Volume 30,Issue 9,2014 Table of Contents

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  • 1  Mechanism of Sepia Ink Polypeptide-induced Apoptosis in DU-145 Prostate Cancer Cells
    JING Yi-wen YANG Zui-su HUANG Fang-fang YU Di DING Guo-fang
    2014, 30(9):1-6.
    [Abstract](1456) [HTML](0) [PDF 567.93 K](885)
    Abstract:
    In this study, the mechanism of apoptosis induced by sepia ink polypeptide (SHP) in DU-145 prostate cancer cells was explored. The effect of SHP on the proliferation of DU-145 cells was examined by the Cell Counting Kit-8 (CCK-8) assay. Typical morphological changes in DU-145 cells were observed with hematoxylin and eosin (HE) and acridine orange/ethidium bromide (AO/EB) staining. The early-stage apoptosis rate was measure using flow cytometry (FCM), and the changes in the expression of apoptosis-related genes (p53, Bcl-2, Bax, Caspase-3, and VEGF) were evaluated via western blotting. The results showed that SHP significantly inhibited the proliferation of DU-145 cells in a time-and dose-dependent manner. DU-145 cells developed morphological features of apoptosis after treated with SHP.FCM studies revealed that the early-stage apoptosis rate of DU-145 cells increased from 12.25% to 34.20% with increasing SHP concentration and duration of treatment. Western blotting results showed that after 24 h treatment with SHP, the expression of anti-apoptotic proteins Bcl-2 and VEGF decreased, while the expression of p53, Bax, and Caspase-3 increased. Collectively, these results suggest that SHP induced apoptosis in DU-145 cells. The mechanism might involve the decrease in Bcl-2/Bax expression ratio by activation of the tumor suppressor gene p53. Moreover, VEGF expression was down regulated, and apoptotic protease Caspase-3 was activated, thus triggering the apoptosis cascade reaction.
    2  Anti-tumor Effect of an Acid Polysaccharide from Gracilaria lemaneiformis in H22-bearing Mice
    FAN Yan-li ZHENG Guo-qiang LIU An-jun
    2014, 30(9):7-12.
    [Abstract](1284) [HTML](0) [PDF 770.60 K](760)
    Abstract:
    In this study, the inhibitory effect of an acid polysaccharide from Gracilaria lemaneiformis (GLSPs) on H22-bearing mice was investigated. The influence of GLSPs on the cell cycle and apoptosis of tumor cells in vivo was studied using flow cytometry. The effect of GLSPs on splenetic lymphocyte proliferation and killing activity of NK cells in tumor-bearing mice were determined by MTT assay. The tissue pathological detection of the immune organs (spleen and thymus) in mice was performed. The results showed that apoptosis of H22 hepatoma cells in mice was promoted by GLSPs, and tumor growth was remarkably inhibited. Intragastric administration of GLSPs at 200 mg/(kg·d) and 600 mg/(kg·d) in tumor-bearing mice for 28 days resulted in an average inhibition rate of tumor volume of 84.65% and 94.58%, respectively. Immunological tests in tumor-bearing mice showed that pathological changes, including splenic enlargement and thymic atrophy, were significantly improved, and the function of the immune organs was reinforced. Moreover, the drastic increase of leukocytes and lymphocytes in the blood of tumor-bearing mice was effectively regulated, while the proliferation of T and B cells induced by ConA and LPS as well as the killing activity of NK cells were significantly improved. Thus, the immunity of tumor-bearing mice was enhanced through different mechanisms. These results indicate that GLSPs have anti-tumor effects in vivo via immunomodulation.
    3  Supramolecular Interaction of Litsea cubeba Essential Oil with β-Cyclodextrin and Physicochemical Properties of the Complex
    KUANG Chun-tao LI Xiang-zhou HAN Yan-li WANG Ling-zhi ZHANG Shan-lin
    2014, 30(9):13-19.
    [Abstract](1105) [HTML](0) [PDF 864.30 K](884)
    Abstract:
    Litseacubeba essential oil is an important condiment and perfume, which is widely used in the food and cosmetics industry. The supramolecular interaction between citral from the plant’s essential oil and β-Cyclodextrin (β-CD) was studied by UV spectrophotometry, and the process of preparing Litsea cubeba oil-β-CD inclusion complex was optimized. In addition, its physicochemical properties were investigated by ultraviolet-visible (UV) spectrometry, infrared (IR) spectrometry, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The results showed that the stoichiometric ratio of Litsea cubeba essential oil-β-CD inclusion complex was 1:1, and the formation constant of the complex decreased with increasing temperature. The thermodynamic parameters (ΔH?<0, ΔS?<0, ΔG?<0) demonstrated that the formation of Litsea cubeba essential oil-β-CD inclusion complex was a spontaneous exothermic process, and the main driving force was a change in enthalpy (ΔH). The physicochemical properties of Litsea cubeba essential oil-β-CD complex were visibly changed and that Litsea cubeba essential oil and β-CD were combined by Van der Waals force or hydrogen bond to form a new phase. Otherwise, the complex showed good thermal stability and photo stability, and the original components of Litsea cubeba essential oil were well preserved in the complex.
    4  Apoptosis in Jurkat Cells Induced by Lfcin from Different Sources
    ZHAO Ning XU Xiao-xi WANG Jing ZHANG Yan-jie ZHANG Shu-yi
    2014, 30(9):20-25.
    [Abstract](1162) [HTML](0) [PDF 636.30 K](739)
    Abstract:
    In this study, the inhibitory effects of bovine lactoferricin (LfcinB) and human lactoferricin (LfcinH) on the proliferation of Jurkat cells were explored and compared, by reducing the mitochondrial membrane potential in the cells. The effect on Jurkat cell proliferation was measured by MTT assay, and nuclear changes were observed by fluorescence microscopy with Hoechst 33258 staining. A flow cytometry of double-labeling by Annexin V-FITC/PI was used to distinguish the apoptosis stages in the Jurkat cells that were induced by LfcinH and LfcinB. The results showed that LfcinB and LfcinH significantly inhibited the proliferation of Jurkat cells (P < 0.05) in a dose-dependent manner. A decreased mitochondrial membrane potential in Jurkat cells was observed by JC-1 staining using laser scanning confocal microscopy. The early phase of apoptosis occurred after Jurkat cells were treated by LfcinH and LfcinB for 48 h; characteristics of apoptosis such as nuclear shrinkage and debris were observed using fluorescence microscopy. The results suggest that the change in mitochondrial membrane potential may have led to apoptosis in Jurkat cells and, eventually, the inhibition of proliferation. When the concentration of both, LfcinH and LfcinB was less than 250 μg/mL, the inhibitory effect of LfcinH on Jurkat cells was noted to be stronger; whereas at concentrations higher than 250 μg/ mL, LfcinH and LfcinB showed similar inhibitory effects.
    5  Effect of Reactive Oxygen Species (ROS) on Structural Changes in Meat Myofibrillar Protein during Ageing
    ZHANG Yu-lin CAO Jin-xuan PAN Dao-dong OU Chang-rong SHEN Jian-liang
    2014, 30(9):26-32.
    [Abstract](1254) [HTML](0) [PDF 755.40 K](818)
    Abstract:
    In this study, Raman spectroscopy was used to analyze changes in the main chain of myofibrillar protein and the microenvironment of amino acid residues in goose meat while ageing. The observations were conducted in a controlled experiment using the ROS inducer, hydrogen peroxide (H2O2), and N-acetyl cysteine (NAC), a ROS scavenger. After treatment with10 mmol H2O2 solution for 96 h, the relative content of ROS in goose muscle tissues was visibly higher than that in the NAC group (p<0.05). With increasing ROS concentration, the α-helix content decreased significantly (p<0.05), where as the β-sheet content increased significantly (p<0.05) in the H2O2 group. While in the NAC group, the α-helix content decreased significantly (p<0.05), but the content of random coils increased significantly (p<0.05). Changes in secondary protein structure, especially the transformation between α-helix and β-sheet forms, are closely related to gelling properties of the protein. The decline in intensity of C-C\C-N skeletal stretching vibrations was greater in the H2O2 group than in the NAC group, indicating that ROS could target the skeletal peptide bond and induce protein degradation. The normalized decline in intensity of the Raman band at 760 cm-1 was more pronounced in the H2O2 group than in the NAC group, suggesting that oxidation could enhance the surface hydrophobicity of proteins.
    6  Effect of Polysaccharides from Wild Jujube on Acute Liver Injury Induced by CCl4 in Mice
    ZHANG Hui-fang ZHOU Yu-zhen CHEN Jia-lu CHEN Shi-ru DING Hong
    2014, 30(9):33-37.
    [Abstract](1509) [HTML](0) [PDF 584.08 K](753)
    Abstract:
    Polysaccharides from wild jujube (PWJS) were isolated by distilled water extraction and its anti-oxidative activity and liver protection capability were investigated. Acute injury models were set by CCl4 in mice and ALT, AST activities in serum, CAT, SOD activities, MDA content in liver homogenates were tested by biochemical assays. Liver tissue of the mice was stained with hematoxylin-eosin (HE) for observing the effect of PWJS on mice liver histopathology. Results showed that PWJS had strong antioxidant ability in vitro. Meanwhile, in vivo study showed that, compared with model group, ALT and ALP activities in serum declined significantly and the maximal decline rate was 34.33%. CAT, SOD activities in liver homogenates significantly increased, with the maximum increasing rate being 35.88%. MDA content in liver homogenates declined significantly and the maximal decline rate was high to 52.07%. Thus, PWJS successfully reduce hepatotoxicity in CCl4-induced liver injury mice, due to the regulation of serum enzymes and antioxidant enzymes activity.
