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01 July 2010, Volume 31 Issue 13
Basic Research
Effects of Different Factors on the Properties of Protease-induced Whey Protein Gel and Elucidation of Its Microstructure
GU Jun-nan,MAO Xue-ying*,ZHANG Chun-jiao,XIAO Yan,REN Fa-zheng
2010, 31(13):  1-5.  doi:10.7506/spkx1002-6630-201013001
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This study focused on the forming process of protease-induced whey protein gel and its affecting factors such as protein concentration, enzyme-to-substrate ratio (E/S), pH, temperature and calcium concentration, which can provide some experimental data for the production of fat substitutes based on enzyme modified whey protein. Results showed that all these factors had influences on the textural properties and water holding capacity of enzyme-induced whey protein gel to different extents. Gels prepared under the conditions of 10g/100mL whey protein concentration, 0.5% enzyme-to-substrate ratio, pH 7.0, 50 ℃ and 2.5 mmol/L calcium concentration had fat-like textural and mouth-feeling properties. Transmission electron micrographic observation showed the gel had a loose aggregated structure.

Effect of High-pressure Treatment on G-actin Structure of Bovine Skeletal Muscle
WANG Zhi-feng,BORJIGIN Gerelt*
2010, 31(13):  6-9.  doi:10.7506/spkx1002-6630-201013002
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G-actin was prepared from bovine skeletal muscle and exposed to pressures ranging from 0.1 to 400 MPa. The high pressure-induced structural change of G-actin was explored in terms of fluorescence spectrum, center of spectral mass, the amount of surface sulfhydryl (SH) group and surface aromatic hydrophobicity. The fluorescence intensity of G-actin decreased as pressure increased from 0.1 to 100 MPa; however, an opposite change was observed as pressure increased from 200 to 400 MPa; and the fluorescence spectrum of G-actin exhibited a blue shift due to exposure to higher pressures. As pressure increased from 100 to 300 MPa, the center of spectral mass of G-actin initially decreased slightly, reaching its minimum value at 100 MPa, followed by a rebound increase, and the amount of surface sulfhydryl group gradually increased, and the surface aromatic hydrophobicity changed in a manner similar to that of the amount of surface sulfhydryl group, reaching its maximum value at 300 MPa. Therefore, high pressure-induced three-dimensional structural change of G-actin might be irreversible.

Carboxymethylation and Antioxidant Activity of Coprinus comatus Polysaccharide
ZHOU Rui1, TIAN Cheng-rui1,*, ZHANG Jing1, LIU Na2
2010, 31(13):  10-15.  doi:10.7506/spkx1002-6630-201013003
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Coprinus comatus polysaccharide prepared in our laboratory was carboxymethylated by solvent method. The effects of reaction medium, time and temperature, chloroacetic acid amount and sodium hydroxide amount on the substitution degree of Coprinus comatus polysaccharide were investigated. In the presence of isopropyl alcohol used as reaction medium, a reaction system consisting of Coprinus comatus polysaccharide 0.5 g, sodium hydroxide 7.5 g and chloroacetic acid 6.0 g was left to react at 55 ℃ for 5 h and as a result, a maximum substitution degree of Coprinus comatus polysaccharide of 0.989 was obtained. Meanwhile, carboxymethylated Coprinus comatus polysaccharide was tested for its scavenging capacities against hydroxyl and superoxide cation free radicals, which were both much better than before carboxymethylation.

Accumulation of Lutonarin and Saponarin in Barley Leaves during Growth and Differences in Their Contents among Different Varieties
JIA Jing1,2, LI Yu-lin1,*, SHEN Yu-hu1,DU Yu-zhi1
2010, 31(13):  16-18.  doi:10.7506/spkx1002-6630-201013004
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The accumulation of lutonarin and saponarin during different growth and the differences in their contents among the leaves of different barley varieties were determined by HPLC. Results indicated that the content of saponarin was higher than that of lutonarin throughout the whole growth period and both of them displayed a similar change trend, i.e., an initial increase followed by a decrease. The optimal time for harvesting barley leaves was between the stage with three leaves and the stage with three leaves and one heart. Of 20 barely varieties, Baikangqing and Kunlun No.8 exhibited the highest contents of lutonarin and saponarin, respectively; however, the lowest contents of lutonarin and saponarin were both determined in Kangqing NO.3. In addition, Kunlun No.8 exhibited the highest total contents (1.69%) of lutonarin and saponarin, followed by Baikangqing and Kunlun No.1. Therefore, Kunlun NO.8, Baikangqing and Kunlun NO.1 are the selected barley varieties for the purpose of exploiting flavonoid resources.

Functional Properties of Pu-erh Tea with Different Storage Years
ZHOU Li-jing,HOU Cai-yun*,QIAO Yan-hui,ZHAO Jing
2010, 31(13):  19-22.  doi:10.7506/spkx1002-6630-201013005
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In order to understand the quality change of Pu-erh tea, separate scavenging capacities against DPPH free radicals and NO2 - as well as inhibition effect on α -amylase of Pu-erh tea with different storage years were evaluated using a spectrophotometer. Results indicated that the antioxidant activity of Pu-erh tea was similar to that of vitamin C and all of the tested Pu-erh tea samples with different storage years had a strong NO2- scavenging capacity, with a scavenging rate of higher than 50%. The separate scavenging capacities against DPPH free radicals and NO2 - of Pu-erh tea failed to exhibit an obvious increase with prolonged storage year; however, the inhibition effect onα-amylase activity increased.

Changes in Texture and Sensory Quality of Pork Chops during Frying Process
ZHANG Wei-yi,LI Chun-bao*,XU Xing-lian,HAN Yan-qing,ZHOU Guang-hong
2010, 31(13):  23-26.  doi:10.7506/spkx1002-6630-201013006
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In order to investigate the dynamic changes in texture and sensory quality of pork chops during frying process, porcine longissimus dorsi were cut into approximately 1 cm in thickness along the vertical direction of muscle fibers and fried at 170-180 ℃ for different periods of time. Texture and sensory quality of pork chops were compared after cooling. Results indicated that as heating time was prolonged, the surface brightness of cooked pork chops significantly decreased, whereas the central counterpart of cooked pork chops significantly increased; the surface a* value of cooked pork chops exhibited a change trend opposite to that of the surface brightness, so did the central a* value. Moreover, an extreme point of surface brightness and red scale in the center of cooked pork chops was shown up after heating for 80 seconds. Throughout the whole heating process, both the surface and central b* values of cooked pork chops exhibited a significant increase As heating time was prolonged, core temperature and cooking loss exhibited an increase and hardness exhibited a phased increase; however, no obvious difference in sensory quality was observed among the samples at the heating time points of 100, 120 s and 140 s.

Bactericidal Efficacy Evaluation of Recycling Used Sodium Hypochlorite during Fresh-cut Vegetable Processing
HOU Tian-ying,ZHAO Yuan-yuan,ZHENG Shu-fang*
2010, 31(13):  27-30.  doi:10.7506/spkx1002-6630-201013007
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In order to ensure the bactericidal efficacy of sodium hypochlorite (NaClO) solution during the recycling use, the bactericidal effect of NaClO on processed fruits and vegetables was explored. In addition, the effect of fruit or vegetable juice on oxidation/reduction potential (ORP) of NaClO solution was also investigated. Results indicated that 1 kg of cucumber slices could lead to a sharp drop in ORP and the active chlorine content in NaClO solution because of the juice osmosis. However, uncut pak choi had less effect on ORP of NaClO solution, and the ORP value of NaClO solution was still 600 mV when the amount of treated pak choi was 9 kg. The ORP curve between NaClO solution and vegetable juices exhibited an opposite“ S” in shape. According to Boltzman equation and isobetic point theory, NaClO solution lost the bactericidal efficacy at the ORP value of 600 mV and new disinfectants should be added to improve the disinfection potential.

Effects of Three Kinds of Non-muscle Proteins on the Gel Properties of Horse-mackerel Surimi
CHEN Hai-hua1,2,XUE Chang-hu2
2010, 31(13):  31-35.  doi:10.7506/spkx1002-6630-201013008
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The effects of soybean protein isolation (SPI), gluten powder (GP) and peanut protein concentrate (PPC) on the gel properties of horse-mackerel surimi were investigated by texture analysis, scanning electron microscopic observation and the determination of TCA-soluble peptides. The results indicated that addition of SPI at more than 1 g/100 g surimi inhibited the hydrolysis of horse-mackerel surimi, while the separate additions of GP and PPC exhibited little inhibition effect on the hydrolysis of horse-mackerel surimi and the inhibition rate was less than 10%. The separate additions of SPI and GP resulted in an increase in the breaking force, deformation and gel strength of horse-mackerel surimi. The best gel properties of horsemackerel surimi were observed with added GP at 10 g/100 g or added SPI at 5 g/100 g. However, the addition of PPC decreased the gel properties of horse-mackerel surimi. All of the separate additions of these kinds of non-muscle proteins resulted in a lower whiteness of horse-mackerel surimi. Separately added GP and SPI could enhance the water holding capacity of horse-mackerel surimi; however, it displayed an opposite change when PPC was added instead of the other kinds of non-muscle proteins.

Separate Effects of Konjac Glucomannan and Konjac Superabsorbent Polymer on Physical Properties of Recombinant Poultry Hams
CHEN Jie1,2,ZHANG Ke1,DU Jin-ping3,WU Yan3,WANG Lan3,WANG Chao1,NI Xue-wen1,*,JIANG Fa-tang1
2010, 31(13):  36-39.  doi:10.7506/spkx1002-6630-201013009
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Konjac glucomannan (KGM) and konjac superabsorbent polymer (KSAP, namely konjac glucomannan-acrylic acid copolymer) were added alone in recombinant poultry ham processing to deal with their effects on sensory quality, microstructure and texture of recombinant poultry hams. Sensory evaluation exhibited that the groups with added KGM or KSAP displayed a higher sensory index of recombinant poultry hams and a lower cooking loss when compared with the control group and the group with added phosphate. Scanning electron microscopic studies demonstrated an even and compact internal network structure in recombinant poultry hams and continuous embedding layers on the surface of meat. In addition, increased internal compactness and gel elasticity in recombinant poultry hams with added KGM or KSAP were observed through texture analysis. Moreover, separately added KGM and KSAP could also reduce the hardness, gumminess and chewiness of recombinant poultry hams.

