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15 November 2011, Volume 32 Issue 21
Basic Research
Properties and Isothermal Crystallization Process of Fractionated Palm Oil
XIE He,LI Lin,ZHANG Xia,LIANG Zhi-li,XIE Si-long,LIU Guo-qin,LI Bing
2011, 32(21):  1-5.  doi:10.7506/spkx1002-6630-201121001
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Triacylglycerol (TAG) composition, solid fat content, isothermal crystallization properties and isothermal crystallization kinetics of palm oils A and B with respective melting points of 44 ℃ and 24 ℃ were compared. The results showed that TAG composition had an important impact on their crystallization. The isothermal crystallization of sample A reached equilibrium faster. The Avrami index of sample A was almost the same as that of sample B under the same isothermal conditions, indicating that both samples experienced the same mechanism of crystallization induced by super cooling.
Anti-tumor Components from Fermentation Products of Fungus Salcoli6 Derived from Salicornia herbacea
ZHAO Yu-hui,YANG Hai-yan,XIN Zhi-hong
2011, 32(21):  6-11.  doi:10.7506/spkx1002-6630-201121002
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The anti-tumor components were isolated and identified from fermentation products of fungus Salcoli6 derived from Salicornia herbacea by bioassay-guided method. Seven compounds were isolated sequentially by solvent extraction, silica gel column chromatography and preparative HPLC. Their structures were identified as cladosporin (1), isocladosporin (2), naphthalenone (3), 2-acetyl-quinazoline (4), 3-hydroxy-2-methyl-chromen (5), 3-methylisobenzofuran (6) and p-hydroxyphenyl-acetic acid (7) by physicochemical properties and spectral analysis, respectively. The anti-tumor activity of the compounds was evaluated by SRB method. Compounds 3, 4 and 7 revealed cytotoxicity with IC50 of 12, 24 and 6μg/mL against p388 cell line, respectively; however, other compounds were inactive.
Effect of Ozone Treatment on the Degradation of Ochratoxin A and Fatty Acids in Corn
DENG Jie,CHEN Wen-jie,GUO Bai-xue,ZHANG Yan
2011, 32(21):  12-16.  doi:10.7506/spkx1002-6630-201121003
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The feasibility of applying ozone in corn storage was analyzed in the present study with the purpose of solving food safety issues caused by mycotoxin contamination during the storage of cereal grains. In the present study, the effects of ozone treatments at the concentrations of 10, 30 g/m3 and 60 g/m3 and exposure time (1-10 h) on the degradation of ochratoxin A (OTA) in corn and its fatty acid composition were explored. The results indicated that OTA at 80μg/L was completely degraded after ozone treatment at 30 g/m3 for 120 min or at 60 g/m3 for 90 min. Corn contaminated with 80μg/kg OTA was degraded to less than 5μg/kg after being treated by 60 g/m3 ozone for 10 h. Ozone had little effect on the fatty acid compostion in corn. Therefore, ozone can be used for the storage of corn as a result of effective degradation of OTA by it.
Effect of 60Co-γ Radiation on Potato Starch Characteristics
FAN Bei,MA Jing,LI Shu-rong,LI Qing-peng,WANG Feng,ZHOU Hong-jie,HA Yi-ming
2011, 32(21):  17-19.  doi:10.7506/spkx1002-6630-201121004
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Potato starch samples were radiated by 0, 4, 8, 10, 12, 16 kGy and 20 kGy 60Co-γ, respectively. The changes of starch granule morphology and the transparency, viscosity thermo-stability and viscosity cold-stability of starch paste were measured. After 60Co-γ radiation, the granular appearance of potato starch underwent little change, and the average size became smaller. The transparency, viscosity thermo-stability and viscosity cold-stability of potato starch paste increased while the peak viscosity revealed opposite changes. When the radiation dose was higher than 10 kGy, the peak viscosity, viscosity thermo-stability and viscosity cold-stability of potato starch tended to be stable. These results can provide a theoretical basis for producing modified potato starch.
Dynamic Effect of Waste Lees Content on Quality of Mechanically Compressed Wrapped Starter
YU You-gui,LI Zhong-hai,LI Juan,XIONG Xiang,XIAO Geng-cheng
2011, 32(21):  20-23.  doi:10.7506/spkx1002-6630-201121005
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In order to optimize waste lees content in mechanically compressed wrapped starter, comparative experiments on the Daqu (a traditional Chinese liquor fermentation starter) making were conducted using wrapped starters containing 5%, 7%, 9% and 11% waste lees and wrapped starter with 100% wheat. The results showed that waste lees content could affect water content, acidity, saccharification capacity, fermentation capacity and major microorganism flora of wrapped starter. Meanwhile, it also affected sensory quality of new starter. The appropriate amount of waste lees in wrapped starter was helpful to improve the quality of Daqu. Wrapped starter containing 9% waste lees showed the best quality. Therefore, it is feasible that waste lees are used in mechanically compressed wrapped starter.
Optical Characteristics of Aspergillus niger Lipase and Application in Biosynthesis of Ethyl Hexanoate in Reversed Micelle System
CHEN Li-mei
2011, 32(21):  24-28.  doi:10.7506/spkx1002-6630-201121006
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The optical characteristics of Aspergillus niger lipase were studied in this paper. The synthesis conditions of ethyl hexanoate by A. niger lipase in reversed micelle system were optimized. The results indicated that the configuration of A. niger lipase in reversed micelle system was different from that in phosphate buffer solution. More aromatic amino acids in reversed micelle system were exposed than in phosphate buffer solution. The optimal synthesis conditions were reversed micelle system containing isooctane, hexanol and water with a volume ratio of 60:4:1, lipase concentration of 0.003 g/L, hexanoic acid concentration of 0.3 mol/L, hexanoic acid/ethanol ratio of 1:0.9, reaction temperature of 35 ℃, and shaker rotation speed of 120 r/min. Under the optimal conditions, the maximum conversion rate of hexanoic acid reached (88.92±1.00)% after 16 h.
Partial Characterization and Antioxidant Activity of Water-soluble Polysaccharide Isolated from Bulbus Fritillariae ussuriensis
LIU Chun-hong,MA Yu, HE Zhong-mei, HAN Bao-rui
2011, 32(21):  29-33.  doi:10.7506/spkx1002-6630-201121007
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A water-soluble polysaccharide was isolated from Bulbus Fritillariae ussuriensis (dried bulbs of Fritillaria ussuriensis Maxim) sequentially through water extraction, ethanol precipitation, ion exchange chromatography and gel permeation chromatography. The molecular mass of FUP-1 was determined by gel filtration chromatography, and its structure was characterized by HPLC and FTIR spectroscopy. The results showed that FUP-1 was a heteropolysaccharide, of which the monosaccharide composition was composed of xylose, glucose and galactose with a molar ratio of 5:1:1. The average molecular weight of FUP-1 was determined to be 4.1 × 104 D. Bioactivity tests in vitro showed that FUP-1 displayed strong antioxidant effect and scavenging capacity against hydroxyl, DPPH, and superoxide anion free radicals. Therefore, FUP-1 may be a potent antioxidant agent.
Antioxidant Activities of Ethanol Extracts of Rape Pollen Collected from Different Regions
CHENG Ni,WANG Bi-ni,DENG Jian-jun,GAO Hui,CAO Wei
2011, 32(21):  34-36.  doi:10.7506/spkx1002-6630-201121008
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Rape pollens collected from different regions including Qinhai, Hubei, Shannxi, Anhui, Xinjiang, Sichuan and Fujian were extracted by 80% aqueous ethanol and total phenolic content, total flavonoid content, reducing power activity and DPPH radical scavenging activity of the resulting extracts were measured. The results revealed that rape pollens from Xinjiang and Hubei had significantly higher antioxidant activity than those from other regions (P<0.05). The antioxidant activity of the rape pollen extract from Anhui was significantly lower than other regions (P<0.05).
Antioxidant Activity of Water-soluble Polysaccharide Fractions from Portabella Mushroom Agaricus bisporus
LI Fang-liang,GAO Yang,LIU Ying,WANG Rui
2011, 32(21):  37-40.  doi:10.7506/spkx1002-6630-201121009
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Water extraction followed by fractional ethanol precipitation was used to purify water-soluble polysaccharides from portabella mushroom Agaricus bisporus (WPPA). The polysaccharide fractions WPPA60, WPPA70 and WPPA80 were obtained using three ethanol concentrations: 60%, 70% and 80%. Their antioxidant activity in vitro was assessed in terms of reducing power, scavenging activity against superoxide anion hydroxyl free radicals and inhibitory activity against H2O2-induced erythrocyte hemolysis. The results showed that WPPA60, WPPA70 and WPPA80 revealed strong reducing power, scavenging capacity against superoxide anion and hydroxyl free radicals and inhibitory effect on erythrocyte hemolysis and MDA generation. The polysaccharide fractions were ranked in decreasing order of antioxidant activity as follows: WPPA70, WPPA80 and WPPA60.