    7  Gelling Properties of High-acyl Gellan Gum Based on the Stress Relaxation Theorem
    CHEN Qing ZHENG Peng-fei WANG Lei
    2014, 30(9):38-43.
    [Abstract](1449) [HTML](0) [PDF 536.53 K](748)
    Abstract:
    In this study, the stress-relaxation model was used to examine the effects of monovalent (K+ and Na+) and divalent (Ca2+ and Mg2+) cations on the gelling properties of high-acyl gellan gels. The results suggested that the stress relaxation behavior of high-acyl gellan gels fitted well with Peleg’s empirical model. The types and concentrations of cation had significant effects on the stress relaxation behavior of high-acyl gellan gels. The values of equilibrium modulus (EA) formed a saddle-shape curve with increasing cation concentration and correlated positively with gel hardness (R = 0.943 to 0.983), indicating that EA could be used to characterize gel strength. The gels formed by divalent cations showed greater gel strength than those formed by monovalent cations. At constant concentrations of cation, gellan gels formed by Na+ were stronger than those formed by K+, whereas gels formed by Ca2+ were stronger than those formed by Mg2+. When subjected to 16,000 ×g centrifugal force for 10 min, all high-acyl gellan gels exhibited water-holding capacity of more than 95%. In addition, the water-holding capacity of high-acyl gellan gels was less sensitive to changes in K+, Na+, Ca2+, and Mg2+ concentrations. The mechanism of stress relaxation appeared to be associated with the movement of physical cross-links in the gel matrix.
    8  Expression Profile of S2P homologsgene sll0528 in Synechocystissp.6803 under Multiple Stress Conditions
    CHEN Gu WANG Yu-ling
    2014, 30(9):44-48.
    [Abstract](1264) [HTML](0) [PDF 541.72 K](625)
    Abstract:
    To explore the functions of site-2 protease (S2P) homolog sll0528 in Synechocystis sp. PCC 6803, real-time fluorescence quantitative polymerase chain reaction (FQ-PCR) was used to detect the time-course expression profile of sll0528 under multiple stress conditions. The results showed that sll0528 was induced significantly under different stress conditions; however, stress induction patterns were different and could be classified into three groups. The first group included early response, i.e., sll0528 promptly responded to stress conditions such as exposure to high intensity light, hydrogen peroxide, sorbitol, and glucose mixotrophic condition, where maximal induction occurred within 0.5 h. The expression level increased by 10-, 80-, and 100-fold at 0.25 h when induced by high intensity light, hydrogen peroxide, and sorbitol, respectively, whereas glucose mixotrophic condition increased the expression level by approximately 9-fold after 0.5 h of treatment. The second group included mid-stage response, which was induced by low and high temperature. High temperature stress increased the expression level by 30-fold after 1 h of treatment, whereas low temperature stress significantly increased the expression level by 280-fold after 2 h of treatment. The third group included late response induced by acid and salt stress, which increased the expression level by 90- and 190-fold, respectively, after 6 h of treatment. Taken together, it could be inferred that sll0528 in Synechocystissp.PCC 6803 might play an important role in multiple stress responses. Under different stress conditions, this gene might participate in different signal transduction pathways and showed an expression peak at different levels and at different time-points. These results provide fundamental knowledge for further research to characterize the function and mechanisms of sll0528 in stress response.
    9  PCR-DGGE to Detect Bacterial Flora Change in Liquid-smoked Tilapia Fillets during Storage
    CHEN Sheng-jun CAI Qiu-xing LI Lai-hao YANG Xian-qing QI Bo MA Hai-xia WU Yan-yan CEN Jian-wei
    2014, 30(9):49-54.
    [Abstract](1132) [HTML](0) [PDF 549.93 K](664)
    Abstract:
    Denaturing gradient gel electrophoresis technique based on polymerase chain reaction (PCR-DGGE) was used to investigate the constitution and changes of bacterial flora in the liquid-smoked tilapia fillets during storage, in order to provide a theoretical foundation for their storage conditions. The results showed that 13 bands were isolated using DGGE and after analysis their sequences, 10 of them had sequence similarity above 90%. These included two strains of Enterobacter, two strains of Clostridium, two strains of Lactococcus, two strains of Pediococcuspentosaceus, one strain of Leuconostoc, and one strain of Pseudomonas. Lactic acid bacteria (LAB) accounted for 50% of all bacteria. The bacterial flora during early storage (<2 d) and the last storage period (>7 d) were quite complex, with more than 10 identified bands. During the mid-storage period (2~7 d), however, the bacterial DGGE bands were distinctly grouped and there were only approximately five identified bands, indicating that the microbial diversity decreased. The bands from DGGE and sequencing results indicated that the dominant bacteria during storage were Lactococcus, Pediococcuspentosaceusand Clostridium.
    10  Purification and Activity of Human Peroxiredoxin 1 Expressed in E.coli
    MAO Shuang CHEN Shao-pei YAN Sheng WANG Hai-ying NING Zheng-xiang LI Shan WANG Ju-fang
    2014, 30(9):55-59.
    [Abstract](1244) [HTML](0) [PDF 516.85 K](615)
    Abstract:
    In order to obtain active human peroxiredoxin 1(Prx1) with high purity, Prx1 cDNA sequence was amplified by polymerase chain reaction (PCR), cloned in expression vector pET28 to construct a prokaryotic expression plasmid pET28-Prx1, containing full-length human Prx1 gene. After endonuclease digestion and DNA sequencing, the plasmid was transferred into Escherichia coli BL21 (DE3) for expression. The expression product was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting. The recombinant protein was purified by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography, the Michaelis constant (Km) for Prx1 was determined, and the activity of Prx1 was identified by plasmid protection assay. The result of endonuclease digestion and DNA sequencing showed that recombinant plasmid was constructed successfully. The expression product was approximately 25 kDa, as determined by SDS-PAGE and western blotting, which is consistent with the actual molecular weight of human Prx1. After purification, the yield of Prx1 was 7.59 mg/g bacteria, with a purity of 88.50%. The Km value of purified Prx1 was 2.06×10-4 mol/L in catalytic reduction of H2O2 at 37 ℃ with a pH value of 7.4. Plasmid protection assay showed that Prx1 could protect pUC18 DNA from oxidative damage. Thus, Prx1 was successfully expressed in E.coli and an active protein with high purity was obtained.
    11  Mass Transfer Process of Peanut Protein Extracted by Enzyme-containing Reverse Micelles
    YANG Chen-Xian CHEN Fu-sheng LIU Kun-lun BU Guan-hao XU Wei-he
    2014, 30(9):60-66.
    [Abstract](1286) [HTML](0) [PDF 576.50 K](821)
    Abstract:
    This study evaluated the mass transfer process of peanut protein extracted by reverse micelles containing enzyme by using a corresponding model. The effects of stirring speed, extraction temperature, peanut particle size, solid-liquid ratio, and ratio of enzyme to substrate ([E]/[S]) on the extraction rate were examined. The results showed that the extraction rate increased with higher temperature, reduced particle size, and increased the solid-liquid ratio. The optimum extraction efficiency was achieved at an [E]/[S] ratio of 40,000 U/g, while changing the stirring speed had little effect on the extraction. Based on the Arrhenius equation, the apparent activation energy for the extraction of peanut protein was calculated as 9.64 kJ/mol. The results suggest that the rate-determining step in the extraction process probably was the internal diffusion control of the protein from the interior to the surface of the particle, which belongs to a first-order reaction. A macroscopic mass transfer model of peanut protein extracted by enzyme-containing reverse micelles was established, which, after model validation, agreed well with the actual extraction process. Thus, this study provides an important theoretical basis for the mass transfer process of peanut protein extracted by reverse enzyme-containing micelles.
    12  Recombinant Expression of Fructosyl Transferase Gene of Aspergillus oryzae in Escherichia coli
    WANG Yu-hai YUE Juan WANG Peng LIN Xiao-shan ZHANG Yi
    2014, 30(9):67-72.
    [Abstract](1182) [HTML](0) [PDF 581.57 K](720)
    Abstract:
    To obtain a higher yield of fructosyl transferase during industrial production, the fructosyl transferase gene from Aspergillus oryzae SBB201 strain was amplified using reverse transcriptase-polymerase chain reaction (RT-PCR) technique and cloned into plasmid pEASY-E1, which was then transformed into E. coli BL21-DE3 strain to achieve successful expression. Optimal conditions for inducing the expression of recombinant genes were ultimately determined for successful expression of fructosyl transferase, namely, induction temperature of 25 ℃ and a dose of 1.0 μmol/mL isopropylthiogalactoside (IPTG,) as an inducer. Taking advantage of the 6 × histidine-tag at the amino terminus of recombinant plasmid PEASY-S1, the expressed fructosyl transferase was purified by chelating affinity chromatography. Sucrose was used as substrate to test the catalyzing ability of fructosyl transferase. The results indicated that the recombinant fructosyl transferase had catalyzing ability and its enzyme activity reached 59.0 U/g. In addition, this recombinant fructosyl transferase could be stably expressed at low temperature. Thus, it has great potential for development and application. In this study, recombinant expression of fructosyl transferase in E. coli was successful, achieving rapid expression of a large amount of fructosyl transferase with catalyzing ability. This study could provide a theoretical basis for industrial production of fructosyl transferase.