Effect of Mechanical Green-making Mode on Physiological Parameters and Sensory Quality of Oolong Tea
WANG Er-mao1,JIANG Jian-jun2,SU Xin-guo1,*
2010, 31(13 ):  40-43.  doi:10.7506/spkx1002-6630-201013010
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In order to improve biochemical and sensory attributes of Fenghuangdancong oolong tea, the effect of green-making technology on biochemical parameters of Fenghuangdancong oolong tea was investigated. Mechanical green-making mode obviously increased the PPO activity Guihua oolong tea from 19.36 to 23.33 U/g, the POD activity from 34.65 to 48.36 U/g and the SOD activity from 252.34 to 341.30 U/g, thereby decreasing the sensory evaluation score from 93.5 to 86.1. This indicates that excessive green-making has an adverse effect on the quality formation of Fenghuangdancong oolong tea. However, no effect of mechanical green-making technology on the properties of Zhilan oolong tea was observed due to its larger thickness. Thus, mechanical green-making mode is unsuitable for the processing of Guihua oolong tea.

Effect of Limited Alkaline Protease Hydrolysis on Functional Properties of Rapeseed Thermoresistant Protein
WANG Su-ya,LIU Sheng,JU Xing-rong,YAN Mei-rong,YUAN Jian
2010, 31(13):  44-47.  doi:10.7506/spkx1002-6630-201013011
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To improve functional properties, the thermoresistant protein extracted from rapeseed meal was limitedly hydrolyzed by alkaline protease hydrolysis. Also, the relationships between protein functions and degree of hydrolysis (DH) were investigated. The solubility, emulsifying capacity and oil absorption capacity of rapeseed thermoresistant protein all increased after alkaline protease hydrolysis. Its solubility increased with increasing DH, and the solubility of rapeseed thermoresistant protein with 10% DH was as high as 63.82% at pH 7, 2.1 times higher than before hydrolysis. The emulsifying capacity of the hydrolysate obtained at 2.0% DH was the best and the emulsifying index was 0.43 and 0.49 at pH 6.0 and pH 8.0, 0.13 and 0.11 higher than unhydrolyzed rapeseed thermoresistant protein, respectively. The hydrolysate obtained at 8% DH presented the highest oil absorption capacity, 4.39 g/g. Rapeseed thermoresistant protein was decomposed into peptides with a smaller molecular weight after the hydrolysis, so changes in some of its functional properties took place.

Separation, Purification and Activity Assay of Antioxidant Peptides from Swimming Crab
FAN Jian-feng,WANG Ze-nan*,YANG Ke,LI Hong-bo,GUO Jun-zhen,ZHOU Xiao-fen
2010, 31(13):  48-51.  doi:10.7506/spkx1002-6630-201013012
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The antioxidant peptides obtained from enzymatic hydrolysis of swimming crab wastes were separated by sequential chromatographic purification with Sephadex G-50 column followed by Sephadex G-25 column. The fractions obtained were evaluated for their scavenging capacities against hydroxyl and superoxide anion free radicals, molecular weight distribution and amino acid composition. The results indicated that subfraction No.3 of fraction No.a of crude antioxidant peptides from swimming crab wastes, the last eluted fraction, more effectively scavenged both of the free radicals and its molecular weight was approximately 1096.5. Totally 11 kinds of amino acids including Tyr, Cys and His with antioxidant activity were obtained through amino acid analysis.

Mechanical Characteristics of Peanut Cracking
ZHANG Li-hua1,2,ZHANG Wen2,QIN Wen2,*,LI Ming-xia2
2010, 31(13):  52-55.  doi:10.7506/spkx1002-6630-201013013
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To improve cracking quality of peanuts from the western part of Sichuan province, mechanical characteristics of peanut cracking were investigated using a computer-controlled electronic tension and compression machine. A 9-run, 3-level orthogonal array design was employed to examine the effects of pressure location, loading rate and water content on peanut breaking force. The results indicated that the thickness of peanut shell was evenly distributed in different parts of peanuts. During the compression of peanut shell, three stages, i.e., elastic deformation, plastic deformation and sudden rupture occurred. The above factors significantly affected the breaking force of peanut shell. Regression equations of loading force with respect to degree of deformation of peanut shell under different compression directions were obtained through force analysis and the optimal values of the above factors for peanut cracking were determined as follows: pressure location, top surface (along the xaxis); loading rate, 30 mm/min; and water content, 15.8%.

Surfactant Precipitation and Recovery of Protamine
LIU Lin1,2,FU Zhao-xia3,LIU Jun-guo1,2,*,DU Li-ye1,ZHAO Zi-hua1
2010, 31(13):  56-59.  doi:10.7506/spkx1002-6630-201013014
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The precipitation and recovery of protamine was investigated using ionic surfactants as precipitating ligands and polar organic solvents as recovery agents. Ionic surfactant such as sodium dodecyl sulfate (SDS) exhibited a complete removal of protamine; however, sodium di-(2-ethylhexyl) sulfosuccinate (AOT) exhibited only 75.02% removal of protamine. In addition, an obvious effect of organic solvent and salt amount on the recovery of protamine from its precipitate. As for SDS-protamine precipitate, n-propanol was the optimal solvent with protamine recovery rate of more than 83.33%. As for AOT-protamine precipitate, acetone was the optimal solvent with protamine recovery rate of more than 85.71%. Compared with original protamine, no significant change in antibacterial activity of recovered protamine was observed.

Preparation and in vitro Digestibility of Tephrosia candida Protein
YU Li-mei,YU Xin,ZENG Xiao-fang,YANG Feng-qing
2010, 31(13):  60-64.  doi:10.7506/spkx1002-6630-201013015
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Tephrosia candida protein (TCP) was obtained through alkaline extraction and acid precipitation. Its digestion behavior was explored through two-step digestion using pepsin and trypsin in mimic digestion environment. Results exhibited that the content of soybean protein was (44.17 ± 0.48)%, the content of TCP was (47.12 ± 0.35)% and this protein was composed of 18 kinds of free amino acids including 8 kinds of essential acids. However, similar amino acid pattern between TCP and soybean protein was observed. The digestibility of TCP was (84.86 ± 0.75)%, while the digestibility of soybean protein was (91.71 ± 0.88)%. The content of total amino acids of TCP hydrolysates was lower than that of soybean hydrolysates, but the contents of some of the tested free amino acids were higher than those of their counterparts in TCP hydrolysates.

Sol and Gel Properties of High-acyl Gellan Gum and Its Structure Analysis
MENG Yue-cheng,LU Jing,JIANG Yi-fei,QIU Rong
2010, 31(13):  65-68.  doi:10.7506/spkx1002-6630-201013016
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The sol and gel properties of high-acyl (HA) gellan gum were investigated. Results indicated that the colloidal viscosity of HA sol increased with increasing gellan gum concentration from 0.05 to 0.1 g/100 mL and HA sol was featured with pseudoplastic behavior. The strength of gel formed at a concentration ranging from 0.2 to 0.5 g/100 mL was pronouncedly affected by polymer and Ca2+ concentrations. The strength of high acyl (HA)/low acyl (LA) mixed gellan gum decreased with increasing HA/LA ratio. Besides, the structure of HA gellan gum was analyzed through IR and NMR.

Effects of Physical Factors and Mineral Salts on Stability of Anthocyanins from Cinnamoummum burmannii Fruits
HUANG Si-mei1,ZHANG Jing1,ZHANG Jing-wei2
2010, 31(13):  69-73.  doi:10.7506/spkx1002-6630-201013017
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Anthocyanins in Cinnamoummum burmannii fruits were extracted with 90% methanol aqueous solution, separated D301 macroporous resin and purified by semi-preparative HPLC, and the effects of physical factors and mineral salts on the stability of the purified anthocyanins were investigated. Their half-degradation time in aqueous solution was 4.7 h at 100 ℃. Their retention rate was 92.702% under indoor scattered light after 40 days of storage; in contrast, that in aqueous solution at pH 1.0-6.0 was more than 90.00% after the same storage period. NaCl and FeSO4 solutions in the concentration range from 1 to 10 mmol/L displayed color-protecting and hyperchromic effects on the purified anthocyanins, respectively. CuSO4 and KCl solutions in the concentration range from 1 to 100 mmol/L accelerated their decomposition. However, 1-50 mmol/L Ca(NO3)2 as well as 1 - 10 mmol/L ZnSO4 and Mg(NO3)2 had no effect on their stability. In the presence of CaNO3, ZnSO4 or Mg(NO3)2 at higher concentrations, the purified anthocyanins were significantly accelerated to be decomposed. These results suggest a higher stability of the anthocyanins purified from Cinnamoummum burmannii fruits.

Structural Characterization of Carboxymethylated Cassava Starch Prepared Based on Mechanical Activation
TAN Yi-qiu
2010, 31(13):  74-77.  doi:10.7506/spkx1002-6630-201013018
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Cassava starch was mechanically activated for 60 min using a stirring type ball mill in order to provide activated cassava starch for preparing carboxymethylated starch using NaOH as a catalyst and ClCH2COOH as an etherification agent. The structure of carboxymethylated cassava starch was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). After mechanical activation, the structure of cassava starch had no obvious changes. Carboxymethylation reaction could be observed on the surface and interior of activated cassava starch. Its carboxymethylated counterpart showed an irregular adhesive form and an aggregative state and maintained both the precarboxymethylation crystal structure and morphological features of starch granules. In contrast, carboxymethylation controlled on the surface area was mainly completed in the amorphous zone and partly in the crystalline area of inactivated cassava starch.

