Volume 31,Issue 7,2015 Table of Contents

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  • 1  Effects of Goose Bone Collagen and Peptides on Bone Marrow Mesenchymal Stem Cell Proliferation and Differentiation into Osteoblasts
    JIANG Jin-li PAN Dao-dong SUN Yang-ying CAO Jin-xuan ZENG Xiao-qun
    2015, 31(7):1-5. DOI: 10.13982/j.mfst.1673-9078.2015.7.001
    [Abstract](977) [HTML](0) [PDF 656.14 K](1254)
    Abstract:
    The effects of collagen, collagen containing calcium, collagen peptides, and collagen peptides containing calcium extracted from goose bones on the proliferation of rat bone marrow mesenchymal stem cells (BMSCs) and their differentiation into osteoblasts (OBs) were studied, and the mechanism by which collagen and peptides influence osteoporosis was described. The effects of goose bone collagen and peptides on BMSC proliferation were determined by an MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The osteogenic differentiation capacity of BMSCs was measured by alkaline phosphatase (ALP) staining, ALP activity, Alizarin Red staining, and osteocalcin secretion. The experimental groups exhibited greater proliferation of BMSCs than the control group. The positive ALP staining rate of the experimental group on day 14 was significantly higher that of the control group (p < 0.05); ALP activity levels of the experimental group on days 7 and 14 were significantly higher than that of the control group (p < 0.05). On day 21, the number of calcified nodules of the experimental groups, detected by Alizarin Red staining, was significantly high than that of the control group (p < 0.05). The osteocalcin secretion of experimental groups was significantly higher than that of the control group. These results indicated that macromolecular collagen, macromolecular collagen containing calcium, small collagen peptides, and small collagen peptides containing calcium promote BMSC proliferation and the differentiation of BMSCs into OBs, and the small collagen peptides containing calcium displayed the strongest effect.
    2  Effect of Oil Tea Camellia Extract on BPH-1 Cells
    SHEN Jun ZHENG Xi-xi WU Xiao-qin SHEN Jian-fu
    2015, 31(7):6-11. DOI: 10.13982/j.mfst.1673-9078.2015.7.002
    [Abstract](958) [HTML](0) [PDF 843.63 K](1062)
    Abstract:
    Benign prostatic hyperplasia (BPH) is associated with high morbidity in older men and 5α-reductase plays an important role in BPH pathogenesis. To confirm the effect of 5α-reductase inhibitors (Fr5 and Fr6) purified from oil tea Camellia extract (OCE) on BPH (with finasteride as positive control), cell proliferation was measured by the thiazolyl blue tetrazolium blue (MTT) assay and apoptosis was detected by the Annexin V/PI double-staining method using the benign prostate hyperplastic epithelial cell line (BPH-1). The effects of different drug concentrations and action times on BPH-1 cells were compared. Our results showed that at 100 μg/mL, the positive control as well as active components, Fr5 and Fr6 showed cell proliferation inhibition rates of 47.20% ± 1.02%, 48.60% ± 1.56%, and 55.23% ± 0.58%, respectively. Fr6 showed stronger inhibition than the positive control at all the concentrations tested, while Fr5 showed effects similar to those of the control. The rate of cell proliferation inhibition for OCE was similar to that for 5α-reductase; thus, both methods were mutually confirming. The effect shown by the active component Fr6 also lasted longer than that by positive control. Additionally, the apoptosis rate for low-dose Fr6 (25 μg/mL) was 12.40% ± 3.78%, which was close to that for finasteride at 13.68% ± 1.02%. These results indicate a potential for OCE active components to inhibit BPH, especially Fr6, which warrants further study.
    3  Protective Effects of Tartary Buckwheat Polysaccharides on Lead-poisoned Mice
    ZHANG Ji YAN Chun-lin WANG Bo-ao ZHANG Peng HOU Yong XUE Gui-ping
    2015, 31(7):12-17. DOI: 10.13982/j.mfst.1673-9078.2015.7.003
    [Abstract](1216) [HTML](0) [PDF 705.99 K](1167)
    Abstract:
    The mechanism and protective effects of Tartary buckwheat polysaccharides (TBP) on lead-poisoned mice were investigated. The mice were injected intraperitoneally with 7 mg/kg lead acetate solution daily, for 8 days to produce the lead-poisoning model. After the model was established, various doses of TBP were administered via gastric infusion by different groups of mice every day from the 12th day on, as treatments for 20 consecutive days. Passive avoidance test and Morris water maze tests were used to test the abilities of learning and memory as well as spatial discrimination, respectively. Lead content in the plasma and tissue were determined by atomic spectrometry. The activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and the content of malondialdehyde (MDA) in tissues and plasma of the mice were determined using ultraviolet spectrophotometry. Ultrastructure of mice hippocampal neurons was observed by transmission electron microscopy. The results showed that TBP could significantly improve the learning and memory as well as spatial discrimination abilities of lead-poisoned mice and could also significantly reduce lead content in tissues and plasma. The activities of SOD and GSH-Px were significantly increased in the tissues and plasma of lead-poisoned mice, while the content of MDA was decreased. Intragastric administration of TBP for 20 consecutive days significantly improved hippocampus neuronal structure, damaged by lead poisoning. Thus, TBP could repair the damage caused by lead poisoning by enhancing antioxidase activity and scavenging free radicals.
    4  Protective Effect of Cod Skin Collagen Peptides on Acute Liver Injury in Mice
    LIU Chen-chen ZHAO Yu-qin YANG Zui-sui DING Guo-fang
    2015, 31(7):18-24. DOI: 10.13982/j.mfst.1673-9078.2015.7.004
    [Abstract](1330) [HTML](0) [PDF 1.13 M](1503)
    Abstract:
    The protective effects of cod skin collagen peptides (CSCPs) on CCl4-induced acute liver injury in mice was examined. The acute toxicology dose and the maximal CSCP dose were determined. An acute liver injury model was established by intraperitoneal injection CCl4 in mice. The activity levels of serum ALT and AST were determined and the GSH-Px, SOD activities, and MDA content in liver homogenates were measured. Liver tissue samples of the mice were stained with hematoxylin and eosin (HE) to observe the effect of CSCP on mouse liver histopathology. Using TEM, the protective effects of CSCP on acute liver injury were examined. Expression of the Bax, Bcl-2, Cleavage Caspase-3, and TNF-α proteins were measured by western blot analysis. For the maximal CSCP dose of 8.0 g/kg, no mice died, indicating that CSCP was safe. ALT and AST activity levels in the serum samples were significantly lower in the CSCP group than the control group, and the maximal decrease was greater than 60%. Additionally, SOD and GSH-Px activity levels in liver homogenates increased significantly by 23% and 29%, respectively. The MDA content in liver homogenates significantly declined and the maximal decrease was 38%. Mouse liver tissue stained with HE revealed improvements in liver histology. The liver microstructure improved substantially based on transmission electron microscope (TEM) observations. Expression levels of Bcl-2 were higher, while the expression levels of Bax, Cleavage Caspase-3, and TNF-α were lower in the CSCP group than the control group. Taken together, CSCP effectively protects against acute liver injury by CCl4 in mice.
    5  Lead-eliminating Function of Auricularia auricular in Lead-poisoned Rats
    HUANG Zi-ying LI Qi-wan WANG Ji-liang HE Li-zhong WANG Wei LI Bo
    2015, 31(7):25-31. DOI: 10.13982/j.mfst.1673-9078.2015.7.005
    [Abstract](1248) [HTML](0) [PDF 705.83 K](1184)
    Abstract:
    Elimination of lead by Auricularia auricular and its extracts was investigated using a preventive, high-lead rat model. Lead content and lead clearance rates in the blood, brain, liver, kidney, femur, urine, and feces of experimental groups treated with A. auricular and its various extracts were analyzed. The results showed that A. auricular could decrease lead content in the femur, blood, liver, kidneys and brain of lead-poisoned rats (P< 0.05), with clearance rates of 28.61%, 59.94%, 59.64%, 15.84%, and 29.41%, respectively. The A. auricular ethanol extract decreased lead content in blood (clearance rate: 63.47%) and increased lead content in urine (clearance rate: -55.45%); aqueous extract caused an increase in lead content in feces (clearance rate: -26.60%). Moreover, the extract residue showed a decrease in lead content in the femur, liver, kidneys, and brain (clearance rates: 49.82%, 74.21%, 74.76%, and 80.59%, respectively). These results indicate that A. auricular exerts good lead-eliminating effects in lead-poisoned rats, achieved by the synergistic action of its multiple components.
    6  The Effect of Phospholipase C on the Membrane Permeabilization of Escherichia coli
    LIU Rui-jie XING Xin-gan YU Zhen-zhen RUI Li-lian CHANG Ming JIN Qing-zhe WANG Xing-guo
    2015, 31(7):32-36. DOI: 10.13982/j.mfst.1673-9078.2015.7.006
    [Abstract](1102) [HTML](0) [PDF 785.64 K](1688)
    Abstract:
    The phospholipase C proteins from Clostridium perfringens(Cp-PLC)and Listeria monocytogenes (lm-PLC) were cloned and expressed in E. coli BL21 (DE3), and the effect of PLC on the permeability of E. coli BL21 membranes was investigated systematically. The recombinant PLCs expressed in C. perfringens and L. monocytogenes clearly affected the permeability of the inner membrane In contrast, the permeability of the outer bacterial membrane increased slightly. In addition, the effect of PLC enzymes incorporation on the permeabilization of E. coli BL21 membranes was tested, indicating that the addition of PLC enzymes markedly increased the permeabilization of the outer membrane. However, the permeabilization of bacterial inner membrane was not affected to the same extent. More importantly, coexpression of Cp-PLC and lm-PLC in E. coli BL21 to increase permeabilization of the host cell membrane opens a promising strategy for enhancing recombinant protein expression.