    13  Relationship between the Characteristics of Dough Pieces and the Rheological Properties of Dough during Noodle Production
    JING Peng ZHENG Xue-ling LIU Chong XU Tian-yun LIU Lin
    2014, 30(9):73-78.
    [Abstract](1223) [HTML](0) [PDF 509.16 K](715)
    Abstract:
    The dough pieces made from thirteen wheat varieties were fractionated based on the particle size. The relationship between the particle size (d) of the dough pieces and the rheological properties of the dough with the quality of the produced noodles was investigated. The results showed that the content of dough pieces with d <0.336 mm was significantly negatively correlated with pasting temperature (r=-0.60, P<0.05). The content of dough pieces with d =0.336~0.75 mm was significantly positively correlated with water absorption(r=0.64, P<0.05), while negatively correlated with the degree of softening (r=-0.65, P<0.05) and pasting temperature (r=-0.60, P<0.05). The content of dough pieces with d =0.75~1.5 mm had a very strong negative correlation with the degree of softening(r=-0.74, P<0.01). The content of dough pieces with d = 1.5~2 mm was very strongly negatively correlated with water absorption (r=-0.72, P<0.01) and significantly positively correlated with the degree of softening (r=0.63, P<0.05). The content of dough pieces with d = 2~3 mm was significantly negatively correlated with water absorption (r=-0.63, P<0.05) and very strongly positively correlated with the degree of softening (r=0.78, P<0.01). The content of dough pieces with d = 3~4 mm had a very strong positive correlation with the degree of softening (r=0.69, P<0.01) and was significantly positively correlated with the pasting temperature (r=0.59, P<0.05). The content of dough pieces with d>4 mm was significantly positively correlated with the pasting temperature (r=0.67, P<0.05). The paper draws the conclusion that a high content in dough pieces with d<1.5 mm can improve the quality of the noodles, but a high content in dough pieces with d>1.5 mm may negatively affect the quality of noodles.
    14  Purification and Structural Analysis of a Polysaccharide from Lentinusedodes Extracted using an Acid Solution
    MEI Guang-ming HAO Qiang ZHANG Xiao-jun GUO Yuan-ming CHEN Xue-chang
    2014, 30(9):79-84.
    [Abstract](1392) [HTML](0) [PDF 573.46 K](804)
    Abstract:
    A new polysaccharide SP2 was isolated from Lentinusedodes using an aqueous HCl solution and purified using gel column chromatography, the purity was determined using filter paper electrophoresis. The relative molecular mass and distribution of SP2 were analyzed by high-performance gel permeation chromatography, and the structure was analyzed by UV-Vis spectroscopy, gas chromatography, infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry, as well as periodate oxidation, Smith degradation, and Congo red experiments. The results indicated that SP2 showed a typical absorption peak for polysaccharides after the color reaction and had a relatively homogeneous composition. In addition, the molecular weight distribution range was relatively narrow, with a weight-average molecular weight of 5.203×104 u. SP2 was found to be composed of mannose, glucose, and galactose with a molar ratio of 0.32:58.6:2.82. Periodate oxidation and Smith degradation experiments indicated that the C-C bonds in the branches of SP2 were composed of (1→2), (1→3), and (1→6) linkages with a molar ratio of 9.43:5.44:1. SP2 was found to be a glycoprotein conjugate containing pyranose rings that was amorphous and could not form the monocry stalline structure. SP2 contained spiral structures and had no strong intermolecular interactions. These results provided evidence to explain the structure-activity relationships of polysaccharides from L. edodes.
    15  Separation and Identification of Dominant Bacterial Strains Producing Amino Acid Decarboxylase in Xinjiang Smoked Horsemeat Sausage
    LI Rui-ting LU Shi-ling LI Kai-xiong MA Yu-xia ZHANG Hui-chao
    2014, 30(9):85-91.
    [Abstract](1307) [HTML](0) [PDF 591.11 K](718)
    Abstract:
    In this study, 32 dominant bacterial strains producingamino acid decarboxylase were isolated from 44 samples of Xinjiang smoked horsemeat sausage, collected from four districts in Xinjiang where producing smoked horsemeat sausage. The ability of the isolates to producebiogenic amines was determined and dominant biogenic amine-producing strains were distiguished by a chromogenic reaction in double-layered media. Subsequently, polymerase chain reaction/denaturing gradient gel electrophoresis (PCR-DGGE) was used to reject repetitive strains and 32 biogenic amine-producing strains were identified viahomology comparison. Finally, high-performance liquid chromatography (HPLC) was used to examine bacterial broth to confirm the production of biogenic amine. The strains thus obtained had strong ability to produce putrescine, tryptamine, histamine, and phenylethylamine. Strain number 4 (Serratia odorifera) showed the highest average production of total biogenic amines (985.14 μg/mL) and the highest production of histamine (7259.64 μg/mL). Strain number 17 (Enterobacter cloacae) showed the second-highest production of total biogenic amines (737.78 μg/mL) and the highest production of tryptamine (4507.81 μg/mL). Strain number 11 (Klebsiella sp.) showed the highest production of putrescine (2550.54 μg/mL), whereas Strain number 8 (Staphylococcus xylosus) showed the highest production of phenylethylamine (3831.50 μg/mL).
    16  Effect of Acid Hydrolysis Time on the Structure and Properties of Rice Starches
    CHEN Pei ZHAO Bing LIU Hong-sheng ZHANG Xiao LI Yuan-zhi
    2014, 30(9):92-95.
    [Abstract](1354) [HTML](0) [PDF 480.99 K](661)
    Abstract:
    In this study, four types of rice starch with different amylose contents ( Younuo 3: 0%; Daohuacan: 10.90%; Juliangyou: 21.03%; Huayouxiangzhan: 28.46%) were used to investigate the effect of acid hydrolysis time on the structure and properties of rice starches. After undergoing acid hydrolysis for different time, the changes in the hydrolysis ratio, particle morphology, crystallization properties, and solubility of hydrolyzed rice starches were measured and used as indicators to evaluate the effects of hydrolysis time. The results showed that rice starches with different amylose content shad different acid-resistant abilities, and thus hydrolysis time had different effects on the structure and properties of the rice starches with different amylose contents. The extent of acid hydrolysis in rice starch was negatively related to the amylose content, as evidenced by the fact that approximately 50% Younuo3 was hydrolyzed, whereas only 30% of Huayouxiangzhan was hydrolyzed. All starch granules showed a degree of breakage after acid hydrolysis, and the cross observed in starch under polarized light deformed before it completely disappeared. With the same acid hydrolysis time, the rice starches with higher amylose contents showed lower breakage rates. Acid hydrolysis did not affect the A-type crystal pattern of the starch in the studied samples; however, with increasing hydrolysis time the relative crystallinity and the solubility of the rice starches increased.
    17  Exploration on Mechanism of Killing Molds in Corn by Microwave Treatment
    XU Yan-yang YU Jing QIU Yang
    2014, 30(9):96-101.
    [Abstract](874) [HTML](0) [PDF 670.51 K](682)
    Abstract:
    In order to discuss the presence of non-thermal effect during the process of killing molds in corn by microwave treatment, growth situation of Aspergillus funigatus, Aspergillus niger, Penicillium chrysogenum and Penicillium citrinum before and after microwave treatment were studied. The growth models of molds were established through the determination of mold growth amount, the absorbance values of protein and DNA, the permeability of electrolyte, and morphological changes of A. niger spore and situation of exudates were observed by atomic force microscope (AFM). Results showed that the lag phases of four kinds of molds became longer, population capacities lessened, and absorbance values of protein and DNA largened after microwave treatment, compared with water bath heating at the same temperature. It was indicated that more damages in molds occurred by microwave than water bath, suggesting non-thermal effects existed in the process of microwave sterilization. AFM examination showed that the morphology of A. niger spores’ before and after microwave treatment was quite different. The form of spores was full and the surface was relatively smooth before the microwave treatment, but they shrinked after the microwave treatment. More cellular content overflowed after microwave treatment, which proved that microwave treatment had damage effect on cell membrane of molds.
    18  Comparison of the Content, Antioxidant Activity, and α-Glucosidase Inhibitory Effect of Polysaccharides from Momordicacharantia L. Species
    DENG Yuan-yuan ZHANG Ming-wei LIU Jie-qing ZHANG Yan ZHANG Rui-fen WEI Zhen-cheng TI Hui-hui LIU Lei QIU Ming-hua
    2014, 30(9):102-108.
