02) mg/mL and (0.279 ± 0.04) mg/mL, respectively, and the concentrations for achieving 0.5 reducing power and 50% ferric-chelating capacity were (0.425 ± 0.01) mg/mL and (0.180 ± 0.04) mg/mL. All these antioxidant properties were dependent on concentration varying in a certain range. Collectively, our findings demonstrate that GCTL1 is better antioxidant than BHT and vitamin C.

Effect of Storage under High Temperature and Humidity on the Composition and Solubility of Soy Protein Isolate Packaged in Different Ways
SHI Yan-guo,SU Chen,SUN Bing-yu,LIU Hong-hong
2010, 31(19):  54-58.  doi:10.7506/spkx1002-6630-201019009
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During storage and transport, the functional characteristics of soy protein isolate (SPI) may deteriorate, which impacts its industrial applications. In the present study, different packaging ways: packaging in aluminium foil bag vacuumed or filled with 100% nitrogen gas or a mixture of nitrogen gas and carbon dioxide (4:1 or 3:2, V/V), practical industrial packaging (packaging with white paper/plastic/high density polyethylene, HDPE) and polyethylene (PE) packaging were used to package SPI, followed by 5-month storage in high temperature (30 ℃) and humidity (80%) environment in order to address the effects of storage environment and period and packaging conditions on the 7S/11S ratio, sulfhydryl group content, disulfide bond content and solubility of SPI. Nigtrogen-filled packaging promptly increased the solubility of SPI and was beneficial to better maintenance of the functional characteristics of SPI. Comparatively, aluminium foil packaging was the best barrier to humidity, followed by practical industrial packaging and PE packaging. The 7S/11S ratio of PE packaged SPI had no significant correlation with its solubility, but there was a significant positive correlation between its sulfhydryl group content and solubility.

Separation of Antioxidant Components from Meat Flavor and Their Antioxidant Capacities
WANG He-ya, YU Xi-yang, QIAN He*,YAO Wei-rong
2010, 31(19):  59-62.  doi:10.7506/spkx1002-6630-201019010
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The antioxidant components in a commercial meat flavor prepared by Maillard reaction were separated by ultrafiltration and silica column chromatographic fractionation and their antioxidant capacities were investigated by measuring their inhibitory effects on the oxidation induced by AAPH or Fe3+/VC and autooxidation of soybean phosphatidylcholine liposomes. The meat flavor was fractionized into three fractions with molecular weights separately varying in three ranges. Among them, the high-molecular weight fraction had the strongest antioxidant activity, and it was further separated into three subfractions, H-MA, H-MB and H-MC and their order of polarity was H-MA < H-MB < H-MC and their order of antioxidant activity was H-MA < H-MB < H-MC. As a conclusion, the major component in the meat flavor responsible for antioxidant activity is the high-molecular weight fraction and the weaker polarity, the stronger antioxidant activity.

Anti-bacterial Mechanism of Essential Oil from Lotus Leaves on Commonly Found Pathogens in Meat Foods
ZHANG Yun-bin1,MIAO Cun-qian1,SONG Qing2,GUO Yuan1
2010, 31(19):  63-66.  doi:10.7506/spkx1002-6630-201019011
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In order to elucidate the inhibitory mechanism of the essential oil from lotus leaves on Escherichia coli, Staphylococcus aureus and Salmonella commonly found in meat foods, the effect of the presence of the oil on the cell membrane permeability, electrical conductivity and reducing sugar and protein contents of the bacterial suspensions of these microorganisms was examined. All the bacterial suspensions presented higher electrical conductivity 5 min after addition of the oil, and their reducing sugar contents after addition of the oil decreased during the first two hours, followed by initial increase up to a climax at three hours and then decrease. During the first four hours of treatment with the oil, the soluble protein contents of the three bacterial suspensions decreased, and the subsequent change trend was initially increase up to a climax at eight hours, followed by decrease. In conclusion, the presence of the oil causes the change of cell membrane permeability and as a result, the leakage of cell contents happens to these three bacteria so that both conductivity and reducing sugar content increase. Moreover, the oil can delay protein synthesis in bacterial cells.

Partitional Behavior of Ficin in PEG/(NH4)2SO4 Two-phase Aqueous System
FENG Zi-li1,MA Na2
2010, 31(19):  67-70.  doi:10.7506/spkx1002-6630-201019012
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Aqueous two-phase system (ATPS) was a new and cheap purification method for ficin. The partition of Ficin in polyethylene glycol and ammonium sulfate aqueous two-phase systems was investigated. The effects of PEG molecular weight, polyethylene glycol concentration and ammonium sulfate concentration, pH and temperature on ficin partition coefficient were also explored. Results exhibited that ficin partition coefficient in two-phase aqueous system at the conditions of 20% PEG1000, 19% (NH4)2SO4, pH 6 and temperature at 25 ℃ was 3.6.

Effect of Lipase Contained in Glutinous Rice Wine on Lipolysis in Traditional Chinese-style Cheese
XUE Lu,WU Hui-fang,HU Zhi-he
2010, 31(19):  71-73.  doi:10.7506/spkx1002-6630-201019013
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Milk coagulant prepared from glutinous rice wine was used to produce Mijiunai, also called traditional Chinese-style cheese. The lipolytic activity of glutinous rice wine used was between 1.0 LU/mL and 1.5 LU/mL. The accumulation of fatty acids happened mainly during milk-clotting period. The free fatty acid composition of Mijiunai was analyzed by GC-MS. Palmitic, oleic, myristic and stearic acids were found at higher concentrations.

Numerical Simulation of Liquid Food during Continuous Ohmic Heating
XU Wei1,JIANG Xin1, SHEN Wu-xiong1,TIAN Ting1,ZHOU Jia-hua1,*
2010, 31(19):  74-78.  doi:10.7506/spkx1002-6630-201019014
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Ohmic heating is a novel heating method characterized by uniform heating, fast temperature rising and high efficiency. But its application is hindered by difficulty in instant monitoring of temperature during heating. In this study, finite element method was employed to simulate 3-D stationary continuous heating tap water and soymilk in cylindrical ohmic heater. The nfluence of inlet velocity on temperature and velocity fields of different cross sections was analyzed. The results were validate dagainst the experimental results from published literature, and the differences were 2.32 ℃ for tap water and 2.65 ℃ for soymilk. Numerical simulation is effective in predicting velocity and temperature fields in liquid food continuous ohmic heating.

Isolation and in vitro Antioxidant Activity of Active Peptides from Taihe Black-bone Silky Fowl (Gallus gallus domesticus Brisson) Muscle
LIU Jian-hua,TIAN Ying-gang,WANG Yong,ZHU Sheng,WANG Chun-yan,ZHANG Pan,XIE Ming-yong*
2010, 31(19):  79-83.  doi:10.7506/spkx1002-6630-201019015
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The Taihe black-bone silky fowl muscle hydrolysate prepared by papain hydrolysis were separated to obtain active peptides by preparative HPLC with 0.01 mol/L phosphate buffer as the mobile phase, and the separated fractions were then pooled and desalted stepwise by 001 × 16 strong acid cation exchange resin and 201 × 7 strong basic anion exchange resin column chromatography. The hydrolysate and its separated fractions were tested for their in vitro antioxidant effects by hydroxyl free radical scavenging array, lipid peroxidation inhibition assay and measuring the ability to chelate Fe2+ and Cu2+ and compared with carnosine and ascorbic acid. Totally 13 fractions were separated from the Taihe black-bone silky fowl muscle hydrolysate, and all of them had obvious antioxidant effect in a concentration-dependent way. Most of the fractions presented stronger abilities to scavenge hydroxyl free radicals, inhibit lipid peroxidation and chelate Fe2+ than the hydrolysate.

Antioxidant Effect of Eucommin
PENG Mi-jun,PENG Sheng,WU Ji-lin,LAN Wen-ju
2010, 31(19):  84-86.  doi:10.7506/spkx1002-6630-201019016
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To provide theoretical evidences for developing novel natural antioxidants, eucommin and high-purity chlorogenic acid were assessed for their antioxidant effects by hydroxyl, superoxide anion and DPPH free radical assays with vitamin C as a positive control. Curves of free radical scavenging ratio versus concentration were plotted for each of these three compounds. As a result, eucommin had different scavenging effects against different radicals and the best ability to scavenge superoxide anion radicals, followed by DPPH and hydroxyl radicals, with corresponding maximum scavenging ratios of 95.85%, 75.31% and 31.10%. Therefore, eucommin is a potential strong antioxidant.

GC-MS Investigation of Dynamic Changes of Mineral Oil Components in Broilers
LIU Liang1,2,TANG Shan-hu1,*,CHEN Nuo1,LIU Nei-sheng1
2010, 31(19):  87-91.  doi:10.7506/spkx1002-6630-201019017
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For animal disease control, vaccines containing mineral oil as a vaccine adjuvant composition are often used to immunize animals, but this may cause residues in animal meat, which will cause health problems to the human body once ingested. The objectives of this study were to determine the residues of mineral oil components in the chicken s body and to investigate the metabolic changes of mineral oil components in a simulated vaccination model. Chickens of 15 days old were injected with white oil No. 7 (a commercially available mineral oil adjuvant) and the residues of mineral oil components in leg muscle, heart, liver and skin were determined using GC-MS method on the 3rd, 7th, 14th, 28th and 56th day after injection. It was found that on both 3rd and 7th day after injection 11 alkanes detected in white oil No. 7 were also detected in the muscle receiving injection, and each of these compounds had similar mean relative percentage in the two analytes; on the 14th day, both the number and quantity of residual alkanes in the injection site had a decrease trend, and on the 56th day reached minimum. While for both heart and liver, the number of detected alkanes was found maximum on the 3rd day, and became smaller on the 7th day, but compared with skin, much more number and quantity of residual alkanes were both determined in heart on the 56th day. These results show that mineral oil reach other tissues and organs via circulation, and using mineral oil as an adjuvant in food production of animal origin might bring some safety risks.

Effect of Nitrogen on the Growth and Polysaccharide Content of Nostoc flagelliforme
TANG Jun1,2,WAN Neng2,HU Zheng-yu1,*
2010, 31(19):  92-95.  doi:10.7506/spkx1002-6630-201019018
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Cultivation of Nostoc flagelliforme in nitrogen-containing (BG11) and non-nitrogen-containing (BG110) media was conducted for figuring out the effects of nitrogen on the growth and the contents of phycobiliprotein (PC), allophycocyanin (APC), phycoerythrin (PE) and endo- and exopolysaccharides of Nostoc flagelliforme were investigated. The results showed that after 20 d cultivation, compared to BG110 medium, N. flagelliforme cultured in BG11 medium had much higher contents of Chl a, carotenoides, PE, APC and PC, but much lower contents of endo- and exo polysaccharides. The maximum content of endopolysaccharides was 1.03 mg/mL in BG110 and 0.78 mg/mL in BG11, while that of exopolysaccharides was 243.8μg/mL in BG110 and 74.9μg/mL in BG11. These results indicate that nitrogen deficiency may inhibit the growth of N.flagelliforme, but promote the synthesis of endo- and exopolysaccharides to a certain extent.

Evaluation of Release Kinetics of Micro-algal Oil Microcapsules
ZHAO Li-ping,HAN Dan,XIONG Hua*,BAI Chun-qing,LIU Yu-zhen,DENG-Bo,SHI Su-hua,WANG Qiang
2010, 31(19):  96-99.  doi:10.7506/spkx1002-6630-201019019
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The release kinetics of microencapsulated micro-algal oil was investigated under different storage conditions. The Avrami equation was employed to analyze the release mechanism parameters and release rate constant (K) and measure the change in retention ratio of DHA, one of the major functional components of micro-algal oil, under different levels of light intensity, temperature and relative humidity. The results indicated that the K value of micro-algal oil microcapsules was smaller though stored at a higher storage temperature (60 ℃) and the DHA retention ratio was 66.69% after 12 days of storage at 60 ℃. DHA retention ratio, however, was very sensitive to humidity and the value was only 3.45% after 12 days of storage at 90% humidity, and K increased obviously. This indicates that micro-algal oil microcapsules should be stored at lower humidity. Light intensity had no remarkable effect on the stability of micro-algal oil microcapsules, and the DHA retention ratio was still 78.33% after 12 days of 10000 lx illumination. Higher storage temperature, relative humidity and light intensity all could result in an increase in K. It is obvious that microalgal oil microcapsules should be stored in light-avoiding, low-temperature and low-humidity environment.