    7  Effect of Lipase Induction on Whole-cell Biocatalyst Behavior during Esculin Acylation and Structural Identification of Products
    LAI Xue-neng LI Xiao-feng ZHAO Guang-lei
    2015, 31(7):37-43. DOI: 10.13982/j.mfst.1673-9078.2015.7.007
    [Abstract](838) [HTML](0) [PDF 791.23 K](1167)
    Abstract:
    A novel method to synthesize flavonoid ester was explored. Different induction media were used to culture six strains for high-yield lipase production. The whole-cell catalyst was prepared and used to catalyze the reaction of esculin and vinyl propionate with pyridine as the reaction solvent. The results indicated that two strains, Pseudomonas aeruginosa GIM 1.46 and P. stutzeri GIM 1.273, showed the ability to catalyze the propionylation of esculin, with P. stutzeri GIM 1.273 showing the highest catalytic activity. The effect of different lipase inducers on biomass and catalytic activity of the whole cells was investigated by adding soy oil, Tween 80, or glucose into the screening culture. The results showed that P. stutzeri GIM 1.273 cultivated in a medium containing soy oil exhibited the highest activity, where conversion rates for esculin propionylation reached 47.9% after 48 h. The products were purified and structurally identified using mass spectrometry (MS) and 13C-nuclear magnetic resonance (13CNMR) spectroscopy, which showed that the whole cells catalyzed the acylation of 6’-OH in esculin, the resulting product was esculin-6’-O-propionate, where the regioselectivity reached 99%.
    8  Inhibition of α-Glucosidase Activity by 3,5-Dicaffeoylquinic Acid from Lonicera japonica Thunb Flower Buds
    YAN Huan QIU Chen ZHONG Kai HUANG Yi-Na GAO Hong
    2015, 31(7):44-49. DOI: 10.13982/j.mfst.1673-9078.2015.7.008
    [Abstract](1105) [HTML](0) [PDF 890.13 K](1362)
    Abstract:
    Inhibitory effect of 3,5-dicaffeoylquinic acid (3,5-DCQA) from flower buds of Lonicera japonica Thunb on α-glucosidase was investigated. The 3,5-DCQA was isolated from a 50%-methanol extract of L. japonica flower buds using chromatography and its structure was identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. The selectivity of 3,5-DCQA in its inhibition of ?-glucosidase was evaluated using ?-glucosidase I from rat small intestine and ?-glucosidase II from Saccharomyces cerevisiae, baker’s yeast, and Bacillus stearothermophilus. The result indicated that the degree of ?-glucosidase inhibition by 3,5-DCQA was related to the origin of the enzyme. In addition, 3,5-DCQA selectively inhibited maltose hydrolysis activity of rat intestinal ?-glucosidase I. Kinetic study revealed that 3,5-DCQA was a noncompetitive inhibitor of rat intestinal maltase with a Ki value of 0.22 mM. Furthermore, the structure-activity relationship (SAR) study suggested that the two caffeoyl groups in 3,5-DCQA play an essential role in ?-glucosidase inhibitory activity and that the number of caffeoyl groups in 3,5-DCQ are related to its activity. Therefore, 3,5-DCQA obtained from the flower buds of Lonicera japonica Thunb can be used in development and application of functional foods for the management of postprandial hyperglycemia.
    9  High-throughput Sequencing Reveals Bacterial Structure in the Mud Pits of Heavy-fragrance Baijiu
    DENG Jie HUANG Zhi-guo WEI Chun-hui LUO Hui-bo DU Li-quan GOU Yun-ling
    2015, 31(7):50-55. DOI: 10.13982/j.mfst.1673-9078.2015.7.009
    [Abstract](954) [HTML](0) [PDF 974.17 K](1270)
    Abstract:
    High-throughput sequencing was used to study the composition of the microbial community within the mud pits of differently-aged, heavy-fragrance Baijiu cellars in northern using the Roche GS Junior high-throughput sequencing platform. The results showed that the main bacterial taxa in the six mud pits tested included 79% Firmicutes, 4.9% Actinobacteria, 4.1% Bacteroidetes, 3.5% Lentisphaerae, 2.5% Synergistetes, and 6% others. With increasing age of the cellar, the Clostridiales Family XI. Incertae Sedis showed a decreasing trend, while the Actinobacteria and Synergistetes taxa showed an increasing trend. The Haloplasmataceae and Clostridiaceae taxa were detected only in the mud pits of a 30-year-old cellar, while the Syntrophomonadaceae taxon was detected in the mud pits of all 5-year-old cellars. The Lactobacillaceae and Porphyromonadaceae taxa were the dominant bacterial groups in only one 30-year-old cellar mud pit.
    10  Toxicology of Flavonoid-propionic Acid Mixtures from Banana Peel
    GU Cai-qin WEN Xiao-long ZHU Dong-xue LIU Peng LAI Ya-ping LIN Jin-ying ZENG Qin-zhu
    2015, 31(7):56-60. DOI: 10.13982/j.mfst.1673-9078.2015.7.010
    [Abstract](940) [HTML](0) [PDF 629.47 K](1112)
    Abstract:
    Crude flavonoid extract was obtained from banana peel by microwave extraction and purified using H103 macroporous resin and combined with propionic acid to produce flavonoid-propionic acid mixtures. Toxicology testing was conducted using these mixtures as per the Procedures for Toxicological Assessment of Food published by Ministry of Health of The People's Republic of China. Toxicology testing included using the acute toxicity test for minimum lethal dose for 50% mice (LD50), bone marrow cell micronucleus test, mice sperm morphology test, and Ames test. The results showed that the LD50 values for female and male mice were 10.8 and 12.6 g/kg body weight (BW), respectively; while the fiducial limits for female and male mice were 7.41~15.7 and 7.75~20.5 g/kg BW, respectively. The results from the acute toxicity test, bone marrow cell micronucleus test, and sperm morphology test were all negative, which implied that flavonoid-propionic acid mixtures from banana peel showed no mutagenic effects on somatic and germ cells and that they did not show indirect or direct mutagenicity. Therefore the mixtures are non-toxic and can be used as preservatives.
    11  Structural Characteristics and Antioxidant Activity of Polysaccharides from Mallotus oblongifolius
    ZHAO Mou-ming LIU Min LIN Lian-zhu LUO Wei WANG Zhu-nian
    2015, 31(7):61-66. DOI: 10.13982/j.mfst.1673-9078.2015.7.011
    [Abstract](1047) [HTML](0) [PDF 712.88 K](1230)
    Abstract:
    A water-soluble polysaccharide (MOWP) and an alkali-soluble polysaccharide (MOAP) were isolated from Mallotus oblongifolius. The MOWP and MOAP yields were 6.00% and 3.07%, respectively. The molecular weights of the MOWP and MOAP were determined by a high performance gel permeation chromatography assay. The molecular weights of the MOWPs were 906 kDa and 49 kDa, and the molecular weight of the MOAP was 95 kDa. The monosaccharide composition was determined by a pre-column derivatization assay. Based on the monosaccharide composition analysis, the MOWP was mainly comprised of glucose, galactose, and xylose. MOAP was mainly comprised of mannose, galactose, and xylose. The glycosidic bonds of MOWPs and MOAPs were determined by a methylation assay. The branched MOWPs and MOAPs were composed mainly of →3)-Xylf-(1→, →3)-Galp-(1→ and →3)-Glcp-(1→ in different ratios. MOWPs and MOAPs exhibited moderate antioxidant capacities. MOWPs showed better DPPH scavenging activity than did MOAPs. MOAPs showed better reducing power and oxygen radical absorbance capacity than did MOWPs.
    12  Antibacterial Mechanisms of Catfish Epidermal Mucus Extracts against Pseudomonas aeruginosa
    LI Ting-ting ZHANG Hui-fang JIANG Yang JIN Gao-wei LI Jian-rong
    2015, 31(7):67-73. DOI: 10.13982/j.mfst.1673-9078.2015.7.012
    [Abstract](1002) [HTML](0) [PDF 829.39 K](1443)
    Abstract:
    Several techniques were used to investigate the mechanism of antibacterial effect of catfish epidermal mucus extracts (CEME) against Pseudomonas aeruginosa. The results showed that the inhibitory effect was significant when the concentration exceeded 0.15% (mg/mL). The bacterial growth curve showed a decrease and scanning electron microscopy (SEM) showed changes in morphology. This indicated that the primary mechanism of CEME inhibitory action was to damage the bacterial cell membrane integrity. CEME also increased bacterial membrane permeability, which led to leakage of cellular small molecules and a proportion of macromolecules. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that CEME causes obvious changes to bacterial membrane proteins, which led to inhibition of bacterial protein synthesis and subsequent decline and loss of intracellular protein content. These results imply that CEME shows relatively good antibacterial effect on Pseudomonas aeruginosa.
    13  Molecular Identification of the Genotype of Staphylococcus aureus Biofilm
    LI Bing LIU Xiao-chen LI Lin XU Zhen-bo
    2015, 31(7):74-79. DOI: 10.13982/j.mfst.1673-9078.2015.7.013
    [Abstract](1251) [HTML](0) [PDF 657.33 K](1360)
    Abstract:
    Typical foodborne Staphylococcus aureus (SA) was selected to investigate microbiological safety. The biofilm-forming ability of 58 SA strains was quantitatively determined using crystal violet staining of biofilm. The biofilm-associated SA genes including those associated with regulation (icaA, icaD, and icaBC) and adhesion property (agr, atlE, and aap) were studied. The result demonstrated that all strains tested formed biofilms, which were strongly adhesive in three (5.2%), moderately adhesive in 23 (39.7%) and weakly adhesive in 32 (55.2%) strains. The icaA gene was amplified from 48 isolates and icaD and icaBC were amplified from 56 and 57 strains, respectively. The agr, aap, and atlE genes were amplified from the genomes of 56, 53, and 57 isolates, respectively. The results indicated that the ica operon is required for SA biofilm formation, the aap gene may act as an independent factor for promoting SA biofilm formation, while the atlE and agr genes are necessary regulatory factors for biofilm adhesion.