    [Abstract](1420) [HTML](0) [PDF 660.90 K](809)
    Abstract:
    In this study, the differences in the content and component of Momordicacharantia L. polysaccharides (MCPs) from 13 different Momordicacharantia L. species as well as their antioxidant activity and inhibitory effect of α-glucosidase were compared. The MCPs molecular weight distribution, polysaccharides, uronic acid, and protein contents were analyzed. In addition, their antioxidant activity was evaluated by oxygen radical absorbance capacity (ORAC). The 4-nitrophenyl-2-β-d-glucopyranoside method was used to measure the α-glucosidase inhibitory activity and to analyze the relationship between the components and the corresponding activity. The results showed that the polysaccharide, uronic acid, and protein content of 13 Momordicacharantia L. species ranged from 5.91% to 10.62% for dry weight, 25.21% to 42.37%, and 3.17% to 4.60%, respectively. Two major components were present in all MCPs, and their molecular weights ranged from 1558.88 to 3048.56 kDa, and 33.19 to 58.74 kDa, respectively. ORAC values of the 13 Momordicacharantia L. species varied from 19.39 to 57.73 μmol Trolox /g. The maximum inhibition ratio of different species on α-glucosidase ranged from 4.80% to 92.67%. Significant positive correlations were observed between ORAC values to polysaccharide, uronic acid, and protein content (P<0.05). Significant genetic differences were detected in their content, antioxidant activity, and inhibitory effect of α-glucosidase from different species. Polysaccharides are the main active component contributing to the antioxidant activity of the plant, and uronic acid and protein can strengthen their antioxidant activities.
    19  Performance Study on Microemulsion Lyophilized Powder of Evening Primrose Oil
    WU Hong-yan SUN Chang-bao LIU Ning GUO Cheng-yu
    2014, 30(9):109-113.
    [Abstract](1018) [HTML](0) [PDF 516.77 K](762)
    Abstract:
    To investigate the effects of cryoprotectants on the freeze-drying of evening primrose oil microemulsion and its stability, the distribution of Sudan II in the lyophilized powder was analyzed by differential scanning calorimeter (DSC). The cryoprotectants for the microemulsion were screened in terms of appearance, size and powder disperse ability. The stability of the powder under various conditions of storage time and temperature was investigated with the entrapment efficiency as the observing index. In summary, mannitol was shown to be the best cryoprotectant. The lyophilized powder showed good granular pattern, dispersion speed, and large-sized particles. After storage for six months, the entrapment efficiency was decreased from 90.92% to 82.58±0.66% at 37 ℃; while it only decreased to 89.50% and 88.80 it on at 4 ℃ and 20 ℃, respectively. DSC results showed that Sudan II had no effect on thermal property of the microemulsion lyophilized powder and existed as amorphous pattern. The microemulsion lyophilized powder, prepared using evening primrose oil as the oily phase and mannitol as the lyoprotectant, was stable, with high entrapment efficiency and no significant change after stored for 6 months.
    20  Isolation and Identification of Bacteria and Yeast from Chinese Traditional Sourdough
    LIU Tong-jie LI Yun WU Shi-rong JIN Le-tian ZHANG Guo-hua YANG Huan-yi HE Guo-qing
    2014, 30(9):114-120.
    [Abstract](1711) [HTML](0) [PDF 591.14 K](1039)
    Abstract:
    In this study, the physicochemical properties and microbial profile of traditionally fermented sourdough for Chinese steamed bread were examined. Six samples of sourdough were collected from northern China. Acidity and colony counts were measured. After isolation, purification, and preliminary screening, 75 strains of bacteria and 60 strains of yeasts were obtained and identified by DNA sequencing. The pH was between 3.73 and 5.46 and total titratable acid (TTA) values ranged from 8.3 to 19.8 mL. In all the samples, the number oflactic acid bacteria (LAB) and yeasts ranged from 8.35±0.07 to 9.75±0.12 Log cfu/g and 6.31±0.22 to 8.68±0.04 Log cfu/g, respectively. Eight LAB species, including Lactobacillus brevis, L. plantarum, and L. sanfranciscensis, and six other bacterial species, including Bacillusamyloliquefaciens, Bacilluslicheniformis, and three species of Acetobacter, were identified. Among the four identified yeasts, the dominant species was Saccharomyces cerevisiae. The results indicate that Chinese traditional starter cultures for flour-based food are complex bacterial floras dominated by LAB and yeast, in addition to several other microorganisms, including Bacillus spp., Acetobacter spp., and even pathogenic bacteria. Differences in microbial species compositions among LAB and yeasts in samples from different areas were identified by comparing species distributions in different sourdough samples.
    21  Isolation and Properties of Lactococcuslactis Strain from Kefir Grains
    GUO Li-dong LIU Qian JIANG Liu-qing LIU Xiao-yan MENG Dan
    2014, 30(9):121-125.
    [Abstract](1235) [HTML](0) [PDF 514.45 K](658)
    Abstract:
    In order to select probiotic, lactic acid bacteria, a predominant strain, named HUCM 201, was isolated from Kefir grains, which is used as a starter culture for traditional fermented dairy products. This bacterial strain was identified as Lactococcuslactis subsp. Lactis based on its morphologic properties, 16S rDNA sequences, as well as physiological and biochemical characteristics. The strain showed a certain degree of tolerance to acid and bile. After 3 h in a simulated gastric fluid, viable counts for the strain were maintained up to 105 CFU/mL. HUCM 201 strain exposed to MRS broth supplemented with 1% oxgall for 4 h showed a slight decrease in cell viability. Meanwhile, Caco-2 cells, a model forintestinal epithelial cells, were used to measure bacterial adhesive ability. HUCM 201 strain exhibited adherence to Caco-2 cells with an adhesion ratio of1.93%. The minimum inhibitory concentration was used to evaluate antibiotic susceptibility of the isolate. This strain was found to be susceptible to ampicillin, vancomycin, erythromycin, chloramphenicol, and penicillin. Thus Lactococcuslactis subsp. lactisstrain HUCM 201 is a good candidate for further investigation.
    22  Structural Characterization of a Nano-TiO2/SiO2 Composite Film and Its Preservative Effect on Agaricus bisporus
    ZHANG Rong-fei WANG Xiang-you LIU Zhan-li
    2014, 30(9):134-141.
    [Abstract](1178) [HTML](0) [PDF 632.87 K](718)
    Abstract:
    In this study, carrageenan/konjac glucomannan films were modified by addition of nano TiO2 / SiO2 and ultrasonic dispersion. These films were characterized by Fourier transform infrared (FT-IR) spectroscopic analysis and scanning electron microscopy (SEM).Effects of the modified nano-composite film on postharvest physiology and quality of Agaricus bisporus during storage at 2 ℃ were studied. The results showed that nanoparticles in the carrageenan/konjac glucomannan/nano-TiO2 composite film, subjected to ultrasonic treatment were highly dispersed. There were a great number of hydrogen bonds between nano-sized SiO2 particles and hydroxyl groups on the surface ofcarrageenan/konjac glucomannan. After 12 d of storage, the values of whiteness, firmness of flesh, and soluble solid content (SSC) of Agaricus bisporus treated with the modified composite films were 87.75 (flesh) and 82.48 (skin),9.0×105 Pa and 6.9%, respectively, which were significantly higher than those of the control group (84.22 (flesh) and78.48 (skin), 7.6×105 Pa, and 5.3%). In addition, the modified carrageenan / konjac glucomannan /nano-SiO2 composite films delayed the increase in relative conductivity as well as weight lossin Agaricus bisporus, significantly inhibited the activity of peroxidase (POD) and delayed the peak of polyphenoloxidase (PPO) activity, thus remarkably improving the preservation of Agaricus bisporus.
    23  Effect of Glycerol on Nano SiOx-chitosan Coating Synthesized in Situ
    SUN Tong HAO Han HAO Wen-ting WU Chao-ling LI Jian-rong
    2014, 30(9):142-148.
    [Abstract](1285) [HTML](0) [PDF 725.19 K](745)
    Abstract:
    Nano SiOx-chitosan preservation coatings were prepared by an in situ method, and the effect of glycerol dosage on their gas permeability, mechanical properties, and freshness storage properties were investigated. The coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and Transmission electron microscope (TEM) analyses. Meanwhile, the gas permeability, mechanical properties, freshness storage properties to the Sciaenops ocellatus when using the preservation coating were studied. The results showed that with an increase in glycerol concentration, the gas permeability and breaking elongation of the nano SiOx-chitosan coating increased but the tensile strength decreased. Upon the addition of glycerol, the coatings became smooth and the crystal structure changed. The preservation properties of the nano SiOx-chitosan coating with glycerol were obvious. However, the results of biochemical indexes and sensoryevaluation indicated that the influence of glycerol on the preservation ability was notobvious.Compared with the 0.30% glycerol, the TBA and texture changes were delayed, and the growth of the total bacteria was reduced by the coating with 0.10% glycerol effectively.
    24  Effects of Acetic Acid on the Growth and Metabolic Activity of Acetobacter pasteurianus
    ZHENG Yu JIANG Chun-yue CHEN Xing-jing YANG Sheng WANG Min
    2014, 30(9):149-153.
    [Abstract](1540) [HTML](0) [PDF 467.43 K](955)
    Abstract:
    Acetic acid is toxic to micro organisms; however, acetic acid bacteria can tolerate high concentrations of acetic acid via a specific mechanism and, therefore, are ideal for use in acetic acid fermentation. In this study, Acetobacter pasteurianus AC2005 was used to evaluate the effect of acetic acid on bacterial growth, glucose metabolism, and intracellular ATP concentration. The results showed that addition of 1% (v/v) acetic acid resulted in an increase in biomass by 92%, glucose consumption per unit mass by 13%, cell metabolic activity by 120%, intracellular ATP concentration by 171%, and pyruvic acid concentration in metabolites by approximately 46%, whereas a decrease in concentration of citric acid and succinic acid in metabolites by 80% and 46%, respectively, as compared to fermentation without addition of acetic acid. Moreover, expression of intracellular proteins, analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) showed that proteins involved in the tricarboxylic acid cycle were up-regulated by addition of acetic acid. Thus, acetic acid bacteria could improve acetic acid tolerance by improving bacterial metabolic activity and increase intracellular ATP concentration.