Effect of Lactic Acid Bacterial Fermentation on the Physico-chemical and Thermodynamic Properties of Oat Starch
WAN Jing-jing1,HUANG Li-qun1,ZHANG Qing1,HUANG Wei-ning1,*,RAYAS-DUARTE Patricia2
2010, 31(19):  100-105.  doi:10.7506/spkx1002-6630-201019020
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Oat flour was fermented solely with two species of lactic acid bacteria, Lactobacillus plantarum (L.p) and Lactobacillus sanfrancisco (L.s) in order to analyze the changes in physio-chemical and thermaldynamic properties of oat starch during lactic acid bacterial (LAB) fermentation. Fermentation with each of the two stains resulted in a decrease in pH, and L.p -fermented oat flour exhibited a faster pH drop and lager amount of acid production when compared to L.s-fermented one, but similar pH values were observed in the late period of fermentation. For both L.p- and L.s-fermented oat flours, solubility and swelling power increased with increasing temperature. For oat flour fermented by one strain, the two parameters at different temperatures both had different change trends as fermentation time increased. L.p-fermented oat flour had lower swelling power but higher solubility than its L.s-fermented counterpart. The results obtained from rapid viscosity analyzer (RVA) and differential scanning calorimetry (DSC) showed that the peak viscosity of fermented oat starch decreased as fermentation time increased, and after fermentation, oat starch had lower onset gelatinization temperature, required longer time for gelatinization, presented higher gelatinization enthalpy, and L.s-fermented oat starch had higher gelatinization enthalpy than L.p-fermented one. Oat starch presented an increasing trend in amylose content during fermentation, and L.p-fermented oat starch had higher amylose content at 6 and 12 hours of fermentation when compared to L.s-fermented one, but the amylose content of the former was slightly lower than that of the latter at 24 hours.

Cloud Stability of Orange Juice
XIANG Chen-xi,JIANG He-ti*
2010, 31(19):  106-110.  doi:10.7506/spkx1002-6630-201019021
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The effects of degree of maturity (DM) of fruit, squeezing way, enzymatic treatment and storage temperature on the cloud stability of orange juice were investigated. As fruit DM increased, the turbidity of squeezed orange juice showed an increasing trend. Micronization by a colloid mill could improve the release of pectin and soluble pectin from fruit pulp, resulting in a significant increase in pectin content in fruit juice (P < 0.05). Pectinesterase presence had notable effect on the cloud stability of orange juice, so this enzyme should be inactivated. Pectinase treatment damaged the cloud stability of orange juice, while the effect of papain treatment was unobvious. No significant change (P > 0.05) was observed for orange juice quality during storage at 4 or 15 ℃, but the turbidity of orange juice decreased significantly during storage at 25 ℃ (P < 0.05). Ambient temperature storage was unbeneficial for the cloud stability of range juice.

Water-holding Capacity and Mechanical and Optical Characteristics of Soy Hull Low and High Methoxyl Pectin Complex Gel
LIU He,LIU Hao-dong,GUO Xiao-fei,ZHU Dan-shi
2010, 31(19):  111-114.  doi:10.7506/spkx1002-6630-201019022
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The effects of sucrose content and the ratio of soy hull low to high methooxyl pectins on the water-holding capacity and mechanical and optical characteristics of soy hull low and high methooxyl pectin complex gel were examined in this work. Sucrose content had large effects on all the water-holding capacity and mechanical and optical characteristics of the complex gel and increasing sucrose content resulted in higher water-holding capacity, failure stress, elasticity and clarity. The ratio of soy hull low to high methooxyl pectins also had obvious effects on the above properties, and an appropriate ratio could induce the synergistic effect between molecules of the two pectins and the resultant product had better water-holding capacity and mechanical properties.

Functional Properties of Products of a Grafting Reaction between Rice Peptide and Glucose in Aqueous Solution
ZHAO Qiang,ZHONG Hong-lan,XIONG Hua*,SHI Su-hua,DENG Bo,LI Wei
2010, 31(19):  115-120.  doi:10.7506/spkx1002-6630-201019023
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Rice peptides were grafted with glucose in aqueous solution under different levels of reaction temperature and time, initial pH, substrate concentration, rice peptide/glucose mass ratio in order to investigate the effects of these reaction conditions on the functional properties of the grafted products including emulsifying activity (EA), emulsion stability (ES) and reducing power. The results indicated that 1) the degree of grafting (DG), browning degree and reducing power of the graft reaction products (GRPs) increase with rising reaction temperature and prolonged reaction time. However, excessively long reaction time led to decreases in DG, EA and ES; 2) The EAs of rice peptides and GRPs were both enhanced as initial pH increased from 6 to 10, their reducing power and ES increased initially and then decreased, and GRPs showed higher levels of EA and reducing power than native rice peptides, and GRPs obtained using an initial pH of 0.798 had the highest reducing activity; 3) both the EAs of rice peptides and GRPs showed a trend to initially increase and then decrease with substrate concentration increased, and the emulsify stability and reducing power were improved remarkably; 4) The EA and ES of GRPs were obviously affected by rice peptide/glucose mass ratio, and EA was most significantly enhanced and reached up to 35.13% when the ratio was 1:2, while the ratio had no significant effect on the reducing power of GRPs.

Analysis of Bitterness-Average Protein Hydrophobicity Relationship and Debittering of Autolysis Products of Shrimp Head
FU Guang-zhong1,ZHANG Chao-hua1,2,*,JI Hong-wu1,2,XIE Wan-cui1,GAO Jia-long1,2,LU Hong-yu2
2010, 31(19):  121-123.  doi:10.7506/spkx1002-6630-201019024
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In order to find out the distribution of bitter peptides in the autolysis products of shrimp head and the relationship between bitterness and their protein hydrophobicity, ultrafitration was employed to fractionate the autolysis products, and the separated fractions were tested for their bitterness and average protein hydrophobicity, and the bitterness-improving effect of synergetic hydrolysis by flavourzyme added during shrimp head autolysis was also investigated. The bitterness of the autolysis products mainly resulted from the presence of peptides with a molecular weight varying from 3 to 5 kD. The autolysis products with smaller average hydrophobicity presented stronger bitterness. Compared with single autolysis, the presence of flavourzyme resulted in an increase in protein recovery by 3.5% and a decrease in bitterness by 50%.

Promoting Effect of Polysaccharides Isolated from Rhizoma Atractylodis Macrocephalae on the Growth of Probiotics and Structure Analysis
LIU Li-sha,WANG Rui,XU Ri-hua,SHANG Nan,WANG Yang,FAN Qin,LI Ping-lan*
2010, 31(19 ):  124-128.  doi:10.7506/spkx1002-6630-201019025
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Among eight common medicinal and edible Chinese herbs, namely Rhizoma Atractylodis Macrocephalae, Fructus Lycii Chinensis, Radix Pseudostellariae, Fructus Schisandrae Chinensis, Radix Codonopsitis, Radix Rehmanniae, Pericarpium Citri Reticulatae and Glossy Ganoderma), the water extract from Rhizoma Atractylodis Macrocephalae had the most obvious promoting effect on the in vitro growth of Bifidobacterium infantis. A neutral polysaccharide fraction was obtained from Rhizoma Atractylodis Macrocephalae after water extraction (1:20 raw material/water ratio), absolute ethanol precipitation (1:3 concentrated crude extract/absolute ethanol), dialysis (through a membrane with a molecular weight cut-off of 3500 D), Sevag deproteinization and DEAE anion exchange column chromatographic separation. The polysaccharide fraction had a promoting effect on the growth of Bifidobacterium and Lactobacillus, especially on B. infantis, B. animalis, B. adolescentis and Lactobacillus plantarum in a concentration-dependent fashion. The infrared spectral analysis showed that the fraction had characteristic absorption peaks of polysaccharides, and its weight-average molecular weight (Mw) was measured to be 5527 g/mol using GPC coupled with a multiangle laser light scattering photometer (GPC-MALLS) and its molecular weight distribution (Mw/Mn) was 1.726. The analysis using acidic hydrolysis followed by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) revealed that the polysaccharide was a hetero polysaccharide and its monosaccharide composition consisted of rabinose, galactose, glucose and mannose in a molar ratio of 13.8:11.8:70.2:4.1.

Effect of Adding Vinegar on the Stability of Vitamin C in Cooked Potatoes
YANG Ming-duo1,2,3,CHEN Jian2,WU Ying-ying1,3,WANG Xu3
2010, 31(19 ):  129-132.  doi:10.7506/spkx1002-6630-201019026
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Vinegar was added before potato boiling and stir-frying for probing into the effect of vinegar presence on the stability of vitamin C in cooked potatoes. Adding 0.3 g of vinegar before boiling 250 g of potato shreds in the presence of salt and chicken essence could stabilize vitamin C best. The best amount of added vinegar for achieving the best stabilization of vitamin C during the stir-frying of 250 g of potato shreds in the presence of salt and chicken essence was 3 g.

Residual Dynamics of Imidacloprid in Tomatoes and Comparative Analysis of Commonly Used Methods for the Removal of Residual Imidacloprid
WANG Ming-ming1,GONG Yan2,CHEN Hao1,SHEN Jing
2010, 31(19):  133-136.  doi:10.7506/spkx1002-6630-201019027
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The residual dynamics of imidacloprid in tomatoes was investigated and the best solid-phase extraction column was selected for the HPLC-MS analysis of imidacloprid. Meanwhile, a comparative study of commonly used methods for removing residual imidacloprid from tomatoes was performed. A HPLC-MS analytical method based on extraction with acetonitrile and clean-up on a NH2 solid-phase extraction column was developed for the determination of imidacloprid residue in tomatoes. There was a good linear relationship between the peak area and concentration of imidacloprid over the range from 0.01 to 2 mg/L, and the linear equation was Y = 69582.5 X + 68.9, with a correlation coefficient of 0.9999. The mean recoveries of the method varied from 87.5% to 96.5% with a relative standard deviation ranging from 1.7% to 6.7% at four fortification levels in the range from 0.01 to1.0 mg/kg, and the limit of detection was 0.01 mg/kg. This method is characteristic of simplicity, rapidity and accuracy. The degradation dynamics suggested that imidacloprid degraded gradually with prolonged time, that the degradation dynamic curve complied with first-order kinetics equation, and that the half-life of imidacloprid in tomatoes was 3.48 day. Rinsing with tap water, hot water or detergent was employed to remove imidacloprid residue. The results revealed imidacloprid residue reduction could be attained to a certain extent, whereas the effectiveness of rinsing with hot water and detergents was not superior to that of rinsing with tap water.

Emulsifying and Foaming Properties of Bovine Serum Albumin
GUO Ling,LIU Ai-guo*,HU Zhi-he,WU Hui-fang
2010, 31(19):  137-140.  doi:10.7506/spkx1002-6630-201019028
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In this work, we evaluated the effects of protein concentration, pH, CaCl2 concentration and temperature on the emulsifying activity (EA), emulsifying stability (ES), foaming activity (FA) and foam stability (FS) of bovine serum albumin (BSA). The highest values of EA and ES were both obtained at protein concentration of 0.1 g/100 mL, and the lowest values were obtained at pH 5. EA increased slowly as CaCl2 concentration increased, whereas ES presented an opposite change. The highest EA was found at 60 ℃ and ES decreased notably when temperature was over 60 ℃. FA increased, and FS ascended first and then descended with increasing protein concentration. FS reached a maximum at 1.5 g/100 mL protein concentration. At pH 5, FA reached a minimum and FS a maximum. CaCl2 concentration had no obvious influence on both FA and FS.

Influence of Ultrasonic-assisted Calcium Chloride Treatment on Beef Quality
WU Qiang1,2,DAI Si-fa1,*
2010, 31(19):  141-145.  doi:10.7506/spkx1002-6630-201019029
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This study was carried out to explore the influence of combined calcium chloride and ultrasonic treatments on the color, water holding capacity (WHC), cooking loss and tenderness of beef. At 12 hours post-mortem, adult yellow cattle rump was injected with 300 mmol/L calcium chloride (5% and 10% injection amounts, as percentage of meat mass) and then treated in a 133 W/m2 ultrasonic field for two different periods of time, 6 min and 12 min. As a result, four treatment groups were generated, namely group one: 5% injection amount plus 6 min ultrasonic treatment, group two: 5% injection amount plus 12 min ultrasonic treatment, group three: 10% injection amount plus 6 min ultrasonic treatment and group four: 10% injection amount plus 12 min ultrasonic treatment. The control group did not receive any treatment. Each group was tested for its color, WHC, cooking loss and tenderness at 1 through 5 d and 7 d of aging at 4 ℃. The best improvement of color, WHC and cooking loss was achieved after 10% calcium chloride injection followed by 6 min ultrasonic treatment. Combination of 5% calcium chloride injection with 12 min ultrasonic treatment had the best improvement on beef color, WHC and cooking loss, and resulted in a decrease in tenderness by 28.41%. These results demonstrate that combination of calcium chloride injection with ultrasonic treatment can notably improve beef quality.