Electronegativity Distance Vector Model for Antioxidant Activity of Polyphenols
ZHU Li-lan
2010, 31(13):  78-81.  doi:10.7506/spkx1002-6630-201013019
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The molecular electronegativity-distance vector (Mf) was used to describe the molecular structures of 33 kinds of polyphenols in this study. The quantitative structure-activity relationships (QSAR) between 4 antioxidant effects, i.e., trolox equivalent antioxidant capacity, ferric reducing/antioxidant power (FRAP), HOCl scavenging capacity and hydroxyl free radical scavenging capacity and 5 Mf variables for polyphenols were established using a leaps-bounds regression (LBR). Fischer tests demonstrated that all of the established models exhibited better robustness. Therefore, the dominant factors affecting the above antioxidant effects of polyphenols are molecular structure, secondary carbon atom, tertiary carbon atom, hydroxyl group and ether oxygen bond.

Using Principal Component Analysis for Investigating the Effects of Processing Conditions on Color Stability of Tea Infusion
ZHANG Rui-lian1 YIN Jun-feng1,* YUAN Hai-bo1 XU Yong-quan1 CHEN Jian-xin1 YE Guo-zhu2 CHEN Su-qin2
2010, 31(13):  82-87.  doi:10.7506/spkx1002-6630-201013020
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Principal component analysis (PCA) was applied to analyze infusion color stability of tea samples made by different processing technologies. Principal components, namely tea polyphenol content, turbidity, and color were used to establish mathematical models for evaluating the effects of processing conditions on the stability of tea infusion. Sensory evaluation was used for verifying the results obtained in this investigation. Consistent results were obtained between PCA and sensory evaluation. Better color stability of tea infusion could be achieved through the following steps: A-1, A-4, A-3, A-7, A-21 and A-2. Therefore, it is feasible to investigate the color stability of tea infusion through PCA, which provides an objective and comprehensive evaluation approach to further exploring the stability of tea infusion.

Antibacterial Activity and Stability of Half-Fin Anchovy (Setipinna taty) Protein Hydrolysate
SONG Ru1,2 WEI Rong-bian2,3 XIE Chao2 WANG Dong-feng1,*
2010, 31(13):  88-92.  doi:10.7506/spkx1002-6630-201013021
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Half-fin anchovy (Setipinna taty) was determine for its amino acid composition. The antibacterial activities of half-fin anchovy hydrolysates separately derived from flavor protease, trypsin, pepsin, alkaline protease and papain digestion were evaluated using Escherichia coli. Half-fin anchovy was rich in essential amino acids. The pepsin hydrolysate exhibited the highest antibacterial activity against Escherichia coli and its relative molecular mass ranged from 3000 to 1000. In addition, pepsin hydrolyzed half-fin anchovy also exhibited high thermal stability and enhanced antibacterial activity at lower acidic pH values. Moreover, pepsin hydrolyzed half-fin anchovy exhibited high tolerance to trypsin andβ-lactamase. Therefore, pepsin hydrolyzed half-fin anchovy appears to be a promising natural antibacterial agent.

Emulsifying and Foaming Properties of Salt-soluble Proteins of Spent Layer Duck
YANG Wan-gen QIN Wei-dong* SHI Ling
2010, 31(13 ):  93-95.  doi:10.7506/spkx1002-6630-201013022
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The contents of total protein and salt-soluble protein (SSP) in breast and leg muscles of spent layer ducks were determined and compared with those of broiler ducks. Micro-Kjeldahl method was used to determine the contents of total protein and SSP derived from breast and leg muscles. Also, the emulsifying and foaming capacities of SSP were determined. The total protein contents of breast and leg muscles of broiler ducks and spent layer ducks were approximately 22% and a slight higher content in breast muscle than in leg muscle was observed. The SSP contents in breast and leg muscles of broiler ducks were (24.61±1.19)% and (28.90±1.57)%, respectively; while those of spent layer ducks were (29.09±1.23)% and (27.27± 1.63)%, respectively. The emulsifying capacities of salt-soluble protein in breast and leg muscles of broiler ducks were (51.13 ±2.27)% and (46.53±2.16)%, respectively; while those of spent layer ducks were (50.00±0.73)% and (43.69±2.08)%, respectively. The foaming capacities of salt-soluble protein in breast and leg muscles of broiler ducks were (52.25±2.50)% and (47.67±0.93)%, respectively; while those of spent layer ducks were (54.38±4.27)% and (42.98±1.89)%, respectively.

Qualitative Analysis of Total Flavonoids from Blueberry Leaves and Their Protecting Effect against Lipid Oxidation
LI Ying-chang1 SUN Jian-hua1 MENG Xian-jun2
2010, 31(13):  96-99.  doi:10.7506/spkx1002-6630-201013023
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Blueberry leaves were extracted with 80% ethanol aqueous solution to prepare total flavonoids and the extract was analyzed qualitatively by means of color development reaction and UV-visible absorption spectroscopy. Meanwhile, its protecting effects against the lipid oxidation in lard and soybean lecithin liposomes prepared in our laboratory were investigated. The major components in the blueberry extract obtained were flavonoid compounds. The extract could effectively protect lard from lipid oxidation in a dose-dependent manner and presented the highest protecting effect at the dosage of 0.4%, which, however, was slightly lower than that of BHT. Synergistic protecting effects between ascorbic acid or citric acid and the extract were observed against the lipid oxidation in lard. In addition, the extract also presented an obvious protecting effect against the lipid peroxidation in soybean lecithin liposomes, which was higher than that of ascorbic acid. The IC50 values of the crude extract from blueberry leaves and its refined counterpart for the protection against lipid peroxidation were 67.46μg/mL and 121.65μg/mL, respectively. Total flavonoids derived from blueberry leaves are a potential natural antioxidant.

Synergic Effects of Cellulase and Pectinase on Extraction of Lycopene from Tomato
YUAN Chun-long1,2 ZHANG Jin1
2010, 31(13):  100-104.  doi:10.7506/spkx1002-6630-201013024
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In the extraction of lycopene from tomato, petroleum ether containing 2% (V/V) dichloromethane was used as extraction solvent. Lycopene extraction was investigated with respect to the effects of respective and synergic hydrolysis of tomato by cellulase and pectinase. The results indicated that a higher extraction yield of lycopene was obtained when pectinase, instead of cellulase was used for hydrolyzing tomato. More lycopene was extracted from tomato using both of the enzymes than using pectinase alone. The optimal parameters for extracting lycopene using both of the enzymes were determined as follows: pectinase/cellulase ratio 2:1, their total dosage 0.6 g/100 g, and pH 5.0 for 5 h hydrolysis at 35 ℃, followed by extraction for 20 min using the above extraction solvent and centrifugation at 4000 r/min for 10 min.

Decolorization of Soybean Oligosaccharides from Waste Sweet Slurry in Soybean Sheet Production
WANG Qiu-shuang1 YING Tie-jin2 CHEN Dong1 ZHAO Chao-yi1 LING Cai-jin1 SUN Shi-li1 JIANG Tian-jia2 YANG Dong-mei3 FU Mao-run4
2010, 31(13):  105-109.  doi:10.7506/spkx1002-6630-201013025
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Soybean oligosaccharides extracted from waste sweet slurry in soybean sheet production had dark color and failed to meet the quality standards for soybean oligosaccharides. The characteristics of static adsorption and desorption of 10 types of resins to impurity pigments in soybean oligosaccharides solution were investigated and the resin with better decolorization efficiency was screened. Meanwhile, adsorption curve and adsorption isotherm model were also established. Results indicated that macroporous absorption resins, DM-130 and AB-8, had the best decolorization efficiency, reaching more than 70%. In addition, they could be both regenerated easily. Moreover, 50% ethanol aqueous solution could almost desorb all of the pigments absorbed. The adsorption of pigments onto DM-130 was monomolecular adsorption, which complied with Langmuir isotherm model. Therefore, the loss of soybean oligosaccharides in the adsorption onto DM-130 or AB-8was less, which provides a promising practical application value.

Extraction, Purification and Bile Acid-binding Capacity in vitro of Polysaccharides from Okra
REN Dan-dan CHEN Gu*
2010, 31(13):  110-113.  doi:10.7506/spkx1002-6630-201013026
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In order to investigate active components having the ability to bind bile acid from okra, Abelmoschus esculentus (L.) Moench, raw polysaccharide (RPS) was obtained from the fresh fruits of okra by water extraction and ethanol precipitation. RPS was further purified by DEAE anion exchange chromatography to obtain fractions E1, E2 and E3. Their bile acid-binding capacities in vitro were determined. The results indicated that fractions E1 and E2 presented different bile acid binding capacities, which accounted for 10.82% and 10.60% of that of cholestyramine, respectively. These investigations provide some significant references for exploring and developing okra as health food or functional additives.

Effect of Special Oil on Baking Quality of Frozen Dough Bread
GE Rui-hong1 WU Wen-min1 WANG De-zhi2 MA Chuan-guo2,*
2010, 31(13):  114-117.  doi:10.7506/spkx1002-6630-201013027
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The special oil based on palm oil and soybean oil was used in frozen dough bread. The effect of this special palm-based oil on the rheological characteristics and baking quality of frozen dough bread was investigated. Frozen dough bread with the addition of this special oil exhibited larger specific volume, delicate texture and good quality. This special oil effectively improved the gel strength and extensibility of frozen dough bread, delayed baking quality deterioration during refrigerated storage, and provided good effect on delaying aging of bread. The optimal amount of this special oil in frozen dough bread was 6% of flour weight.

Establishment and Application of a Mathematical Model for Formulation of Nutrition-based Cooking Oil
LI Xin-hua1 CHE Xin1 SHAO Shuai2
2010, 31(13):  118-121.  doi:10.7506/spkx1002-6630-201013028
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According to the recommended proportion of edible fatty acids issued by Chinese Nutrition Society in 2000, the ratio of SFA: MUFA: PUFA is 1:1:1 in mass, and the ratio of n-6: n-3 polyunsaturated fatty acids is (4-6): 1. A mathematical model was established through programming and calculation by Matlab math software. This model was convenient to obtain appropriate ratio of raw materials in cooking oil for frying, rice bran cooking oil, and cooking oil with quality and low price. The proportion of fatty acids in formula met the recommended requirements. Thus, this mathematical model can be effectively applied to explore the formula of nutrition-based cooking oil.