    25  Effect of Moisture Content on Glass Transition Temperature and Diffusion Properties of Low-molecular-weight Sugars by Molecular Dynamics Simulation
    ZHOU Guo-hui LIU Cheng-mei WAN Jie AI Yi-min WANG Ling-hua LUO Da-wen
    2014, 30(9):154-160.
    [Abstract](1056) [HTML](0) [PDF 709.00 K](918)
    Abstract:
    In this study, the effect of different moisture contents on glass transition temperature (Tg) and diffusion properties of low-molecular-weight sugars (such as sucrose and trehalose) were evaluated, using the COMPASS force field and isothermal-isobaric (NPT) ensemble. Molecular dynamics simulation was used to obtain the glass transition temperatures of sugars by simulating a plot of the specific volume of low-molecular-weight sugar in a temperature range of 180 K to 460 K versus the corresponding temperature. At 298 K, the mean square displacement (MSD) of water molecules in the sugar systems with varying moisture content was simulated, and the effect of moisture content on the diffusion properties was analyzed. In addition, when the temperature was 298K and the moisture content was 5%, the radial distribution function (RDF) of oxygen atoms in water and in the low-molecular-weight sugar system was studied. The results indicated that the value of Tg and the ability to form hydrogen bonds with water molecules were higher for trehalose than for sucrose at the same moisture content. With increasing moisture content, the value of Tg in the two sugar models showed a significant downward trend, water molecules more easily diffused into the sugar systems, and the chance to interact with sugar molecules increased.
    26  Effect of High Solid Content on Enzymolysis by Yeasts and Antioxidant Activity of the Products
    CUI Chun WANG Hai-ping QIAN Yang-peng ZHAO Mou-ming SUN Wei-zheng
    2014, 30(9):161-165.
    [Abstract](1197) [HTML](0) [PDF 470.61 K](734)
    Abstract:
    Enzymolysis with high solid content (HSC) is one of the current hotspots in food research worldwide. In this study, active yeasts from bread containing different levels of solid content were hydrolyzed using papain. The levels of ammonia nitrogen, total nitrogen, soluble solids, reducing sugar, and total sugar, as well as osmotic pressure, antioxidant activity, and extent of browning of the enzymatic hydrolysate were measured to determine the effect of HSC on enzymolysis and the antioxidant activity of yeast enzymolysis products. The results showed that the levels of ammonia nitrogen, total nitrogen, soluble solids, reducing sugar, total sugar, and osmotic pressure increased with increasing solid content, suggesting that increasing solid content could promote the efficiency of yeast enzymolysis. Antioxidant activity measurement demonstrated that when the solid content was 30%, the enzymolysis hydrolysate had a relatively high diphenylpicrylhydrazyl (DPPH) and hydroxyl radical scavenging activity,with half maximal inhibitory concentration (IC50) of 0.83±0.09 mg/mL and 21.53±1.18 mg/mL, respectively, after 13 hours of enzymolysis; whereas the IC50 reached 1.01±0.13 mg/ml and 23.17±1.33 mg/mL, respectively, after 21 hours of enzymolysis. The addition of an appropriate amount of SDS could decrease the degree of browning of yeast.
    27  Effect of Frozen Storage After Different Washing Methods on Functional Properties of Myofibrillar Proteins in Cyprinuscarpio
    LI Yan-qing KONG Bao-hua XIA Xiu-fang CHEN Hong-sheng
    2014, 30(9):166-172.
    [Abstract](1017) [HTML](0) [PDF 814.65 K](706)
    Abstract:
    Protein oxidation is the leading cause of quality deterioration during processing and storage of food. In this study, the effects of different washing methods, followed by storage under frozen conditions, on myofibrillar proteins (MPs) of common carp (Cyprinuscarpio) meat was examined. Fish meat was stored at -25 ℃ for 0, 30, 60, 90, and 120 d after it was washed using traditional washing, washing with sodium ascorbate, and washing with propyl gallate [PG] or left unwashed, respectively. The emulsifying properties, gelation properties, and rheological properties of MPs in common carp were evaluated using texture analyzer, electron microscope, and rheometer. The results showed that protein oxidation during frozen storage significantly reduced the functional properties of MPs in common carp (P < 0.05) butthe change could be minimized by washing with PG. This indicates that addition of PG during washing could effectively inhibit the occurrence of protein oxidation, thus reducing the changes in functional properties of MPs in common carp.
    28  Effect of Freeze-processing on the Microstructure and Physicochemical Properties of Soybean Oil
    WANG Li-li LI Zai-gui
    2014, 30(9):173-178.
    [Abstract](966) [HTML](0) [PDF 667.87 K](788)
    Abstract:
    In this study, the effect of freeze-processing on the microscopic structure and physicochemical properties of soybean oil was evaluated. This study provided a reference for the application of soybean oil as raw material for functional food. Morphological changes in soybean oil particles within cotyledons of soybeans before and after freeze-processing were examined using a transmission electron microscope. Large-diameter oil body was found to be aggregated during freezing. Oil was extracted from soymilk by performing ultra-high-speed centrifugation. Oil body dispersion was visualized by light microscopy and measured by particle size distribution and SDS-PAGE. The results suggested that the smallest diameter of oil body was that of unprocessed oil (0.54 μm), most diameters of freeze-processed oil ranged from 2 to 4 μm, while the number of oil body with a diameter >4 μm increased with increasing freeze duration. Electrophoretic results showed that the amount of oleosin, with a molecular weight of 24 kDa, decreased after freeze-processing. The Zeta-potential and hydrophobicity of oil body at different pH values (pH 2~8) and NaCl concentrations (0~250 mM) were measured. The results indicated that freeze-processing could slightly decrease the isoelectric point (pI) and increase the hydrophobicity at the surface of the oil body.
    29  The Quality Assessment of Edible Oils and Fats by LF-NMR Coupled with PCA
    ZHAO Ting-ting WANG Xin LU Hai-yan LIU Bao-lin
    2014, 30(9):179-185.
    [Abstract](1400) [HTML](0) [PDF 635.59 K](783)
    Abstract:
    Principal component analysis (PCA) was used to analyze the low field nuclear magnetic resonance (LF-NMR) relaxation characteristics (T21, T22, T23, S21, S22, S23) of a variety of different oil samples. The results indicated that application of PCA to the LF-NMR data allowed a good differentiation between edible soybean oil and cottonseed oil; while palm oil and lard could not be obviously distinguished. Different kinds of fried oil samples could be properly differentiated, regardless of the frying degree. As the frying process prolonged, the distribution of the fried oil samples moved to upper right based on the principal component scores. And the fried oil samples could be obviously divided into two groups: palm oil and lard, soybean oil and cottonseed oil. In addition, it was easy to distinguish adulterated lard from edible lard according to their corresponding principal component scores. With adulteration ratio of fried lard increased, higher distinguish ability was found and experimentally verified correctly. Therefore, LF-NMR combined with PCA is feasible to analyze the variety of edible oil, the degree of fried oil, and the quality of adulterated lard.
    30  Effect of NaNO3 on Nostoc flagelliforme Growth under Intermittent Flow of CO2
    LV He-xin JIA Shi-ru SHEN Shi-gang CUI Xiang-gan YUAN Nan-nan
    2014, 30(9):186-191.
    [Abstract](1455) [HTML](0) [PDF 532.91 K](700)
    Abstract:
    In this study, the effect of different concentrations of NaNO3 on the growth, photosynthetic rate, exopolysaccharide accumulation, protein and pigment content, phosphate and nitrate consumption, cell sequestration rate, and photosynthetic efficiency of Nostoc flagelliforme, incubated with intermittent CO2 flow, was investigated. The results showed that addition ofNaNO3with intermittent flow of CO2 could significantly promote the growth of N. flagelliforme. The optimal NaNO3 concentration for biomass production was 2 g/Land the dry weight could reach up to 1.56 g/L, which was 2.29 times as much as that for the control. Maximum respiration as well as net photosynthetic rate was achieved. However, when the concentration of NaNO3 was increased to 2.5 g/L, the biomass no longer increased. Cell chlorophyll content increased with increasing NaNO3 concentration. However, in the NaNO3 group, exopolysaccharide content decreased compared with the groups without NaNO3, and polysaccharide content increased with increasing NaNO3 concentration. The protein content of N. flagelliforme cells increased with increasing NaNO3 concentration and reached maximum value at 2.0 g/L. Corresponding to the increase in biomass, the highest utilization rate of nitrite and phosphate was achieved when the concentration of NaNO3 was 2.0 g/L. With intermittent CO2 flow incubation, addition of NaHCO3 could further promote cellular growth. When two carbon sources co-existed, the growth-promoting effect of NaNO3on cells was similar to that when there was only one carbon source.
    31  Effect of Ultraviolet Irradiation on Performance of Propolis/Nano Silica Composite Film
    ZHANG Bei HAN Peng-xiang FENG Xu-qiao DUAN Xiao-ming
    2014, 30(9):192-198.