    14  Comparison of Microstructure and Thermal Properties of Starch from Nine Mung Bean Cultivars
    ZHANG Ling-wen JI Hong-fang BAI Shi-shi YANG Ming-duo MA Han-jun HU Peng-li
    2015, 31(7):80-85. DOI: 10.13982/j.mfst.1673-9078.2015.7.014
    [Abstract](1022) [HTML](0) [PDF 876.47 K](1303)
    Abstract:
    Starch was extracted from nine different mung bean cultivars and their morphological characteristics, crystal structure, and thermal properties were studied by scanning electron microscopy (SEM), laser particle-size analysis, differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). SEM results showed that the mung bean starch particles were kidney-shaped, elliptical, dome-shaped, and small spherical, with no significant morphological differences between different cultivars. Laser particle-size analysis indicated significant differences in the size of starch granules between different cultivars, varying from 18.46 to 26.81 μm, with an average of 20.71 μm. Starch extracted from all nine cultivars had a typical C-type X-ray diffraction pattern, but their relative crystallinity was significantly different, lying between 16.23% and 42.39%. DSC analysis demonstrated that gelation temperatures (To, Tp, and Tc) and enthalpy (?H) varied greatly, ranging from 51.02 ℃ to 63.03 ℃, 64.81 ℃ to 73.04 ℃, 70.04 ℃ to 79.44 ℃, and 1.09 to 1.97 J/g, respectively, where the differences were statistically significant (p < 0.05) among some cultivars.
    15  Effects of Pulsed Microwaves on Aspergillus parasiticus in Rice
    ZENG Shu-wei HUANG Jing-jing ZHAO Si-ming CHE Li HUAGN Qi-lin
    2015, 31(7):86-91. DOI: 10.13982/j.mfst.1673-9078.2015.7.015
    [Abstract](1067) [HTML](0) [PDF 1.08 M](1079)
    Abstract:
    The potential application of pulsed microwave radiation in the control of Aspergillus parasiticus growth in rice during storage was evaluated in terms of fungal growth and cell membrane permeability. The parameters evaluated were microwave dose, pulse width, total time, and interval time. The results showed that fungal DNA, protein, and electrolyte leakage, as well as intracellular Ca2+ fluorescence intensity, of A. parasiticus increased with an increase in microwave intensity, followed by a slight decrease. This indicated that pulsed microwaves could cause electroporation of the cell membrane, leading to increased cell membrane permeability and accelerated leakage of the cytoplasm. Moreover, threshold values of pulsed microwave irradiation on A. parasiticus under thermal and non-thermal conditions included the following: pulsed microwave dose of 5 to 7.5 W/g, pulse width of 200 ms, total processing time of 20 s, and interval time of 150 ms. Beyond these threshold values, fungal growth was significantly inhibited, according to the Gompertz equation. Additionally, the pulsed microwave radiation caused the mycelial surface of A. parasiticus to become rough, with a crimped and shrunken appearance, which further confirmed that pulsed microwaves could alter the A. parasiticus cell membrane and its permeability.
    16  Selection of Feruloyl Esterase-producing Strains and Estimation of Phenolic Acid Production
    HU Bo-han WU Hui LAI Fu-rao YIN Zhi-na LEI Zhuo-gui CHEN Cai-wei ZHOU Fu-zhen CHEN Hua-min CHEN Guo-zhi
    2015, 31(7):92-98. DOI: 10.13982/j.mfst.1673-9078.2015.7.016
    [Abstract](984) [HTML](0) [PDF 1.03 M](1263)
    Abstract:
    The agar plate screening and Oxford cup testing methods were used to select microorganisms that could produce feruloyl esterase. The isolated strains were inoculated into wheat bran for solid-phase fermentation. Spectrophotometry and High Performance Liquid Chromatorgphy (HPLC) were used to analyze the activity of feruloyl esterase as well as the quantity of total phenolic acid and ferulic acid released in the fermented wheat bran. The individual morphology, colony characteristics, and iternally transcribed spacer (TIS) sequencing analysis, and identification of the strains was performed. The results identified one screened strain with highest feruloyl esterase activity, with a peak value of 163.5 mU/g on the 4th day. In addition, this strain yielded higher amounts of total phenolic acids, with 6.6× increase in fermented wheat bran. Among the total phenolic acids, ferulic acid accounted for 0.697% and its production was enhanced by 0.22% compared to that in unfermented wheat bran. Molecular identification revealed 100% homology of this strain with Aspergillus clavatus, and it was named Yanqing. This strain has potential applications in improving ferulic acid content during wheat bran fermentation in the fields of agriculture, value-adding utilization of sideline products, and medicine.
    17  Identification of Selenoproteins Formed via Biotransformation of Selenium-enriched Streptomyces platensis and Their Oxygen Free Radical Scavenging Activities
    HUANG Feng SHAN Xue-feng ZHANG Shui-mei CAI Zhi-hui LING Qin-jie HUANG Zhi
    2015, 31(7):99-104. DOI: 10.13982/j.mfst.1673-9078.2015.7.017
    [Abstract](928) [HTML](0) [PDF 802.52 K](1122)
    Abstract:
    Selenium (Se) content and distribution of Se-containing biotransformation proteins (SeP) in Se-enriched Streptomyces platensis (SeSP) were explored. Additionally, the in vitro scavenging activity of oxygen free radicals by SeP was studied. Total proteins (TP) in S. platensis were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Se content in different molecular-weight proteins was measured using inductively-coupled plasma mass spectrometry (ICP-MS). Laser ablation (LA)-ICP-MS was used for in situ detection of Se content in purified Se phycocyanin (SePC) within the electrophoresis gel. The in vitro clearance of superoxide and hydroxyl free radicals by SeP was investigated by chemiluminescence. The results showed that Se content in SeSP-TP was 32-fold higher than that in non-enriched S. platensis (SP), reaching 805.48 μg/g, while 75.81% oftotal Se was distributed in low-molecular weight SePs (LMWSeP), with molecular weights ≤ 25 ku. LA-ICP-MS results confirmed that purified SePC subunits contained stable, covalently-bound, active Se. The maximum clearance rate of free radicals by LMWSeP was over 70%. The findings suggest that SeSP cultures could be used to produce active SeP by biotransformation. The LMWSeP components in SeSPs are a source of natural Se with high anti-oxidation activity. Further studies are required to determine the form of Se, transformation mechanism, and in vivo bioactivity.
    18  Antibiotic Resistance of Foodborne Multidrug-resistant Listeria monocytogenes
    LI Li-li SHI Lei HE Jian-hua YAN He MENG He-cheng
    2015, 31(7):105-110. DOI: 10.13982/j.mfst.1673-9078.2015.7.018
    [Abstract](779) [HTML](0) [PDF 667.27 K](1290)
    Abstract:
    The mechanism of antibiotic resistance in foodborne, multidrug-resistant (MDR) Listeria monocytogenes was investigated to develop measures to control the MDR phenomenon. Genetic factors of antibiotic-resistance were screened by polymerase chain reaction (PCR), the position and dissemination capacity of these factors were evaluated by plasmid curing and natural transformation, and the stability of drug-resistance dissemination was verified by consecutive subculture. The results showed that the MDR strain LM78 (resistant to chloramphenicol, erythromycin, streptomycin, tetracycline, trimethoprim/sulfamethoxazole) carried the cat, ermB, and tetS genes. Following plasmid curing, the minimum inhibitory concentration (MIC) was reduced to the sensitive range. Moreover, the plasmid could be transferred between species by natural transformation. Plasmid curing and transformation results suggested that these resistance genes were encoded in the plasmid. After consecutive subculture without antibiotics, these plasmids remained sufficiently stable. The MDR trait of foodborne pathogens may be transferred between bacterial species, and subsequent infection in humans via contaminated foodposes a potential threat against human health.
    19  Influence of the Agouti Gene on Production and Quality of Colored Rex Rabbit Meat
    YANG Cui-jun GE Jian LIU Ya-juan CHEN Sai-juan LIU Jin-jun YANG Guo-zhong GU Zi-lin
    2015, 31(7):111-116. DOI: 10.13982/j.mfst.1673-9078.2015.7.019
    [Abstract](994) [HTML](0) [PDF 623.63 K](1045)
    Abstract:
    Apart from regulating the coat color in mammals, the agouti gene also affects a variety of physiological processes including feeding behavior. In this study, the effects of agouti gene polymorphism and expression on production and quality of colored Rex Rabbit meat were examined. The results showed that colored Rex Rabbits exhibited three agouti gene alleles: “A” (wild type), “at” (Tan), and “a” (non-agouti), which represent castor, otter, and black coat color, respectively. With regard to meat yield, colored Rex Rabbits showed higher dressing percentage, meat percentage, and meat-bone ratio. The overall meat quality was generally excellent, with good water retention capability, high cooked-meat percentage, and good meat tenderness. Thus, Rex Rabbit farming not only focuses on the value of colored Rex Rabbit skin, but also the value of the rabbit meat. The influence of agouti gene polymorphisms on meat production and meat quality were in the following order of color: castor > black > otter. Agouti gene expression did not show a significant correlation with meat production (p >0.05), but was significantly correlated with meat quantity (p < 0.05). In summary, the agouti gene not only controls the color of Rex Rabbit fur, but also the meat quality, and may be associated with fat formation in mammals. When the agouti gene is over-expressed, it may affect other traits such as meat production.