Chemical Composition and Antioxidant Activities of Different Apple Cultivars
DING Xiu-ling,ZHANG Jing-fang,HAN Ming-yu
2011, 32(21):  41-47.  doi:10.7506/spkx1002-6630-201121010
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The contents of L-ascorbic acid, soluble sugar, titrable acid and total phenols and pH of 13 apple cultivars were determined. Meanwhile their antioxidant activities were also evaluated based on reducing power, scavenging capacity agaisnt 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH ·) and hydroxyl radical ( ·OH), and anti-lipid peroxidation activity. Moreover, cluster analysis was performed. The results indicated that 13 apple cultivars revealed significant difference in chemical composition and antioxidant activity. Starkrimson, Rattan No. 1 and Yanguang had the highest antioxidant activity, whereas Qinguan, Pink Lady and Red Fuji had the lowest antioxidant activity. A significant correlation between antioxidant activity and total phenolic content was observed. Furthermore, cluster analysis revealed the highest content of L-ascorbic acid in U.S. Pat and Pacific Rose, the highest content of soluble sugar in Jonagold, Pacific Rose, Pink Lady, Qinguan and Red Fuji, the richest titrable acid in Pink Lady and the highest sugar/acid ratio in Qinguan and Red Fuji, respectively. Meanwhile, the most abundant phenols were observed in Rattan No. 1, Yanguang, Starkrimson and Jonagold.
Isolation, Purification and Monosaccharide Composition Analysis of Polysaccharides from Two Umbilicaria Species
Gulzar ABDUKEYUM,Nurbiya YALKUN,Kerimjan TURSUNJAN,Abdulla ABBAS
2011, 32(21):  48-51.  doi:10.7506/spkx1002-6630-201121011
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Objective:To analyze the monosaccharide composition of polysaccharides extracted from two Umbilicaria species: Umbilicaria decussate (Vill.) Zahlbr and Umbilicaria virginis Schaer.. Methods: Water-soluble polysaccharides from both Umbilicaria species were obtained by water extraction, ethanol precipitation and freeze-dried and purified into fractions SUv and ZUd, respectively by sequential column chromatography on DEAE-52 and Sephadex G-150. Gas chromatography (GC) was used to analyze their monosaccharide composition. Results: The monosaccharide composition of crude Umbilicaria virginis polysaccharides was composed of mannose, glucose and galactose at a ratio of 16.00:50.96:6.17. The monosaccharide composition of SUv was comprised of mannose, glucose and galactose at a ratio of 2.97:17.70:1.52. The monosaccharide composition of crude Umbilicaria decussate polysaccharides was made up of mannose, glucose and galactose at a ratio of 3.90:38.086:2.00. ZUd contained only 5.37% glucose. Conclusion: Both Umbilicaria decussata and Umbilicaria virginis contain glucose and a small amount of mannose and galactose.
in vitro Antioxidant Activity of Lyophilized Rape Royal Jelly
GAO Hui,CHENG Ni,JIA Qi,WANG Bi-ni,DENG Jian-jun,CAO Wei
2011, 32(21):  52-55.  doi:10.7506/spkx1002-6630-201121012
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Water-soluble protein, total phenol and 10-HDA in lyophilized samples of rape royal jelly from different regions: Qinghai, Shaanxi, Anhui and Zhejiang were analyzed in this study. The antioxidant activities of water-soluble extract from these samples were determined using DPPH radical scavenging and FRAP assays. The results showed that there were no significant differences in total phenol content among royal jelly samples from the different regions above. Royal jelly samples collected from Qinghai and Shaanxi had the highest water-soluble protein and 10-HDA contents, reaching 190.32 mg/g and 4.28%, respectively. All the samples investigated had powerful DPPH radical scavenging activity and total antioxidant capacity. Strong correlations were observed between total antioxidant capacity and water-soluble protein content (r=0.88) or total phenol content (r=0.95).
in vitro Antioxidant Capacity of Chaenomeles sinensis (Thouin) Koehne Juice
ZHANG Shu-juan,XU Huai-de,MI Lin-feng
2011, 32(21):  56-61.  doi:10.7506/spkx1002-6630-201121013
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The in vitro antioxidant capacity of Chaenomeles sinensis (Thouin) Koehne juice was evaluated and the correlations of antioxidant capacity with total phenol and ascorbic acid contents of the fruit juice were analyzed. The results showed that this juice possessed strong scavenging activity against ABTS radical, DPPH radical, hydroxyl radical and superoxide anion radical. The corresponding IC50 values were 0.0043, 0.021, 0.22 mL and 0.39 mL, respectively. The juice showed strong reducing power and significant inhibitory effects on Fe2+-induced peroxidation in yolk lipoprotein. Correlation analysis showed that total phenol content in Chaenomeles sinensis (Thouin) Koehne juice was higher correlated with free radical scavenging ability against DPPH and ABTS and with yolk lipoprotein peroxidation inhibiting ability than ascorbic acid. This study demonstrates that Chaenomeles sinensis (Thouin) Koehne juice possesses high antioxidant capacity and a great commercial development.
Effect of Ultra-high Pressure Processing on the Quality of Fresh-squeezed Coconut Juice
CHENG Lei-jing,MA Yong-kun,,YAN Rui,MA Shan-li,ZHANG Long
2011, 32(21):  62-65.  doi:10.7506/spkx1002-6630-201121014
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The effects of ultra-high pressure processing (UHPP) (200-600 MPa for 10 min) on physicochemical properties, nutritional quality and antioxidant activity of fresh-squeezed coconut juice were studied. The results showed that, compared to the control, UHPP did not significantly change the contents of soluble solid content, total sugar, total acid and total phenol and pH in coconut juice (P > 0.05). The contnent of free amino acids increased significantly after 500 or 600 MPa processing (P < 0.05). The content of vitamin C reduced significantly, with a retention rate of 87.9%-97.6% after UHPP treatment. The antioxidant activity decreased significantly after 400 MPa processing, but increased after 600 MPa processing (P < 0.05). Sensory evaluation showed no difference between UHPP treated coconut milk and the control. In summary, UHPP can effectively protect the natural flavor and and nutritional components of fresh-squeezed coconut juice.
Effects of Amino Acid Content on Antioxidant Activity of Honey from Different Sources and Geographic Origins
DONG Rui,ZHENG Yi-nan
2011, 32(21):  66-70.  doi:10.7506/spkx1002-6630-201121015
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Significant differences were found in 17 free amino acids among 14 honey samples from different regions of China and different flowers. The result showed that proline was the major free amino acid and constituted over 65.27% of total free amino acids, averaging at about 349.829 mg/kg in the honey samples. The antioxidant ability of honeys was evaluated by NO2- · radical scavenging assay. The results obtained showed that all the honey samples had antioxidant activity, with an EC50 ranging from (0.55±0.021) to (0.25±0.034) g/mL. Among these samples, longan honey from Guangxi had the highest antioxidant ability. Correlation analysis revealed that the antioxidant ability of honeys was correlated with proline content and the contents of 17 total free amino acid, with R=0.7513 and R=0.8051 respectively. Conclusion: Free amino acids in honeys are positively correlated with NO2- · radical scavenging activity. As a known functional food, honey may have more health benefits than previously reported and more attention should be paid to it for its full utilization.
Physico-chemical Properties and Thermal Oxidative Stability of Seed Oil from Camellia serniserrata Chi.
ZHANG Wei-guo,JIN Gui-min
2011, 32(21):  71-79.  doi:10.7506/spkx1002-6630-201121016
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In this paper, we reported the physicochemical characteristics and thermal oxidative stability of Camellia serniserrata Chi. seed oil. The oil content in Camellia serniserrata Chi. seed was 34.8% (wet weight). The extracted oil exhibited iodine value of 82.1 g I2/100 g, saponification value of 215.3 mg KOH/100 g, acidity value of 1.51 g FFA/100 g, peroxide value of 2.98, and p-anisidine value of 0.96 g-1. The K232nm and K270nm were 2.14 and 0.12, respectively. Differential scanning calorimetry analysis revealed that two characteristic peaks were detected in both crystallization and melting curves. Potassium, aluminium, potassium, magnesium and calcium were found at higher levels in the oil, which ranged from 9.7 to 26 mg/kg. The contents of other minerals were below 4.3 mg/kg. α-Tocopherol content in the oil was 5.6 mg/100 g, and the total content of β-tocopherol and γ-tocopherol were 0.79 mg/100 g. Oleic acid (74.74%) was the most predominant fatty acid followed by palmitic acid, linoleic acid and stearic acid and a small amount of other fatty acids. The scavenging activity toward DPPH radicals was also measured. The oil showed good thermal oxidative stability as evaluated based on K232nm, K270nm, POV and p-PAV values (microwave heating and 130 ℃ oven heating). These results suggest that Camellia serniserrata Chi. is a valuable special oilseed crop, providing highly nutritional oil.