Antioxidant and Free Radical Scavenging Activities of Extract from Kalimeris indica (L.) Sch-Bip
LU Li-shuang XIE Tian-fei FAN Yu-jie
2010, 31(13):  122-126.  doi:10.7506/spkx1002-6630-201013029
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The present study was carried out to investigate the antioxidant activity and free radical scavenging activities of water and ethanol extracts from Kalimeris indica (L.) Sch-Bip. DPPH, hydroxyl and superoxide anion free radical as well as hydrogen peroxide scavenging assays were carried out to evaluate the antioxidant potential of both of the extracts. Along with this, their reducing powers and ferrous iron chelating capacities were determined. Flavonoid compounds were the major compounds in both of the extracts. The order for the free radical scavenging activities and ferrous iron chelating capacity of the water extract from Kalimeris indica (L.) Sch-Bip was superoxide anion free radicals (IC50 2.2 μg/mL), H2O2 (IC50 2.8μg/mL), hydroxyl free radicals (IC50 5.6μg/mL), DPPH (IC50, 8.5μg/mL) and ferrous iron chelating capacity (IC50, 28.0μg/mL). As for the ethanol extract, its free radical scavenging activities and ferrous iron chelating capacity were ranked in the following order: H2O2 (IC50, 2.0μg/mL), superoxide anion fee radicals (IC50, 2.1μg/mL), hydroxyl free radicals (IC50, 2.5μg/mL), DPPH free radicals (IC50, 5.6μg/mL) and metal chelating activity (IC50, 51.2μg/mL). Considering the above results collectively, both of the extracts from Kalimeris indica (L.) Sch-Bip appear to be a promising antioxidant.

Isolation, Purification and Structural Identification of Flavor Peptides from Enzymolyzed Parma Ham
DANG Ya-li1 ZHANG Zhong-jian1 YAN Xiao-wei1 WANG Zhang2,* XU Shi-ying2
2010, 31(13):  127-131.  doi:10.7506/spkx1002-6630-201013030
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Nine fractions were obtained by Sephadex G-15 gel filtration chromatography from enzymolyzed Parma ham. G-15-P2-E2 was identified to be a flavor peptide through sensory evaluation analysis and electronic tongue determination. G-15-P2-E2-r1 and G-15-P2-E2-r2 were obtained by semi-preparative RP-HPLC chromatography. Through MS/MS analysis, the amino acid sequence of G-15-P2-E2-r1 was Leu-Ser-Glu-Arg-Tyr-Pro (LSERYP, LP6) or Asn-Gly-Lys-Glu-Thr (NGKET, NT5), and that of G-15-P2-E2-r2 Pro-Asp-Leu-Pro-Asn-Thr (PDLPNT, PT6). Moreover, Leu-Ser-Glu-Arg-Tyr-Pro exhibited flavor properties similar to those of enzymolyzed Parma ham.

Stability of Pigment from Morus nigra Linn.
LI Wen-juan1 YONG Xiao-hua2 WANG Bin3 ZHOU Jing1,*
2010, 31(13):  132-135.  doi:10.7506/spkx1002-6630-201013031
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The pigment extracted from Morus nigra Linn. from Xinjiang was evaluated for its stability. The pigment was soluble in polar solvents such as water and ethanol, and insoluble in non-polar solvents such as petroleum ether and benzene. It was stable in acidic media and had no light stability. In addition, the pigment was sensitive to hydrogen peroxide, sodium sulfite and sodium bisulfite. Metal ions such as Na+, K+, Mg2+ and Mn2+ had almost no effect on the stability of the pigment; however, Al3+ and Fe3+ displayed an obvious effect on its stability. Moreover, common food additives including sorbic acid, vitamin C and sodium chloride exhibited a certain hyperchromic effect, whereas sodium benzoate exhibited a certain hypochromic effect.

Correlations between Anti-pressure Capacity and Major Components of Soybean
CHENG Yu-lai PENG Zhi-lian
2010, 31(13):  136-138.  doi:10.7506/spkx1002-6630-201013032
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In order to provide a theoretical basis for harvesting, transport and processing of soybean, the anti-pressure capacities and major components of different varieties of soybean were determined, and the correlations between them were analyzed. Results indicated that different varieties of soybean had different anti-pressure capacities. Anti-pressure capacity was negatively correlated with water content, while positively correlated with fat and protein contents.

Inhibition Effect of Auricularia auricula Extract on Biofilm Formation of Escherichia coli
LI Bin DONG Ming-sheng*
2010, 31(13 ):  139-142.  doi:10.7506/spkx1002-6630-201013033
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The inhibition effect of Auricularia auricula extract on the biofilm formation of Escherichia coli 8099 was investigated using Calgary biofilm device and colony count method. Meanwhile, the morphology and structure of E. coli biofilm were also examined using optical microscope and confocal laser scanning microscope after treatment of Auricularia auricula extract. The results indicated 0.3 g/mL of Auricularia auricula extract obviously inhibited the biofilm formation of E. coli and the inhibition rate reached up to 73.0%.

Effect of Supercritical CO2 on Physical Properties of Dietary Fiber from Treated Rice Bran
WANG Da-wei FENG Yan LI Yi-li GUO Xue-fei
2010, 31(13 ):  143-147.  doi:10.7506/spkx1002-6630-201013034
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Rice bran subjected to supercritical CO2 treatment for the removal of fat was extracted to obtain dietary fiber. Dietary fibers from treated bran and untreated rice bran were compared for the differences in their physical properties including expansibility, water-holding capacity, water-retention capacity and oil-retention capacity. The expansibility, water-holding capacity, water-retention capacity of the dietary fiber from treated rice bran with the same particle sizes all increased when compared with that from untreated rice bran, while the oil-retention capability displayed an opposite change. For both of the dietary fibers, the highest water-holding capacity and oil-retention capacity were both achieved at the particle size of 0.246 mm, and the highest expansibility and water-retention capacity at 0.900 mm and 0.175 mm, respectively, and the highest weighted value of the above 4 parameters at 0.246 mm. The highest weighted value of the above 4 parameters of the dietary fiber from treated rice bran was 27.75% higher than that of the dietary fiber from untreated rice bran. Supercritical CO2 treatment resulted in an increase in dietary fiber yield of 36.63%.

A Mechanism of Antibacterial Activity of Chitosan against  Gram-negative Bacteria
LI Xiao-fang FENG Xiao-qiang YANG Sheng *
2010, 31(13):  148-153.  doi:10.7506/spkx1002-6630-201013035
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The antibacterial activities of chitosan against Pseudomonas aeruginosa (P. aeruginosa), Proteus mirabilis (P. mirabilis) and Escherichia coli (E. coli) were evaluated by optical density method. Meanwhile, bacterial cell surface hydrophilicity and negative charge analysis were investigated to illustrate the relationship between surface characteristics of Gram-negative bacterial cell wall and antibacterial activity of chitosan. To investigate the action mode of chitosan towards Gram-negative bacterial, E. coli was selected to be representative of bacteria. The permeability of the outer membrane was investigated by determining the changes in the fluorescence intensity of cells treated with the fluorescent probe of 1-N-phenylnaphthylamine (NPN). Furthermore, the interaction of chitosan with E. coli was studied by Fourier-transform infrared spectroscopy (FT-IR). Results showed that the Gram-negative bacteria with better hydrophilicity and more negatively charged cell surfaces exhibited greater interaction with chitosan and accordingly chitosan had preferable antibacterial activity against them. Chitosan increased the permeability of outer membrane and ultimately disrupted bacterial cell membranes. This damage was likely caused by the electrostatic interaction between —NH3+ groups of chitosan and carbonyl or phosphoryl groups of phospholipid components of cell membranes.

in vitro Antioxidant and Anti-microbial Activities of Lignan Compounds from Gynostemma pentaphyllum
WANG Xiao-wen1 ZHANG Hua-ping2 CHEN Feng2 WANG Xi3 WEN Wei-ye4
2010, 31(13 ):  154-157.  doi:10.7506/spkx1002-6630-201013036
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Chemical investigations of the EtOH extract of Gynostemma pentaphyllum (Cucurbitaceae) led to the isolation of 3 lignans, named compounds Ⅰ, Ⅱ and Ⅲ. Compound Ⅲ showed stronger DPPH free radical scavenging activity when compared to BHT at the same concentrations, while compound Ⅰ had only very little DPPH free radical scavenging activity and compound Ⅱ failed to scavenge DPPH free radicals within the experimental concentration range. All the compounds had a weaker ability to chelate Fe2+ when compared to EDTA. Compound Ⅱ inhibited Streptococcus mutans to a certain extent and strongly inhibited Staphylococcus aureus, while had very little inhibitory effect against Salmonella enteritidis and Escherichia coli; also, compound Ⅲ could weakly inhibit Staphylococcus aureus, Salmonella enteritidis and Escherichia coli; and compound Ⅰ had the same but weaker antimicrobial spectrum as that of compound Ⅲ.

Bioengineering
Enzymological Properties of a New Recombinant Lipase and Its Effect on Thermomechanical and Baking Properties of Dough
ZHANG Luan1,HUANG Li-qun1,YU Xiao-wei2,XU Yan2,HUANG Wei-ning1,*,TILLEY Michael3
2010, 31(13):  158-163.  doi:10.7506/spkx1002-6630-201013037
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In this study, the enzymological properties of a new recombinant lipase (Rhizopus chinensis lipase, RCL) were investigated. Besides, its effect on the thermomechanical and baking properties of dough was evaluated using Mixolab enzymatic rhelogical analyzer and texture analyzer. The optimal reaction conditions for this enzyme were at 40 ℃ and pH 8.5. Better stability of this enzyme was observed below 50 ℃ or within pH 2.0-6.0. The activity of its lyophilized powder was 17640 U/g. Compared with another commercial lipase ( AY AMANO ), RCL not only affected the thermomechanical properties, but also improved the specific volume and elasticity, and decreased the hardness, cohesiveness and chewiness of bread.