    20  Isolation and Identification of Strains Inhibiting Toxigenic Fusarium Isolated from Intestinal Bacteria of Prawns
    YE Ri-ying WANG Ya-ling SUN Li-jun XU De-feng CAI Kun-rong XIE Yi-hong CHEN Yan-xian LIU Kun
    2015, 31(7):117-122. DOI: 10.13982/j.mfst.1673-9078.2015.7.020
    [Abstract](911) [HTML](0) [PDF 1000.21 K](1153)
    Abstract:
    In order to identify marine bacteria with the ability to inhibit the toxigenic fungus Fusarium, beneficial bacteria were isolated from prawns intestines and cultured on a solid medium in antagonism with Fusarium graminearum (FG1207), which produces the T-2 toxin. Bacteria with inhibition zones were regarded as being able to inhibit toxigenic FG1207. These were isolated and grown with FG1207 in a liquid medium. Liquid chromatography-mass spectroscopy/ mass spectroscopy (LC-MS/MS) was used to estimate the T-2 toxin present in the liquid medium. Bacterial strains found to both inhibit FG1207 growth and degrade T-2 toxin were identified using 16s rRNA sequencing and VITEK 2 biochemical identification methods. Thus, eight strains of beneficial bacteria were isolated. Of these, one strain (H5) showed a significant inhibitory effect on FG1207 growth, wherein LC-MS/MS did not detect T-2 toxin in the liquid medium containing H5 and FG1207. This result indicated that not only could this bacterial strain inhibit the growth of toxigenic Fusarium but it could also degrade T-2 toxin. The strain H5 was identified via 16s rRNA sequencing as Nepal Staphylococcus aureus, with 99.93% similarity seen, while VITEK 2 biochemical identification showed 96.86% similarity.
    21  Biological Activity of Anthocyanins and Total Flavonoids in Pigment Extraction Residue from Ipomoea batatas L.
    WU Zhi-shuang WANG Rui-xin ZHOU Jian-yu WANG Qi WU Shao-xiong PAN Hong-mei FENG Yue-mei WANG Song-mei ZHANG Xue-hui XU Fang YIN Jian-zhong
    2015, 31(7):123-129. DOI: 10.13982/j.mfst.1673-9078.2015.7.021
    [Abstract](798) [HTML](0) [PDF 757.05 K](995)
    Abstract:
    Anthocyanins and total flavonoids present in pigment extraction residue obtained from Ipomoea batatas L. were evaluated for their biological activity. Inhibitory effects on Escherichia coli and Staphylococcus aureus were studied by filter paper diffusion, antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging ratio, and growth inhibition of human breast cancer cell line was determined by MTT assay. The results showed that proliferation of E. coli, S. aureus, and human breast cancer cell line, MDA-MB-231 was significantly inhibited, while significant DPPH radical-scavenging activity was also observed. The minimal inhibitory concentration (MIC) of anthocyanins and total flavonoids for E. coli and S. aureus was 400 and 4.0 mg/mL, respectively. Additionally, the values of half-maximal inhibitory concentration (IC50) and standard control (Vc) for DPPH radicals were 42.32 and 44.65 μg/mL for anthocyanins, and 0.023 and 0.011 μg/mL for flavonoids, respectively. The IC50 for MDA-MB-231 within 24, 48, and 72 h were 202.12, 58.01, and 0.232 μg/mL for anthocyanins, and 0.42, 12.05 and 12.11 mg/mL for flavonoids, respectively. These results demonstrate potential for value-added utilization of the residue after pigment extraction of Ipomoea batatas L.
    22  Meat Image Segmentation Using Fuzzy Local Information C-Means Clustering for Generalized or Mixed Kernel Function
    WU Yi-quan CAO Peng-xiang WANG Kai ZHU Li
    2015, 31(7):130-136. DOI: 10.13982/j.mfst.1673-9078.2015.7.022
    [Abstract](1095) [HTML](0) [PDF 1.17 M](1244)
    Abstract:
    Focusing on the lack of a strong adaptive ability to noise of the meat image segmentation method that is based on the traditional kernel fuzzy C-means (KFCM) clustering, two image segmentation methods (KFLICM_UG and KFLICM_MG) were applied to meat samples; these segmentation methods used fuzzy local information C-means clustering (FLICM), which is based on generalized or hybrid kernel function. Firstly, the generalized or hybrid kernel functions were used to strike a good balance between learning and generalization abilities. Each image pixel was mapped onto a high-dimensional feature space, which leads to a larger inter-class difference between the useful features of pixels. Thus, those pixels could be clustered more easily in the high-dimensional feature space. Then, the fuzzy membership of each pixel was determined based on the combination of its local space information with grayscale information. Finally, meat image segmentation was completed via the fuzzy local information C-means clustering according to the image features in the high-dimensional feature space. Considering results of previous studies, compared with the existing FCM (Fuzzy C-Means) segmentation methods such as KFCM and FLICM segmentation methods, the proposed method (KFLICM_UG, KFLICM_MG) can achieve better segmentation results with lower segmentation error rate, stronger adaptiveness, and robustness against noise.
    23  Effect of Cold Storage and Ethylene Regulation on Sugar Metabolism and Its Key Gene Expression in Post-harvest Apple Fruit
    QI Xiu-dong WEI jian-mei
    2015, 31(7):137-145. DOI: 10.13982/j.mfst.1673-9078.2015.7.023
    [Abstract](1044) [HTML](0) [PDF 1.37 M](1239)
    Abstract:
    ‘Fuji’ and ‘Golden Delicious’ apple fruits were taken as material to study the sugar metabolism and the key enzyme gene expression during fruit softening and how they were affected by cold storage or ethylene treatment. The results indicated that the starch content and amylase (AM) activity showed the most significant changes between ‘Fuji’ and ‘Golden Delicious’ and were dramatically regulated by low temperature and ethylene. Accordingly, the expression of MdAM was significantly promoted by the treatment of 2 mL/L ethephon while inhibited by 0.5 μL/L 1-MCP treatment at the late stage of storage in ‘Fuji’ fruit or at the early stage of storage in ‘Golden Delicious’ fruit. Meanwhile the expression of MdAM was significantly inhibited under 0 ℃ storage in both cultivars. This suggest that post-harvest starch degradation involved in apple fruit softening and are significantly affected by cold storage and ethylene treatment. Among the soluble sugars, the sucrose content increased clearly and was significantly subjected to the regulation by ethylene and low temperature, and the SPS had much stronger effect on sugar metabolism in post-harvest apple fruit than those of SS and AI. The SPS activity and the expression of MdSPS were significantly promoted by ethephon treatment and inhibited by 1-MCP treatment in ‘Golden Delicious’ fruit. This phenomenon was stronger than that in ‘Fuji’ fruit during storage. Less variation was observed on the fruit sugars content and the enzyme activity under cold storage, and the expression of MdSPS was significantly inhibited. These indicated that sucrose accumulation and SPS may have more close correlation with fruit softening among the regulation of sugar metabolism.
    24  Effect of Light Quantum Field on Preservation and Internal Structure of Strawberries
    ZHAO Dong-qian ZHOU Qing-li WANG Chang-lu LI Zhen-jing CHE Yu-xiang MAN Ying-ying CHEN Di
    2015, 31(7):146-151. DOI: 10.13982/j.mfst.1673-9078.2015.7.024
    [Abstract](1032) [HTML](0) [PDF 1.11 M](1319)
    Abstract:
    Freshly harvested “Japan Hong Tian 99” strawberries were placed in light quantum field and then stored in common storage boxes at 0 ℃ and -3 ℃ for 14 days, to investigate the effects of light quantum field on the quality and structure of fruits. The results showed that weight-loss rate and decay index were reduced in the light quantum field, while the decline of titratable acid, soluble sugar, soluble solid, and Vc contents was delayed at 0 ℃ and -3 ℃. Additionally, -3 ℃ light quantum treatment resulted in better preservation than that at 0 ℃, maintaining the integrity of the fruit’s internal structure. In the absence of light quantum field, the preservation effect at 0 ℃ was better than that at -3 ℃. The results suggest that light quantum preservation could be considered as a potential alternative for preservation of strawberry fruits.
    25  Effect of Controlled-atmosphere Storage on Ascorbate-glutathione Metabolism in Kiwifruit
    HU Hua-li WANG Yu-ning LI Peng-xia
    2015, 31(7):152-159. DOI: 10.13982/j.mfst.1673-9078.2015.7.025
    [Abstract](823) [HTML](0) [PDF 1.17 M](989)
    Abstract:
    Potential mechanisms underlying the effects of controlled-atmosphere (CA) storage on the senescence of the kiwifruit cultivar Hongyang were studied. The effect of different gas compositions [CA1 (2% oxygen + 3% carbon dioxide), CA2 (2% oxygen + 6% carbon dioxide), CA3 (5% oxygen + 3% carbon dioxide), and CA4 (5% oxygen + 6% carbon dioxide), with CK (20.9% oxygen + 0.04% carbon dioxide) as control] was investigated on soluble solid (SSC), total soluble sugar, starch, titratable acid (TA), ascorbic acid (AsA), and glutathione (GSH) content; scavenging capacities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide anions; and the activities of enzymes involved in the ascorbate-glutathione cycle in postharvest kiwifruit. The results showed that treatment with CA1 inhibited the increase in SSC and total soluble sugar content, as well as alleviated the decrease in starch and TA content compared with CK and the other CA treatments. In addition, treatment with CA1, CA2, and CA3 increased AsA and GSH content in kiwifruit as compared to that with CA4 and CK. Moreover, treatment with CA1, CA2, and CA3 alleviated the decrease in superoxide anion- and DPPH-scavenging rates as well as the activities of enzymes involved in the ascorbate-glutathione cycle in kiwifruit, of which CA1 treatment showed the strongest effect. Therefore, senescence inhibition in the kiwifruit cultivar Hongyang by CA1 treatment was associated with higher AsA and GSH content.