Effects of Cu2+, Ca2+ and Mg2+ on the Interaction of Pirimicarb with Calf Thymus DNA
HU Xing1,ZHANG Guo-wen1,*,FU Peng1,ZHAN Chun-rui2
2010, 31(19):  146-149.  doi:10.7506/spkx1002-6630-201019030
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The interaction between pirimicarb and calf thymus DNA was studied by UV absorption spectroscopy, fluorescence spectroscopy and melting point measurement in the respective presence of Cu2+, Ca2+ and Mg2+ in physiological buffer (pH 7.4). From the results of ethidium bromide (EB) competition and DNA melting point measurement, pirimicarb reacted with DNA basic groups mainly through intercalative binding. All the three metal ions were found to be able to complex with pirimicarb, and the generation of complexes made a difference to the ultraviolet absorption peak intensity and shape of the reaction systems and quenched the fluorescence intensity of the EB/DNA complex to different extents. In the respective presence of Cu2+ and Ca2+, the binding constant of the DNA/pirimicarb complex initially decreased, followed by increase, and the involvement of Mg2+ could enhance the binding between DNA and pirimicarb. It can be concluded that the binding between DNA and pirimicarb mainly depends on the relative affinity ratio between metal ions and DNA basic groups or phosphate groups.

Content Determination and Antioxidant Activity Evaluation of Usnic Acid in Ramlina sinesis Jatta
Tugunay TURSUN,Reyim MAMUTI,Adilijiang,Abdulla ABBAS*
2010, 31(19 ):  150-152.  doi:10.7506/spkx1002-6630-201019031
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In this study, usnic acid in Ramalina sinesis Jatta growing in August First forest farm, Tianshan mountain area, Xinjiang autonomous region was extracted with ethyl acetate by reflux extraction for content determination by HPLC and antioxidant activity evaluation by reducing power and hydroxyl free radical scavenging assays. The content of usnic acid in Ramalina sinesis Jatta was 18.32%, and usnic acid derived from Ramalina sinesis Jatta had interesting reducing power and hydroxyl free radical scavenging capacity (with vitamin C as the control).

Modeling for the Ultrafiltration Concentration of Engraulis japonicus Cooking Soup
YANG Xian-qing1,ZHOU Xiao-lei1,2,LI Lai-hao1,CEN Jian-wei1,HAO Shu-xian1,DIAO Shi-qiang1,
2010, 31(19):  153-156.  doi:10.7506/spkx1002-6630-201019032
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In this work, tangential flow ultrafiltration was used to concentrate proteins in the cooking soup of Engraulis japonicus. Based on the studies on operating pressure and sample flow rate and pH, a mathematic model describing membrane flux as a function of permeate pressure, protein concentration and sample flow rate was established. The results showed that the predicted results of membrane flux as a function of permeate pressure at three constant levels of protein concentration and sample flow rate were in good agreement with the experimental results well, with a relative error varying between 0.44% and 10.00%, and the correlation coefficients were all around 0.99. Using this model in industrial design and practice, flux change can be predicted and optimal operating conditions can also be selected for solving the problems of concentration polarization and membrane pollution.

Molecular Mass and Conformation of Corn Starches with Ddifferent Amylose/Amylopectin Ratios
ZHANG Pan-feng,CHEN Ling,LI Xiao-xi*,LI Lin,LIU Guo-qin,SU Jian-yu
2010, 31(19):  157-160.  doi:10.7506/spkx1002-6630-201019033
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The determination of molecular mass, molecular mass distribution, mean square radius of gyration and conformation using gel permeation chromatography coupled with multi-angle laser light scattering (GPC-MALLS) with refractive index detector with DMSO as the mobile phase was carried out for waxy, common, G50 (with 50% amylase content) and G80 (with 80% amylase content) corn starches. The results showed that the weight-average molecular masses (Mw) of waxy, normal, G50 and G80 corn starches were 1.416 × 108, 2.744 × 107, 1.026 × 107, 3.992 × 106 g/mol, respectively. Similarly, higher-amylose corn starch had smaller mean square radius of gyration. The conformation of waxy corn starch was compact random coil and the three others were compact globular structure in DMSO.

Eating Quality of Germinated Polished Rice with the Germ Left Intact
WU Jun-ni,LIU Yong-le*,LI Xiang-hong,YU Jian,WANG Fa-xiang,WANG Jian-hui
2010, 31(19):  161-165.  doi:10.7506/spkx1002-6630-201019034
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In this study, brown rice, germinated brown rice, polished rice with the germ left intact and germinated polished rice with the germ left intact were comparatively evaluated for their main aspects of eating qualities, including cooking method and characteristics, starch gelatilization characteristics, texture characteristics and sensory evaluation. Germinated polished rice with the germ left intact had lower water absorption and swelling power but higher soluble solid content and iodine-blue value than the three other kinds of rice; its breakdown value and hardness were both lower, and the setback value (SBV) was higher. The sensory evaluation results demonstrated that the colour, aroma and taste of germinated polished-rice-with-germ were all the best among the four kinds of rice.

Development of a Beef-marbling Extraction Method Based on Incomplete Information Algorithm
QIU Jin-hong1,PENG Zeng-qi2,*,SHEN Ming-xia1,LIU Ying-ying1,LIANG Kun1,WU Hai-juan1,SHI Jie2
2010, 31(19):  166-169.  doi:10.7506/spkx1002-6630-201019035
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A method for beef marbling extraction based on incomplete information algorithm was proposed. First of all, an incomplete information algorithm was constructed on the basis of the travelling theory and relevant object validity principles. Then, the method was realized by combining the weighted average gray algorithm, adaptive optimal threshold algorithm and improved adaptive fuzzy multilevel median filter algorithm. It was found that the actual distribution of beef marbling could be reflected efficiently using this method.

Quantified Analysis of Textural Properties of Goat Yoghurt by Near Infrared Spectroscopy
ZHU Jing,DING Wu*
2010, 31(19):  170-173.  doi:10.7506/spkx1002-6630-201019036
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The aim of this study was to assess the feasibility of using near infrared spectroscopy (NIRS) to rapidly determine three textural properties of goat yoghurt: firmness, cohesiveness and water holding capacity. Forty five goat yoghurt samples fermented by different strains under different process conditions were subjected to near infrared spectral analysis, and their spectra were resolved, and based on pre-processing by second derivative (SD) method, prediction models for firmness, cohesiveness and water holding capacity were developed with partial least square (PLS), with determination coefficients (R2) of 0.6668, 0.6461and 0.7269, respectively. The correlation coefficient of external-validation for 12 goat yoghurt samples was 0.7577 for firmness, 0.7200 for cohesiveness and 0.7174 for water holding capacity. No significant difference was found in t tests between the predicted and experimental values of these three parameters (P> 0.05). The above results show that NIRS is applicable to assess the textural properties of goat yoghurt with good accuracy. However, further studies on statistical modeling need to be done for improving prediction precision.

Physico-chemical and Sensory Characteristics of Restructured Yak Meat Patties with Different Amounts of Added Peanut Powder
TANG Shan-hu1,WANG Liu1,YU Xiao-zhen1,HU Ting-wu2
2010, 31(19):  174-178.  doi:10.7506/spkx1002-6630-201019037
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The objectives of this study were to evaluate the physicochemical and sensory characteristics of restructured yak meat patties with different amounts of added ground peanut and to determine the optimal amount of peanut. Ground yak meat was added with 0, 5%, 10%, 15% or 20% peanut powder to prepare yak meat patties. The prepared patties were stored under -20 ℃ after curing for 24 hours at 2-4 ℃. The thawing loss, baking yield, oil and water binding properties, pre- and postbaking pH values and textural parameters, pre- and post-thawing colour and post-baking parameters L*, a*, b*, c and h and postbaking sensory quality of the patties were measured. The results showed that added peanut powder significantly increased prebaking adhesiveness (P <0.01), but did not affect pre-baking hardness, springiness, cohesiveness, chewiness and toughness (P>0.05), while notably reduced post-baking hardness, cohesiveness, chewiness and toughness (P<0.01), and increased postbaking adhesiveness (P<0.01). Both pre- and post-baking springinesses were little influenced by adding peanut powder (P>0.05). Baking yield and water binding capacity significantly increased with increasing amount of added peanut powder (P<0.01), while oil binding capacity had no obvious change after the addition of peanut powder. Meanwhile, the addition of peanut powder also had no significant effect on colour parameters L* and a*. However, both peanut powder amounts of 15% and 20% resulted in a notable increase of b*. In addition, texture score significantly descended as peanut amount ascended, and the amount for obtaining the best overall acceptability was between 5% and 15%. A peanut powder amount exceeding 15% resulted in a strong bean-like odor.

Alpha-glucosidase Inhibiting Effect of DPPH free Radical Scavenging Activity of Flavonoid-rich Extract from Leaves of Crataegus cuneata Sieb. et Zucc
DONG Hua-qiang1,ZHEN Chang-di1,ZHANG Yi2,LI Mei1,LIU Fu-lai1,HUANG Jian-bo1
2010, 31(19):  179-181.  doi:10.7506/spkx1002-6630-201019038
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A flavonoid-rich extract obtained by ethyl acetate extraction from the 80% ethanol extract from the leaves of Crataegus cuneata Sieb. et Zucc was evaluated for its alpha-glucosidase inhibiting effect and DPPH free radical scavenging activity. The extract had an inhibitory effect on alpha-glucosidase derived from yeast, and the maximum inhibitory rate was up to 64.3%, and the inhibition was uncompetitive according to the Lineweaver-Burk plot. The maximum DPPH free radical scavenging rate of the extract was up to 52.8%, and the IC50 was 0.57 mg/mL. In conclusion, the extract had strong ability to inhibit yeast-derived alphaglucosidase and certain antioxidant activity.

Ethanol Fractional Precipitation and Characterization of Polysaccharides from Herba Moslae
LI Juan-mei,NIE Shao-ping*,LI Jing-en,LI Chang,XIE Ming-yong
2010, 31(19):  182-185.  doi:10.7506/spkx1002-6630-201019039
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A polysaccharide-rich extract was obtained from Herba Moslae by hot water extraction and purified by fractional precipitation with gradient concentrations of ethanol (20%, 30%, 40%, 50%, 60% and 70%). The separated fractions were deproteinized by Sevag method and six purified polysaccharide fractions, named HMP-1 through 6 were obtained. These fractions were subjected to UV-visible spectral analysis, the determination of sugar, soluble protein and uronic acid contents and monosaccharide composition analysis by gas chromatography (GC). Each of these fractions was an acidic polysaccharide, with high protein content. Arabinose and glucose were the main monosaccharides in HMP-1 and HMP-2, arabinose, glucose, galactose and ribose were the main monosaccharides in HMP-3, arabinose, glucose and galactose were the main monosaccharides in HMP-4, and arabinose, glucose, galactose and mannose were the main monosaccharides in HMP-5 and HMP-6. In addition, small amounts of rhamnose and xylose were also detected in each of the six fractions.

Influence of Ozone Treatment on the Volatile Flavor and Characteristic Components of Dried Capsicum
DING Zhu-hong,WANG Zhi-song,HAN Jiang-xue,LI Gui-zhu,YU Lu
2010, 31(19):  186-189.  doi:10.7506/spkx1002-6630-201019040
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Head space solid-phase microextraction coupled with capillary gas chromatography-mass spectrometry (SPMEGC-MS), high performance liquid chromatography (HPLC) and ultraviolet (UV)-visible absorption spectrometry were employed to explore the influence of ozone treatment on the volatile flavor components, capsaicin and capsanthin in dried capsicum. As ozone treatment time prolonged, the number and amount of volatile flavor components in dried capsicum both decreased. A total of 35, 34, 31 and 12 volatile flavor components were found in non-ozone-treated dried capsicum and ones treated with ozone for 1, 2 h and 3 h, respectively. Dried capsicum treated for a longer period of time had lower contents of both capsaicin and capsanthin, and there was a significant difference between the control and the experimental groups (P < 0.05). These findings demonstrate that ozone treatment deteriorate the quality of dried capsicum.