Purification, Identification and Characterization of Membrane-bound Alcohol Dehydrogenase from Gluconobacter oxydans DSM 2003
WEI Liu-jing1,LIN Jin-ping1,YANG Xue-peng2,WEI Dong-zhi1,*
2010, 31(13):  164-168.  doi:10.7506/spkx1002-6630-201013038
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The membrane fraction of Gluconobacter oxydans DSM 2003 was collected by ultra-centrifugation, and an enzyme with dehydrogenase activity to 1,2-propanediol was isolated from the membrane fraction and purified by CM-cellulose column chromatography. The purified enzyme was composed of two subunits with molecular weights of approximately 80 and 50 kD, respectively. Meanwhile, this enzyme was confirmed to be alcohol dehydrogenase (ADH) by mass spectrometry. The optimal reaction pH and temperature for this enzyme were 5.5-6.0 and 30 ℃, respectively. Although this enzyme exhibited a broad substrate spectrum including primary and secondary alcohols, alcohols containing 3 hydroxyl groups and more failed to be oxidized by it. The activity of this enzyme was inhibited by most of the selected metal ions, especially by Cu2+ and Fe3+.

Immunological Characterization and Mutational Analysis of Allergen TBa in Tartary Buckwheat
REN Xiao-xia1,ZHANG Xin2,CUI Xiao-dong1,LI Yu-ying1,WANG Zhuan-hua1,*
2010, 31(13):  169-173.  doi:10.7506/spkx1002-6630-201013039
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Buckwheat not only contains abundant nutriments such as flavoniods, but also has allergenic proteins that cause hypersensitive reactions. A natural allergenic protein with molecular weight of 24 kD named TBa (tartary buckwheat allergen A) has been obtained after separation and purification in our previous studies. According to its biological information, 5 mutants including L39R, L42R, L47R, V52R and L54R were constructed through site-directed mutagenesis and expressed in Escherichia coli BL21. The expressed products were purified by Ni2+ affinity chromatography. Purified recombinant proteins were examined using ELISA and dot blot and mutants L42R, L47R and L54R presented a weaker ability to bind tartary buckwheat allergic patients serum IgE than original E1, which suggests that Leu42, Leu47 and Leu54 might play a significant role in TBa allergenity.

Optimal Medium and Growth Metabolism of Lactobacillus reuteri
CHEN Guo,XIAO Ya-qin,CHEN Hong-wen
2010, 31(13):  174-179.  doi:10.7506/spkx1002-6630-201013040
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MRS medium for Lactobacillus reuteri is an enrichment medium. It is essential for industrial fermentation to simplify medium composition and optimize selected constituents and culture conditions. Based on traditional MRS medium, nitrogen sources were optimized through single factor experiments. Plackett-Burman and central composite designs were then used to optimize medium and cultureconditions for exploring the growth of L. reuteri CG001. Finally, the growth metabolism of L. reuteri CG001 was investigated under optimized conditions. Results indicated that the concentrations of yeast extract, glucose, manganese sulfate and culture temperature were the most important factors affecting the growth of L. reuteri CG001. According to response surface analysis, the optimal conditions were 20 g/L yeast extract, 20 g/L glucose, 7 g/L sodium acetate, 1 g/L ammonium citrate, 3 g/L K2HPO4, 0.2 g/L magnesium sulfate, 0.23 g/L manganese sulfate, 1 g/L Tween-80, initial pH 6.2, and culture temperature of 38.6 ℃. The final cell amount reached up to 0.984 g/L under the optimal conditions, which exhibited 1.102-fold improvement. An “S”-shaped pattern of the growth curve for L. reuteri CG001 in fermentor was observed. Cell growth was at the logarithmic phase during the period of 4-12 h, followed by a balance state between glucose metabolism and cell growth.

Preparation and Identification of Anti-Lead-chelate Complex Polyclonal Antibody
ZHAI Yi-fan1,XIANG Jun-jian1,*,TANG Yong1,GUO Chang-wei1,LIU Xiao-feng2,YANG Hong-yu1
2010, 31(13):  180-183.  doi:10.7506/spkx1002-6630-201013041
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Objective: BAS and OVA were individually conjugated with lead-chelate complex (Pb-DTPA) to prepare 2 antigens, namely Pb-DTPA-BSA, immunogen and Pb-DTPA-OVA, detective antigen. The synthesized antigens were then used to immunize BALB/c mice for preparing polyclonal antibodies. Finally, the antisera withdrawn from immunized BALB/c mice were assessed for their titers and specificities. Methods: The artificial antigens were identified by SDS-PAGE and scanned with ultraviolet spectrophotometer. The Pb2+ concentrations of the synthesized antigens were determined using inductively coupled plasma (ICP) spectrophotometer. Indirect ELISA and competitive ELISA were used to determine antiserum titer and specificity, respectively. Results: Compared with carrier proteins, the synthesized antigens exhibited lagged protein bands in SDS-PAGE pattern and blue shift of UV absorption peaks. The antiserum titers of the fourth and fifth mice reached up to 1:400,000 without cross-reactivity with OVA. The IC50 determined by IC-ELISA was 1.5 ng/mL and the cross reactivity with the other heavy ions were less than 1% although the cross-reactivity with Fe3+ was close to 5%. Conclusion: The above results suggest that anti-leadchelate complex polyclonal antibodies are prepared successfully.

Synthesis and Identification of Imazalil Antigen
ZHOU Ying-xia1,2,3,ZHANG Li-jie2,PAN Jia-rong2,JIAO Bi-ning1,3,*,WANG Lei2
2010, 31(13):  184-188.  doi:10.7506/spkx1002-6630-201013042
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In this study, imazalil (6-[1-(2,4-dichloro-phenyl)-2-(1-imidazolyl) ethoxy] hexanoic acid) was synthesized via substitution reaction between imidazole ethanol and 6-bromo-ethyl followed by hydrolysis reaction to provide a hapten. The synthesized product was identified by thin-layer chromatography (TLC) and 1H-NMR. The hapten was conjugated with bovine serum albumin (BSA) and ovalbumin (OVA) to obtain artificial immune antigen and artificial coating antigen, respectively. The coupling molar ratios were calculated to be 13:1 and 7:1 according to UV spectroscopy analysis, which suggests that artificial antigens are both synthesized successfully. The titer of the antibodies secreted by immunized animals was 1:64000 and the IC50 value was 1.76 μg/L determined by indirect ELISA, which further confirms successful synthesis of artificial antigens. The obtained antibodies can be used for the development of ELISA test kit.

Allergenicity Identification of Cow s Milk Substitutes
CONG Yan-jun1,REN Fa-zheng2,*
2010, 31(13):  189-192.  doi:10.7506/spkx1002-6630-201013043
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In order to find alternatives to cow s milk, serum IgE from patients with allergic reactions was used to identify allergens in cow s milk and cow s milk products and was assessed for its separate immune cross-reactivity with goat, donkey and buffalo milk proteins. Results exhibited that β-lactoglobulin andα-casein were the major cow milk allergens and that goat milk and donkey milk were promising alternatives to cow s milk.

Influence Factors on the Amount of Probiotics in Brown Dairy Drink
XU Zhi-yuan1,HANG Feng1,GUO Xiang2,GUO Ben-heng1,*,CHEN Wei2
2010, 31(13):  193-195.  doi:10.7506/spkx1002-6630-201013044
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A brown dairy drink developed in our laboratory was examined for its viable count of Lactobacillus casei in an effort to explore the effects of inoculum amount, fermentation time and solid content of raw milk on the microbiological index. Based on single factor experiments, the optimal parameters were obtained by orthogonal array design to be 6×106 CFU/mL inoculation amount, 78 h fermentation and 120 g/L solid content. Under these optimal conditions, the viable counts of L. casei reached up to 1.5 × 109 CFU/mL, which was higher than similar commercially available products.

Construction of Phytoene Desaturase (Pds) Gene Expression Vector with Tomato Fruit Specific E8 Promoter
LIU Shun-zhi,SUN Li-li,YANG Li-xiang,WANG Xiao-lan *
2010, 31(13):  196-199.  doi:10.7506/spkx1002-6630-201013045
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Phytoene desaturase (Pds) is a key enzyme in the biosynthesis pathway of carotenoid. The target gene pds and the sequence of tomato fruit specific E8 promoter were amplified by PCR and then cloned into pMD1 vector, respectively. PCR, restriction enzyme map, and sequence analysis were used to identify the reconstructed plasmid. The experimental results confirmed the successful construction of a recombinant plasmid carrying pds gene and promoter E8. The recombinant plasmid successfully transformed Atumefaciens LBA4404 and EHA105. These investigations will provide references for further study of pds expression in tomato fruits.

Metabolism of Yeast and Lactic Acid Bacteria during Dough Fermentation of Mantou
SU Dong-min1,HU Li-hua1,SU Dong-hai2,*, XIN Xiu-lan2,LI Zi-hong1
2010, 31(13):  200-204.  doi:10.7506/spkx1002-6630-201013046
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When mixing dough of Mantou, 20% Laomiantuan fermented by Saccharomyces cerevisiae (CGMCC 2.0562) and/ or Lactobacillus brevis (CGMCC 1.0579) was added in dough. The pH, total acidity and soluble sugars were determined to explore the growth and metabolism characteristics of microorganisms during dough fermentation of Laomian Mantou. Soluble sugars including maltose, sucrose, fructose and glucose were determined using high performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD). The detection conditions were as follows: mobile phase, acetonitrile/water mixture (70:30, V/V); flow rate 1.0 mL/min; column temperature, 25 ℃; ELSD drift tube temperature, 83.5 ℃; and flow rate of carrier gas, 2.2 L/min. Compared with the control group, the samples with the addition of Laomian exhibited a lower pH and higher total acidity, especially the samples with addition of Laomian derived solely from Lactobacillus brevis (CGMCC 1.0579). The contents of soluble sugars and corresponding change trend differed in different samples with the addition of different Laomian starters during the fermentation. Therefore, acid-producing metabolism and soluble sugar content during the fermentation of dough may affect the quality of Mantou.