    26  Effect of pH on the Gel Properties of Lamb Plasma Protein during Heat-induced Gelation
    NI Na WANG Zhen-yu CHEN Li-juan XU Wei-wei PAN Han GAO Yuan ZHANG De-quan
    2015, 31(7):160-166. DOI: 10.13982/j.mfst.1673-9078.2015.7.026
    [Abstract](776) [HTML](0) [PDF 838.53 K](1080)
    Abstract:
    The effect of pH on the heat-induced gel properties of lamb plasma proteins under various pH conditions was investigated by texture and rheology analysis. The pH had a significant impact on each of the properties tested. The lowest water-holding capacity and hardness were observed at pH 5.0, which resulted in a typical particulate gel with a coarse and disordered microstructureas well as large holes (based on diameter) in the network. The highest water-holding capacity and hardness of the lamb plasma proteins were both detected at pH 8.6, which resulted in a typical fine-stranded gel with a compact and ordered microstructure. The storage modulus vs temperature curve of the heat-induced gelation included two segments, stabilizing at 0 Pa and then increasing. The denaturation temperatures of the lamb plasma protein were 71.5 ℃ at pH 5.0 and 80.9 ℃ at pH 8.6. The temperature corresponded to that of the gelation point obtained from rheology analysis for the respective pH value. Based on SDS-PAGEpatterns, globins and albumin aggregates are the main structural blocks of the gels, for gels, and part of proteins with MW of 51 kU aggregated to form dimers, aggregates, finally 3-dimentional network of gels at pH 5.0. This work indicated that the performance of Lamb Plasma Protein gels can be improved via the modulation of pH values.
    27  Effect of Biological Preservatives on Quality and Changes in Biogenic Amines in Argopecten irradians during Chilled Storage
    QI Feng-sheng ZHANG Hao-jie LIU Hong-ying WANG Jie
    2015, 31(7):167-172. DOI: 10.13982/j.mfst.1673-9078.2015.7.027
    [Abstract](958) [HTML](0) [PDF 703.56 K](1060)
    Abstract:
    Argopecten irradians was stored at 4 ℃ and 0 ℃ to -1.6 ℃ after pre-treatment with biological preservatives. Possible correlation between biogenic amines and decay index was investigated in terms of sensory quality, total bacteria counts (TBC), total volatile basic nitrogen (T-VBN), K value, and content of seven biogenic amines. The results showed that with the extension of storage time, TBC, T-VBN and K values increased, but thesamples stored at low temperature and treated with preservatives showed slower rates of increase. In addition, low temperatures and biological preservatives prevented the production of seven kinds of biogenic amines. In these samples, the inhibitory effect on putrescine and cadaverine was significant (p < 0.05), while that on the remaining five kinds of biogenic amines was not significant (p > 0.05). Variations in putrescine and cadaverine were the most significant in Argopecten irradians stored under chilled conditions. Moreover, putrescine and cadaverine significantly correlated with other evaluation indicators at the 0.05 significance level. Cadaverine and putrescine were indicators of the spoilage process, and therefore, can be used as quality indicators for Argopecten irradians.
    28  Establishment of Quantitative Model to Predict the Freshness of Crucian Carp (Carassius auratus) Based on Near-infrared Spectroscopy
    LIU Huan XU Wen-jie LIU You-ming XIONG Shan-bai
    2015, 31(7):173-182. DOI: 10.13982/j.mfst.1673-9078.2015.7.028
    [Abstract](945) [HTML](0) [PDF 906.12 K](1108)
    Abstract:
    To rapidly determine the freshness of crucian carp (Carassius auratus), near-infrared (NIR) diffuse reflectance spectroscopy- based quantitative analysis coupled with chemometric methods was used to collect spectral data in the range of 1000~1799 nm for 144 carp samples. Freshness quality indexes including pH, total volatile basic nitrogen (TVB-N) content, the thiobarbituric acid (TBA) value, and the K value were measured for all samples. After the optimum spectral pretreatment method and suitable spectra bands were determined, quantitative prediction models for crucian carp freshness were established using partial least squares (PLS) regression, principal component analysis (PCA) combined with back propagation artificial neural network (BP-ANN), and PLS combined with BP-ANN. The ranges of the four indicator values for crucian carp samples were wide and met the assumptionss for modeling. When pH was used as the freshness indicator, the prediction model developed using PLS combined with BP-ANN was the best, and the correlation coefficient was 0.9945. When the TVB-N content, TBA value, and K value were used as freshness indicators, PLS prediction models were the best, and the corresponding correlation coefficients were 0.9857, 0.9985, and 0.9952, respectively. The established quantitative models for the four freshness indicators all had strong prediction capabilities.
    29  Effect of Pre-slaughter Water Deprivation Time on Quality and Energy Metabolism of Duck Meat
    LU Yao-bin WU Wen-jin LI Xin XIONG Guang-quan WANG Hai-bin QIAO Yu WANG Jun LIAO Li WANG Lan
    2015, 31(7):183-190. DOI: 10.13982/j.mfst.1673-9078.2015.7.029
    [Abstract](871) [HTML](0) [PDF 756.66 K](973)
    Abstract:
    To determine the effect of pre-slaughter water deprivation for different periods (0, 1, 3, and 5 h) on meat quality and energy metabolism, the initial pH (pHi), final pH (pHu), color, cooking loss, pressurized water-holding capacity, and shear force values were determined in this study. In addition, the muscle glycogen, lactic acid, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), inosine monophosphate (IMP), hexokinase, pyruvate kinase, creatine kinase, and lactate dehydrogenase levels of 38-day-old ducks were analyzed. Possible correlations between results were analyzed. The results revealed a negative correlation between pyruvate kinase activity and ATP content in the duck meat. The hexokinase activity showed a pronounced positive correlation with muscle glycogen content. The 5-h water deprivation group showed the highest muscle glycogen content, lowest IMP content, while ATP content remained at a high level. The pHi of the 5-h water deprivation group was significantly lower than that of the 3-h water deprivation group, which may result in deterioration of meat quality. It was concluded from the results that depriving the ducks of water for no more than 5 h before slaughter helped preserve the meat quality and energy metabolism parameters at a good level and minimized stress in the birds.
    30  Effect of Mildew and γ-Irradiation on the Physicochemical Property and Structure of Soybean Proteins
    ZHANG Zhen-shan LI Chen-yang LIU Yu-lan
    2015, 31(7):191-196. DOI: 10.13982/j.mfst.1673-9078.2015.7.030
    [Abstract](1056) [HTML](0) [PDF 1.05 M](1320)
    Abstract:
    Soybeans with different levels of mildew were prepared from fresh soybeans and then irradiated using cobalt-6060Co-γ rays. The effects of mildew and γ-irradiation on the in vitro digestibility, composition, and protein structure were investigated in terms of in vitro pepsin digestibility, amino acid composition, and results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as well as Fourier transform infrared spectroscopy (FT-IR). The results indicated that mildew on soybeans reduced pepsin digestibility and total amino acid content by 23.74% and 2.07%, respectively, after 30 d culture. Moreover, the amount of β-turns and random coils increased by 2.67% and 4.14%, respectively, while the amount of α-helices and β-sheets decreased by 3.62% and 3.21%, respectively, in the secondary structure of soybean proteins. In fresh soybeans, γ irradiation had no significant effect (p > 0.05) on the amino acid composition, pepsin digestibility, and protein subunit composition within the dose range studied (10 to 30 kGy). However, a significant effect (p < 0.05) was observed on α-helices and β-sheets in the secondary structure of soybean proteins. On the other hand, in moldy soybean, γ irradiation resulted in a decrease in total amino acid content, a decrease in the amount of α-helices and β-sheets, as well as an increase in the amount of random coils in the secondary structure of soybean proteins.
    31  Effect of Pulsed Electric Field on the Preparation and Properties of Cassava Starch Acetate
    ZENG Xin-an CHEN Ru-jiao PAN Yong-kang HAN Zhong
    2015, 31(7):197-204. DOI: 10.13982/j.mfst.1673-9078.2015.7.031
    [Abstract](887) [HTML](0) [PDF 1.11 M](1182)
    Abstract:
    Starch acetate was prepared from cassava starch with acetic anhydride as the esterifying agent by the wet process assisted by pulsed electric field (FET) treatment. The effect of PEF) parameters on the formation of cassava starch acetate was evaluated using different strengths (0, 2, 3, 4, 5, 6, and 7 kV/cm), and treatment durations (0, 3, 6, 9, 12, and 15 ms).The effect of the concentration of acetic anhydride added (4%, 6%, 8%, 10%, and 12%) was also explored. In addition, the properties of cassava starch acetate such as paste transparency, solubility, swelling power, freeze-thaw stability, and viscosity were evaluated. Acetyl content and degree of substitution measurements showed that both were increased after PEF treatment. The degree of substitution increased from 0.084 to 0.110 under the following conditions: 6% added acetic anhydride, 4 kV/cm PEF, and 12 ms of reaction duration, indicating that PEF could facilitate esterification. Infrared spectroscopy was used for structural characterization of cassava starch acetate, which showed that the acetyl group was introduced into the cassava starch molecules and improved paste transparency, solubility, swelling power, and peak viscosity, with no effect on freeze-thaw stability.