    [Abstract](1122) [HTML](0) [PDF 599.28 K](695)
    Abstract:
    The effect of ultraviolet (UV) irradiation on the quality indexes-TS (tensile strength), E (elongation), T (transmittance), S (solubility), WVP (water vapor permeability), and OP (oxygen permeability)-of propolis/nano silica composite film was investigated. The TS and S values of the film increased to a maximum and subsequently declined, while E and OP values decreased gradually and then increased; T and WVP values decreased and bottomed out gradually upon irradiation. The TS value of the film treated with UV irradiation for 12 h improved by 3.07 MPa, and a UV treatment of 16 h resulted in an increase of 5.68 in the S value as compared to that of the untreated control. Additionally, decreases of 2.88%, 4.33%, 5.26%, 2.13 g/(cm·s·Pa) and 0.5 cm3/(m2·24 h·0.1 MPa) in the E, T, S, WVP, and OP values respectively, were observed. Multiple index analysis of the test results by principal component and cluster analysis simultaneously indicated that the composite film showed good overall performance when the irradiation time was 16 h, which was in line with the results of the single factor experiment. Therefore, the optimal processing time of propolis/nanosilica composite film could be confirmed by principal component and cluster analysis.
    32  Change in Iron, Zinc, and Copper Concentrations during Vinegar Production
    XU Qing-ping MENG Jun ZHANG Yan-li
    2014, 30(9):199-204.
    [Abstract](1024) [HTML](0) [PDF 569.59 K](895)
    Abstract:
    Iron-, zinc- and copper-producing pathways and factors influencing vinegar fermentation were examined in this study. Iron, zinc, and copper content at different stages of fermentation during the production of Zhenjiang fragrant vinegar were analyzed using atomic absorption spectrometry. The results showed that these three minerals were mainly present in the soluble state in the liquid phase during various stages of fermentation and were enriched due to precipitate formation. The key factors that influenced the increase in the mineral content in vinegar fermentative substrates originated from corrosion of the fermentation equipment or pipes due to long-term exposure to acetic acid and organic acid, as well as from materials containing iron, zinc, and copper, which might be added during the fermentation process. Iron was introduced into the process mainly at the acetic acid fermentation stage and during sealing for maturation. Furthermore, iron concentration reached highest levels, of 59.69 mg/L at the leaching stage during vinegar production. In addition, alcohol fermentation was the main stage for enrichment of zinc and copper, where their concentrations in vinegar reached 18.12 mg/L and 0.60 mg/L, respectively. The fermentative substrates for vinegar had a strong ability to absorb elemental iron, zinc, and copper, thus contributing regulatory effects on the metal concentration in vinegar. The results indicate that the metal content during vinegar production could be controlled by improving the quality of equipment, optimizing filtering methods, or use of metal ion adsorbents.
    33  Effect of Vacuum Concentration on Nutritive Quality and Flavor of Green Asparagus Juice
    CHEN Xue-hong MA Li-hua SONG Hui SUN Hong ZHENG Yong-hua
    2014, 30(9):205-209.
    [Abstract](1232) [HTML](0) [PDF 496.12 K](660)
    Abstract:
    To explore the effect of vacuum concentration on the nutritive quality and flavor of green asparagus juice, fresh juice was vacuum concentrated at 50 ℃ and 0.1 MPa. Four kinds of concentrated juice were obtained with soluble solid content of 10%, 20%, 30%, and 45%, respectively. The color, vitamin C content, total sugar content, total phenolic content, and flavonoid content were determined in the concentrated and fresh juice samples. Volatile flavoring compounds in the asparagus juice samples were comparatively analyzed by headspace solid-phase micro extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results showed that vacuum concentration significantly affected the nutritive quality and flavoring compounds in green asparagus juice. As the soluble solid content increased, the color of the juice became dark-green, the vitamin C and total flavonoid contents decreased, and the total sugar and total phenolic contents increased. The main volatile compounds of green asparagus juice were found to be aldehydes, ketones, and alcohols. As the soluble solid content in the juice increased, the flavoring compound content first increased and then decreased. The quality and flavor were better preserved in the concentrated green as paragus juice with 30% soluble solid content.
    34  Extraction of Papain by Ionic Liquid/Aqueous Two-phase System and Optimization of Process Conditions
    WANG Wei-tao ZHANG Hai-de JIANG Zhi-guo XU Ying-hao DONG An-hua PENG Jian YANG Xue-fang
    2014, 30(9):210-216.
    [Abstract](1259) [HTML](0) [PDF 637.91 K](792)
    Abstract:
    Papain was extracted by a [C4mim] Br/K2HPO4 ionic liquid/aqueous two-phase system. First, the influence of reagents on the activity of papain was investigated. Second, the effects of alkyl chain length and concentration of the ionic liquid, dosage of papain, pH, and temperature on the partitioning behavior of papain were discussed concretely, and the extraction conditions were optimized using the central composite design (CCD). The results showed that ionic liquids had little impact on the activity of papain and could promote the activity at low concentrations, while the inorganic salt had a larger influence on the activity of papain. There was a negative?influence on the extraction of papain in the ionic liquid/aqueous two-phase system at high temperature. The influence of the various parameters was in the following order: concentration of K2HPO4 > concentration of [C4mim]Br>dosage of papain> pH. The optimized extraction conditions were as follows: [C4mim] Br content, 0.30 g/mL; K2HPO4 content, 0.30 g/mL; pH, 6.0; dosage of papain, 3.0 mg/mL; reaction temperature, 30.0 ℃. Under the optimum conditions, the activity recovery of the enzyme and purification factor reached 91.20% and 1.73, respectively. The result provided the experimental basis for further research and large-scale production.
    35  Degradation of Aflatoxin B1 in Soybean by Ultraviolet and γ Irradiation
    ZHANG Zhen-shan
    2014, 30(9):217-221.
    [Abstract](1234) [HTML](0) [PDF 501.95 K](693)
    Abstract:
    The aim of this research was to study the effect of ultraviolet irradiation, γ irradiation, and a combination of the two on the degradation of aflatoxin B1 (AFB1) in soybean. In this work, fresh soybean was used as the raw material, and contaminated soybeans that contained 0.1, 0.5, and 1.0 mg AFB1/kg soybean were obtained by adding AFB1 to soybean. The ultraviolet irradiation intensity had a significant influence on the degradation of AFB1 (P<0.05), whereas the moisture content and AFB1 content had no significant effects on the degradation (P>0.05). The degradation of AFB1 increased with increasing ultraviolet irradiation time up to 10 min, after which the degradation ratio remained stable. On the other hand, the degradation of AFB1 increased with increasing γ irradiation dose and moisture content, but decreased with increasing AFB1 content. The γ irradiation dose, moisture content, and AFB1 content had a significant influence on the degradation of AFB1 (P<0.05). A synergistic effect between ultraviolet irradiation and γ irradiation was also observed.
    36  Effect of Ultrahigh-pressure and Mild-temperature Processing on Quality and Sterility of Coconut Puree
    WAN Bin DUAN Zhen-hua LUO Shan-Shan LUO Wei HU Jing
    2014, 30(9):222-229.
    [Abstract](1210) [HTML](0) [PDF 665.25 K](858)
    Abstract:
    The sterilization process for coconut puree was studied using ultrahigh-pressure and mild-temperature processing. A combination mode was developed, which applied pressure intermittently to study the effect of different pressure combinations, holding time, and processing temperatures on the colony count, non-enzymatic browning degree, peroxide value, pH value, and color of coconut puree. The sterilization conditions were optimized by orthogonal experimentation. In addition, the process was compared to pasteurization; the sterilization effect and changes in sensory characteristics of the coconut puree were analyzed before and after sterilization. The results indicated that ultrahigh pressure treatment at mild temperature had a very good sterilization effect, inhibited non-enzymatic browning, and protected the color of coconut puree. The optimized sterilization process was as follows: low-pressure treatment (200 MPa at 35 ℃) for 5 min followed by high pressure(500 MPa at 35 ℃) for another 5 min. Under these conditions, the colony count was 63 cfu/g, and the sterilization rate was up to 99.9%. Compared to pasteurization, the ultrahigh-pressure processing at mild temperature preserved the original color, aroma, and flavor of coconut puree to a greater extent. This study thus provides a theoretical basis for storage and preservation of coconut puree.
    37  Effect of Pre-slaughter Transport Time on Lamb Quality
    XIA An-qi LI Xin CHEN Li CHEN Li-juan LIU Yue ZHANG De-quan
    2014, 30(9):230-235.