Application of Cell Culture Model to Antioxidant Activity Analysis of an Ethanol Extract from Propolis
WU Zheng-shuang1,2,DONG Jie2,ZHANG Hong-cheng2,ZHAO Liang-liang3,GAO Wen-hong1,*
2010, 31(19):  190-193.  doi:10.7506/spkx1002-6630-201019041
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A cellular antioxidant activity (CAA) assay for quantifying the antioxidant activity of an ethanol extract from propolis (EEP) provided by Bee Research Institute, Chinese Academy of Agricultural Sciences has been developed. Dichlorofluoresceindiacetate (DCFH-DA) as a probe, which is easily oxidized into fluorescent dichlorofluorescein (DCF) by reactive oxygen species (ROS), was trapped within cells and the method was used to measure the ability of EEP to prevent the formation of DCF by 2,2′-azobis(2-amidinopropane) dihydrochloride (ABAP)-generated peroxyl radicals in human liver carcinoma HepG2 cells with multi-functional microplate reader and inverted fluorescence microscope. The decrease in cellular fluorescence intensity compared to the control cells indicates the antioxidant capacity of EEP. In addition, this bioactivity depended on dose. The concentration of EEP corresponding to CAA unit50 was only 0.14 mg/mL. A ROS clearance rate of 47.05% was obtained at an EEP concentration of 0.5 mg/mL.

Biosorption of Cr6+ by Immobilized Waste Beer Yeast Biomass
WU Yun,LIU Yong-jian,GE Feng,TIAN Yong-gang,WEI Qian-yun,GU Linazi
2010, 31(19):  194-196.  doi:10.7506/spkx1002-6630-201019042
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Waste beer yeast was embedded into sodium alginate based spheres for providing a bioadsorbent for industrial wastewater treatment. The effects of length of adsorption time, temperature, adsorbent amount, Cr6+ concentration and pH on Cr6+ adsorption ratio were examined. The optimal adsorption conditions were determined as follows: length of adsorption time 1 h; temperature 15 ℃; adsorbent amount 3 g/20 mL; Cr6+ concentration 40 mg/L; and pH 3. Under these conditions, the maximum adsorption ratio was 27.6%, and the maximum adsorption quantity was 10.8 mg/g. pH, Cr6+ concentration and adsorbent amount had larger effect on Cr6+ adsorption than two other factors.

Physico-chemical and Functional Properties of Enzymatically Prepared Tatary Buckwheat Protein
ZHU Hui,TU Shi,LIU Rong-rong,LIU Rui*
2010, 31(19):  197-203.  doi:10.7506/spkx1002-6630-201019043
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A crude protein-rich extract was enzymatically prepared from tatary buckwheat, and fractionation of the extract was carried out and four fractions (albumen, globulin, prolamin and prolamine) were obtained. The physico-chemical and functional properties of the extract and its four fractions were then characterized. The isoelectric point of the crude extract was determined to be 4.6, and those of separated albumen, globulin, prolamin and glutenin were 4.4, 5.1, 4.5 and 5.2, respectively. Their denaturation temperatures were 95.5, 100.0, 94.3, 53.4 ℃ and 84.0 ℃, respectively. Tartary buckwheat was rich in low molecular weight proteins, but lacked in high molecular weight ones, indicating that it is easy to digest and absorb. Moreover, its amino acid composition was reasonable, with a complete range and abundant lysine content. The crude extract and glutenin with the largest yield obtained in this study showed good functional properties in a simulated ham system.

Effect of Adding Superfine Wheat Bran Powder on Dough Characteristics and Steamed Bread Quality
TANG Wei-dong,WU Jing-tao,ZHAO Dan
2010, 31(19):  204-208.  doi:10.7506/spkx1002-6630-201019044
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To extend the application range of superfine wheat bran powder, different amounts (0, 5%, 10%, 15% and 20%) of superfine wheat bran powder were added to wheat flour before the making of dough and flour farinogram characteristics in the presence of superfine wheat bran powder and the tensile characteristics of the obtained doughs were measured. Adding superfine wheat bran powder resulted in increases in flour water absorption and dough formation time and weakening degree and a reduction in dough stabilizing time. The farinogram properties of flour were collectively considered to be improved by adding superfine wheat bran powder. A good fuzzy evaluation of steamed bread with added superfine wheat bran powder was achieved, and it had good acceptability in color, smell, texture and mouthfeeling.

in vitro Antimicrobial Activity of Essential Oil from Artemisia annua
GAO Zhi-ling,CHEN Yan,XIE Ying-hui
2010, 31(19):  209-211.  doi:10.7506/spkx1002-6630-201019045
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The essential oil extracted from Artemisia annua by steam distillation was determined for its in vitro antibacterial activity (inhibition zone diameter) by disk diffusion method and minimum inhibitory concentration (MIC) by test tube method. Twelve species of common bacteria or fungi were the indicator strains used. The essential oil had different inhibitory effects on these test strains. Comparatively, fungi were more sensitive to the oil, and its anti-fungus activity was stable, and it had the strongest inhibitory effect on Aspergillus niger, followed by Saccharomyces cerevisiae, Penicillium chrysogenum, Penicillium marneffei, Mucor racemosus, Penicillium sp. and Rhizopus sp. Thus, the essential oil has broad application prospects for the development of a natural preservative or an antimicrobial drug.

Bioengineering
Screening of an Optimal Strain for Producing Rapeseed-originated Angiotensin I-converting Enzyme Inhibitory Peptides by Liquid-state Fermentation
JU Xing-rong1,JIN Jing1,YUAN Jian1,WANG Li-feng1,2,HE Rong1,2
2010, 31(19):  212-215.  doi:10.7506/spkx1002-6630-201019046
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In order to search for an optimal stain for the production of angiotensin I-converting enzyme (ACE) inhibitory peptides from rapeseed meal by liquid-state fermentation, seven common microorganisms including Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, Geotrichum candidum, Candida utilis, Actinomucor elegans and Aspergillus oryzae as a starter for rapeseed meal fermentation were compared for their differences in five fermentation parameters, namely peptide yield, nitrogen solubility index (NSI), amino nitrogen yield, soluble nitrogen in aqueous trichloroacetic acid (SN-TCA) content and ACE inhibition activity. Among the above microorganisms, Bacillus subtilis was found to give both the highest peptide yield and ACE inhibition activity and grow dominantly, thereby being a superior strain for the production of ACE inhibitory peptides from rapeseed meal by liquid-state fermentation.

Cloning and Sequence Analysis of Potato α-Amylase Gene
WANG Yong-gang,MA Jian-zhong*,MA Xue-qing,ZHOU Xian-jing,LI Kun-peng,ZHAO Hu-biao
2010, 31(19):  216-220.  doi:10.7506/spkx1002-6630-201019047
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A cDNA for potato α-amylase was amplified by RT-PCR and then cloned. The sequence analysis showed that the cDNA had a 1224bp-ORF, which encodes an α-amylase with 407 amino acid residues (GenBank accession number: GQ406048.1). Semi-quantitative RT-PCR assay was used to detect the expression of the α-amylase genes in potato leaves and stems, and the results showed that the expression in stems was a little stronger than that in leaves. The amino acid sequence was bioinformatically analyzed, including its codon usage bias, physical and chemical properties, subcellular localization and conserved structures. Totally 29 α-amylase genes from the same or different species were taken from the GenBank for constructing a phylogenetic tree. The bioinformatical analyses showed that the putative protein shared 98% identity with a published potato α-amylase (M79328.1) at the amino acid level. The deducted α-amylase also contained a catalytic domain (PF00128 and SM00624) between sites 20 and 348 and a C-terminal beta-sheet domain between sites 349 and 407, which were similar to their counterparts in the amylase family 13. The postulated eight-stranded alpha/beta barrel was also found in the enzyme, which is thought as an active site of α-amylase. According to the constructed phylogenetic tree, the two genes from potato presented closer homology to those from cassava and apple, followed by kidney bean, but distant homology to those from the monocotyledonous plants including barley, rice and maize.

Microbial Conversion of Flavonoid Glycosides in Sea-buckthorn Fruit into Aglycones
TU Shao-yong1,LI Feng-jiao1,YANG Ai-hua2
2010, 31(19):  221-224.  doi:10.7506/spkx1002-6630-201019048
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This paper reports the optimization of Aspergillus niger fermentation of sea-buckthorn (Hippophae rhamnoides) fruit slurry for the conversion of flavonoid glycosides into aglycones. The effect of nitrogen source type on the contents of isorhannetin and quercetin in fermentation broth was examined and fermentation temperature and duration, shaking speed and volume percentage of medium occupying fermentor were optimized using orthogonal array design for obtaining maximum sum of the contents of isorhannetin and quercetin in fermentation broth. Soybean dregs were the best choice for maximum aglycone content. The optimal levels of fermentation temperature and duration, shaking speed and volume percentage of medium occupying fermentor were 30 ℃, 96 h, 180 r/min and 40%, respectively, and the resultant contents of isorhannetin and quercetin 78 mg/g and 22 mg/g.

Fermentation Conditions for the Production of Recombinant Mucor pusillus Rennet and Its Enzymological Characterization
LI Yu-qiu,WANG Jing-hui,LI Tie-zhu,ZHANG Li,YANG Zhen-nai*
2010, 31(19):  225-230.  doi:10.7506/spkx1002-6630-201019049
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The aims of this study were to investigate the fermentation conditions for the production of recombinant Mucor pusillus rennet (RMPR) and to enzymologically characterize the enzyme obtained. An optimum enzyme activity was obtained after 96 h of induction with 1% methanol as the inducer under the following conditions: initial OD600 nm, 0.5; and volume of medium contained in 500 mL flask, 100 mL.The incubation both obtained was centrifugated, and the supernatant was then salted out with ammonium sulfate to prepare crude enzyme solution, and enzymological characterization was carried out for the crude enzyme solution. The optimal reaction temperature of the enzyme was 60 ℃, and it kept stable in the temperature range from 30 to 45 ℃ and the residual enzyme activity was still 86.5% after 90 min of incubation at 45 ℃. As pH increased from 5.5 to 7.0, the activity of the enzyme presented a gradual decrease and the highest enzyme activity was observed at pH 5.5. At a Ca2+ concentration of 0.03 mol/L, the enzyme had the highest activity to clot milk, and Na+ had no notable effect on the enzyme, and Ni+ and Fe2+ were both an enzyme inhibitor, while Mn2+, K+ and Mg2+ all had promoting effect on the enzyme.

Separation, Purification and Characterization of Glutamate Dehydrogenase from Duck Liver
ZHU Hong,LI Xiang-yun,WANG Song,FU Wei-li,TANG Liang-ting,GAO Zhao-wei,TANG Yun-ming*
2010, 31(19):  231-235.  doi:10.7506/spkx1002-6630-201019050
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Objective: To obtain high-purity glutamate dehydrogenase (GDH) from duck liver and characterize this enzyme. Methods: Crude GDH solution was obtained from duck liver after acetone defatting, addition of MnCl2 for impurity precipitation, ammonium sulfate salting-out and DEAE-Sepharose ion exchange and Sephacryl S-200 gel permeation chromatographic fractionation. Purity identification and relative molecular mass determination were conducted using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Results: A GDH enzyme of electrophoretic homogeneity was obtained, with a purification fold of 60.93, an activity recovery of 11.02% and a specific activity of 24.37 U/mg. This enzyme had a relative molecular mass of 371.41 and a subunit relative molecular mass of 61.60. It was deduced that this enzyme was composed of the same six subunits. Its apparent Km towards NADH was 53.19μmol/L, and the optimal reaction pH and temperature 10.0 and 35 ℃, respectively. This enzyme had excellent stability at around pH 8.0 and at a temperature below 40 ℃. Zn2+, Li+ and Cu2+ had significant inhibition on this enzyme. Conclusion: A high-purity GDH enzyme has been successfully prepared. This enzyme greatly deserves to be developed and utilized.

Optimization of Ion Exchange Immobilization of β -Fructofuranosidase Using Response Surface Methodology
ZHANG Yuan-yuan,NIE Shao-ping,WAN Cheng,XIE Ming-yong*
2010, 31(19):  236-240.  doi:10.7506/spkx1002-6630-201019051
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D311 type macroporous anion exchange resin was used as a carrier for the immobilization of β-fructofuranosidase derived from Aspergillus japonicus. The effects of immobilization time and temperature, pH and enzyme activity of free β-fructofuranosidase solution on the catalytic ability of immobilized β-fructofuranosidase were investigated by single factor method and based on this, except immobilization temperature, three other conditions were optimized using response surface methodology. The optimum immobilization conditions were determined as follows: enzyme activity of free β-fructofuranosidase solution 900 U/mL and pH 6.6 for 4 h immobilization at room temperature, and the yield of fructooligosaccharides using immobilized β-fructofuranosidase under these conditions was 58.16%.