    32  Effect of Various Extraction Methods on the Antioxidant Activity of Superoxide Dismutase from Rhodobacter sphaeroides
    LI Zu-ming AN Jun HUI Bo-di GAO Li-ping BAI Zhi-hui YANG Wei-dong WANG dong
    2015, 31(7):205-210. DOI: 10.13982/j.mfst.1673-9078.2015.7.032
    [Abstract](888) [HTML](0) [PDF 673.15 K](1070)
    Abstract:
    Superoxide dismutase (SOD) activity levels were determined for the samples extracted from the biomass of Rhodobacter sphaeroides by grinding, ultrasonic extraction, enzyme assisted ultrasonicextraction, and nanomilling. The in vitro antioxidant activity of SODs extracted by the four methods from R. sphaeroides 3757 wet biomass were evaluated via evaluating their reducing power and scavenging capacity against ABTS+?, ?OH, and O2-?. The in vitro antioxidant activity of SODs extracted by ultrasonic approach and nanomilling from R. sphaeroides 3757 dry biomass were compared based on scavenging capacity against ?OH and O2-?. SODs extracted from wet and dry biomass of R. sphaeroides 3757 by nanomilling exhibited activities of 36.90 ± 1.25 U/g and 214.20 ± 7.72 U/g, respectively, which were higher than those of any other extraction method. The SOD antioxidant activity observed for nanomilling from wet biomass of R. sphaeroides 3757 was higher than that of grinding, ultrasonic extraction, and enzyme assisted ultrasonic extraction . For nanomilling, the reducing power was 11.3 ± 0.35 and the scavenging capacities against ABTS+?, ?OH, and O2-? were 92.1 ±3.32%, 76.90 ± 2.67%, and 36.90 ± 1.22%, respectively, when the solid/liquid ratio was 1:15. The antioxidant activity of SOD extracted by nanomilling from dry biomass of R. sphaeroides 3757 was higher than the counterpart extracted by the ultrasonic method. For nanomilling, when solid/liquid ratio was 1:20, the scavenging capacities against ?OH and O2-? were 57.10 ± 1.96% and 79.40 ± 2.71, respectively. The SODs extracted by different methods from both wet and dry biomass of R. sphaeroides 3757 exhibited significant antioxidant activity in vitro in a concentration-dependent manner. These results showed that SODs from R. sphaeroides 3757 exhibit potent in vitro antioxidant activity, and that nanomilling is the optimal extraction method.
    33  Effect of Different Substitution Ratios of Inulin for Maize Distarch Phosphate on Sensory and Textural Properties of Sausages
    LUO Deng-lin WU Yan-hui XU Bao-cheng
    2015, 31(7):211-217. DOI: 10.13982/j.mfst.1673-9078.2015.7.033
    [Abstract](1187) [HTML](0) [PDF 826.01 K](1153)
    Abstract:
    Different substitution ratios of short-chain inulin (0%: control, 10%, 30%, 50%, 70%, 100%) for maize distarch phosphate were used during the preparation of sausages and their effect on chicken and pork sausage quality was investigated. Textural properties and color parameters of sausages were determined by texture and chromatic aberration analyzers. Cooking loss and sensory evaluation were measured as well. The springiness of the sausages in the experimental and control groups (p > 0.05) was similar. Inulin-containing sausages showed an overall improvement in mouthfeel due to the significant decrease in hardness and chewiness (p < 0.05) as well as decreased redness (a*) and yellowness (b*). Except for the substitution ratio of 70%, the lightness of the experimental and control groups were similar (p > 0.05). Cooking loss in the experimental groups was lower than that in the control group, suggesting that the yield of inulin-containing sausages was higher. In summary, sausages scored the highest and showed obvious improvement in quality with 70% substitution ratio of short-chain inulin for maize distarch phosphate.
    34  Microwave Drying of Apples Based on Stage-changed High-temperature Treatment
    LI Jing SONG Fei-hu PU Hong-jie LI Zhen-feng
    2015, 31(7):218-224. DOI: 10.13982/j.mfst.1673-9078.2015.7.034
    [Abstract](1115) [HTML](0) [PDF 1008.09 K](1181)
    Abstract:
    Microwave drying can shorten the drying time and improve the product quality of dehydrated apples. The drying characteristics of apple were investigated using six fixed-temperature and three stage-changed temperature microwave-drying strategies. The results showed that the drying rate with the fixed-temperature strategy slowly decreased in the middle stage, leading to reduction in the quality of dehydrated apple. The controlled drying-rate strategy showed a constant drying rate in the middle stage, but a defective initial stage. The drying rate for the linear-temperature strategy was nearly constant; drying time and energy consumption were acceptable, while sensory and color quality improved. To simplify the linear-temperature strategy, a three-step temperature strategy was used. The quality of the products decreased slightly, but the equipment used was greatly simplified so as to be more conducive for industrial applications. These results indicate a potential application of microwave drying techniques for apple processing.
    35  Effect of Combined Microwave-ultrasound Treatment on the Properties of Soy Protein Isolate-chitosan Composite Films
    CHEN Shan-shan WANG Ya-jing TAO Hong-jiang SUI Si-yao MA Zhong-su
    2015, 31(7):225-229. DOI: 10.13982/j.mfst.1673-9078.2015.7.035
    [Abstract](1108) [HTML](0) [PDF 612.57 K](1067)
    Abstract:
    Soy protein isolate-chitosan mixtures were treated with a combination of micro and ultrasonic waves. This resultant dispersions were then used to prepare composite films using a casting-evaporation method. The effect of different microwave powder on tensile strength, elongation at break, water vapor permeability, gas permeability, and light transmittance of composite films was investigated. In addition, infrared (IR) spectroscopy and scanning electron microscopy (SEM) were also performed. The results indicated that with 500-W microwaves, the tensile strength of the composite films reached a maximum of 21.98 ± 0.54 MPa and the elongation at break reached a minimum of 13.48 ± 0.01%. In contrast, the lowest water vapor permeability [0.61 ± 0.05 × 10-12 g/(cm?s?Pa) ] and minimum oxygen permeability [1.95±0.02×10-5 cm3/(m2?d?Pa)] was obtained with 400-W microwaves. Additionally, with 300-W microwaves, carbon dioxide permeability reached a minimum value [1.58±0.12×10-5 cm3/(m2?d?Pa)]. IR analysis indicated that mechanical and barrier properties of the composite film were improved, probably resulting from hydrogen bonding or covalent bond formation between soy protein isolate and chitosan. These results indicate potential applications for soy protein isolate-chitosan composite films.
    36  Growth Kinetics of Staphylococcus aureus Biofilm
    YU Ming CHEN Hai-qiang ZHANG Quan-kai QIAN Yang-peng YANG Gong-ming
    2015, 31(7):230-235. DOI: 10.13982/j.mfst.1673-9078.2015.7.036
    [Abstract](1185) [HTML](0) [PDF 881.32 K](1226)
    Abstract:
    The optimized Liu kinetic equation was used to fit the adhesion process of Staphylococcus aureus biofilm. The results showed that culture temperature and pH as well as inoculum concentration influenced the adhesion process. The adhesion equilibrium of S. aureus biofilm was reached at approximately 60 min. Maximum microbial attachment was achieved at 35 ℃ and pH 7. Additionally, higher inoculum concentration led to increased microbial attachment. The Gompertz model was used to fit the growth and maturation process of the biofilm. The S. aureus biofilm growth curve showed a typical S type, with apparent lag, logarithmic, and stationary phases. This was different from the growth curve of suspended bacteria, which has a relatively short logarithmic phase. The adjusted coefficient of determination R2 (Adj) for the S. aureus biofilm models for adhesion, growth, and maturity were > 0.97, indicating that the Liu kinetic equation and the Gompertz model were suitable to describe the relationship between the external environment and S. aureus biofilm attachment as well as between growth and maturity, respectively.
    37  The Correlation between Changes in Lipid Composition and Enzymatic Activity in Eggs during High-temperature Storage
    WANG Qing-ling JIN Guo-feng SHI Mu-xia SHAN Ning MA Mei-hu
    2015, 31(7):236-240. DOI: 10.13982/j.mfst.1673-9078.2015.7.037
    [Abstract](826) [HTML](0) [PDF 640.06 K](1267)
    Abstract:
    Changes in lipid composition, lipase activity, and oxidation during egg storage at 37 ℃ were investigated, and the relationship between lipase activity and lipid oxidation was analyzed by a correlation analysis. The rate of egg weight loss, yolk pH, and moisture content of the yolk increased significantly, while the yolk index and Haugh unit (HU) decreased significantly during storage (p < 0.05). After a 15-day storage period at 37 ℃, the total lipid content decreased owing to moisture migration (from 28.93 g/100 g egg yolk to 24.20 g/100 g egg yolk), the phospholipid content decreased significantly (from 45.55 g/100 g lipid to 34.37 g/100 g lipid), and the free fatty acid content increased significantly (from 1.24 g/100 g lipid to 3.67 g/100 g lipid. By the end of the storage period, the neutral lipase, acid lipase, and phospholipase activity levels decreased by 76.50%, 56.78%, and 56.81%, respectively. The content of the phospholipid components phosphatidylcholine (PC), phosphatidyl ethanolamine (PE), and phosphatidylinositol (PI) all decreased during storage, whereas the peroxide value (POV) and amount of thiobarbituric acid reactive substances (TBARS) increased significantly. A correlation analysis showed that the changes in lipid composition were significantly correlated with changes in enzyme activity. These results reveal that apparent lipolysis and lipid oxidation occur during egg storage, and these changes are caused in part by enzymatic oxidation.