Effect of Urea on Conformation Changes of Dynamic High-pressure Microfluidization (DHPM)-induced Unfolded Trypsin
LIU Jun-ping,LIU Wei,ZOU Li-qiang,LIU Cheng-mei,FANG Li-chun,ZHANG Zhao-qin
2011, 32(21):  80-85.  doi:10.7506/spkx1002-6630-201121017
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The conformational changes of native trypsin and DHPM-induced unfolded trypsin during the denaturation by urea have been investigated using the methods of ultraviolet (UV) spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. Results indicated that native trypsin showed the most significant changes when the concentration of urea was from 4.0 to 6.0 mol/L. The absorbance at 280 nm decreased from 0.2746 to 0.1824, and the absorption peak showed red shift from 279 to 283 nm; the relative fluorescence intensity decreased from 105.9 to 98.27, and the emission peak showed red shift from 352 to 355 nm. The percentage of β-sheet content decreased from 46.9% to 30.6%. In contrast, the most significant changes were observed in unfolded trypsin when the concentration of urea was from 2.0 to 4.0 mol/L. The UV absorbance decreased from 0.3121 to 0.2159 and the peak showed red shift from 281 to 283 nm; the fluorescence intensity decreased from 108.24 to 99.07 and the emission peak showed red shift from 353 to 360 nm. The percentage of β-sheet content decreased from 40.6% to 38.9%. These findings show that urea has a more significant impact on DHPM-induced unfolded trypsin compared with native trypsin. In the presence of urea at different concentrations, trypsin has different conformations of intermediates that show characteristics of molten globule state.
Kinetic Modeling of the Thermal Stability of EGCG in an Ultrasonic Filed
XU Nan,ZHUO Ya,CAO Yan-ping,,XIAO Jun-song,WU Ge-yang
2011, 32(21):  86-90.  doi:10.7506/spkx1002-6630-201121018
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In this study the stability of epigallocatechin gallate (EGCG) in a weakly acidic environment alone and in combination with an ultrasonic filed of 0.25 W/cm2 and 135 kHz was quantitatively analysis by high performance liquid chromatography. It was shown that under 20 ℃ and the same pH conditions, ultrasonic treatment caused a decrease of the stability of EGCG, and the loss rate of EGCG was 10.70 %, after 40 min exposure to pH 6.2 with ultrasonic treatment, exhibiting a 5.63-fold increase compared to the absence of ultrasonic. Linear regression indicated that the reaction of EGCG in an ultrasonic field and in a nonultrasonic field followed first-order kinetics. The rate constant was 0.00228 min-1 in the presence of ultrasonic, the activation energy 22861.13 kJ/mol, and the pre-exponential factor 28.30 s-1, which were increased 4.3 times, decreased by 14.0% and increased by 13.5%, respectively.
Degradation Behavior of Different Types of Lac Films
XU Juan,ZHANG Hong,SUN Yan-lin,ZHOU Mei-cun,ZHENG Hua,LI Kai,LI Kun
2011, 32(21):  91-97.  doi:10.7506/spkx1002-6630-201121019
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The degradation behavior of three different types of lac films (seedlac, shellac, and bleached lac) was studied in terms of weight loss rate. Each type of lac film under investigation could be degraded naturally and the degradation rate increased with increasing soil moisture content and temperature but decreased with increasing soil pH. A dynamic model describing their degradation respectively was established. Under the same conditions, the degradation half-lives of bleached lac, seedlac and shellac decreased sequentially. Moreover, their pre- and post-degradation samples were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and capillary viscosimeter, and the results showed that these three types of lac films presented no considerable changes in their molecular structure but revealed significant changes in their morphology and tissue and exhibited a remarkable decrease in their relative molecular weights after degradation.
Kinetic Modeling of the Thermal Stability of EGCG in an Ultrasonic Filed
SHUI Dan,WANG Li-feng,YUAN Jian,HE Rong,WANG Xue-feng,GAO Yu-long,JU Xing-rong
2011, 32(21):  98-101.  doi:10.7506/spkx1002-6630-201121020
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In this study the stability of epigallocatechin gallate (EGCG) in a weakly acidic environment alone and in combination with an ultrasonic filed of 0.25 W/cm2 and 135 kHz was quantitatively analysis by high performance liquid chromatography. It was shown that under 20 ℃ and the same pH conditions, ultrasonic treatment caused a decrease of the stability of EGCG, and the loss rate of EGCG was 10.70 %, after 40 min exposure to pH 6.2 with ultrasonic treatment, exhibiting a 5.63-fold increase compared to the absence of ultrasonic. Linear regression indicated that the reaction of EGCG in an ultrasonic field and in a non-ultrasonic field followed first-order kinetics. The rate constant was 0.00228 min-1 in the presence of ultrasonic, the activation energy 22861.13 kJ/mol, and the pre-exponential factor 28.30 s-1, which were increased 4.3 times, decreased by 14.0% and increased by 13.5%, respectively.
Degradation Behavior of Different Types of Lac Films
XU Zeng-hui,GUO Hong,JIA Jian-hui,LU Xiao-lian,PENG Yi-jiao
2011, 32(21):  102-106.  doi:10.7506/spkx1002-6630-201121021
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The degradation behavior of three different types of lac films (seedlac, shellac, and bleached lac) was studied in terms of weight loss rate. Each type of lac film under investigation could be degraded naturally and the degradation rate increased with increasing soil moisture content and temperature but decreased with increasing soil pH. A dynamic model describing their degradation respectively was established. Under the same conditions, the degradation half-lives of bleached lac, seedlac and shellac decreased sequentially. Moreover, their pre- and post-degradation samples were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and capillary viscosimeter, and the results showed that these three types of lac films presented no considerable changes in their molecular structure but revealed significant changes in their morphology and tissue and exhibited a remarkable decrease in their relative molecular weights after degradation.
Decolorization and Anti-tumor Activity in vitro of Exopolysaccharides from Lactobacillus plantarum 70810
FENG Mei-qin,ZHANG Qi,Mahinur·MUTUVULLA,HUANG Li-juan,CAO Lin,DONG Ming-sheng
2011, 32(21):  107-111.  doi:10.7506/spkx1002-6630-201121022
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The effects of various operating conditions on decolorization of exopolysaccharides (EPS) from Lactobacillus plantarum 70810 by macroporous resin adsorption were explored in the current work. In addition, the anti-tumor effects of crude EPS from Lactobacillus plantarum 70810 and two fractions thereof obtained by sequential column chromatographies on DEAE-Cellulose and Sephadex G-100, named as EPS-1 and EPS-2, respectively, on large intestine carcinoma cells HT-29 in vitro were tested by cell counting kit-8 (CCK-8) assay. The results showed that macroporous resin S-8 provided optimal decolorization of crude EPS from Lactobacillus plantarum 70810 among all resins tested. After 4 h decolorization under the following conditions: macroporous resin S-8 amount 4 g/100 mL, sample pH adjustment until pH 6, 25 ℃ and polysaccharide concentration in samples 2 mg/mL, the decolorization rate and retention rate of EPS were 72.58% and 69.15%, respectively. Crude EPS, EPS-1 and EPS-2 exhibited a significant inhibitory effect on the cell growth of large intestine carcinoma cells HT-29 in vitro (P<0.01) in a dose-dependent manner.
Antioxidant Activity of Ethanol Extract from Honeybee Comb
HOU Shuang,DONG Jie,ZHANG Gen-sheng,ZHANG Hong-cheng
2011, 32(21):  112-117.  doi:10.7506/spkx1002-6630-201121023
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The total polyphenolic and flavonoid contents of different concentrations (0, 25%, 50%, 75%, 95% and 100%) of ethanol extracts from honeybee comb were determined and meanwhile, their antioxidant activity was comprehensively evaluated based on total antioxidant capacity, scavenging capacities against ABTS, DPPH, superoxide anion and hydroxyl free radicals and reducing power activity. Among 6 honeybee comb extracts, 50% ethanol extract showed the highest total polyphenolic content, reaching (9.75 ± 0.16) mg gallic acid equivalent/g and 95% ethanol extract had the highest total flavonoid content, reaching (14.2 ± 0.26) mg rutin equivalent/g. Viewed comprehensively, the antioxidant activity of 6 honeybee comb extracts could be ranked from high to low in the following order: 50% ethanol extract, 75% ethanol extract, 25% ethanol extract, 95% ethanol extract, 0% ethanol extract and 100% ethanol extract. In conclusion, ethanol extract from honeybee comb is an excellent natural antioxidant.