Preparation of Monoclonal Antibody for Simultaneous Detection of Enrofloxacin and Ciprofloxacin
GUO Jie-biao,XU Yang*,LIU Shi-wen
2010, 31(13):  205-208.  doi:10.7506/spkx1002-6630-201013047
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In order to generate a monoclonal antibody with specificity to simultaneously detect enrofloxacin and ciprofloxacin, glutaraldehyde was used to prepare the artificial antigens with common structures of enrofloxacin and ciprofloxacin exposed as the major epitopes. Balb/c mice were immunized with the prepared immunogens. Results indicated that glycosylated BSA used for immunogen synthesis resulted in a higher antiserum titer when compared to unglycosylated BSA. A monoclonal antibody with respective IC50 values of 9.6 ng/mL and 10.2 ng/mL to enrofloxacin and ciprofloxacin was successfully prepared through cell fusion.

Diversity and Distribution of Bacteria in Luzhou-flavor Wine Factory
ZHOU Rui-ping,CHEN Yun-zong,TANG Dai-yun
2010, 31(13):  209-213.  doi:10.7506/spkx1002-6630-201013048
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Totally 82 bacterial strains were separated from air, koji, grain stuff and pit mud in Luzhou-flavor wine factory using improved NA medium, of which 24 were the dominant strains, accounting for 29.27% of the total number. According to the 16S DNA sequence analysis, the 24 strains comprised 13 belonging to the genus Bacillus, 9 belonging to the genera Lysinibacillus, Staphylococcus, Rummeliibacillus, Brevibacillus or Brachybacterium and 2 presumed to be new species belonging to the genera Bacillus or Brevibacillus due to less than 97% similarity in 16S rDNA gene sequence compared with type strains from database. Meanwhile, most species and population of bacteria were observed in grain stuffs prepared for fermentation and endosporebearing bacteria were observed in koji. However, amylase-producing bacteria were distributed in manufacturing environment. These findings suggest that the distribution of bacterial species and their number appears to exhibit a significant effect on the manufacturing of liquor and favor formation of wine.

Preparation and Identification of Tetrachloroisophthalonethile Artificial Antigen
GUO Nai-fei1,2,GAO Xing1,2,JI Shu-juan1,YU Ji-cheng2,*
2010, 31(13):  214-218.  doi:10.7506/spkx1002-6630-201013049
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In this work, tetrachloroisophthalonethile (TCPN) was derivatized into TCPN-COOH through two-step chemical reactions to prepare a hapten. TCPN artificial antigens, TCPN-COOH-BSA and TCPN-COOH-OVA were prepared from the hapten separately conjugated with carrier proteins, i.e., bovine serum albumin (BSA) and ovalbumin (OVA) by activated ester and mixed anhydride methods. An antisera was obtained through the immunization of New Zealand white rabbits using TCPNBSA. Antiserum titer was detected by enzyme-linked immunosorbent assay (ELISA). Meanwhile, TCPN-COOH and its intermediate product TCPN-OH were characterized by IR, MS and NMR methods, and TCPN-COOH-BSA and TCPNCOOH- OVA were qualitatively analyzed by UV/Vis spectrophotometry. TCPN-COOH, TCPN-COOH-BSA and TCPNCOOH- OVA were successfully synthesized, and the coupling ratios between TCPN-COOH and BSA or OVA were 27.86 and 12.32, respectively. The antiserum titer was about 1:1.28 × 104.

Cloning and Sequence Analysis of Dihydroflavonol 4-Reductase Genes from Tartary Buckwheat and Common Buckwheat
ZHU Ting,LI Cheng-lei,WU Qi*,MENG Hua,CHEN Hui,SHAO Ji-rong
2010, 31(13):  219-223.  doi:10.7506/spkx1002-6630-201013050
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The cDNA sequence of dihydroflavonol 4-reductase (DFR) gene was amplified from total RNA from the leaves of tartary buckwheat (Fagopyrum tataricum) and common buckwheat (Fagopyrum esculentum) by RT-PCR using homology-based cloning strategy. The amplified fragments were then cloned into T-vector. Sequence analysis indicated that both cDNAs had open reading frames of 1026 bp in full length, which encoded a polypeptide composed of 341 amino acids with typical structure characteristics and functional module of DFR enzyme, respectively. The nucleotide similarity of dfr gene among Fagopyrum tataricum, Fagopyrum esculentum and other plants ranged from 71% to 98%. In addition, the phylogenetic analysis based on amino acid sequence enconded by dfr gene indicated that both buckwheat varieties, Leguminosae, Moraceae and Rosaceae were classified into one class.

Development of a Novel Koji Accelerator for Soy Sauce Production
GU Li-zhong,JIAO Yu-zhi
2010, 31(13):  224-227.  doi:10.7506/spkx1002-6630-201013051
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A novel koji accelerator was developed using fragrant-enhancing yeast powder prepared from fermented starch syrup and adjuncts including plant extracts from Portulaca oleracea and Absinthin and inorganic sodium propionate. The effects of this accelerator on the protease activity of soy sauce koji, the bacteria contamination and the koji-making cycle were explored in this study. The addition of 0.4 g/100g koji accelerator could increase protease activity by 32%, reduce bacteria contamination by 92%, and shorten the fermentation cycle to 4 h. Moreover, the utilization rate of nitrogen increased by 5.1% during fermentation and the amino acid generation in soy sauce by 5.8%.

Optimal Fermentation Conditions for Melanin Production by Streptomyces G-HD-4
ZHENG Chen-na1,LUO Wan-mei1,CHEN Hui-qin1,WU Xiao-lan1,FANG Bai-shan2
2010, 31(13):  228-232.  doi:10.7506/spkx1002-6630-201013052
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In order to improve melanin production by Streptomyces G-HD-4 fermentation, the optimal conditions for fermenting L-tyrosine by this strain were investigate by single factor and uniform design methods. The optimal medium compositions (on the basis of 100 mL medium) were 15 g potato, 2.5 g lactose, 2.07 g casein, 0.25 g KH2PO4, 0.11 g MgSO4, and 0.25 g L-tyrosine. The optimal fermentation process was that 25 mL of medium was contained in a 250 mL flask for 5-day fermentation at initial pH 6.0, 28 ℃ and 150 r/min shaking speed. As a result, the maximum melanin yield reached up to (13.4 ± 0.05) g/L, approximately 2.3 times higher than that obtained using preoptimization fermentation medium.

Isolation, Screening and Identification of Bacillus sp. with Antifungal Activity against Penicillium sp.
ZHAO Yi-nan,CONG Yuan,KONG Wei-jia,SHANG Nan,ZHANG Xu,LI Ping-lan*
2010, 31(13 ):  233-236.  doi:10.7506/spkx1002-6630-201013053
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In order to screen antifungal Bacillus sp. strains for applications in food preservation, 132 strains were separated from 30 kinds of fruits and herbs, of which 18 were assessed by plate confrontation tests to have strong antifungal activity against Penicillium sp. The fermentation supernatants of 3 of the 18 strains with stronger antifungal activity were tested for their antifungal activity, and LPL40 revealed the strongest antifungal activity against Penicillium sp. and the inhibition zone of cell-free supernatant was (13.94 ± 1.90) mm in diameter. Based on morphological characteristics, physiological and biochemical tests and identification of 16S rDNA sequence, LPL40 was identified as Bacillus amyloliquefaciens.

Isolation and Identification of a Mildew Strain from Beef Jerky
JIANG He1,CHENG Ke-wei2,TU Hai-yun1
2010, 31(13 ):  237-239.  doi:10.7506/spkx1002-6630-201013054
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A mildew strain was isolated from mold-contaminated beef jerk. Based on the evaluation of colony growth, the isolated strain was identified to be Aspergillus penicillioides. This strain was osmophilic. It preferred to grow in dry medium and could grow at 0.75 water activity, while slowly grew at lower water activities below 0.7. Therefore, in order to avoid the occurrence of mildew in beef jerky, the strict cleaning grade in environment and water activity below 0.7 should be controlled during production. 

Effects of Microbial Changes on Physical and Chemical Characteristics of Agaricus bisporus  Compost during Fermentation
LIU Can1,SHENG Ji-ping1,ZOU Ji-hua2,WANG Hong-lei2,DING Qiang2,SHEN Lin1,*
2010, 31(13 ):  240-243.  doi:10.7506/spkx1002-6630-201013055
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The microbial numbers and physical and chemical characteristics of Agaricus bisporus compost during fermentation were detected to study the effect of microbial growth on substrate properties. Samples of Agaricus bisporus compost were collected at 6 key points throughout the entire two-phase fermentation to measure their microbial (total bacterial count, total count of actinomycetes and mold count), sensory (odor, color and physical toughness) and chemical characteristics (water content, pH and nitrate content). The results indicated that the microbial numbers of 6 collected samples of Agaricus bisporus compost all decreased in the following order: bacteria>actinomycetes>molds and the numbers of all of the microbial species initially decreased and then increased during fermentation. The sour smell of Agaricus bisporus compost gradually became weak. The ammonia smell presented a change trend opposite to that of microbial numbers. The color displayed a gradual change from yellow to brown-black and the white area increased. The toughness and water content gradually decreased, whereas the percentage wax removal increased. The pH and nitrate content both initially declined and then rose.

Ultrasonic-assisted Stepwise Enzymatic Hydrolysis of Rapeseed Meal Protein and Screening of Enzymes
ZHU Jun-wang1,JU Xing-rong1,*,WANG Li-feng1,2,YUAN Jian1,HE Rong1,2
2010, 31(13):  244-248.  doi:10.7506/spkx1002-6630-201013056
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In this study, rapeseed meal protein prepared by reverse micelles extraction was sequentially hydrolyzed with two enzymes under ultrasonic assistance. Papain, protamex, alcalase, flavourzyme and trypsin were used to comprise 6 pairwise combinations for two-step hydrolysis of rapeseed meal protein. The hydrolysis efficacy of each combination was assessed using degree of hydrolysis (DH), trichloroacetic acid nitrogen-solution index (TCA-NSI), peptide yield and molecular weight distribution. The sequential hydrolysis with papain followed by flavourzyme or with trypsin followed by flavourzyme presented higher DH and peptide yield and the corresponding products both contained less small peptides.