    38  Effect of Electron Beam Irradiation Dose on the Quality of Vacuum-packaged Chilled Fresh Beef
    WANG Ning WANG Xiao-tuo WANG Zhi-dong DING Wu
    2015, 31(7):241-247. DOI: 10.13982/j.mfst.1673-9078.2015.7.038
    [Abstract](852) [HTML](0) [PDF 972.64 K](1226)
    Abstract:
    The effect of the dose rate of electron beam irradiation on the quality of vacuum-packaged chilled fresh beef was studied, providing a theoretical basis for the application of electron beam irradiation to the preservation of chilled fresh meat. Vacuum-packaged chilled fresh beef was treated with a 2-kGy irradiation dose at a dose rate of 0, 700, 1500, 2500, or 3500 Gy/s and stored in a refrigerator at 2°C for 15 days. During the storage period, physicochemical indicators (i.e., total volatile basic nitrogen (TVB- N) content, peroxide value (POV), thiobarbituric acid-reactive substances (TBARS), sulfhydryl (SH) groups, disulfide bonds (SS), lightness L*, and redness a*) and a microbiological indicator (total bacterial count (TBC)) of quality were estimated, and the impacts of various dose rates on the effect of irradiation were compared. For a dose of 2 kGy, increasing the dose rate resulted in significantly reduced values of TBC, TVB-N, TBARS, POV, SS, and L*, but increased values of SH and a* (p < 0.05). After 15 days of storage, the treatment group (irradiated with a dose of 2 kGy and a dose rate of 2500 Gy/s) exhibited TBC, TVB-N, POV, TBARS, SH, SS, L*, and a* values of 5.161 colony-forming units (CFU)/g, 16.6 mg/100 g, 1.126 meq/kg, 0.218 mg/100 g, 0.395 mmol/g pro, 0.379 mmol/g pro, 40.34, and 19.57, respectively, representing the optimal irradiation effects.
    39  Maillard Reaction of Soybean Protein Isolate with Ribose during Dry Heating
    XU Zhen-zhen HUANG Guo-qing XIAO Jun-xia
    2015, 31(7):248-252. DOI: 10.13982/j.mfst.1673-9078.2015.7.039
    [Abstract](874) [HTML](0) [PDF 833.31 K](1107)
    Abstract:
    The Maillard reaction has been reported to be capable of improving the functional properties of soybean protein isolate (SPI). This work attempted to explore the possibility of the Maillard reaction between SPI and ribose under the dry heating circumstance, and the effects of temperature, SPI/ribose mixing ratio, relative humidity, and reaction duration were investigated in terms of absorbance at 290 nm and L values. In addition, thermal behavior and rheological properties of the resultant products of the Maillard reaction were characterized as well. The results indicated that the reaction occurred readily using dry heat and the optimum conditions were: temperature 80 ℃, SPI to ribose ratio 1:1 (m/m), relative humidity 26.10% and reaction duration 6 h. Differential scanning calorimetry (DSC) analyses confirmed that labile intermediates were produced during the reaction. Furthermore, rheological measurements indicated that the reaction endowed the products with enhanced elastic properties and increased viscosity, implying the formation of high-molecular weight products. Compared with the widely used wet heating method, the dry heating method was simpler and more feasible, thus showing great potential for modification of SPI.
    40  Physicochemical Properties of Stored Plain Caramel Color
    ZHOU Yan-bin GUO Feng LUO Jian-yong LIAN Xiao-dong CHENG Shi-jie YE Xiao-lei
    2015, 31(7):253-257. DOI: 10.13982/j.mfst.1673-9078.2015.7.040
    [Abstract](1082) [HTML](0) [PDF 806.54 K](1236)
    Abstract:
    Caramel color is an important component of edible coloring. Plain caramel color has a good safety profile and therefore, has currently received a lot of research interests. The effects of thermo holding time, concentration, and heat treatment on the physicochemical properties of plain caramel color were studied. The results showed that pH of plain caramel color decreased with increasing thermo holding time, which then approached an equillibrium. The color index of plain caramel color increased first and then decreased as thermo holding time increased, and then became stable after 120 min. Both, red and yellow indices of plain caramel color decreased at first and then increased as thermo holding time increased, and stabilized after 120 min. Increase in thermo holding time caused more changes in the color, namely, red and yellow indices before and after heat treatment; however, the changes were similar after 90 min. Thermo holding procedure following the plain caramel color prepareation promoted further reactions of substances , improving stability and quality indices of plain caramel color. Concentration also affected the stability of plain caramel color, where higher concentration inhibited the transfer of substances within the caramel color, leading to higher stability.
    41  Effect of Staphylococcus and Micrococcus on Residual Nitrite and Color of Cantonese Sausages
    ZHANG Da-lei WU Lan-fang CHEN Wei-wei FAN Meng-meng JIANG Ai-min
    2015, 31(7):258-264. DOI: 10.13982/j.mfst.1673-9078.2015.7.041
    [Abstract](846) [HTML](0) [PDF 965.83 K](1137)
    Abstract:
    Two beneficial bacterial strains (Staphylococcus H33B and Micrococcus X142B) were isolated from Cantonese sausage and inoculated into fresh sausages to investigate the effects of the starter culture on residual nitrite and meat color, as well as nitrosomyoglobin and metmyoglobin content. Ultraviolet (UV)-visible (Vis) spectroscopy was then used to determine if the starter culture could convert metmyoglobin into nitrosylmyoglobin (NO-Mb). The results indicated that inoculation with single or multiple-strain starter culture increased the amount of NO-Mb in Cantonese sausages. Lower residual nitrite and metmyoglobin content was also observed as compared to that for the control and the optimal effect was observed when the Staphylococcus:Micrococcus ratio was 2:1. UV-Vis spectroscopy showed that Staphylococcus reduced metmyoglobin to NO-Mb, indicated by an absorption spectrum characteristic of NO-Mb, while the nitrite content was also at a minimum. Thus, Staphylococcus H33B caused greater reduction of myoglobin, which subsequently reacted with nitrite to produce more nitric oxide, further reducing nitrite concentration and improving the color of the Cantonese sausages.
    42  Effects of Hot Air and Far-infrared Drying Temperatures on Quality of Bitter Gourd (Momordica charantia L.) Powder
    ZHU Xiang-yan ZHANG Jun HE Yi-yan DENG Fang-ming
    2015, 31(7):265-269. DOI: 10.13982/j.mfst.1673-9078.2015.7.042
    [Abstract](1086) [HTML](0) [PDF 822.97 K](1395)
    Abstract:
    Fresh bitter gourds were powdered using hot air and far-infrared (FIF) drying methods at different temperatures (40 ℃, 50 ℃, 60 ℃, 70 ℃, and 80 ℃). Quality indicators such as drying characteristics, color parameters, content and retention rate of Vc, and momordicoside content, were compared. The results showed that all indicators exhibited regular changes with variations in temperature. As temperature increased, the moisture content decreased faster and drying time was shortened. Compared with fresh bitter gourd, values L (lightness) and b (+ yellow, - blue) of the color parameters of the powder reduced, while value a (+ red, - green) increased as the temperature increased. Vc content and retention rate increased at first and then decreased with increasing temperature, reaching a peak at 60 ℃. Additionally, momordicoside content decreased as temperature increased. Hot air drying was found to be more effective as compared to FIF drying at the same temperature. In summary, when hot air drying at 60 ℃ was used, drying time was shorter, energy loss was low, and the bitter gourd showed satisfactory color. Additionally, the retention rate of Vc reached as high as 69.31% with a content of 63.42 mg/100 g and 1.74% momordicoside.
    43  Effects of Rehydration Conditions on Quality of Dehydrated Toona sinensis
    ZHANG Bei-bei MA Zheng-qiang ZHANG Jing MIAO Xiu-gang YU Xiang ZHANG Jing-fang
    2015, 31(7):270-276. DOI: 10.13982/j.mfst.1673-9078.2015.7.043
    [Abstract](928) [HTML](0) [PDF 966.39 K](1152)
    Abstract:
    Effects of rehydration conditions on the quality of dehydrated Toona sinensis were studied by analyzing the aromatic components, color, rehydration ratio, as well as nitrite and vitamin C content. Results showed that 40 ℃ rehydration temperature was favorable for retention of the characteristics of dehydrated T. sinensis as well as its major aromatic components (terpenes and sulfur-containing compounds). When rehydration time was prolonged the L* of dehydrated T. sinensis was reduced, whereas rehydration temperature had no significant effect on the L*. The value of a* decreased at the beginning of rehydration and subsequently increased, wherein a* decreased to a minimum at 30 min, that is, the greenness was at a maximum, while b* was relatively low. a* and b* were observed to be the lowest at a rehydration temperature of 40 ℃. Dehydrated T. sinensis, rehydrated at 40 ℃ with solid:liquid ratio of 1:60 and 30 to 40 min soaking time, showed a higher rehydration ratio and nitrite dissolution rate. Vitamin C retention rate decreased significantly at the beginning of rehydration and levelled off after 20 min. Reducing rehydration temperature and shortening rehydration time moderately were beneficial for protecting the color, aroma and nutrients of rehydrated T. sinensis, while also ensuring its safety. These results provide scientific and reasonable potential for utilization of T. sinensis, which is a unique resource in China.
    44  Impact of Harvest Maturity on Storage Quality of Apricot Fruits
    YANG Ting-ting ZHU Xuan XIANG Yu-jie SHU Zhen
    2015, 31(7):277-282. DOI: 10.13982/j.mfst.1673-9078.2015.7.044
    [Abstract](3689) [HTML](0) [PDF 855.70 K](1153)
    Abstract:
    Harvested Xinjiang "Saimaiti" apricot fruits were classified according to the yellowing rate, into three different stages of maturity: I (colored area < 50%), II (colored area 50% to 80%) and III (colored area > 80%). These were stored at 4 ℃ with 90% to 95% relative humidity (RH). The effect of harvest maturity on storage quality of the fruits was studied in terms of fruit firmness, soluble solid content, titratable acidity, chlorophyll, Vc content, and the commodity rate every 7 days. The results showed that the values of firmness, titratable acidity, and chlorophyll content of the apricots at maturity stage I were higher than those at maturity stages II and III during early phase of storage. After 35 d of storage, the titratable acid content at maturity stage I was still higher than that at the other two stages, while the firmness, soluble solid content, and Vc content at maturity stage II were higher than those at maturity stages I and III. In contrast, there was no significant difference in chlorophyll content among the three maturity stages. The commodity rates at maturity stages I, II, and III were 31.25%, 72.44%, and 16.08%, respectively, within their shelf life. Therefore, maturity stage II was most appropriate, implying maintenance of good quality during storage and shelf life for apricots harvested at this maturity stage.