Adsorption Characteristics and Mechanism of Grass Carp Scales towards Hydroquinone
XIONG Jin,WANG Hai-bo,OU Qi-yu,LI Yan,LIU Liang-zhong,ZHANG Han-jun
2011, 32(21):  118-122.  doi:10.7506/spkx1002-6630-201121024
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In the present study, grass carp scales were used to remove hydroquinone aqueous solutions under different experimental conditions. The effects of pH, adsorbent dose, adsorption time, adsorption temperature and initial hydroquinone concentration on adsorption efficiency were systematically investigated to explore the optimal conditions for the removal of hydroquinone. Meanwhile, its adsorption mechanism was also elucidated. The results showed that the adsorbent grass scrap scales revealed good adsorption capacity towards hydroquinone and the optimal adsorption conditions were pH 7, 25 ℃ adsorption temperature, 0.5 g/L adsorbent dose, 100 mg/L initial hydroquinone concentration and 8 h adsorption time. Under the optimal adsorption conditions, the adsorption amount of hydroquinone was 76.71 mg/g. Further, kinetic and thermodynamic analyses indicated that the adsorption of hydroquinonegrass carp scales was mostly a physical adsorption process, which was a multilayer adsorption and fitted well with a pseudo-secondkinetic model. Moreover, the Freundlich isotherm model could well describe the isothermal adsorption of hydroquinone onto grass carp scales.
Separation and Purification of Amylose and Amylopectin from Cassava Starch and Content Determination by Dual-wavelength Spectrophotometry
SHI Hai-xin,HAO Yuan-yuan,FANG Huai-yi,XIONG Zheng
2011, 32(21):  123-127.  doi:10.7506/spkx1002-6630-201121025
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Objective: To separate and purify amylose and amylopectin from cassava starch and to establish a dual-wavelength spectrophotometric method for determining their contents. Methods: The amylose and amylopectin in cassava starch were separated by n-butanol crystallization method. The purity of amylose and amylopectin was characterized by blue value of starch-iodine complex. According to the principle of dual-wavelength spectrophotometry method, the contents of amylose and amylopectin in cassava starch were determined at the selected wavelengths of 624 nm and 538 nm with respective reference wavelengths of 440 nm and 750 nm. Results: The blue values of purified amylose and amylopectin were 0.979 and 0.144, respectively, which were in the distribution range of corresponding standard samples. A high purity of cassava amylose and amylopectin was achieved. An excellent linear relationship between starch-iodine complex and absorbance was achieved in the range of 0-80 mg/L (r=0.9992) for amylose and 0-220 mg/L (r=0.9995) for amylopectin. Conclusion: n-butanol crystallization method amylose and amylopectin from cassava starch. The developed dual-wavelength spectrophotometry method is convenient, accurate and suitable for determining the contents of amylose and amylopectin in cassava starch simultaneously.
Ultraviolet Spectroscopic Investigations into Melamine Molecular Imprinting Pre-assembly System
ZHANG Xiao-gang,ZHU Qiu-jin,,HU Ping
2011, 32(21):  128-132.  doi:10.7506/spkx1002-6630-201121026
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According to the ultraviolet spectrum (UV) of melamine (MEL) molecular imprinting pre-assembly system, hydrogen-bonding interactions existed between melamine (MEL) and three monomers including methyl acrylic acid (MAA), itaconic acid (IA) and acrylamide (AM). AM revealed the greatest impact on the system, the second place was taken by MAA, and IA had the smallest effect. π-π* electron transitions of the conjugated double bonds in the triazine ring and the aromatic nucleus replaced by chromophore in MEL took place under hydrogen-bonding interactions and therefore maximum absorption wavelength of each pre-assembly system revealed a red shift. The optimal molarity ratios between MEL and three monomers were c(MEL): c(MAA) = 1:6, c(MEL): c(AM) = 1:8, and c(MEL): c(IA) = 1:8. Differential ultraviolet spectral analysis showed that one MEL molecule could be conjugated with two MAA molecules, three AM molecules and one IA molecule to form their own complex types in three pre-assembled systems.
Effects of Organic Acids and Tea Tree Oil on Physiological Indexes of Germinating Brown Rice
ZHONG Ye-jun,LIU Cheng-mei,LIU Wei,WU Jian-yong,XU Xin-yuan,XIE You-fa,WAN Jie
2011, 32(21):  133-136.  doi:10.7506/spkx1002-6630-201121027
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The present study was carried out to determine total microbial count andγ-aminobutyric acid (GABA) content on the surface, respiration intensity and reducing sugar content during the germination of brown rice from late Indica rice cultivar Ganxian 923 in the presence of either tea tree oil alone, organic acids such as ascorbic acid, citric acid and calcium lactate together, all of them or none of them. The results indicated that 4.0 g/L ascorbic acid/2.0 g/L citric acid/3.0 g/L calcium lactate solution could enhance respiratory intensity, promote the accumulation of GABA and accelerate the degradation of starch to reducing sugars. On the contrary, tea tree oil (4.5 g/L) had obvious inhibitory effect on respiration intensity, starch degradation and GABA accumulation. Moreover, tea tree oil and organic acid solution revealed a synergistic effect on the inhibition of bacterial growth in germinating brown rice.
Effect of Wheat Flour Properties on the Quality of Youtiao (Chinese Fried Breadstick)
ZHANG Jian,ZHANG Jie,MA Yan-bing,LI Meng-hui
2011, 32(21):  137-141.  doi:10.7506/spkx1002-6630-201121028
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In order to achieve a comprehensive evaluation of Youtiao-making characteristics of wheat flour, the property parameters of wheat flour from 20 cultivars grown in Henan province, China and the quality characteristics of Youtiao made from them were determined. Along with this, correlation analysis, multiple regression analysis and path analysis were employed to analyze the effects of wheat flour properties on Youtiao quality. The result of correlation analysis showed that the effects of wet gluten content, water-absorbing capacity, stability time, softening degree, resistance to extension, maximum resistance, extension rate, extensograph energy, alveograph dough tenacity (P) and alveograph dough strength (W) on the quality of Youtiao were significant or extremely significant. The results of linear regression analysis and path analysis showed that wet gluten content, water-absorbing capacity, stability time, softening degree, resistance to extension, extension rate and alveograph dough tenacity (P) were the most important factors that affect the quality of Youtiao. In addition, of all wheat cultivars investigated, 8 could provide the best specialized flour for Youtiao making. The appropriate ranges of important flour traits for making high-quality Youtiao were suggested as follows: ash content less than 0.55%, wet gluten content 29.1%-35.3%, water-absorbing capacity 61.5%-64.7%, stability time 4.4-7.2 min, softening degree 42.7-70.5 FU, resistance to extension 346.6-525.4 BU, extension rate 2.1-3.9, and alveograph dough strength (W) 71.4-105.4 mmH2O.
Bioengineering
Screening and Breeding of a High Diacetyl-producing Lactococcus lactis Strain and Optimization of Fermentation Conditions
DING Hai-bing,PAN Dao-dong,,ZHOU Pei-dong
2011, 32(21):  142-147.  doi:10.7506/spkx1002-6630-201121029
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A strain of Lactobacillus lactis highly capable of producing diacetyl, named as DX, was screened out of 6 lactic acid bacterial isolates and the fermentation conditions for diacetyl production by strain DX were optimized. The 16S rDNA sequence analysis and phylogenetic tree indicated that the 16S rDNA gene sequence of strain DX revealed 99% homology with Lactococcus lctis. Therefore, this strain was identified as Lactococcus lctis. Using central composite experimental design combined with response surface methodology, the optimal fermentation conditions for diacetyl production by strain DX were determined as follows: skim milk concentration 10 g/100 mL, inoculum amount 2%, fermentation medium initial pH 6.5, and fermentation temperature 37 ℃. Under these conditions, the diacetyl production was up to 22.383 mg/L.
Development and Optimization of Immunoassay Method for Detection of Norfloxacin Residues
JIANG Jin-qing,LI Guang-ling,WANG Zi-liang,LIU Xing-you,YANG Xue-feng,HUANG Hua-guo
2011, 32(21):  148-151.  doi:10.7506/spkx1002-6630-201121030
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Modified EDC method was employed to synthesize norfloxacin (NOR) artificial antigen and New Zealand rabbits were immunized for anti-NOR polyclonal antibody (pAb) production. An indirect competitive ELISA standard curve was established. The developed assay was sensitive and had a linear range from 0.07 to 31.8 ng/mL (R2 = 0.9627), with IC50 and LOD of respectively 1.5 ng/mL and 0.04 ng/mL. The optimal pH and phosphate ion concentration in assay buffer were determined to be 7.4 mmol/L and 10 mmol/L, respectively, and the concentration adjustments for methanol and NaOH (30 mmol/L) in dilute solutions did not exceed 30% and 10%, respectively. The produced pAb had broad-spectrum specificity and exhibited a high cross-reactivity with ciprofloxacin (83.3%), pefloxacin (78.9%), enoxacin (68.2%), enrofloxacin (51.7%) and lomefloxacin (41.7%). The results obtained suggest that the established icELISA method be used for the multi-determination of fluoroquinolone residues.