Determination ofβ -Glucosidase Activity and Source in Honey
YI Song-qiang,ZHENG Huo-qing,ZHANG Cui-ping,WEI Wen-ting,HU Fu-liang*
2010, 31(19):  241-244.  doi:10.7506/spkx1002-6630-201019052
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The determination conditions of β-glucosidase activity in honey were investigated by using p-Nitrophany β-DGluopyranoside (pNPG) as substrate. The optimal reaction pH and temperature of β-glucosidase were 5.0 and 60 ℃, respectively. The enzymatic reaction curve at 37 ℃ and a substrate concentration of 30 mmol/L presented the best  inearity. This enzyme may be added into honey during harvest and processing and its activity can be an indicator for the freshness of honey.

Optimization of Culture Conditions for Producing Tannase by Aspergillus sp.T3-5-1
LIN Jian-hui1,HUANG Man-man1,CHEN Xue-xiang1,WANG Zheng2,XIAO Su-yao1,CAO Yong1,*
2010, 31(19):  245-249.  doi:10.7506/spkx1002-6630-201019053
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The conditions for producing tannase by a strain of Aspergillus sp.T3-5-1, which was derived from 60Co-induced mutation, were optimized using single factor and orthogonal array design methods. The optimal carbon source, nitrogen source, medium initial pH, tannic acid concentration, inocumlum size, rotational speed of shaking flask, medium volume contained in 250 mL shaking flask and culture temperature were β-cyclodextrin, peptone, 5.5, 3.5%, 5%, 120 r/min, 50 mL /250 mL and 30 ℃, respectively. The maximum tannase activity was up to 202.16 U/mL under these conditions, approximately 4-fold higher than before optimization.

Respective and Combined Effects of Heat and High-pressure Treatments on the Antigenicity of Egg White Ovalbumin
ZHANG Yin1,2,TONG Ping1,3,MA Xiao-juan1,2,LI Xin1,3,CHEN Hong-bing1,3,*
2010, 31(19):  250-253.  doi:10.7506/spkx1002-6630-201019054
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Single heat treatment and high-pressure microfluidization and their combination were used to process egg white in order to study the effects of different processing approaches on the antigenicity of egg white ovalbumin. The results indicated that the antigenicity of heat-treated ovalbumin decreased by up to 68% with increasing temperature. The critical temperature for a steep decrease of ovalbumin antigenicity was 80 ℃. The change in antigenicity of high-pressure-treated ovalbumin exhibited an initial decrease, followed by a rebound increase. During single heat treatment and combination of heat treatment and highpressure microfludization, the antigenicity of egg white ovalbumin had a similar changing trend, but the change extent during combination of heat treatment and high-pressure microfludization was comparatively less, up to only 52.5%. Thus, heat treatment had more effect on ovalbumin antigenicity than high-pressure microfluidization. This conclusion is helpful for the development of hypoallergenic or non-allergenic egg products.

Enzymatic Preparation of Antioxidant Peptides from Channel Catfish (Ictalurus punctatus) Skin Gelatin
WANG Yun-gai,LIN Lin,LI Ming-hui,WENG Shi-bing,YE Ying-wang,JIANG Shao-tong,LU Jian-feng*
2010, 31(19):  254-258.  doi:10.7506/spkx1002-6630-201019055
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Five enzyme preparations were solely used to hydrolyze channel catfish (Ictalurus punctatus) skin gelatin and pepsin and trypsin were screened for further studies in view of higher hydroxyl free radical scavenging activity of the hydrolysates. Optimization of the conditions for trypsin hydrolysis was carried out using orthogonal array design L9(34) and the optimal hydrolysis conditions were determined as follows: temperature 40 ℃; pH 7.5; enzyme/substrate ratio (E/S) 3.5%; substrate concentration 2.5 g/100mL; and hydrolysis duration 3 h. In addition, pepsin and trypsin were used together for the two-step hydrolysis of channel catfish gelatin in different orders of addition or one-step hydrolysis, namely adding the two enzymes simultaneously. Initial trypsin hydrolysis for 3 h followed by another 3 h of pepsin hydrolysis resulted in the generation of peptides with the highest hydroxyl free radical scavenging rate, up to 47.38%.

Optimizing the Brewing Technology of Pineapple Wine
CHEN Wen-xue1,2,HU Yue-ying2,LIN Jun-fang1,*,LI Cong-fa2,3,*
2010, 31(19):  259-262.  doi:10.7506/spkx1002-6630-201019056
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The production technology of pineapple wine using active dry yeast D254 as the fermentation starter was optimized by quadratic general rotary unitized design. The changes of alcohol concentration, total sugar content and density were tested during 17-day fermentation. The optimal conditions for the fermentation of active dry yeast D254 were: initial sugar content 219.8 g/L; pH 3.5; and fermentation temperature 19.8 ℃ and that the maximum sensory score of pineapple wine under these conditions was up to 91.5.

Cloning and Prokaryotic Expression of Squalene Synthase Gene from Schizochytrium limacinum
ZHU Lu-ying1,2,ZHU Qing-hua3,2,ZHANG Xue-cheng2,*
2010, 31(19):  263-267.  doi:10.7506/spkx1002-6630-201019057
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A full length cDNA of squalene synthase (SQS) gene was isolated from Schizochytrium limacinum using homologybased cloning and RACE methods. Molecular biological analysis showed that the full length cDNA was of 1672 bp, with a 1338 bp open reading frame encoding 446 amino acids, and the SQS gene was a single copy gene in Schizochytrium limacinum. Homology analysis showed that Schizochytrium limacinum SQS cDNA had five consensus regions. The SQS cDNA was constructed into the prokaryotic expression vector pGEX-4T-3 and expressed in E.coli BL21. SDS-PAGE and Western blotting analyses showed that the recombinant protein was mainly in the form of inclusion body, of which molecular weight was as expected, and had good immunogenicity.

Extraction of Cell-envelope Proteinase from Lactobacillus fermentum
ZHU Xu1,PAN Dao-dong1,2,*
2010, 31(19):  268-272.  doi:10.7506/spkx1002-6630-201019058
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Lysozyme treatment was selected out of three commonly used ways for extracting cell-envelope protainase from Lactobacillus fermentum cells in the present study. The composition and pH of cell lysis solution and three extraction conditions were optimized using orthogonal array design. The best cell lysis solution was a mixture of 50 mmol/L Tris-HCl, 150 mmol/L NaCl, 3% Tween-20 and 2 mg/mL lysozyme at pH 8.9. Cell lysis solution/ Lactobacillus fermentum cells ratio of 10:1 (V/m) and incubation time of 5 h at a constant temperature of 37 ℃ were found optimal for the extraction of cell-envelope protainase, and the maximum specific enzyme activity was up to 38.957 U/mg under these conditions.

Flocculation Mechanism of Sweet Potato Starch by Addition of Lactobacillus paracasei-fermented Sweet Potato Slurry
LI Xin-hua1,ZHAO Xiao-yang1,ZHANG Li-li2
2010, 31(19):  273-276.  doi:10.7506/spkx1002-6630-201019059
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The goal of this work was to explore the mechanism of sedimentation separation of starch by acidic steeping liquor method so as to provide experimental guidance for the development of highly efficient bioflocculant. The Lactobacillus paracasei-fermented sweet potato slurry and its centrifugation supernatant and resuspended precipitate were separately added with sweet potato starch, and the flocculation of sweet potato starch in the three liquors was studied by the determination of Zeta potential, granular size and ionic bond. The flocculation of sweet potato starch was based on the bridging mechanism, and starch granules were conjugated with bacterial cells through ionic bond, and after flocculation, mean starch granular size decreased and granular density increased, resulting in the aggregation and sedimentation of starch granules. Moreover, from the results of experiments on the thermal and enzymatic stability of substances with flocculating activity, proteins were the active components in Lactobacillus paracasei responsible for flocculation.

Optimization of Extraction of Soluble Dietary Fibre from Peanut Hull by Aspergillus niger Solid-state Fermentation
LI Hong-xia1,2,LU Jing-jun3,LU Feng-sheng4,YU Li-na2,WANG Shi-qing1,YANG Qing-li2,*,
2010, 31(19):  277-282.  doi:10.7506/spkx1002-6630-201019060
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In order to promote the high value-added utilization of peanut hull, a byproduct of peanut processing, the solid-state fermentation of Aspergillus niger was employed to extract soluble dietary fibre (SDF) from the resource. The growth curve of Aspergillus niger in standard PDY medium was plotted for determining the optimal seed age. This was followed by optimizing the medium composition by orthogonal array design and four fermentation conditions including temperature, seed age, inoculum size and fermentation period by response surface methodology. The optimal medium composition was found to be composed of 8 g of peanut hull and 1.88-fold volume of water containing 1.88 g/100 mL (NH4)2SO4, 1.88 g/100 mL KH2PO4 and 5.63 g/100 mL MgSO4, and the optimal fermentation period and temperature, seed age and inoculum size were 9.1 days, 27 ℃, 2.9 days and 16 mL, respectively. The resultant hydrolysis efficiency, SDF polymerization degree and comprehensive score were 11.03%, 152.71% and 105.48, respectively.

Construction of a Phage Single Chain Fv Library against Derivatives of Furaltadone Metabolites
LUO Cui-hong1,WANG Hong1,*,LIU Xi-xia1,SHEN Yu-dong1,SUN Yuan-ming1,Huang Jia-jia1,ZHANG Hong-bin2
2010, 31(19):  283-287.  doi:10.7506/spkx1002-6630-201019061
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Objective: To construct a phage single chain Fv (scFv) library against derivatives of furaltadone metabolites (AMOZ). Methods: The total RNA extracted from a hybridoma cell line (BC3-E8) secreting monoclonal antibodies against AMOZ was reverse-transcribed into cDNA by RT-PCR. The heavy chain (VH) and the light chain (VL) variable region genes were amplified respectively by PCR with the previously designed degenerate primer. The VH and VL genes were spliced into scFv fragment with a DNA linker encoding (G1y4Ser)3 by splicing overlap extension (SOE). Then the scFv fragment was cloned into the phagemid pCANTAB5E and after the cloning, the phagemid was transformed into the competent Escherichia coli TG1. With the rescue of helper phage M13K07, a phage scFv library was constructed. Ten positive clones were randomly selected and identified by PCR and double enzymatic digestion. Furthermore, the sequences of these positive clones were sent for sequencing and analyzed by the DNAMAN software. Results: VH, VL and scFv DNA fragments were amplified successfully. The constructed phage scFv library had a capacity of 1.2 × 106 and the titre was about 2.0 × 1010 PFU. PCR and double enzymatic digestion identification showed that the ratio of positive insert was high. Multiple sequence alignment showed that the difference of scFv sequences was 8.38%, and those of VH and VL sequences were 3.68% and 14.34%, respectively, and the discrepancy were mostly concentrated in corresponding nucleic acid sequences of the CDR antigen region. Conclusion: a scFv phage antibody library against derivaties of furaltadone metabolites has been constructed successfully. This will lay a foundation for the further enrichment and expression of scFv.

Optimizing the Fermentation Conditions of Penicillium funiculosum for Producing Dextranase
ZHU Hui-xia1,WANG Ya-jie2,DENG Sheng-song1,YAO Ri-sheng1,*,ZHANG Hong-bin1
2010, 31(19):  288-291.  doi:10.7506/spkx1002-6630-201019062
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This study aimed at investigating the optimal fermentation conditions of Penicillium funiculosum for producing dextranase. The optimal carbon and nitrogen sources were dextran and peptone, respectively. The orthogonal array optimization showed that the optimal fermentation conditions of Penicillium funiculosum were as follows: the volume of the medium contained in a 250 mL Erlenmeyer flask 80 mL; medium initial pH 5.5; and fermentation temperature 28 ℃, and the resultant dextranase was 18.963 U/mL under these conditions.

A Novel Method for Enhancing Ethanol Fermentation by Saccharomyces cerevisiae
HUI Feng-li,CHU Xue-ying,KE Tao,ZHANG Cai-ying
2010, 31(19):  292-294.  doi:10.7506/spkx1002-6630-201019063
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Solid matrix was added to fermentation medium for exploring the effect of solid matrix on ethanol fermentation in yeast cells. Results indicated that the addition of 2 g of straw, peanut hull, rice hull or wood shavings to 100 mL medium could improve ethanol production by 15.5%-24.8%. Rice hull was the most suitable solid matrix and the optimal technological parameters for rice hull were found to be: rice hull amount 2.5 g/100 mL; initial glucose concentration 12 g/100 mL; fermentation temperature 30 ℃, and fermentation time 48 h. Under these optimal conditions, the actual production of alcohol reached up to 51.8 g/L, which was 92.7% of the theoretical value.