    [Abstract](1224) [HTML](0) [PDF 587.88 K](770)
    Abstract:
    Pre-slaughter transportation is one of the most important factors affecting meat quality of livestock and poultry. Forty six-month-old rams, the hybrid of Ujimqin sheep and small-tail Han sheep, divided into four groups that were transportedfor0 h (control group), 1, 3, and 6 h before slaughter. The effect of pre-slaughter transport time on lamb quality was analyzed by evaluating the palatability, sensory characteristics, and protein content. The results showed that the pH and shear force values of lamb at 24 h after slaughter were significantly higher than those in the control group, where both had increased by 0.54% to 2.90% and 15.60% to 24.61%, respectively (P< 0.05). Pre-slaughter transport for 3 and 6 h caused an increase in ΔE value by 6.12% and 6.50%, respectively, and significantly reduced the overall acceptability score (via sensory evaluation) by 13.51% and 20.82% (P< 0.05), respectively. Cooking loss recorded in the group transported for 6 h before slaughter was lower than that in the control group, with a 7.37% decrease(P< 0.05). The lamb in the group transported for 1 h showed a lower degree of myofibrillar protein degradation than that observed in the other groups (P< 0.05). Thus, pre-slaughter transport for 1, 3, and 6 h showed a negative effect on lamb meat quality, to varying degrees. These results suggest that pre-slaughter transport should be avoided as much as possible or other pre-slaughter treatments should be employed to allow sheep to recover from transportation stress.
    38  Effect of Propyl Gallatein Different Concentrations on Preservation of Fresh-cut Ginger Root
    DING Jun YANG Shao-lan WU Hao WANG Cheng-rong
    2014, 30(9):236-240.
    [Abstract](1217) [HTML](0) [PDF 567.28 K](809)
    Abstract:
    In this study, the effect of propyl gallate (PG) on the preservation of fresh-cut ginger roots was investigated. Fresh ginger roots of similar size without scabs or mechanical wounding were selected for the study. The ginger roots were cut into 5-mm-thick section after cleaning and peeling, then soaked in 0.10%, 0.20%, and 0.30% PG and stored at 14 ℃ (±1.0 ℃).The preservative effect of PG was evaluated by measuring weight-loss, degree of browning, soluble solid content, Vc content, malondialdehyde (MDA) content, polyphenol oxidase (PPO) activity, peroxidase (POD) activity, hardness, elasticity, and changes in degree of chewiness. The results showed that soaking in PG solution helped maintain the texture of fresh-cut ginger roots to a varying degree, reduced weight loss and MDA content, delayed the development of browning, and inhibited PPO and POD activities. Additionally, Vc content, soluble solid content, and hardness were maintained at a relatively high level, while chewiness and elasticity were maintained at a relatively low level. Among all the concentrations of PG tested, treatment with 0.20% PG provided best preservation result for fresh-cut ginger roots.
    39  Effect of Microwave Inactivation on Oatmeal Quality
    GU Jun-qiang ZHONG Kui ZHOU Su-mei TONG Li-tao LIU Li-ya ZHOU Xian-rong WANG Li
    2014, 30(9):241-245.
    [Abstract](1112) [HTML](0) [PDF 583.88 K](752)
    Abstract:
    In this study, the effect of enzyme inactivation by microwaves or steam on the quality of oatmeal was investigated, and the effect of microwave time on the nutritional quality, digestion characteristics, and pasting properties of oatmeal with complete enzyme inactivation was explored. The results showed that oatmeal treated with microwave inactivation for 40 s showed no significant differences (p>0.05) in the content of β-glucan, crude protein, and crude fat, as well as in the initial gelatinization temperature as compared with oatmeal treated with normal pressure steaming for 30 min. The content of total phenols, total starch, and rapidly digestible starch significantly increased by 43 mg/100 g, 1.66%, and 9.17%, respectively (p<0.05); peak viscosity significantly decreased by 14 cm·g (p<0.05), and the setback value significantly increased by 11.9 cm·g (p<0.05). With increasing time of microwave treatment, the content of β-glucan and total phenols as well as in vitro protein digestibility decreased; however, the contents of crude fat and rapidly digestible starch increased. The content of total phenols and rapidly digestible starch showed significant changes, and the peak viscosity, final viscosity, breakdown value, and setback value all significantly increased. Therefore, the microwave time for enzymatic inactivation had obvious effects on the quality of oatmeal.
    40  Determination of Seeded Metastable Zone Width of L-Arabinose by an Automated Temperature Logging Device
    HU Biao ZHANG Ping-jun HUANG Kai ZHANG Xin-lin YU Shu-juan
    2014, 30(9):246-252.
    [Abstract](1138) [HTML](0) [PDF 503.76 K](690)
    Abstract:
    Determination of the metastable zone width (MSZW) is of great importance in L-arabinose crystallization, yet it has not been reported before. In this study, the use of an automated temperature logging device (ATLD) to monitor the nucleation temperature (Tm) of L-arabinose in an aqueous solution was demonstrated. Direct comparison with focused beam reflectance measurements (FBRM) confirmed that the Tm determined by the ATLD was reliable. A multiple linear regression model of the Tm and a set of exploratory factors indicated that the Tm was affected by the solution concentration and stirring rate but not the cooling rate. The MSZW of L-arabinose in an aqueous solution was not constant, but ranged from 27.36 to 31.55 ℃.The addition of 2% and 4% impurities (sodium chloride, galactose, glucose, and xylose) decreased the MSZW of L-arabinose. This study offers new opportunity for the use of ATLD as simple, inexpensive, and convenient alternative tool in crystallization monitoring.
    41  Determination of Penicillin in Honey by the Nano-Ag / Horseradish Peroxidase Self Assembly Immunosensor
    DU Ping SHANG Xi-li GAO Zhi-jie YUE Wu LI Chang-hai
    2014, 30(9):253-257.
    [Abstract](938) [HTML](0) [PDF 1.16 M](710)
    Abstract:
    Aminobenzene sulfonic acid, nano-Ag particles and horseradish peroxidase (HRP) labelled penicillin antibody was successfully immobilized on the glassy carbon electrode by the layer-by-layer assembly technique. The poly aminobenzene sulfonic acid/nano-Ag /HRP amplified electrochemical immunosensor was prepared and an enhanced sensitivity electroanalysis method for the detection of penicillin was established. HRP can catalyze the reduction of H2O2 to promote the oxidation of 3,4-diaminobenzonic acid, causing the changes of the peak current, thus realizing the detection of penicillin by the current changes. The effects of buffer solution pH,reaction temperature and time were investigated. Under optimized conditions, the current response of the sensor showed a good linear relationship with the concentration of penicillin within 0.05~6.00 μg/L, with a correlation coefficient of 0.9946 and the detection limit of 1.02 μg/L. The penicillin content in the honey samples was also detected by the modified electrode, and the detection results were compared with the traditional ELISA method. It is proved that this method has good sensitivity and specificity and suitable for detection of penicillin residues in honey samples.
    42  Identifying the Age and Geographical Origin of Chinese Rice Wine by Olfactory Fingerprints
    YU Hai-yan WANG Li HE Lan-lan DAI Xin YAO Gui-yan WANG Jun-kui
    2014, 30(9):258-264.
    [Abstract](1206) [HTML](0) [PDF 610.68 K](686)
    Abstract:
    This study was performed to establish a method that can quickly and accurately identify the age and origin of Chinese rice wine. A nultra-fast gas chromatography-based electronic nose (E-nose) was used to collect olfactory fingerprints of wine samples from different age and origins. Dimension reduction of the olfactory fingerprints was performed using principal component analysis (PCA) followed by discriminant factor analysis (DFA), to establish a model for the purpose of this study. After dimension reduction by PCA, the points of one-year-old and three-year-old base wine samples fell in similar regions, as did the points of seven-year-old and nine-year-old base wine samples; the results indicated that the fifth year was a turning point in the aging process of base wine. The correct identification rate model built using DFA for rice wine was 100%. After the dimension reduction by PCA, obvious differences were observed between rice wine samples from Shaoxing and Shanghai/Jiashan/Nantong. The DFA models for the identification of geographical origin showed that the correct identification rates were 100%. The results demonstrate that the model built using an E-nose in combination with chemometric methods could be used for the identification of age and geographical origin of Chinese rice wine.
    43  Analysis of Volatile Components and Fatty Acids Derived from Eriocheir sinensis Gonad before and after Cooking
    GAO Xian-chu WANG Xi-chang GU Sai-qi TAO Ning-ping ZHUANG Jing XIE Yu-cen ZOU Lei LIU Ming-ying
    2014, 30(9):265-274.
    [Abstract](1323) [HTML](0) [PDF 771.34 K](592)
    Abstract:
    The volatile flavor compositions of Chinese mitten crab (Eriocheir sinensis) gonads were trapped by a new material (Mono Trap) and analyzed by gas chromatography-mass spectrometry (GC-MS); meanwhile, the fatty acids in raw and cooked gonads were also studied. A total of 62 volatile compounds were identified by GC-MS. Male/female gonads existed significant difference. A large number of aldehydes, furans, nitrogen-containing, sulfur-containing compounds were produced in cooking process, especially 3-methylbutanal, 2-methylbutanal, octanal, 2-pentylfuran, dimethyl disulfide, which also had high OAVs and played an important role in gonads aroma. It was inferred that these compounds were produced by the decomposition of the aromatic precursors. Unsaturated fatty acids (UFA) in raw/cooked Chinese mitten crab gonad was as high as 75%. Besides, the contents of flavor related acids (e.g.: oleic acid, linoleic acid and linolenic acid) changed remarkably, and positively correlated with the changes of volatile compounds during cooking. Therefore, lipid was the important aromatic precursor of Chinese mitten crab gonad.
    44  ELISA-based Method to Detect Microbial Transglutaminase in Frozen Surimi
    LI Yi FAN Da-ming GU Zhen-nan HUANG Jian-lian LIAN Hui-zhang ZHAO Jian-xin CHEN Wei ZHANG Hao
    2014, 30(9):275-279.