Nutrition & Hygiene
Effect of Emulsification on Bio-accessibility of Natural Lycopene in Male Rats
HUI Bo-di1,LI Jing2,ZHANG Yi-lin1
2010, 31(13):  249-252.  doi:10.7506/spkx1002-6630-201013057
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Objective: To explore the effect of emulsification on the bio-accessibility of natural lycopene in male rats. Methods: Totally 30 SD male rats with body weight of 250 g were randomly divided into 3 groups for 10 in each group. The rats were administered emulsified natural lycopene solutions with final lycopene concentrations of 0.263, 0.525 mg/mL and 1.575 mg/mL, respectively once a day for 4 consecutive days. The amount of lycopene in feces collected within 24 h after each administration was determined and the bio-accessibility of natural lycopene was calculated. Results: The bio-accessibilities of emulsified and unemulsified lycopene reached their separate maximum values on the 3th day of administration; increasing administration amount resulted in a lower bio-accessibility of emulsified and un-emulsified lycopene. Conclusion: Emulsification is able to increase the bio-accessibility of natural lycopene.

Hypoglycemic Effect of Lactoferrin-chromium Complex in Experimental Diabetic Mice
WU Yang,HU Zhi-he*,GUO Jia,LI Wen-long,ZHANG Min
2010, 31(13):  253-258.  doi:10.7506/spkx1002-6630-201013058
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In order to explore the hypoglycemic effect of lactoferrin-chromium in mice with experimental diabetes mellitus induced by alloxan, the diabetic animals were randomly divided into 3 lactoferrin groups administered lactoferrin at varying dosages (i.e., 1.4, 7 mg/(kg bw·d) and 14 mg/(kg bw·d), 3 lactoferrin-chromium complex groups administrated lactoferrinhromium complex at the same dosages as those of lactoferrin (1.67, 8.35 μg/(kg bw·d) and 16.7μg/(kg bw·d), calculated on the basis of chromium amount), negative control group administered saline at 10 mL/(kg bw·d), positive control group administered diformin at 250 mg/(kg bw·d). All the animals were administered once a day for 14 consecutive days. The results indicated that the high-dosage lactoferrin-chromium complex groups after 7 days of administration displayed a significantly lower blood glucose level (P < 0.05) and a significant higher glucose tolerance (P < 0.01) when compared with the negative control group. After 14 days, a significantly lower blood glucose level and a significantly higher glucose tolerance (P < 0.01) were observed in the medium- and high-dosage lactoferrin-chromium complex groups. In contrast, after 7 and 14 days, lactoferrin failed to cause significant changes in blood glucose level and glucose tolerance (P > 0.05) when compared with diabetic control group. Therefore, lactoferrin-chromium complex has significant hypoglycemic and glucose tolerance improving effects in diabetic mice in dosedependent and time-dependent manners.

in vitro Antioxidant and Free Radical Scavenging Activities of Total Flavonoids from the Leaves of Lycium ruthenicum Murr.
LI Jin,LI Shu-zhen,FENG Wen-juan,YUAN Hui
2010, 31(13):  259-262.  doi:10.7506/spkx1002-6630-201013059
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In this study, the total flavonoid extract from the leaves of Lycium ruthenicum Murr. was tested for its reducing power, hydroxyl free radical scavenging activity, inhibitory effects on H2O2-induced hemolysis of mouse erythrocytes and on the generation of MDA, one of the end products of lipid peroxidation in hepatic tissue of mice in an effort to assess its in vitro antioxidant and free radical scavenging activities. The results indicated that the extract could significantly inhibit hemolysis of mouse erythrocytes with an IC50 of 0.124 mg/mL, enhance the tolerance to reactive oxygen species in mouse serum, and reduce MDA generation in hepatic tissue of mice in a dose-dependent manner. Hence, the extract is a promising free radical scavenger and antioxidant.

Effect of Resveratrol on Antioxidant Status and Insulin Sensitivity in Rat Primary Adipocytes
CHEN Si-fan1,XIAO Xin-cai2,SUN Yan-shuang1,ZHENG Lin1,ZHANG Zi-li1,FENG Xiang1,*
2010, 31(13):  263-266.  doi:10.7506/spkx1002-6630-201013060
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The effect of resveratrol on the antioxidant status and insulin sensitivity in insulin-resistant rat primary adipocytes was investigated. Rat primary adipocytes were separated and an insulin-resistant model was established using dexamethasone. Glucose consumption as well as SOD and MDA contents in medium and cells treated with resveratrol at varying concentrations was determined. In order to explore the possible mechanisms, the expression and phosphorylation levels of Sirt1, IRS-1, AKT and GLUT4 proteins were examined by western blot. The results indicated that resveratrol increased the glucose consumption and SOD content and suppressed MDA generation in insulin-resistant rat primary adipocytes. Meanwhile, resveratrol also enhanced Sirt1 expression and improved GLUT4 translocation through insulin signaling pathway. Therefore, resveratrol is able to enhance the antioxidant status and insulin resistance in rat primary insulin-resistant adipocytes by exerting its antioxidant activity through Sirt1 pathway.

Antioxidant Effects of Coprinus comatus Polysaccharides in the Blood and Liver of Normal and Alloxan-induced Diabetic Mice
CHENG Guang-yu1,LIU Jun2,WANG Feng2,TAO Ming-xuan2,JIN Bang-quan2
2010, 31(13):  267-272.  doi:10.7506/spkx1002-6630-201013061
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Objective: The antioxidant effects of polysaccharides from Coprinus comatus fruit bodies (CCP) were evaluated in the blood and liver of normal and alloxan-induced diabetic mice. Methods: Mice were randomly divided into normal control group and diabetic model groups. The diabetic mice were induced by intraperitoneal injection of alloxan. The mice in diabetic model groups were administered glibenclamide at 100 mg/(kg·d) dosage or CCP at 200 and 400 mg/(kg·d), respectively. After treatment for 30 consecutive days, all of the mice were sacrificed to assay antioxidant parameters in blood and liver. CAT and SOD Isozymes in liver were analyzed by 4%-35% gradient polyacrylamide gel electrophoresis. Results: CCP treatment for 30 consecutive days significantly increased the activities of SOD and GPx in the blood, the activities of total SOD, CuZnSOD, CAT and GPx in the liver of diabetic mice and the levels of GSH and TAOC in both tissues and significantly reduced the contents of MDA. One band for CAT and four bands for SOD were detected in mouse liver and the staining intensities of CAT and CuZnSOD bands were both lower in alloxan-induced diabetic mice and increased to the normal level after CCP treatments; however, the staining intensity of MnSOD bands was higher in alloxan-induced diabetic mice and recovered to the normal level after CCP treatments. No significant differences in the antioxidant parameters in normal mice were observed before and after CCP treatments. Conclusion: CCP has an obvious improving effect on enzymatic and non-enzymatic antioxidant activities and is able to regulate gene expression of antioxidant isozymes. Therefore, CCP exerts an excellent antioxidant activity in the blood and liver of alloxan-induced diabetic mice without antioxidant parameter changes.

in vivo Anti-tumor Activity of Total Saponins from Asparagus officinalis
SONG Qing1,CHAI Qiu-yan2,ZHANG Li-wei1,*
2010, 31(13):  273-275.  doi:10.7506/spkx1002-6630-201013062
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The anti-tumor activity and immune regulation activity of total saponins from Asparagus officinalis were investigated by determining tumor weight and immune organ weight. The results indicated that total saponins from Asparagus officinalis had significant dose-dependent inhibitory effects on the growth of sarcoma S180 (S180) and hepatoma H22 (H22) cells implanted into healthy mice. The inhibition rate in high-dose group was 39.53% (P < 0.05) on S180 and 34.81% (P < 0.01) on H22 cells.

Analysis and Evaluation of Nutritional Composition in Two Freshwater Fingersnails
LI Xiao-ying1,LI Yong2,ZHOU Shu-qing2,YAN Bin-lun1
2010, 31(13):  276-279.  doi:10.7506/spkx1002-6630-201013063
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In this study, the nutrition composition in the muscles of two freshwater fingersnails, Bellamya aeruginosa and Cipangopaludina cathayensis was analyzed and evaluated. The results showed that water content and crude protein in both fingersnails were similar, which were 76.43%-78.3% and 13.89-14.46%, respectively. However, obvious differences in ash, crude fat and carbohydrates between both fingersnails were observed. The content of crude fat was 0.57% in C. cathayensis and 0.75% in B. aeruginosa; however, the content of carbohydrates in C. cathayensis was significantly higher than that in B. aeruginosa (2.08%). There were 18 common amino acids in Bellamya aeruginosa and Cipangopaludina cathayensis, of which 10 were essential amino acids, and the first limiting amino acid was Val and the second limiting amino acid Ile. The content of Glu was the highest among 18 amino acids, which was up to 113.78 mg/g (on the basis of dry muscle weight) in B. aeruginosa and 99.22 mg/g (on the basis of dry muscle weight) in C. cathayensis. The contents of delicious amino acids were very close in both fingersnails, which was up to 40%. The ratio of essential amino acids to total amino acids was approximately 35% and close to the value recommended by WHO/FAO (35.38%). The essential amino acid index IEAA was low in B. aeruginosa (52.09) and C. cathayensis (44.48). Hence both freshwater fingersnails cannot be used as daily main foods.

Anti-fatigue Effect of Fresh Donkey Milk
SU De-qi1,MA Long1,DING Yu-song2,YU Dan1,ZHANG Lin1,WANG Wen-lei1,FU Wen-hui1
2010, 31(13):  280-282.  doi:10.7506/spkx1002-6630-201013064
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Objective: To investigate whether fresh donkey milk alleviates swimming exercise fatigue in mice. Methods: ICR mice were randomly divided into 4 groups (n = 12), which were administered with fresh donkey milk at low, middle and high dosages (5, 10 mL/ kg and 20 mL/ kg) once a day for consecutively 30 days and saline as (control), respectively. According to Technical Standards for Testing & Assessment of Health Food (2003 Edition), mouse exhaustive swimming time, serum urea level, blood lactate content and hepatic glycogen content were determined. Results: Compared with the control group, the swimming time, serum urea level, lactate content in blood and hepatic glycogen content in mice administered with fresh donkey milk at high dosage exhibited a significant enhancement (P < 0.05-0.01). Conclusion: Fresh donkey milk has an obvious anti-fatigue effect.