Prokaryotic Expression and Antibiotic Activity of Recombinant Bovine Lactoferricin Fusion Protein
WEI Xin-yuan1,WEN Pan-pan1,CHOU Min-xia2, FAN Ming-tao1
2010, 31(19):  295-298.  doi:10.7506/spkx1002-6630-201019064
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In order to establish a bovine lactoferricin biosynthesis method, the bovine lactoferricin-encoding gene was determined on the basis of amino acid sequence. A recombinant fusion gene was obtained by means of overlapping PCR following the purification of the separate PCR products of the bovine lactoferricin-encoding sequence and the split intein Asp dnaEIn gene from the DNA polymerase gene dnaENI of Anabaena sp. PCC 7120, and the obtained fusion gene was subsequently cloned into the expression plasmid pET-28a to construct a recombinant fusion expression plasmid. The results showed that recombinant fusion proteins were over-expressed after the expression host Escherichia coli BL21 (DE3) containing the recombinant bovine lactoferricin fusion expression plasmid was induced and that reaction products of over-expressed recombinant bovine lactoferricin lysates and the purified Anabaena sp. PCC 7120 DnaECI, which contained split intein Asp DnaEIc, could inhibit Staphylococcus aureus.

Construction of Alpaca-derived Naive Single-domain Antibody Phage Display Library by Semi-nested PCR
TU Zhui1,2,XU Yang1,2,*,HE Qing-hua1,2,TAO Yong2
2010, 31(19):  299-303.  doi:10.7506/spkx1002-6630-201019065
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Objective: To construct a single-domain heavy chain antibody phage display library for food safety detection. Methods: Total RNA was purified from peripheral lymphocytes of two healthy non-immune alpaca (Lama pacos) and directly used for complementary DNA (cDNA) synthesis. The repertoire of VHH encoding DNAs was amplified by semi-nested PCR, and the PCR products were cloned into the phagemid vector pHEN1. Through the electroporation of E. coli TG1, a primary library was established and then rescued by the helper phage KM13 to generate a phage display library. The generated phage display library was used to pan three different artificial antigens by solid phage biopanning. Results: The VHH encoding DNAs was amplified. After electroporating for 10 times, the primary library named as SNAL was generated containing more than 107 independent clones. The cloning efficiency was up to 87%. The titter of the phage display library obtained after the rescue with KM13 named as SNA-PDL was up to 1013 CFU/mL. All antigen screening data exhibited a significant enrichment in phage particles. Conclusion: A naive single-domain antibody phage display library has been successfully constructed. This library exhibits good diversity and can be used to the recovery of binders.

Medium Optimization for Producing Gamma-aminobutyric Acid by the Fermentation of Lactobacillus brevis BS2 with Zinc-enriching ability and Cloning and Sequencing of Its Glutamate Decarboxylase Gene
XIE Xiao-yang,CHEN Yao,LIU Zhi-wen,GUO Xiao-yan,CHENG Xin,GAO Xiao-yu,XU Bo*
2010, 31(19):  304-308.  doi:10.7506/spkx1002-6630-201019066
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The objectives of this work were to optimize the medium composition for improved production ofγ-aminobutyric acid (GABA) by the fermentation of Lactobacillus brevis BS2 with Zinc-enriching ability and to clone and sequence the glutamate decarboxylase (GAD) gene of this strain. GABA quantification was performed using pre-staining paper chromatography method. The optimal medium composition was determined as follows: carbon source, glucose; nitrogen source, soybean peptone plus beef extract; carbon/nitrogen ratio, 1:1; and substrate concentration, 1%, and the maximum GABA production reached up to 6.32 g/L under such conditions. CTAB method was used for the extraction of genomic DNA from stain BS2, and the extracted genomic DNA was used as the template for the amplification of a 1407 bp gad gene by touch down PCR. The gad gene was finally cloned into the T vector. The sequencing analysis showed that the gene had 98% homology with that of Lactobacillus brevis BH2, suggesting that the obtained target gene is the gad gene of Lactobacillus brevis.

Cloning and Expression of a New Thermostable Pullulanase Gene from a Deep-sea Archaeaon Strain Thermococcus siculi HJ21
WANG Shu-jun1,LU Ming-sheng1,LI Hua-zhong2,XU Jin-li1,2,JIAO Yu-liang1,FANG Yao-wei1,LIU Shu1
2010, 31(19):  309-312.  doi:10.7506/spkx1002-6630-201019067
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The gene of pullulanase was amplified from Thermococcus siculi HJ21 with degenerate primes designed based on the NCBI published conserved sequence information. The DNA sequencing and BLAST (NCBI) analysis showed that this DNA sequence was a new pullulanase gene with an open reading frame (ORF) of 4056 bp in length encoding 1351 amino acids.The gene was cloned into the expression vector, pET28a, producing a hybrid plasmid pET28a-pull. Subsequently, pET28a-pull was introduced into Escherichia coli BL21(DE3). The lysate of the transformant cells showed thermostable pullulanase activity. The SDS-PAGE analysis showed a band with apparent molecular weight of 150 kD.

Biodiversity of Yeast in Soils from Longan Grape Plantations in Shacheng Region
LI Yan1,2,LU Jun1,ZHANG Li-zhong3
2010, 31(19):  313-316.  doi:10.7506/spkx1002-6630-201019068
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To isolate and screen characteristic yeast strains, 210 yeast strains were isolated from soils from three Longan grape plantations in Shacheng region by gradient dilution and streak plate methods. These stains were classified into nine groups according to their morphological phenotypes, and the nine groups were identified by 5.8S ITS restriction fragment length polymorphism (RFLP) analysis, and two of them, Issatchenkia orientalis and Candida tropicalis, were common yeast strains. This study confirms the biodiversity of yeast in the oil of this region.

Nutrition & Hygiene
Anti-proliferative Effect of Tartary Buckwheat Protein Fraction TBWSP31 on Breast Cancer Cells
GUO Xiao-na,YAO Hui-yuan
2010, 31(19):  317-320.  doi:10.7506/spkx1002-6630-201019069
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The inhibition effect of a protein fraction TBWSP31 prepared from tartary buckwheat as described in our previous study on the proliferation of Bcap37 cells was investigated by MTT assay, HE staining and scanning electron microscopic (SEM) observation. TBWSP31 exhibited a notable anti-tumor activity in dose- and time-dependent manners and was also sensitive to human mammary cancer cell Bcap37 with IC50 values of 43.37 (48 h)μg/mL and 19.75μg/mL (72 h), respectively. After treated with TBWSP31 for 48 h, Bcap37 cells revealed typical apoptotic characteristics. The HE-stained cells exhibited visible morphological changes such as nuclear fragmentation, chromatin condensation, plasma-membrane blebbing and production of apoptotic bodies under a light microscope. The SEM observations revealed that the decrease of villus, even partial disappearance, plasma-membrane blebbing and production of apoptotic bodies.

Effect of Erucic Acid Content in Rapeseed Oil on Food Intake Safety in Mice
LEI Hong,CAI Liang-liang,CAO Li-li,JIANG Shao-tong
2010, 31(19):  321-324.  doi:10.7506/spkx1002-6630-201019070
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The erucic acid contents of cold-pressing double-low rapeseed oil and common rapeseed oil were analyzed by gas chromatography (GC). Sixty Kunming mice (half male and half female) were divided into 3 groups of 20 mice each (also half male and half female): control (fed normal diet), cold-pressing double-low rapeseed oil-treated (fed diet containing cold-pressing double-low rapeseed oil with 2% oil content) and common rapeseed oil-treated (fed common rapeseed oil with 2% oil content) groups. All these mice were fed for 5 consecutive weeks. The general status, body weight, food consumption, blood lipid indexes including total cholesterol (TC), triglyceride (TG) and high-density lipoprotein (HDL) and the weights of the visceral organs including heart, liver, spleen, lung and kidney of mice were measured once a week during the period of feeding. The results indicated that the erucic acid content of cold-pressing double-low rapeseed oil was 4.744%, and that of common rapeseed oil was 32.595%. Obviously, the former was much lower than the latter. The mice fed diet containing cold-pressing double-low rapeseed oil presented lower serum TC and TG levels but slightly higher HDL-C level than the mice fed diet containing common rapeseed oil. Therefore, cold-pressing double-low rapeseed oil is more suitable for animal feeding due to lower increments of the above serum lipid parameters when compared with common rapeseed oil. Compared with control and cold-pressing double-low rapeseed oil-treated mice, common rapeseed oil-treated mice showed an obvious increase in the weights of heart and liver, which might be related to fat deposition in heart and liver induced by the presence of erucic acid. No significant differences in body weight, food consumption and the weights of spleen, lung and kidney were observed among mice fed normal diet and diet containing cold-pressing double-low rapeseed oil or common rapeseed oil.

Antioxidant Effect of Wheat Germ Bioactive Peptides in D-galactose-induced Aging Mice
CHEN Ying1,ZHU Ke-xue1,PENG Wei1,LIU Hong-tao2,GU Yao-xing3,ZHOU Hui-ming1,*
2010, 31(19):  325-328.  doi:10.7506/spkx1002-6630-201019071
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Objective: To explore the antioxidant effect of wheat germ bioactive peptides (WGBP) in aging mice induced by D-galactose. Methods: Fifty male Kunming mice were randomly divided into five groups, control group, model group, and WGBP low-, medium- and high-dose groups. Except the control group, all the other groups were subjected to subcutaneous injection of D-galactose solution at a dose of 600 mg/(kg bw·d). Mice were treated with WGBP at doses of 200, 800 mg/(kg bw·d) and 1000 mg/(kg bw·d) once a day for the creation of the WGBP low-, medium- and highdose groups. The activities of SOD and GSH-Px, T-AOC and the content of MDA in serum, brain, liver and heart were determined after a trial period of 45 days. Results: The activities of GSH-Px, SOD and T-AOC exhibited a significant increase (P < 0.01) in serum, and the activities of SOD and T-AOC also exhibited a significant increase in heart (P < 0.01) due to WGBP treatment. The activity of GSH-Px in brain and liver exhibited an obvious increase (P < 0.05); meanwhile, an obvious increase of SOD activity in brain was also observed (P < 0.05). Furthermore, the content of MDA in serum and the above organs revealed a reducing trend (P < 0.05). Conclusion: WGBP has good antioxidant effect in vivo as expected.

Morphological Study on Hela Cells Apoptosis Induced by Lycium barbarum Polysaccharides
ZHU Cai-ping1,ZHANG Sheng-hua2,XIAO Jun-xia2
2010, 31(19):  329-334.  doi:10.7506/spkx1002-6630-201019072
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Lycium barbarum polysaccharides (LBP), isolated with boiling water from Lycium barbarum fruits, a famous Chinese medicinal herb, is one of the most important functional constituents in Lycium barbarum. In this study, the effect of LBP at the range of 3.125 to 200 mg/L on the proliferation of Hela cells was measured. After Hela cells were treated with LBP, typical apoptotic morphological changes were observed by fluorescence microscope, transmission electron microscope (TEM) and laser scanning confocal microscope (LSCM). Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay also confirmed that LBP-treated Hela cells showed apoptotic features. The results suggest that LBP is a potential antitumor compound.

Effect of α -Casein Hydrolysate on Blood Pressure in Spontaneously Hypertensive Rats
ZHANG Yan,HU Zhi-he*
2010, 31(19):  335-338.  doi:10.7506/spkx1002-6630-201019073
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Different doses (low dose, 0.0245 g/kg bw; medium dose, 0.1225 g/kg bw; and high dose, 0.6125 g/kg bw) of an α-casein hydrolysate prepared by sequential enzymatic hydrolysis with pepsin followed by trypsin were orally administered to spontaneously hypertensive rats (SHRs), and the SHRs were tested for their systolic blood pressure (SBP) during 8 hours postadministration once a day for continuously 3 days in order to the anti-hypertension effect of single administration of theα-casein hydrolysate in SHRs. Moreover, in the continuous administration trial, high-dose administration was performed once at the time intervals of four hours twice a day and SBP measurement was done 2 hours after each administration. The results showed that in the single administration trial, normal Wistar rats administered high dose of theα-casein hydrolysate did not present any obvious change in SBP within 8 hours after administration. Each of the three doses had a notable inhibitory effect on the increase of SBP in SHRs. Among them, the antihypertensive effect of high dose was the best within the first 6 hours, and the SBP level of SHRs administered high dose for the longest period of time, reaching up to 6 hours, and the largest decrease by (29.50 ± 1.0) mmHg was observed at 5 hours. Furthermore, continuous administration of high dose could keep SBP at a lower level for a long time period.