Preparation of Angiotensin-converting Enzyme Inhibitory Peptides with Low Molecular Mass from Casein by Stepwise Enzymatic Hydrolysis
WANG Gui-chun,LU Bing
2011, 32(21):  152-155.  doi:10.7506/spkx1002-6630-201121031
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The aim of this study was to prepare ACE inhibitory peptides with low molecular mass from casein by stepwise hydrolysis with a single enzyme followed by double enzymes as a mimic for the gastrointestinal tract digestive system. Peptides with high ACE inhibitory activity were first produced by hydrolyzing casein under optimized operating conditions and then further hydrolyzed by trypsin and chymotrypsin together into small peptides still having high ACE inhibitory activity. The optimal conditions for pepsin hydrolysis were enzyme/substrate ratio of 6%, substrate concentration of 0.015 g/mL, initial hydrolysis pH of 1.8, hydrolysis temperature of 37 ℃ and hydrolysis time of 2 h, and the ACE inhibitory rate of the 10-fold diluted hydrolysate obtained was 84.5%. The optimal conditions for further hydrolysis by trypsin and chymotrypsin together were trypsin/chymotrypsin ratio of 2:1 (m/m), initial hydrolysis pH of 7.8, hydrolysis temperature of 48℃ and hydrolysis time of 5 h, and the resulting 10-fold diluted hydrolysate showed an ACE inhibitory rate of 85.9% and a molecular mass of less than 500 D. Thus, the stepwise enzymatic hydrolysis process proposed in this study can enable the preparation of casein-derived small peptides with high ACE inhibitory activity.
Effect of Anthocyanin on Nuclear Receptor Report Genes in LO2 Cells
ZHANG Ying-hui, WANG Bing-yun,JI Hui-qin,DONG Hua-qiang, SONG Dong-guang,ZHONG Xi-qiong , HUANG Jian-bo
2011, 32(21):  156-160.  doi:10.7506/spkx1002-6630-201121032
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The effects of anthocyanin [cyanidin-3-O-β-D-glucoside (C3G)] and its aglycone [cyanidin] on transcriptional activity of nuclear receptors closely related to metabolic syndrome were investigated. Human liver LO2 cells were transfected with several plasmids including retinoid X receptor (RXR), pregnane X receptor (PXR), estrogen receptor (ER), farnesol X receptor (FXR), liver X receptors (LXRα and LXRβ), and peroxisome proliferator activated receptors (PPARα, PPARγ and PPARδ), respectively. Plasmids with the nuclear receptor element luciferase gene, and green fluorescent protein were constructed as nuclear receptor reporter models. The transfected cells were cultured with media containing cyanidin or C3G at the concentrations of 1, 10 μmol/L and 100 μmol/L, respectively for 24 h. The results indicated that RXR was inhibited by cyaniding at all concentrations tested, and only PXR model was slightly stimulated by cyanidin at the concentration of 100 μmol/L (1.42 ± 0.19 fold, P <0.05 compared with 0.1% DMSO as the control). However, other nuclear receptors including PXR, ER, LXRα, LXRβ, PPARγ and PPARδ could be significantly stimulated by C3G (P <0.05), and the transcriptional activity of PXR, LXRα, LXRβ and PPARγ could be increased by over 50% when compared to 0.1% DMSO. Therefore, the mechanism of anthocyanidin improving metabolic syndrome was likely to be correlated with its augmentative effect on transcriptional activity of nuclear receptors, and it could be concluded that C3G was generally more effective than its aglycone cyanidin.
Effect of Hydrolysis Conditions on Immunoactivity of Enzymatic Hydrolysates from Extruded High-temperature Soybean Meal
ZHANG Zhi-yu,ZHU Xiu-qing,,REN Wei-cong
2011, 32(21):  161-164.  doi:10.7506/spkx1002-6630-201121033
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In order to improve the immunoactivity of enzymatic hydrolysates from extruded high-temperature soybean meal, the hydrolysis of the substrate by trypsin was optimized using central composite rotary design. Spleen lymphocyte proliferation (expressed as the stimulation index, SI) was investigated with respect to four variables including hydrolysis temperature, enzyme amount, substrate concentration and hydrolysis time. Using SPSS 13.0 and Design Expert 7.0.0, the experimental data were analyzed to determine the optimal hydrolysis conditions as follows: enzyme amount of 7999.97 U/g, hydrolysis temperature of 55.14 ℃, hydrolysis time of 4.34 h, and substrate concentration of 4.41%. Under the optimal hydrolysis conditions, the ConA-induced spleen lymphocyte stimulation index was determined by MTT method to be 1.1894.
Process Conditions Optimization for Antioxidant Peptide Preparation from Small Yellow Croaker by Response Surface Methodology
XU Xin,HE Jia-yi,LIU Guo-yan,CAI Li-li,WEI Xiao-rui,XU Na
2011, 32(21):  165-170.  doi:10.7506/spkx1002-6630-201121034
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Objective: To optimize trypsin (PTN 6.0S) hydrolysis conditions of small yellow croaker for preparing antioxidant peptides. Methods: The optimization was performed using one-factor-at-a-time method and response surface methodology based on DPPH radical scavenging activity. Results: The optimal hydrolysis conditions were substrate concentration of 4.2 g/100 mL, enzyme-to-substrate ratio of 6‰, hydrolysis time of 19 h and hydrolysis temperature of 52 ℃. Maximum DPPH scavenging rate was obtained under the system of pH 7.0, reaching (46.90 ± 0.3)%. Response surface analysis showed that hydrolysis time had a significant effect on antioxidant activity of products and that the interactions between hydrolysis temperature and enzyme-to-substrate ratio, between hydrolysis time and substrate concentration, and between enzyme-to-substrate ratio and substrate concentration were complicated.
Immobilization and Characterization of Lipase Immobilized onto Cellulose Acetate-Polytetrafluoroethylene Composite Membrane
LIANG Dan-qiong,ZHOU Xiao-dan,SHI Min,WANG Xue,YU Dian-yu
2011, 32(21):  171-176.  doi:10.7506/spkx1002-6630-201121035
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In the present work, we immobilized lipase onto cellulose acetate (CA)-polytetrafluoroethylene (PTFE) composite membrane by a combined method of adsorption and cross-linking. The effects of different immobilization conditions such as immobilization temperature, adsorption time, lipase concentration, cross-linking time and cross-linking agent concentration on lipase immobilization efficiency and catalytic activity were explored. Immobilized lipase was also characterized. The optimal immobilization conditions were reaction temperature of 25 ℃, adsorption time of 2 h, lipase concentration of 0.02 g/mL, crosslinking time of 3 h, and cross-linking agent concentration of 0.2%. Under the optimal immobilization conditions, the maximum activity of immobilized lipase reached up to 17.2 U/cm2. The optimal temperature and pH of immobilized lipase were 35 ℃ and 8.5, respectively, which exhibited a decrease by 5 ℃ and shift to alkaline side by 1.0 when compared with the free enzyme. After repeated use for 10 times for 10 h each time, the residual activity was still up to 55.5%. The SEM micrographs revealed better immobilization of the enzyme on CA-PTFE composite membrane.
Screening of Monacolin K-producing Monascus and Fermentation Condition Optimization by Response Surface Methodology
HUANG Qun,MA Cheng-jin,YU Ji,WANG Jing-jing,GAO Yao-fu
2011, 32(21):  177-182.  doi:10.7506/spkx1002-6630-201121036
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The purpose of this study was to isolate high monacolin K-producing Monascus from Xiangxi natural savory vinegar by primary UV spectrophotometric screening and secondary high performance liquid chromatographic (HPLC) screening. The primary screening resulted in 7 Monascus strains capable of producing monacolin K, out of which strain M3 with the highest monacolin K-producing ability (achieving a concentration of 157 mg/L in fermentation broth) was isolated through the secondary screening. Further, fermentation conditions optimization for monacolin K production by strain M3 was carried out based on a mathematical model established using Box-Behnken central composite design. The optimal fermentation conditions were found to be: initial pH of 5.3, culture temperature of 25 ℃, shaking speed of 112 r/min and fermentation time of 10.5 days. Under the optimal fermentation conditions, the yield of monacolin K reached up to 354.68 mg/L.
Screening and Identification of High Protease-producing Bacteria
MA Gui-zhen,BAO Zeng-hai,WANG Shu-fang,WU Shao-jie,FU Hong-run,GE Ping-hua
2011, 32(21):  183-187.  doi:10.7506/spkx1002-6630-201121037
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Totally 44 bacterial strains were isolated from 9 soil samples collected from Guangdong, Hebei, Liaoning, Hunan and Jiangsu by diluted plate method. The protease-producing ability of the bacteria isolated was screened by transparent cycle plate assay. The results indicated that of these bacterial isolates, 16 exhibited clear transparent cycles. Meanwhile, strains G1-b, GD-2-2 and HX-B-1 revealed the strongest protease activity. The ratio of transparent circle diameter to colony diameter was higher than 3.5. Strain GD-2-2 had stronger protease activity than the other two, reaching 447.6 U/mL. Based on morphological observations and physiological and biochemical tests, strain GD-2-2 belonged to Bacillus. The 16S rDNA sequence analysis showed that the isolate was 100% similar with Bacillus licheniformis strain YB915 (GQ996726.1). Therefore, strain GD-2-2 belonged to Bacillus licheniformis.