    [Abstract](1095) [HTML](0) [PDF 396.60 K](645)
    Abstract:
    In this study, a sandwich-type enzyme-linked immunosorbent assay (ELISA) was developed to detect microbial transglutaminase (MTG) in frozen surimi, using rabbit anti-MTG polyclonal antibody as the capture antibody and mouse anti-MTG monoclonal antibody as the detection antibody. Combined with anti-IgG1 secondary antibody horseradish peroxidase (HRP) conjugate, the sandwich ELISA was developed to quantitatively detect MTG in frozen surimi samples, thus providing a means to prevent adulteration of frozen surimi. The results showed that the optimum working concentration of the capture antibody was 2 μg/mL whereas that of the detection antibody was 0.1 μg/mL, and the optimum dilution of HRP-conjugated secondary antibody was 1:5,000. The visual detection limit of the assay was 20 ng/mL, and alinear relationship between OD450 values and the log values of MTG concentration was observed in the range of 0.6~10 mg/mL. A simulation model of adulteration in frozen surimi was established to determine the amount of added MTG. The recovery rate of MTG was over 94%, whereas the intra- and inter-plate coefficients of variation during the measurement were 1.12%~4.02% and 5.43%~6.87%, respectively. These results proved that this method was sensitive, required simple sample pretreatment, and was suitable for the quantitative detection of MTG added to frozen surimi.
    45  Chromatographic Characterization of Organic Acids in Prunus mume and Its Application
    LIN Yao-sheng LIU Xue-ming ZHONG Wei-xiong WANG Si-yuan YANG Chun-ying TANG Qiu-shi
    2014, 30(9):280-285.
    [Abstract](1683) [HTML](0) [PDF 535.95 K](957)
    Abstract:
    To more effectively characterize and evaluate the quality of Prunus mume and its products, high performance liquid chromatography (HPLC) was used to simultaneously detect the composition and concentration of eight organic acids (oxalic acid, tartaric acid, malic acid, lactic acid, acetic acid, citric acid, succinic acid, and ) in P.mume samples. This analysis was performed on a Zorbax SB-Aq C18 column (4.6×250 mm, 5 μm) at 25 ℃ using methanol and 0.01 mol/L KH2P04 (pH 2.65) as the mobile phase at a flow rate of 1.0 mL/min. The wavelengths of 210 and 215 nm were selected for the double-wavelength detection. The recovery of the organic acids ranged from 97.18% to 111.57% with relative standard deviations of 0.53%~4.67%, and the detection limits were in the range of 0.05~6.33 μg/mL. The results showed that, in P.mume, the dominant organic acid was citric acid, followed by malic acid, oxalic acid, and small amounts of tartaric acid, lactic acid, acetic acid, and succinic acid. These organic acids constitute the characteristic organic acid profile of P.mume. Using this HPLC method to analyze the organic acid profiles of P. mume and its products showed that, although the total organic acid content greatly varied during the production processes of different P. mume products, these products had the same characteristic organic acid profile. Therefore, the characteristic organic acid profile of P.mume could be used to evaluate the quality of P. mume products and identify any adulterated products.
    46  Study of EGCG3"Me Content in Zijuan Tea
    LV Hai-peng YANG Ting LIANG Ming-zhi WANG Li-bo ZHANG Yue LIN Zhi
    2014, 30(9):286-289.
    [Abstract](1608) [HTML](0) [PDF 425.68 K](763)
    Abstract:
    Zijuan is a unique tea variety from Yunnan Daye tea [Camelliasinensis var. assamica (Mast.) Kitamura]. The bud, leaf, and stem of the fresh Zijuan tea shoot appear purple because they are rich in anthocyanins. The functional components of Zijuan tea have attracted significant attention worldwide in the field of tea science, due to its scientific value and economic potential. The composition of 3"-methyl-epigallocatechin gallate (EGCG3"Me) in Zijuan tea was detected by HPLC and LC-MS and its processing technology were analyzed. The results showed that the content of EGCG3"Mein fresh leaves was 1.05%; meanwhile, the highest EGCG3"Mewas observed in the third leaf (1.24%) among the leaves of young shoots with a bud and five leaves. Processing methods such as steaming green tea or sun-drying green tea did not affect the EGCG3"Me content in the tea leaves. Moreover, higher epicatechin gallate and epicatechin contents and lower epigallocatechin gallate content were found in the tea catechins of Zijuan as compared to normal roasted green tea.
    47  Prevalence and ERIC−PCR Typing of Enterohemorrhagic Escherichia coli O157 in Meat and Vegetables
    LAI Ze-bing ZHANG Shu-hong ZHU Xue-mei WU Qing-ping XU Ming-fang ZHANG Ju-mei
    2014, 30(9):290-296.
    [Abstract](1053) [HTML](0) [PDF 688.21 K](819)
    Abstract:
    The aim of this study was to investigate the prevalence and genotypic diversity of enterohemorrhagic Escherichia coli O157 (EHEC O157) in meat and vegetables. Food samples were collected randomly from 18 cites in China and processed according to the GB/T 4789.36-2008method with slight modifications. The isolates were identified by duplex PCR targeting the rfbE and fliCH7 genes. The presence of four virulence genes (eae, hlyA, stx1, and stx2) in EHEC O157 was determined by single-PCR. Additionally, enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) was used for molecular typing of EHEC O157 isolates. The results showed that 18 (4.35%) of 414 samples were positive for EHEC O157, including 12 fresh meat samples and 6 frozen meat samples. None of the vegetable samples was positive. Furthermore, a total of 52 isolates were identified as EHEC O157 by serotyping, biochemical tests, and duplex-PCR, of which 29 strains were O157:H7, 3strains were O157:NM (carried fliCH7 gene, non-mobile), 2 strains were O157:NM (without fliCH7 gene, non-mobile), and 18strains were O157:hund (undetermined H type). The distribution of virulence genes indicated that 50 out of 52 EHEC O157 isolates carried at least one virulence gene,40 (76.92%) isolates possessed eae gene, 31(59.62%) isolates harbored hlyA gene, 20 (38.46%) isolates harbored stx1 gene, while 24 (46.15%) isolates harbored stx2 gene. ERIC-PCR molecular fingerprint clustering analysis showed that, when the similarity coefficient was 0.80, the strains could be divided into 12 types, and F type was the dominant gene type, indicating a high diversity of genes in these isolates.
    48  Variation in Volatile Components of Grass Carp Muscle under Different Storage Conditions
    YANG Jing WANG Jian-hui LIU Yong-le CHEN Qi YU Jian WANG Fa-xiang LI Xiang-hong
    2014, 30(9):297-303.
    [Abstract](1267) [HTML](0) [PDF 582.07 K](706)
    Abstract:
    To investigate the variationin volatile components of grass carp muscleunder different storage conditions, solid phase micro-extraction-gas chromatography-mass spectrometry(SPME-GC-MS) was performed to detect volatile components from samples stored at 0~4 ℃ and 25 ℃, at different time points. Nine types of volatile compounds were detected, including aldehydes, ketones, alcohols, acids, amines, hydrocarbons, and small amounts of other compounds. In addition, the relative content, flavor, and possible origin of the main volatile compounds were further analyzed. The results showed that carbonyl compounds and alcohols were the main volatile components in fresh grass carp muscles, those under cold storage for 9 d, and those stored at room temperature for up to 6 h. In addition, these samples showed higher content of alcohols, and heavy grassy and earthy flavors were noted. After cold storage for 9 d and room-temperature storage for 6 h, the quantities of low-thresh old substances such as acids and amines, were significantly increased. In addition to the effects of aldehydes, strong, sour, and ammonia-like odors were noted. Under room-temperature storage, the characteristic odor of spoilt fish developed more quickly. Thus, fish at room temperature spoilt more quickly than that under cold storage.
    49  Application of Dense-phase Carbon Dioxide in the Processing of Meat and Aquatic Products
    CHEN Ya-li QU Xiao-juan GUO Ming-hui LIU Shu-cheng JI Hong-wu HAO Ji-ming
    2014, 30(9):304-311.
    [Abstract](1247) [HTML](0) [PDF 551.86 K](826)
    Abstract:
    Dense-phase carbon dioxide is a novel non-thermal food processing technology, which has many advantages such as mild processing conditions, minimal damage of heat-sensitive material, effective preservation of food nutrients, flavor, and freshness. Recently, several studies have evaluated the application of dense-phase carbon dioxide in food processing, but these have mainly focused on liquid food sterilization and kinetics, enzyme inactivation and kinetics, and its effects on food quality. Studies of dense-phase carbon dioxide in solid food processing are relatively scarce because solid food systems are complex, owing to the low CO2 permeability. In this article, various studies evaluating the application of dense-phase carbon dioxide in the processing of meat and aquatic products are reviewed, and its effects on sterilization of meat and aquatic products, muscle quality (including pH, color, water-holding capacity, texture, tenderness, nutrients, flavor, etc.) are discussed. In addition, key points for future research regarding this novel processing technology are presented. This review can provide a reference to promote further research on the industrial applications of dense-phase carbon dioxide in meat and aquatic product processing.

    Editor in chief:李琳

    Inauguration:现代食品科技

    International standard number:ISSN 1673-9078

    Unified domestic issue:CN 44-1620/TS

    Domestic postal code:46-349

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