Effect of Cordyceps militaris on Oxidases in Brain and Liver Tissues of D-Galactose-induced Senile Mice
YANG Zhan-jun,ZHANG Jian,TANG Yang,WEN Lu
2010, 31(19):  339-341.  doi:10.7506/spkx1002-6630-201019074
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Objective: The enzymes related to aging were used as the indexes to explore the effect of Cordyceps militaris on Dgalactose-induced senile mice. Methods: A mouse model with senile disturbance of brain tissue was established by D-galactose induction and the experimental mice were treated with Cordyceps militaris by gavage. After the administration of Cordyceps militaris for six weeks, the activities of T-AOC, GSH-Px, MAO and the content of MDA in brain and liver tissues were analyzed. Results: Compared with the control group, the activities of T-AOC and GSH-Px of the model group exhibited an obvious decrease, and the activity of MAO and the content of MDA exhibited a significant increase (P < 0.05 or P < 0.01). Compared with the model group, the activities of T-AOC and GSH-Px in mice administered with Cordyceps militaris was ameliorated, and the activity of MAO and the content of MDA exhibited an obvious decrease (P < 0.05). Conclusion: Cordyceps militaris can improve the antioxidant capability of brain and liver tissues.

Effect of n-3 PUFA-containing Diet on Obesity and Obesity-related Cell Factors in Mice
ZHENG Zheng,GE Yin-lin*,XUE Mei-lan,QIN Wei-wei,XU Yan-jun,HOU Lin
2010, 31(19):  342-346.  doi:10.7506/spkx1002-6630-201019075
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Objective: To determine the effect of n-3 PUFA diet on obesity and obesity-related cell factors in mice. Methods: A total of 36 healthy female mice were randomly divided into three groups: high fat diet group, n-3 PUFA-containing diet group and control group. Body weight and food intake were recorded once a weed during the trail period and the levels of serum adiponectin, orexin-A and resistin were determined by ELISA method at the end of the trial. Results: The adiposity and serum orexin-A level in the n-3 PUFA-containing diet group were significantly lower than that in the high fat diet model group (P <0.05), and the level of serum resistin in the n-3 PUFA-containing diet model group was significantly higher than that in the high fat diet model group (P < 0.05). Conclusion: An obvious reduction on the development of adiposity was observed in mice fed n-3 PUFA-containing diet.

Establishment of an Animal Model for Shrimp Protein Sensitivity Test
WANG Li-juan1,2,HU Zhi-he1,2,CHEN Zhao-li2,ZHOU Xun2,WU Hai-ming2
2010, 31(19):  347-350.  doi:10.7506/spkx1002-6630-201019076
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Egg albumin was used as the positive control and balanced salt solution (PBS) was used as the negative control to observe general allergic reactions of shrimp protein. Guinea pig was used to establish an animal model for shrimp protein sensitivity test by observing the effect of shrimp protein on isolated ileal smooth muscle contraction reaction (Schultz-Dale reaction). Results indicated that the general allergic reactions in each guinea pig were positive after stimulated by egg albumin at a concentration varying from 0.01 to 1 g/100mL. All the guinea pigs died after the stimulation with egg albumin at a concentration of 0.1 g/100mL. The general allergic reactions of shrimp protein were similar with those of egg albumin at the similar concentration range from 0.01 to 1 g/100mL. Meanwhile, the Schultz-Dale reaction results were also similar with those of systemic allergic reactions. Therefore, an animal model for shrimp protein sensitivity test has been successfully established.

Effect of Polysaccharides from Ganoderma atrum on Spleen Lymphocyte Proliferation and Induction of Cytokine in Mice
ZHU Ke-xue,NIE Shao-ping,LI Wen-juan,YU Qiang,ZHANG Shen-shen,XIE Ming-yong*
2010, 31(19):  351-354.  doi:10.7506/spkx1002-6630-201019077
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Objective: To investigate the effect of polysaccharides from Ganoderma atrum (PSG-1) on spleen lymphocyte proliferation and induction of cytokine in mice. Methods: The effects of treatments with PSG-1 and with PSG-1 containing motigen at different concentrations on spleen lymphocyte proliferation were determined by MTT. The contents of IL-2 and TNF-α were determined by using ELISA. Results: PSG-1 at a concentration ranging from 20 to160 μg/mL resulted in a significant increase of lymphocyte proliferation, and 48 h administration gave the best proliferation. PSG-1 could also enhance the effect of Con A-induced T lymphocyte proliferation and the stimulation index of LPS-induced B lymphocytes. Moreover, PSG-1 could significantly increase the secretion of IL-2 and TNF-α in spleen lymphocyte. Conclusion: PSG-1 can effectively increase lymphocyte proliferation and enhance the effect of Con A, LPS-induced T and B cell growth. PSG-1 has the ability to enhance immune responses by increasing the secretion of IL-2 and TNF-α.

Analysis and Evaluation of Nutrient Composition of Dried Engraulis japonicus
WU Yan-yan,LI Lai-hao,YANG Xian-qing,WEI Ya,CHEN Sheng-jun
2010, 31(19):  355-358.  doi:10.7506/spkx1002-6630-201019078
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In this study, the nutrient components in dried Engraulis japonicus from the sea areas near Zhejiang, Xiamen and Hainan were analyzed and evaluated. The results showed that protein contents in dried Engraulis japonicus from Zhejiang, Xiamen and Hainan coastal areas were 45.25%, 42.42% and 38.95%, and fat contents were 4.71%, 3.42% and 3.05%, respectively. Dried Engraulis japonicus from the three sea areas exhibited a proportional balance in total content of amino acids in the range of 34.4% to 38.7%. All essential amino acids essential for human body were contained in dried Engraulis japonicus from the three sea areas, and methionine acted the first limited amino acid, and lysine content was up to 3.86 g/100 g and flavor amino acids represented 48.23% of the total amount of amino acids. Dried Engraulis japonicus was low in fat but rich in polyunsaturated fatty acids, especially DHA, of which the content was between 21.21% and 25.83%, and Ca, P, Fe, Zn, Se and other trace elements. The detection and analysis of heavy metal elements and other toxic substances in dried Engraulis japonicus indicated that all the dried products from these three coastal areas met national safety and health standards. Therefore, dried Engraulis japonicus is a kind of marine product with good quality and high nutritional value.

Anti-oxidant Effect of Flavonoid Glycosides from Rape Bee Pollen
SUN Li-ping1,XU Xiang1,LIAO Lei2,LIU Kui-ying2,YANG Jia-lin1
2010, 31(19):  359-362.  doi:10.7506/spkx1002-6630-201019079
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Flavonoid glycosides were prepared from rape bee pollen, and their ability to scavenge DPPH free radicals and reducing power in simulated chemical systems were determined. The antioxidant activity of the extracted flavonoid glycosides was not as strong as that of kaempferol or quercetin. The antioxidant activity of the extracted compounds in vivo against CCl4-induced lipid peroxidation in mice was investigated, and the antioxidant mechanisms were also elucidated. The results showed that the extract could significantly inhibit the generation of MDA in liver, and increase the level of T-AOC in liver and serum. The possible antioxidant mechanism was the generation of flavonoid aglycone with plentiful antioxidant phenolic groups due to the hydrolysis of flavonoid glycosides by in vivo relevant enzymes. Therefore, flavonoid glycosides derived from rape bee pollen had a good protective effect against in vivo oxidative damage.

Effect of Ingestion of Trans-Fatty Acids on Lipid Metabolism in Rats
ZHANG Jia1,LI Jing1,*,DENG Ze-yuan1,2,CAO Jun1,LIU Rong1,FAN Ya-wei1,HU Jiang-ning1
2010, 31(19):  363-366.  doi:10.7506/spkx1002-6630-201019080
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Epidemiological studies have demonstrated that trans-fatty acid (TFA) intake from diet increase the risk of some chronic diseases through blood lipid metabolism and inflammation pathway. Under the condition of oil added TFA with cholesterol-free (0% cholesterol) and 33% energy supplement from fat, the effect of TFA on lipid metabolism of rats was observed during 90 d feeding. The experimental diet with TFA significantly increased TG, lowered HDL-C, LPL and HL activity, suggesting that TFA could change fatty acid profile to induce the abnormity of TG metabolism. Meanwhile, TFA significantly depressed TC and LDL-C and improved HDL-C/LDL-C ratio, but did not exhibit effect on C-reactive protein (CRP) due to having no effect on the abnormity of cholesterol metabolism.

Effect of a Polysaccharide Fraction from Fruit Bodies of Morchella esculenta (L.) Pers on Short-chain Fatty Acids in Intestinal Tract of Rats
MING Jian1,2,WU Su-rui3,ZENG Kai-fang1,2,GUI Ming-ying3,CHEN Zong-dao1,2,ZHAO Guo-hua1,2,*
2010, 31(19):  367-371.  doi:10.7506/spkx1002-6630-201019081
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In this study, the effect of a polysaccharide fraction from fruit bodies of Morchella esculenta (L.) Pers, named PMEP-1 on short-chain fatty acids in the intestinal tract of rats was investigated. SD rats were orally administered PMEP-1 at high dosage (400 mg/kg bw·d), medium dosage (200 mg/kg bw·d) and low dosage (100 mg/kg bw·d) for a period of four weeks. Rat feces were collected periodically during the trial. Short-chain fatty acids in intestinal tract of rats were determined by gas chromatography. The results indicated that PMEP-1 had an obvious effect on the production of acetic acid, propionic acid, isobutyric acid, butyric acid, valeric acid and caproic acid, but had no obvious effect on the production of heptanoic acid and isovaleric acid. PMEP-1 at various dosages exhibited considerably different effects on short-chain fatty acids. An obvious effect of medium and low dosages of PMEP-1 on short-chain fatty acids was observed. The highest productivity of short-chain fatty acids in intestinal tract of rats in each dose group appeared at 7 - 14 days.

Effect of Oleic Acid on Proliferation of Human Umbilical Vein Endothelial Cells
YU Hua-hong,LI Xiang-mei,LIU Rong,DENG Ze-yuan*,LI Jing,FAN Ya-wei,HU Jiang-ning
2010, 31(19):  372-374.  doi:10.7506/spkx1002-6630-201019082
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Objective: To observe the effect of oleic acid on the proliferation of human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were treated with oleic acid at concentrations of 50, 100, 200, 400μmol/L and 600 μmol/L (in combination with NaOH at a final concentration of 200μmol/L), respectively. The normal group receiving no treatment was served as the negative control, and the groups treated with NaOH at 200μmol/L alone were used as the positive control. MTT assay and trypan blue exclusion tests were used to evaluate the toxicity of oleic acid on cells. Results: Compared with the normal group, oleic acid significantly inhibited the proliferation of HUVECs. In addition, compared with the group treated with oleic acid at a low concentration (50μmol/L), an obvious strong inhibition effect on cell proliferation was observed in groups treated with oleic acid at high concentrations (400μmol/L and 600μmol/L). However, no significant difference was observed between the positive control and the normal group. Moreover, the amount of viable cells in oleic acid-treated groups was obviously reduced. Conclusion: Oleic acid has obvious side effect on HUVECs in a concentration- and time-dependent manner.

Effect of Dietary Cholic Acid on Apoptosis and Proliferation of Large Intestinal Epithelial Cells in Irradiation-Exposed Rats
XU Hong1,ISHIZUKA Satoshi2,SONG Huan-lu1
2010, 31(19):  375-380.  doi:10.7506/spkx1002-6630-201019083
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The effect of dietary cholic acid (CA) on the acute response of the rat large intestinal epithelial cells following a singledose irradiation was investigated. Rats were exposed to whole-body gamma-irradiation after being fed a control or 0.2% CA diet for 10 days. The rats were then sacrificed at 1, 3, 6, 12 h and 24 h post-irradiation. Segments of cecum and distal colon were collected for histochemical analysis. Apoptosis in the epithelial cells of cecum and distal colon was stimulated and peaked at 3 h postirradiation in both dietary groups, however, in CA group, apoptosis was markedly inhibited at 6 h post-irradiation in the distal colon. In epithelial cells of rats fed the control diet, the number of bromodeoxyuridine (BrdU)-incorporated cells began to decrease at 1 h post-irradiation in both distal colon and cecum. Interestingly, the proliferation of the cells was transiently stimulated by CA intake before decreasing. It should be noted that the effect of dietary CA on proliferation and apoptosis in the colonic epithelial cells was more significant than that in the cecal epithelial cells. In conclusion, these results demonstrate that dietary CA alters the regeneration regularity of colonic cells and serves as an inhibitor of apoptosis in the intestinal epithelial cells following DNA damage induced by gamma-irradiation.