Purification of Cell-envelop Proteinases from Lactobacillus casei and Biological Activity of Casein Hydrolysates Prepared with Them
WU Zhen,PAN Dao-dong,,YAN Li
2011, 32(21):  188-192.  doi:10.7506/spkx1002-6630-201121038
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Crude cell-envelop proteinase extracted from Lactobacillus casei cells was purified/fractionated by DEAE-Sephadex A-25 and subsequent Sephadex G-100 column chromatographies. Two cell-envelop proteinase fractions, named as CEP-1 and CEP-2, were obtained, of which the activity was 12.50 U/mg and 16.67 U/mg, the purification folds 50 and 66.68, and the recoveries 33.61% and 55.17%, respectively. The hydrolysis characteristics of CEP-1 and CEP-2 on α-casein and β-casein under different conditions of hydrolysis time and substrate concentration were assessed in terms of angiotensin-I-converting enzyme (ACE) inhibitory activity and superoxide anion radical scavenging activity of hydrolysates. Both CEP fractions resulted in casein hydrolysates with obvious ACE inhibitory activity and superoxide anion radical scavenging activity. Maximum ACE inhibitory activity was achieved after 6 h hydrolysis of α-casein at an enzyme/substrate ratio of 1:10 by CEP-2, reaching 84.66%. Theβ-casein hydrolysate obtained after 4 h of hydrolysis with an enzyme/substrate ratio of 1:40 revealed the best superoxide anion radical scavenging activity with a 0.2138 mg/mL IC50.
Optimization of Production Conditions for Fermented Frozen Fried Bread Stick
YANG Nian,SONG Xiao-yan,DONG Zhen-jiang,WANG Xiao-lan
2011, 32(21):  193-197.  doi:10.7506/spkx1002-6630-201121039
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In order to optimize the production process of fermented frozen fried bread stick, main factors that affect the quality of fried bread stick were investigated. On the basis of one-factor-at-a-time experiments, the response surface methodology was employed to study the effects of yeast amount, fermentation time and leavening agent amount on specific volume of fried bread stick. Results indicated that the optimal conditions for production of fermented frozen fried bread stick were found as follows: yeast amount 1.0 % (calculated on the basis of dry flour weight, m/m), leavening agent amount 3.0% (calculated also on the basis of dry flour weight, m/m), fermentation time 2.4 h, freezing temperature -35 ℃, and freezing time 20 min. Under these conditions, the specific volume of fried bread stick was (4.54 ± 0.03) mL/g.
An Investigation of Salmonella Serotypes Isolated from Diseased Poultry and Meat Products Derived from Poultry and Livestock in Nanning, Guangxi during 2009-2010
ZHAO Zhi-wei,Francesco CHIESA,WEI Ping,LIANG Dong-ying,XU Jia-fang,XIE Yong-deng
2011, 32(21):  198-200.  doi:10.7506/spkx1002-6630-201121040
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Objective: To understand the situation of Salmonella contamination and its serotype distribution in food products of animal origin in Nanning, Guangxi during 2009-2010 and to provide useful information for monitoring and control for foodborne diseases. Methods: The isolation and serotyping of Salmonella isolates were carried out according to the method of Microbiological examination of Food Hygiene: Examination of Salmonella (GB/T 4789.4-2008). Results: Detectable levels of S. gallinarum, S. typhimurium, S. javiana etc in diseased poultry and S. derby, S. gallinarum, S. typhi etc in meat products derived from poultry and livestock were found. Conclusion: More Salmonella serotypes more extensively spread in food products of animal origin, indicating diverse contamination pathways. Consequently, Salmonella contamination risks can be effectively reduced only by strengthening hygiene supervision throughout the whole food chain from production to distribution.
Preparation of Antioxidant Peptides Derived from Ginkgo biloba Kernel by Dual-enzymatic Method
JIA Shao-qian,WU Cai-e,FAN Gong-jian,LI Ting-ting,PENG Fang-ren
2011, 32(21):  201-206.  doi:10.7506/spkx1002-6630-201121041
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In the present study, the preparation of antioxidant peptides derived from Ginkgo biloba kernel by stepwise enzymatic hydrolysis with alkaline protease 2709 and pepsin was optimized. Four process conditions affecting total reducing power activity of antioxidant peptides including enzyme dosage, temperature, pH and hydrolysis time were investigated. Using response surface methodology, the optimal conditions for hydrolysis of alkaline protease 2709 were determined as follows: 6976 U/g enzyme dosage, 55 ℃ hydrolysis temperature, pH 8.9 and 5 h hydrolysis time, and the total reducing power activity (expressed as absorbance at 700 nm, A700 nm) of the resulting hydrolysate was 1.278. For the subsequent pepsin hydrolysis, the optimal hydrolysis conditions were determined using orthogonal array design to be: 9000 U/g enzyme dosage, pH 3.0, 50 ℃ hydrolysis temperature and 2 h hydrolysis time, and the resulting reducing power A700 nm was 1.636.
Isolation and Identification of a High Exopolysaccharide-producing Strain from Biological Soil Crusts on Sand Dunes
WANG Zheng-rong,SHENG Ji-ping,TIAN Xiao-lei,WU Ting-ting,LIU Wan-zhen,CHENG Fan-sheng,JIAO Yu-cui,SHEN Lin
2011, 32(21):  207-209.  doi:10.7506/spkx1002-6630-201121042
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Twenty-seven stains producing exopolysaccharides were isolated from biological soil crusts in the Gurbantunggut Desert, Xinjiang by the traditional method. A strain with 7445.80 mg/L exopolysaccharide-producing activity was picked out of them by phenol-sulfuric acid method and named as XJ-27. Based on phenotypic and physiological-chemical characterization, XJ-27 was primarily identified as Bacillus thuringiensis and further confirmed through 16S rDNA sequence analysis, resulting in a 1452 bp PCR amplification sequence, homology comparison with NCBI databases using the software Blast and phylogenetic tree construction using the software MEGA 4.0.
Breeding of a High Melanin-producing Plectania Strain
HU Xue-qin,QIAN Mei-shuang,ZHU Li,GUO Geng-yi,YE Ming
2011, 32(21):  210-213.  doi:10.7506/spkx1002-6630-201121043
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In order to breed a Plectania strain with higher melanin-producing ability, the preparation and UV mutagenization of protoplasts from Plectania YM421 mycelium was optimized. Results indicated that maximum rate of protoplast formation was observed after 3 h hydrolysis of helicase added at a level of 2.5 g/100 mL at 33 ℃. After exposure to UV radiation for 15-25 s at the distance of 30 cm, mutant strain YM421-2# was obtained, which exhibited respective increases of melanin yield by 10.03% and biomass by 11.33% when compared with the start strain. This mutant strain can be used for industrial production of melanin as a candidate.
Purification of α-Amylase Using CTAB/Tween-60 Mixed Reverse Micellar System
GAO Shu-gang, SONG Wei-ming, AN Hong
2011, 32(21):  214-217.  doi:10.7506/spkx1002-6630-201121044
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Reverse micellar system consisting of the surfactants cetyltrimethyl ammonium bromide (CTAB) and Tween-60 in dissolved in n-butanol-isooctane mixture was used for α-amylase purification by reversed micellar extraction. Extraction efficiency of α-amylase was investigated under different extraction conditions using a reverse micellar phase consisting of 4 g/L (CTAB +Tween-60, 2.0:1.0, n/n) in n-butanol-isooctane mixture (1.0:1.0, V/V) and an aqueous phase made up of crude α-amylase solution containing 0.04 mol/L NaCl. The extraction efficiency of α-amylase was 91% when the extraction temperature, ratio of organic phase to aqueous phase and oscillation time were 40 ℃, 2.0:1.0 and 10 min, respectively. The reverse extraction efficiency of α-amylase was 65% after 10 min oscillation at 50 ℃ when the aqueous phase was comprised of aqueous phase and organic phase at a ratio of 1.0:2.0 (V/V) at pH 4.5 containing 2.5 mol/L NaCl. The reverse micelles could be repeatedly used and the extraction efficiency of α-amylase at an aqueous phase-to-organic phase ratio of 1.0:2.75 remained 71% in the second use.