Antioxidant and Immunomodulatory Effects of Polysaccharide from Rapeseed Meal in D-galactose-induced Aged Mice
LEI Hong,SUN Han-ju,JIANG Shao-tong
2010, 31(13):  283-286.  doi:10.7506/spkx1002-6630-201013065
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Subcutaneous injection of D-galactose was used to artificially induce aging in mice and the aged mice were randomly divided into 4 groups to investigate the in vivo antioxidant and immunomodulatory effects of polysaccharide from rapeseed meal (PRM) by evaluating oxygen free radical metabolism and immunomodulatory activities. The results showed that PRM at 400 and 200 mg/kg bw obviously reduced the higher MDA contents and unregulated the lower SOD activities in liver and kidney of D-galactose-induced aged mice. Also, PRM not only increased the thymus index as well as lower ConA proliferation response of spleen lymphocytes and IL-2 production, but also reduced the proliferation response of macrophages and the generation of IL-1 and NO in D-galactose-induced aged mice. These investigations demonstrate that PRM is able to improves protective immune response and inhibit destructive immune response. Therefore, PRM has remarkable antioxidant and immunomodulatory effects in D-galactose-induced aged mice.

Analysis & Detection
Research Progress of Screening Methods for Hypolipidemic Components in vitro
CHEN Ji-cheng,LU Xiao-feng,HE Guo-qing*
2010, 31(13):  287-291.  doi:10.7506/spkx1002-6630-201013066
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Abnormal lipid metabolism is one of risk factors for atherosclerotic cardiovascular disease. The commonly used hypolipidemic drugs have toxicity to some extents. Screening effective, non-toxic, natural hypolipidemic ingredients has become one of hot topics in the fields of modern medicine, nutrition and biotechnology at home and abroad. Animal models with hyperlipidemia were high cost, time-consuming and unsuitable for high throughput screening. A convenient strategy for developing hypolipidemic drugs and health foods is to screen bioactive components in vitro. In this paper, screening methods for hypolipidemic drugs in vitro have been reviewed, which will provide references for further research of hypolipidemic components.

Application of Predictive Microbiology in Quality and Safety Control of Poultry
ZHANG Qiu-qin,XU Xing-lian*
2010, 31(13):  292-296.  doi:10.7506/spkx1002-6630-201013067
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Predictive microbiology is an interdisciplinary subject of mathematics, engineering, statistics and microbiology, to develop and establish mathematical models for qualitatively analyzing the growth and survival of microorganisms in food. In this paper, predictive softwares at home and abroad were introduced, and current research achievements of predictive microbiology in quality and safety control of poultry industry were discussed.

c9t11- and t10c12-CLA: Difference in Biological Functions and Mechanisms
LIU Pei1,SHEN Sheng-rong1,RUAN Hui1,LIU Qi2,HE Guo-qing1,*
2010, 31(13):  297-301.  doi:10.7506/spkx1002-6630-201013068
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Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers, and numerous biological functions such as anticancer, reduction of body fat content, diabetes prevention, lower blood lipids and inhibition of arteriosclerosis are due to individual or synergistic action of most isomers including c9t11- and t10c12-CLA. Because of different positions of double bounds between c9t11- and t10c12-CLA isomers, high oxidization possibility of c9t11-CLA isomer was observed. Therefore, c9t11-CLA isomer exhibited a major responsibility for anticarcinogenic effect, whereas, t10c12-CLA isomer exhibited stronger reduction effect on body fat and blood lipids. Increasing studies suggested that the mechanisms of both isomers on cancer and fat metabolism were different.

Research Progress of Lead Contamination in Animal Food and Corresponding Control Technology for Feed
WANG Long-chang,WANG Tian,ZHOU Yan-min*
2010, 31(13):  302-306.  doi:10.7506/spkx1002-6630-201013069
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Lead is one of the most toxic substances to animals and human. Lead in environment could be accumulated in animal food through food chains such as feed or water, and result in problems of food safety. The sources of lead pollution, lead metabolism and factors in animals, and lead contamination in feed and animal products were reviewed in this paper. In addition, methods of feed control technologies to decrease lead content in animal products were also discussed. Moreover, future research directions were proposed.

Research Progress in Structure-activity Relationship of Food-derived Bioactive Peptides with Functions to Improve Cardiovascular Health
WANG Chun-yan,TIAN Jin-qiang,WANG Qiang*
2010, 31(13):  307-311.  doi:10.7506/spkx1002-6630-201013070
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Food-derived bioactive peptides with health-enhancing components can be released from a multitude of plant and animal proteins during gastrointestinal digestion or food processing. Bioactive peptides exhibit a series of functions such as antioxidant, immunomodulatory, opiate-like, antimicrobial, hypocholesterolemic, antithrombotic and antihypertensive functions. Through modulating and improving physiological functions, bioactive peptides can provide therapeutic applications for the prevention or treatment of chronic diseases. The sources and structures of these bioactive peptides have important effects on their functions. Structure-activity relationships of bioactive peptides related to cardiovascular health enhancement have been summarized, and future research and application of bioactive peptides have been proposed in this paper.

DNA Degradation of Genetically Modified Soybean during Processing
YE Ke-ping1,ZHOU Guang-hong1,*,XU Xing-lian1,ZHU Chang-qing1,2
2010, 31(13):  312-315.  doi:10.7506/spkx1002-6630-201013071
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Genetically modified soybean and its products were in Chinese markets; however, the safety of these products is still being debated. In this paper, current research progress in degradation of DNA derived from genetically modified soybean during its processing has been discussed. This investigation will provide effective and scientific references for the traceability and monitoring of genetically modified soybean in food chains.

Research Progress in Structure, Activity and Synthetic Gene Regulation of Flavonoids in Corn Silk
LIU Jun,LIU Jing-bo*,WANG Zuo-zhao,WANG Er-lei,WANG Cui-na
2010, 31(13):  316-320.  doi:10.7506/spkx1002-6630-201013072
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Corn silk, a kind of traditional Chinese drug, contains bioactive components that play important roles in the regulation of many physiological functions. In this paper, current research including purification, structure identification, biological activity and gene regulation of flavonoids in corn silk was comprehensively summarized. These investigations will provide theoretical references for future research and development of corn silk.

Supported Liquid Membrane Extraction and Its Application in Food Safety Inspection
LIU Jia1,2,XIANG Jin-xin3,LIU Xun-yu1,3,ZHAO Guo-hua1,3,*
2010, 31(13):  321-325.  doi:10.7506/spkx1002-6630-201013073
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Supported liquid membrane extraction, a novel extract technique with advantages of economic organic solvents, high selectivity and good reproducibility has been attracted extensive attention. In this paper, working principle, structure and factors of this extraction technique were introduced and its applications in the detection of pesticides, chemical pollutants, heavy metals, and other toxic substances in food was discussed, which will provide valuable references for food safety control and inspection.

Research Progress in Detection of Antibiotic Residues in Milk by Immunosensor
SUN Xia,WANG Xiang-you*
2010, 31(13):  326-330.  doi:10.7506/spkx1002-6630-201013074
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Mastitis is one of the most prevalent diseases and requires the treatment of antibiotics. Therefore, antibiotic residues will remain in milk. Immunosensor is a novel detection method with the integration of antibody-antigen interaction and high sensitivity. It is a convenient instrument for detecting antibiotic residues in milk due to the characteristics of portability, miniaturization and automation. Basic principle, constitution and classification of immunosensors for detecting antibiotic residues in milk have been introduced in this paper. The research progress of immunosensors at home and abroad has been comprehensively discussed and the future development trends of immunosensors for antibiotic residues have been proposed.

Research Progress in Drying and Preservation Technology of Tropical Fruits in China
YI Yang1,2,ZHANG Ming-wei1,*
2010, 31(13):  331-336.  doi:10.7506/spkx1002-6630-201013075
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Drying and preservation are important technologies to ensure healthy and stable developments of tropical fruit industries. In this paper, the drying and preservation technologies of major tropical fruits such as banana, pineapple, litchi, longan and mango in China have been reviewed, which will provide a theoretical basis for post-harvest preservation and pretreatments including drying process, heating treatment, solvent treatment, and modified atmosphere storage or packaging.

Research Progress of Essential Oils from Ledum palustre
JIANG Wei,LIU Jing-bo*,LU Jing,GUAN Shuang,ZHANG Yan
2010, 31(13):  337-341.  doi:10.7506/spkx1002-6630-201013076
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Ledum palustre is a traditional herb and a perfume plant. A large number of essential oils such as cumin aldehyde, p-cymene andα-pinene in ledum palustre execute multiple functions. The components and contents of essential oils in Ledum palustre were highly correlated with their growth environment, harvest seasons and nutritional organs. Essential oils from Ledum palustre have many physiological functions including skin absorption enhancement, anti-inflammatory, analgesic, reparative, diuretic, hepatoprotective, acaricidal, insecticidal, radioprotective and antitoxic functions. Based on the reports at home and abroad, Ledum palustre will have promising development value.

Current Research Progress of Key Technologies during the Processing of Persimmon
HU Wan-shan,GUO Lin-bo,LI Yu-hua,CHEN Xiang-ning*
2010, 31(13 ):  342-346.  doi:10.7506/spkx1002-6630-201013077
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Persimmon is a kind of major agricultural product in China. Persimmon productivity and planting area in China was rank in the first all over the world. However, different processed products of persimmon were less due to the low utilization rate of persimmon. Large amounts of tannin, pectin and protein in persimmon affected the quality of persimmon products. In this paper, key technologies in persimmon processing such as removal of astringency, inhibition of re-astringency, and prevention of browning and non-biological turbidity, have been discussed. Meanwhile, advantages and disadvantages of different processing strategies and corresponding practical applications have been compared.