Reviews
Progress in Protein Metabolism of Lactic Acid Bacteria
BAI Feng-ling1,ZHANG Bo-lin2,ZHAO Hong-fei2
2010, 31(19):  381-384.  doi:10.7506/spkx1002-6630-201019084
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Due to the lack of various biosynthetic pathways, lactic acid bacteria (LAB) are nutritionally fastidious and unable to synthesize some essential amino acids and vitamins. LAB possess extracellular proteinase and this enzyme hydrolyzes dairy casein into oligopeptides and amino acids, which can be transported into cells by the oligopeptide transport system (Opp) and the di-tripeptide transport systems (DtpT and DtpP), followed by the hydrolysis of intracellular oligopeptides by endogenous peptidases into free amino acids supporting the synthesis and metabolism of LAB cells during their growth. Hence, studies of protein metabolism in lactic acid bacteria have great significance for improving LAB growth, establishing high-density culture systems and promoting the formation of flavor compounds and their precursors during the fermentation of cheese and other dairy products.

Extraction of Antioxidants from Peels and Application in Food: a review
ZHU Jun,ZHANG Xiao-juan,CHANG Si-si,JIANG Yong
2010, 31(19):  385-389.  doi:10.7506/spkx1002-6630-201019085
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Abundant antioxidant compounds exist in a variety of fruit peels and can be used in food as natural antioxidants. The extraction methods of antioxidants such as flavonoids, polyphenols, polysaccharides and vitamin C, their antioxidant properties and applications in food are discussed in this paper.

Research Advances in Nutritional Composition and Exploitation of Chinese Giant Salamander (Andrias davidianus)
LUO Qing-hua
2010, 31(19):  390-393.  doi:10.7506/spkx1002-6630-201019086
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Numerous studies have proved that the muscle of Chinese giant salamander (Andrias davidianus) has high nutritional value and is rich in high quality proteins, plentiful essential amino acids and delicious amino acids at high content levels. The fatty acid composition consists of high percent unsaturated fatty acids, especially DHA. The current situation of research of Chinese giant salamander meat based foods is analyzed in this article, and the development of healthcare foods such as protein and amino acids products and functional fats is predicted to be the main direction of exploitation of characteristic Chinese giant salamander meat based foods.

Effect of Cross-linking on Protein Foods: a review
YANG Liu1,2,LIU Yu-huan1,2,*,RUAN Rong-sheng1,2,WANG Yun-pu1,2,
2010, 31(19):  394-398.  doi:10.7506/spkx1002-6630-201019087
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The effect of protein cross-linking on sensory quality of food has attracted extensive attention. Unfortunately, the effect of protein cross-linking on protein digestibility lack of systematic studies. In this paper, the mechanisms of freeze-thaw cross-linking, enzymatic cross-linking and thermal cross-linking for proteins in the past 20 years are reviewed and the effects of cross-linking on functional characteristics, digestibility and food quality are discussed.

Research Progress in Quality and Safety of Fresh Cut Lettuce
ZHANG Xue-jie1,YE Zhi-hua2,*
2010, 31(19):  399-404.  doi:10.7506/spkx1002-6630-201019088
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In recent years, due to the increasing consumption of fresh cut lettuce products, quality and safety are becoming a major issue to human health. Major problems involved in quality and safety of fresh cut lettuce are introduced and research progress from processing to storage involved in chemicals, physical or combinatorial disinfections, browning control and nutrients loss and predicted models on quality and safety are also discussed in this paper. Further research directions are also proposed, which will provide a theoretical reference for future research and application in quality and safety control of fresh cut lettuce.

Grasping the Starting Point of Food Safety Control: A Study on Chinese Food Safety in the View of Pesticide Residues
WU Wen-han,SUN Xue-an
2010, 31(19):  405-408.  doi:10.7506/spkx1002-6630-201019089
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Based on the starting point of food safety control, pesticide residues in food have attracted extensive attention. Although pesticides play an important role in production quantity, the application and continuous development of pesticides exhibit an emerging harm to human health and ecological civilization. The effective management methods from four aspects including behavioral norms of producers and users, residues of planting environment and final products, and improvement of the life quality for people related to pesticides, and correct supervision and appropriate punishment for violations are discussed in this paper. Therefore, the balance point of the conflict between high and stable yield of farm products and pesticide application is highly desired.

Research Progresses in Enzymatic Modification of Food Proteins
LIU Xiao1,WU Jin-ju1,2,GAO Jin-yan3,CHEN Hong-bing1,2,*
2010, 31(19):  409-413.  doi:10.7506/spkx1002-6630-201019090
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The enzymatic modification is an important method for improving functional properties of food proteins. In this paper, four modification methods including covalent cross-linking, proteolysis, deamidation and phosphorylation are introduced to explore the mechanisms and applications of enzymatic modification in food proteins. Covalent cross-linking exhibits a promising application and proteolysis is a matured method to modify food proteins; deamidation has received extensive attention, while phosphorylation is rarely used in enzymatic modification of food proteins.

Research Progress in Extraction Methods of Active Components from Sesame Cake
DOU Fu-liang,WEI Dong
2010, 31(19):  414-417.  doi:10.7506/spkx1002-6630-201019091
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Sesame cake is a by-product obtained after oil extraction. The nutritional value of sesame cake is analyzed in this paper. Extraction methods of protein, polypeptide and sesamin from sesame cake are also discussed. All of these investigations are expected to provide a reference for in-depth processing and comprehensive utilization of sesame cake.

Prospects for the Application of Modern Processing Technology in Gelatin Preparation
CHEN Li-qing1,MA Liang1,2,ZHANG Yu-hao1,2,*
2010, 31(19):  418-421.  doi:10.7506/spkx1002-6630-201019092
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Based on traditional preparation methods of gelatin and the existing problems, the theoretical feasibility of using modern processing technology to improve the traditional preparation of gelatin is analyzed in this article. Meanwhile, the effect of modern processing technology on the properties of gelatin is also discussed. Moreover, the future development trends of gelatin preparation are predicted.

Current Progress in Gel Stability of Soy Protein Isolate
ZHU Xiao-ye,CHI Yu-jie,XU Yan,LIU Hong-yu*
2010, 31(19):  422-425.  doi:10.7506/spkx1002-6630-201019093
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Soy protein isolate is widely applied in food industry due to its high protein content and functional properties, especially for gel properties. However, the gel stability of soy protein isolate usually exhibits a decrease during storage, which reduces the quality of gel products. According to the research progress at home and abroad, protein compositions, protein concentration, temperature, pH and ionic strength affect the formation of soy protein gel during storage. Many modification methods for improving gel stability of soy protein isolate are also discussed in this paper.

A Review of Quantitative Detection of Food Allergens
YAN Fei1,LIAO Zhi-yong2,WU Zhi-hua1,*,CHEN Hong-bing1
2010, 31(19):  426-429.  doi:10.7506/spkx1002-6630-201019094
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The increasing phenomena of food allergy have highlighted the importance of quantitative analysis of food allergens. Currently, most methods for the quantitative detection of food allergens are indirect methods based on a single protein. Due to the development of mass spectrometry, quantitative proteomics is being widely used for the direct quantitative detection of trace allergens in complex food mixtures. In this paper, the research progress in quantitative detection methods for food allergens is discussed.

Application of Food Safety Risk Analysis in Pesticide Residue Standards
CHEN Xia,LI Jiang-hua*
2010, 31(19):  430-434.  doi:10.7506/spkx1002-6630-201019095
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Food safety risk analysis is internationally recognized as food safety management idea. The scientific approach method to ensure food safety has been adopted and widely used in more and more countries. In the formulation of standards of pesticide residues in food safety, risk analysis has become a common way. However, there are still many problems involved in the current Chinese pesticide residue standards. The practice of advanced international organization and developed countries can provide useful references for the formulation of pesticide residue standards in China.

Research Progress in Analytical Methods of Organotin in Food
LIU Ying-xia1,LI Juan1,YAN Ai-ping1,GUO Lan1,WAN Yi-qun1,2,*
2010, 31(19):  435-442.  doi:10.7506/spkx1002-6630-201019096
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Organotin is fat-soluble and easy to access to biological body and concentrate through food chains, which will produce toxicity to human and animals. Therefore, studies on organotin analysis in food to ensure food safety and promote human health are important. The current development of analytical methods for organotin in food, including gas chromatography, liquid chromatography and capillary electrophoresis, are reviewed in this paper. Various pre-treatment methods for organotin analysis are also discussed.

Research Progress in Transformation and Degradation of Trichothecenes
ZOU Zhong-yi,HE Zhi-fei,LI Hong-jun*,ZOU Cheng-han,HAN Peng-fei,YANG Jia-yi
2010, 31(19):  443-448.  doi:10.7506/spkx1002-6630-201019097
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Trichothecenes are commonly found in grain and animal feed and human food produced from contaminated grain, which brings a food safety risk. Physical, chemical and biological methods have been posed to evaluate their usefulness in the transformation and degradation of trichothecenes. These methods are reviewed in this paper and their research progress is discussed in detail. Meanwhile, the mechanisms of transformation, transformation products and toxicity are also elucidated, This paper is expected to provide some references for further studying the transformation and degradation of trichothecenes.

Research Progress in Cured Cooked-meat Pigments Derived from Blood
WANG Ji-xia,WANG Rui-hua,WANG Hai-bo,SUN Ming-sheng,YANG Guo-feng,XIAO He,CAI Ke-zhou,
2010, 31(19):  449-452.  doi:10.7506/spkx1002-6630-201019098
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It has been an urgent issue to find an alternative to nitrate and nitrite in the field of meat industry. In this paper, the preparation principle and methods, properties and applications of cured cooked-meat pigments (CCMP) are reviewed. Meanwhile, the current problems as well as further research direction are also discussed. All of these investigations will be helpful fools for the further development of CCMP.

Interference Factors of Protein Determination in Fish using Kjeldahl Method
LU Jian-zhang,SUN Li-hua,ZHOU Yan-gang*
2010, 31(19):  453-456.  doi:10.7506/spkx1002-6630-201019099
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In order to improve the accuracy of Kjeldahl method for the determination of fish protein, the conversion factor between amino acid nitrogen and non-amino acid nitrogen in fish protein is analyzed and a series of feasible improvement strategies for the determination of fish protein by Kjeldahl method are discussed in this paper.

Effect of Oxidative Degradation Products from Carotenoids on Flour Quality
LIU Xiao-geng
2010, 31(19):  457-460.  doi:10.7506/spkx1002-6630-201019100
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Carotenoids abundantly existing in flour and its raw materials have many special functions. However, carotenoids can degrade into a variety kind of substances with characteristic aroma such as colorless volatile ionone, pseudo ionone, dihydroactinidiolide, oxoisophorone during the storage and processing of flour. Oxidative degradation products of carotenoids can improve the color and form characteristic aroma of flour, indicating that they have beneficial impact on flour quality. In addition, these degradation products are also useful and important for the exploitation of new staple foods with rich nutrients, pleasant aroma and excellent taste. In this paper, an overview of carotenoids oxidative degradation is introduced, and oxidative degradation pathways and mechanisms, the aroma characteristics of the major degradation products and their effects on the quality of flour and flour products are discussed. Oxidative degradation and further utilization of carotenoids are also analyzed. All of these studies will provide a promising prospect on oxidative degradation products of carotenoids.

A Review of Exploitation and Application of Angiotension-converting Enzyme Inhibitory Peptides Derived from Milk
YANG Ming,HU Zhi-he*
2010, 31(19):  461-464.  doi:10.7506/spkx1002-6630-201019101
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Angiotensin-converting enzyme (ACE) plays an important physiological role in the regulation of blood pressure. Currently, many kinds of ACE inhibitory peptides derived from lactoprotein have been prepared. In this paper, the mechanisms and sources of ACE-inhibitory peptides are discussed, and the exploitation and application of ACE-inhibitory peptides in food and clinical field are reviewed.

Current Situation and Improvement Strategies of Meat Product Safety in China
CHENG Li
2010, 31(19):  465-468.  doi:10.7506/spkx1002-6630-201019102
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The current situation and development of meat product processing industry in China is summarized and the major food safety issues regarding meat products are analyzed. In order to enhance the management of livestock environment, regulate cultivation management, improve food safety knowledge of consumers, and accomplish effective inspection and control of meat products, a strict control strategy for meat product safety is proposed to introduce HACCP and detection systems during the processes of manufacturing, storage, transport and distribution of meat products. Meanwhile, governments and corresponding departments should borrow foreign experience to establish a prefect system for cultivation, manufacturing, management and quality control.