Response Surface Methodology for Optimization of Small Peptide Preparation from Paphia undulate Meat by Acid Hydrolysis
CHEN Xiao-gang,LI Wen-hai,CHEN Xin,RONG Hai-wu,MIAO Qing,SUN Hui-li
2011, 32(21):  218-222.  doi:10.7506/spkx1002-6630-201121045
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In this study, an acid hydrolysis procedure for preparing small peptides from Paphia undulate meat was proposed and optimized using response surface methodology (RSM). A quadratic regression model describing small peptide yield as a function of 3 variables was created based on a 5-level quadratic orthogonal rotation combination design, whose goodness of fit was 92.09%. The optimal hydrolysis conditions were found as follows: raw material-to-water ratio of 1:3, hydrochloric acid concentration of 6.4 mol/L, hydrolysis temperature of 92 ℃ and hydrolysis time of 5.3 h. Under the optimal conditions, the predicted and experimental recovery rates of small peptides were 84.04% and 82.21%, respectively. SDS-PAGE revealed that the smallest peptides in the resulting hydrolysate were less than 2 kD.
Screening of Cholesterol-reducing Lactic Acid Bacteria and Its Effect on Blood Lipids in Rats
YANG Qin,HU Ying,GAN Sheng-li,ZHU Qiu-jin,HE La-ping,,HU Ping,,ZHU Jian-rong
2011, 32(21):  223-228.  doi:10.7506/spkx1002-6630-201121046
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In this study, lactic acid bacteria with the ability to degrading cholesterol were screened from fermented products and human feces. Strains R-2 and I-2 had the highest cholesterol degradation rate in the MRS-CHOL culture medium among the selected strains, reaching( 26.97 ± 0.51)% and (23.72 ± 0.41)%, respectively. Both strains exhibited good tolerance to low pH (3.0). In the presence of 0.3 g/100 mL bile salt, the viable cell counts of I-2 and R-2 after 6 hours of cultivation were 1.1 × 104 CFU/mL and 2.2 × 106 CFU/mL, respectively. Moreover, R-2 and I-2 could inhibit the increase of TC (P < 0.01) and LDL-C (P <0.05) to some extent. R-2 and I-2 were identified as Enterococcus faecium and Enterococcus hirae, respectively by bacterial identification technology.
Nutrition & Hygiene
Effect of Conjugated Linoleic Acid on Weight Loss of Obesity Mice
LI Qi-ling,WANG Wu,ZHANG Li-xin
2011, 32(21):  229-232.  doi:10.7506/spkx1002-6630-201121047
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The effect of intragastric administration of conjugated linoleic acid (CLA) for 4 consecutive weeks on body weight, body fats, blood lipids and liver fatty acid synthase in animal models of dietary obesity created using Kunming mice. Meanwhile, the correlation between FAS and obesity was also explored. The results showed that Lee,s index, fat coefficient, serum total cholesterol (TC), serum total triglyceride (TG), serum low density lipoprotein cholesterol (LDL-C) and liver FAS in obese mice administered with CLA at the dosages investigated exhibited a significant difference from those in obese mouse models. Moreover, an obvious correlation between FAS and Lee,s index, fat coefficient or blood lipid was observed. Therefore, CLA has effective weight-lowering effect. Furthermore, the view that FAS is the potential target of obesity is further confirmed.
Effect of Casein Glycomacropeptide (CGMP) on Dendritic Cells: A Preliminary Study of Its Immunoregulatory Functions
LI Rong-hua,PANG Guang-chang,CHEN Qing-sen
2011, 32(21):  233-242.  doi:10.7506/spkx1002-6630-201121048
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The present study was undertaken to discover the effect of casein glycomacropeptide (CGMP) on maturation of in vitro cultured mouse bone marrow-derived dendritic cells and gain a preliminary understanding of the immunoregulatory functions of CGMP as a functional food ingredient. Bone marrow-derived dendritic cells (BM-DCs) from 6-8 week-old male C57BL/6 mice were isolated, cultured and differentiated in the presence of both rmIL-4 and rmGM-CSF. On day 6 of the culture process, three doses of CGMP (0, 0.1, 1.0μg/mL and 10μg/mL), RPMI 1640 complete medium (blank control) and LPS (positive blank) were added respectively and the BM-DCs were cultured for another 2 days, harvested, labeled with three fluorescence and examined for the surface markers CD11c, CD80, CD86, and MHC-Ⅱ by flow cytometry. Meanwhile, the harvested BM-DCs and T lymphocytes were co-cultured for 96 h before Cell Counting Kit-8 (CCK-8) examination of T lymphocyte proliferation resulting from mixed lymphocyte reaction (MLP). The results showed that all three doses of CGMP could promote the maturation of BM-DCs. All the maturation markers of dendritic cells reached their maximum at the dose of 1 μg/mL. Among the markers, MHC-Ⅱ, which plays a significant role in antigen presentation by BM-DCs, was promoted most. Co-culture of BM-DCs and T lymphocytes showed that BM-DCs treated with CGMP promoted the proliferation of T lymphocytes. T lymphocytes BM-DCs showed maximum proliferation when the initial ratio of BM-DCs to T lymphocytes was 1:10.
Effects of Ovotransferrin on Th1/Th2 Cells Balance in Immunosuppressed Mice
LIN Ri-xin,XU Ming-sheng,DU Hua-ying,TU Yong-guan,TANG Qun
2011, 32(21):  243-246.  doi:10.7506/spkx1002-6630-201121049
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Objective: To investigate the repairing effects of ovotransferrin (OVT) on immune imbalance of mice induced by cyclophosphamide. Methods: Fifty mice were randomly divided into five groups (ten animals per group): normal control group, model control group, and high dosage (10 mg/mL), middle dosage (1 mg/mL) and low dosage (0.1 mg/mL) OVT groups. Normal and model control groups were administered with normal saline. Each mouse in the OVT groups was administered with OVT of different concentrations at a dosage of 20 mL/(kg ·d) for 15 successive days. On the 15th day, all the mice except the normal group were injected with cyclophosphamide after OVT or saline administration and then administered for four more days (determined by the model group). At the end of the administration process, all the mice were sacrificed to measure serum IFN-γ, serum IL-4 ratio, their ratio, spleen index and thymus index. Results: Serum IFN-γ and IFN-γ/IL-4 ratio of the model control group were significantly lower than those of the normal control group (P < 0.01), while IFN-γ concentration and IFN-γ/IL-4 ratio in the serum of the high-dose OVT group were significantly higher than those of the model control group (P <0.01), but no significant difference was observed compared to the normal control group. Meanwhile, spleen and thymus indexes of the high-dose OVT group were higher than those of the model control group (P < 0.01). Conclusion: OVT can repair mouse humoral and cellular immune damage induced by cyclophosphamide and improve the immune function of immunosuppressed mice.
Immunoregulatory Function of γ- Linolenic Acid in Mouse
QIAO Dong,PANG Guang-chang,LI Yang
2011, 32(21):  247-252.  doi:10.7506/spkx1002-6630-201121050
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Objective: To analyze the effects of three different administration approaches of γ-linolenic acid on 24 cytokines in mouse serum, with the purpose to reveal the immunoregulatory effect of γ-linolenic acid Methods: γ-linolenic acid was given to mice by intragastric administration, intraperitoneal injection or ear vein injection and serum was collected from eye ball at 3, 2 and 2 h after administration of γ-linolenic acid, respectively. Luminex xMAP technology was used to determine 24 cytokines in mouse serum. Results: 8 cytokines, 6 cytokines, and 7 cytokines, respectively, showed significant changes after intragastric administration, intraperitoneal injection and vein injection of γ-linolenic acid. Based on the change patterns of cytokines after administration of γ-linolenic acid, cells that secrete these cytokines and their target cells were analyzed and intercellular communication networks responding to these administration methods were proposed. Conclusion: γ-Linolenic acid signals through mouse gastrointestinal mucosa and blood system to regulate the immune system. Signal transduction might involve NF-KB, P38/JNK/MAPK, JAK-STAT etc. γ-Linolenic acid not only is an essential fatty acid, but also has significant immunoregulatory effects. It stimulates inflammation and plays an anti-inflammatory role as well.
Reviews
Application of Low-field Nuclear Magnetic Resonance in Determining Water Contents and Other Related Quality Characteristics of Meat and Meat Products: A Review
XIA Tian-lan,LIU Deng-yong,XU Xing-lian,ZHOU Guang-hong,SHAO Jun-hua
2011, 32(21):  253-256.  doi:10.7506/spkx1002-6630-201121051
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Low-field nuclear magnetic resonance, with the advantages of rapid and non-destructive determination and small volume samples, has been exploited and applied in the field of meat science. The principle of low-field nuclear magnetic resonance is introduced in this paper. Moreover, recent advances in the application of low-field nuclear magnetic resonance in determining water contents and other related quality characteristics of meat and meat products is outlined.
Recent Research Progress on Techniques and Methods for Determining Ractopamine Residues in Animal-derived Products
ZHANG Hong-cai,WENG Zhi-ying,SHANG Jing,LIU Guo-yan, ,CHAI Chun-yan,
2011, 32(21):  257-260.  doi:10.7506/spkx1002-6630-201121052
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Many countries have prohibited ractopamine from being added into animal diets. Effective determination methods are key points for controlling the illegal application of ractopamine. Some methods and techniques that have recently been applied for detecting ractopamine residues at home and abroad and their current situation of research and application and development prospects are outlined, which will provide a helpful reference for keeping animal-derived products safe.
Migration and Determination of Bisphenol Compounds in Can Linings
BAO Yang,WANG He-ya,LI Zhu-qing,YAO Wei-rong
2011, 32(21):  261-267.  doi:10.7506/spkx1002-6630-201121053
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Due to the potential toxicity and health risk of bisphenol A and epoxy derivatives thereof, the application of can linings for food packaging has been strictly prohibited in China, the United States and the European Union. In this article, the structures, application, toxicity, migration and analytical methods of four bisphenol compounds such as bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE), bisphenol F (BPF) and bisphenol F diglycidyl ether (BFDGE) are summarized. Meanwhile, recent applications of solid-phase extraction in the sample pre-treatment for determination of these bisphenol compounds are reviewed in brief.
An Overview of Evaluation Methods for Predictive Microbial Growth Models
WANG Jun,DONG Qing-li,DING Tian
2011, 32(21):  268-272.  doi:10.7506/spkx1002-6630-201121054
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In predictive microbial growth modeling, it is necessary to validate the reliability and applicability of developed models before applications. The major objective of this review is to outline common evaluations methods for predictive microbial growth models with emphasis on the concept and role of 10 related evaluation parameters. Additionally, the square root and Ratkowsky models which has been proposed in our previous work were validated by the internal validation and external validation methods based on the evaluation parameters described in this review.
Research Progress of Soybean Allergens and Its Desensitization Methods
YANG Hui ,CHEN Hong-bing,,CHENG Wei,GAO Jin-yan,LI Xin
2011, 32(21):  273-277.  doi:10.7506/spkx1002-6630-201121055
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Soybean is one of the common allergic foods and its consumption is still increasing. How to reduce the allergenicity and ensure consumption safety has become an important issue in the field of food safety. There are many soybean protein allergens including storage proteins, structure proteins and disease-related proteins. Among them, Gly m Bd 30K, Gly m Bd 28K located in 7S conglycinin fragments and Gly m Bd 60K located in β-conglycinin protein are recognized as the major allergens. Currently, many methods including heating treatment, enzymatic treatment, high-pressure treatment and genetic engineering have been developed to desensitize their allergenicity. Heating or enzymatic treatment has been successfully applied in the food industry. Since high-pressure technology does not affect the nutritional value and flavor of the food, it is a promising method for allergy desensitization. Although genetic engineering can eliminate allergenicity of food materials, its practical application in desensitization is still ongoing due to its safety.
Research Progress of Phenolic Compounds and Antioxidant Activity from Bee Honey
MU Xue-feng,XU Xiang,SUN Li-ping,PANG Jie,SHEN Xin-feng,HUANG Lan,HE Wei
2011, 32(21):  278-282.  doi:10.7506/spkx1002-6630-201121056
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Phenolic compounds including phenolic acids, flavonoids and derivatives are biologically active components of bee honey, which have strong antioxidant activity and scavenging capacity against superoxide anion, peroxide nitrite, lipid peroxidation, DPPH, ABTS+ and hydroxyl free radicals. In this paper, recent research progresses on the extraction, detection, major composition and antioxidant activity of phenolic compounds from bee honey is systematically reviewed, which will provide evidence for the development and application of phenolic compounds from bee honey.
Research Progress in Enzymatic Synthesis of Polysaccharides Esters
HUANG Zhen-hua,LIU Chen-guang
2011, 32(21):  283-288.  doi:10.7506/spkx1002-6630-201121057
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Polysaccharides can obtain many excellent properties after selective esterification thereby broadening their application in industry. As an biocatalyst, enzyme catalyzes polysaccharide esterification enantio-selectively and regio-selectively with superiority in line with the concept of green chemistry, like mild reaction conditions, simple reaction process, no need for protective groups in reaction and biodegradable products. Here, we review recent progresses made in the study of enzymatic synthesis of polysaccharide esters.
Progress in Research of Deoxynivalenol
FU Yang,LI Hong-jun,HE Zhi-fei,HUANG Ye-chuan
2011, 32(21):  289-292.  doi:10.7506/spkx1002-6630-201121058
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Deoxynivalenol (DON), a trichothecene compound, is a secondary metabolite produced by Fusarium. DON is present in crops, animal feed and human food. A number of reports in the literature indicate that DON has been found in many areas all over the world. Due to its strong toxity, it not only causes severe agricultural economic losses, but also brings serious threat to human and animal health and give rise to a series of adverse reactions such as vomiting, diarrhea, gastrointestinal bleeding and so on. Recent progresses made in the studies of DON toxicity, detectable levels in different areas of the world, factors affecting DON level and DON degradation approaches are reviewed, which will provide some references for further study of DON.
Recent Advances in Research on Dietary Advanced Glycation End Products
LI Ju-xiu,FANG Hong-juan,HU Hui-xiang,LI Li-xia`
2011, 32(21):  293-297.  doi:10.7506/spkx1002-6630-201121059
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Advanced glycation end products (AGEs) are a complex group of compounds that are formed through Maillard reaction, a nonenzymatic reaction between reducing sugars and free amino groups. AGEs contribute to the development and progression of various chronic diseases, such as vascular complications of diabetes, Alzheimer,s disease, cancer growth and aging. AGEs occurs both exogenously (in food) and endogenously (in the human body). Dietary AGEs, dAGEs, are an important source of the total AGEs in the human body. However, no methods have been available for the determination of dAGEs, and there are few reports in the literature concerning the effect of food processing on AGEs formation. Consequently, the formation, structure and determination methods of dAGEs, the metabolism in the human body, the effect on the human body and prevention measures are systematically elucidated in this article with the purpose of laying the foundation for further study of AGEs.
Characteristics and Safety of Chinese Functional Food Materials
ZHANG Bo
2011, 32(21):  298-300.  doi:10.7506/spkx1002-6630-201121060
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Functional foods have a long history in China. Functional foods with Chinese medical features are playing an increasingly important role in people,s health care. Accordingly, the safety of Chinese functional food materials has become an important food safety key point. The characteristics and safety of Chinese functional food materials are discussed in this paper.
Application of 3T3-L1 Preadipocytes in the Evaluation of Functional Components: A Review of the Literature
CAI Jiao-ying,LIU Yao,WANG Wen-jun,YANG Wu-ying
2011, 32(21):  301-305.  doi:10.7506/spkx1002-6630-201121061
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The anomaly of adipocyte proliferation and differentiation plays a key role in the development of obesity, cardiovascular disease and non-insulin-dependent diabetes. 3T3-L1 preadipocyte is a well-accepted model cell for study on adipogenesis. Recently the proliferation and differentiation of adipocytes have become a hot research topic. In this paper, the in vitro culture of 3T3-L1 preadipocyte, mechanisms regulating 3T3-L1 preadipocyte proliferation and differentiation and the application thereof in the evaluation of functional components are reviewed with the purpose to provide some references for the prevention and therapy of obesity and diabetes mellitus.
Research Progress of Functional Components in Military Functional Foods
WANG Hong-yu
2011, 32(21):  306-310.  doi:10.7506/spkx1002-6630-201121062
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The research and development of military functional foods is gradually moving towards serialization, nutritionalization, functionalization and standardization. Today, high-tech applications are increasing in this field. In this paper, the current research situation and development range of military functional foods are introduced. Meanwhile, recent advances in the study of the anti-fatigue, anti-radioactive, anti-hypoxia and anti-stress functions of functional components in military functional foods are also reviewed. This article also presents an illustration for the development trend of military functional foods with the aim of offering an important guidance for the future development of military functional foods.
Current Situation and Suggestions for the Management of Baked Food Safety in China
DUAN Wen-feng,PENG Ya-feng,LIN Yi-kan
2011, 32(21):  311-317.  doi:10.7506/spkx1002-6630-201121063
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In this article, the current situation of baked food safety in China is introduced. The situation of food safety management for baked food trade in China is deeply analyzed on the basis of following aspects: the food safety legal system, the food safety management institutions, the construction of food safety standards and food safety inspection technologies. The suggestion that the management of bakery food safety should be strengthened is proposed.
Current Status of Chinese Legal System and Standard System for Health Food
LI Jiang-hua, LI Dan
2011, 32(21):  318-323.  doi:10.7506/spkx1002-6630-201121064
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With the rapid development of health food in China, there have been an increasing number of relevant laws and regulations as well as standards for health food from 1995, when Food Hygiene Law granted health food legal status, until the implementation of Food Safety Law. In order to ensure a good development situation of health food regulation and standard systems, the current status of China’s regulation system and standard system for health food is summarized based on the promulgated laws and regulations related to application and approval, raw materials and auxiliary materials, labels and instructions, test and inspection, and production management of health food.