    45  Genetic Diversity and Pathogenicity of Vibrio parahaemolyticus Strains Isolated from the Pearl River Delta District
    WU Kui WU Qing-ping ZHANG Ju-mei GUO Wei-peng
    2015, 31(7):283-292. DOI: 10.13982/j.mfst.1673-9078.2015.7.045
    [Abstract](717) [HTML](0) [PDF 957.29 K](1170)
    Abstract:
    Vibrio parahaemolyticus is a common food-borne pathogen. The work attempted to evaluate the genetic diversity of V. parahaemolyticus strains isolated from food and clinical samples in the Pearl River Delta (PRD) district. In total, fifty four V. parahaemolyticus strains were included in the study. Biochemical reaction tests were performed with the API20E system and antibiotic susceptibility was examined for eight common antibiotics: nalidixic acid (NAL), streptomycin (STR), cephalothin (CEP), ampicillin (AMP), ciprofloxacin (CIP), tetracyclin (TCY), chloramphenicol (CHL), and aztreonam (ATM). O-serotypes and prevalence of tdh and trh were determined using PCR methods. Enterobacterial repetitive intergenic consensus (ERIC)-PCR assays were performed for molecular typing. The 54 V. parahaemolyticus strains were grouped into six biochemical clusters, and Biochem-A was the dominant cluster. None of the strains was resistant to NAL, CIP, or CHL, while 48 strains (88%) were resistant to AMP. Nine O-serotypes (O1, O2, O3, O4, O5, O6, O8, O10, and O11) were detected; O2 was the main serotype and O3 was the main clinical serotype. Forty-seven genotypes were found by ERIC-PCR molecular typing and 12 clusters with a similarity of 0.80 were established, but none was dominant. Twelve strains (22%), including ten clinical isolates and two isolates derived from food sources, were tdh-positive. Only two strains (4%) from food samples were trh-positive. Dramatic genetic diversity of V. parahaemolyticus strains from the PRD district was confirmed in this study.
    46  Detection of Volatile Flavor Compounds in Pumpkin Species using Solid-phase Microextraction-gas Chromatography-mass Spectrometry and Electronic Nose
    ZHOU Chun-li LIU Wei CHEN Dong ZHAO Jing ZHANG Ming ZHANG Xiao-yang LI Quan-hong
    2015, 31(7):293-301. DOI: 10.13982/j.mfst.1673-9078.2015.7.046
    [Abstract](983) [HTML](0) [PDF 855.03 K](1681)
    Abstract:
    Volatile flavor compounds in the pulp obtained from different species of pumpkin were extracted and characterized using electronic nose (E-nose), solid-phase micro-extraction (SPME) combined with gas chromatography (GC)-mass spectrometry (MS), and gas chromatography olfactometry (GC-O). The relative content of these volatile compounds was determined by area normalization. A total of 44, 51, and 25 volatile compounds were detected from Cucurbita moschata, C. maxima, and C. pepo respectively. The characteristic flavor compounds present in high quantities in the fruit pulp included: ethyl acetate, ethanol, β-ionone, borneol, 1-(1,5-dimethyl-4-hexene)-4-methyl-benzene, and α-cedrene in C. moschata; hexanal, nonyl aldehyde, 3-methyl-butyl aldehyde, 3-hexylene glycol, butyl aldehyde, and 1–hexanol in C. maxima; and ethyl acetate, ethanol, hexane, 2-heptyl ketone, 3-methyl-n-butyl alcohol, and benzene in C. pepo. Significant differences in quantities of volatile flavor compounds were found between the three pumpkin species using E-nose, which confirmed that this technology could effectively distinguish between the species tested. Similar results were found using E-nose and SPME- GC-MS methods. This study provides a basis for applications in identification and quality control of different pumpkin varieties.
    47  Principal Component Analysis and Cluster Analysis of the Elements in Sugar Beet Roots of Different Geographical Origins in Xinjiang
    JIA XUE-feng ZHU SI-ming WANG Qiang LONG Wei ZHANG Xin-lin
    2015, 31(7):302-308. DOI: 10.13982/j.mfst.1673-9078.2015.7.047
    [Abstract](997) [HTML](0) [PDF 703.29 K](1256)
    Abstract:
    The quality of sugar beet roots from different geographical regions in Xinjiang was comprehensively evaluated. The content of 11 elements (potassium, sodium, boron, nitrogen, phosphorous, magnesium, iron, calcium, zinc, manganese, and copper) in 34 sugar beet root samples collected from five major production regions in Xinjiang were determined and used as indicators to comprehensively evaluate quality by principal component analysis (PCA) and cluster analysis (CA). There were significant differences among the element content between sugar beet roots from different geographical regions. The average content of potassium, sodium, boron, nitrogen, phosphorous, magnesium, iron, calcium, zinc, manganese, and copper in sugar beet roots were 2821.1, 710.0, 19.8, 4855.2, 736.9, 2362.1, 58.7, 2590.1, 58.7, 602.0, and 18.7 mg/kg, respectively. A three-factor model was obtained from the PCA and accounted for 79.45% of the total variance. The cumulative contribution of the first and second components to the total variance was 67.23%. The 34 sugar beet root samples were classi?ed into five groups by PCA and CA, reflecting genetic relationshipi and geographical distribution of sugar beet root samples to some extent. Based on the content of several elements, the overall pattern and differences among sugar beet roots from different geographical origins in Xinjiang were clearly revealed by PCA and CA.
    48  Novel Multiplex Polymerase Chain Reaction Assay to Detect Virulence-related Genes in Vibrio parahaemolyticus
    XIAN Yu-yin YI Min-ying WEI Shuang YU Chong LI Zhi-yong WU Xi-yang LING Li
    2015, 31(7):309-315. DOI: 10.13982/j.mfst.1673-9078.2015.7.048
    [Abstract](1037) [HTML](0) [PDF 756.88 K](1186)
    Abstract:
    Two multiplex polymerase chain reaction (PCR) assay systems were developed to detect 11 common virulence-related Vibrio parahaemolyticus (V. parahaemolyticus) genes (toxR, collagenase gene, toxS, trh, tdh, tlh, UreR, FlaA, ompW, AspA, and fur). The two systems were applied to investigate the distribution of these virulence genes in 248 strains of V. parahaemolyticus isolated from the environment and aquatic products. The results showed that FlaA, encoding flagellin protein; ompW, encoding the outer membrane protein; and fur, encoding the ferric uptake regulator were the most widely distributed (100%) genes, followed by the alkaline serine protease gene, AspA (99.60%). Genes with > 90% distribution included collagenase gene; tlh, encoding the thermolabile hemolysin; and the virulence regulatory genes, toxR and toxS, and tlh and toxR possessed similar distribution. The urease encoding UreR was distributed at a very low level (1.21%), while the thermostable direct hemolysin gene, tdh and the thermostable related hemolysin gene, trh were not detected in any of the 248 V. parahaemolyticus strains. The multiplex PCR assays established in this study can be kconsidered as a rapid and efficient method to investigate the distribution of virulence genes, which can provide data for virulence research and ris assessment regarding V. parahaemolyticus.
    49  Changes in Volatile Components of Maize during Storage
    MA Liang WANG Ruo-lan
    2015, 31(7):316-325. DOI: 10.13982/j.mfst.1673-9078.2015.7.049
    [Abstract](898) [HTML](0) [PDF 889.38 K](1042)
    Abstract:
    Optimized headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze changes in relative content of volatile components in maize during airtight storage at 25 ℃. The major components identified could be categorized into seven groups: alkanes, aldehydes, esters, alcohols, ketones, acids, and small amounts of other compounds. The results showed that relative content of alkanes increased; while that of acids remained at a low level, in spite of a slow increase; whereas ketones decreased slowly and remained at a low level. The relative content of alcohol, aldehydes, and esters increased during the initial 120 d storage, and then decreased. As primary contributors to the volatile components of maize during storage, the total relative content of aldehydes and esters at 180 d approximated that at 0 d. Alkanes and alcohols were not considered to be major contributors due to their high odor thresholds. After airtight-storage at 25 ℃ for 180 d, no significant off-flavors were detected as compared to that at 0 d, probably due to the moderate storage conditions.
    50  Application of Loop-mediated Isothermal Amplification to Detect the aph Gene in Staphylococcus
    LI Xiu-mei LIANG Zhi-xuan LI Ying LI Xia HUANG Jin-hai WANG Hong-jun
    2015, 31(7):326-330. DOI: 10.13982/j.mfst.1673-9078.2015.7.050
    [Abstract](926) [HTML](0) [PDF 778.54 K](1091)
    Abstract:
    Since the use of antibiotics in animal breeding, bacterial resistance has become a worldwide concern. Detection of drug-resistance genes is a new method for assessing biosecurity. The aph gene was cloned into the pEASY-T1 vector using PCR-based methods and sequenced. A set of loop-mediated isothermal amplification (LAMP) detection primers was designed against a highly conserved region of the aph gene based on homology with aph loci in GenBank. The reaction conditions were optimized and LAMP detection methods for the aph gene were established. The optimal detection conditions were as follows: 0.8 mol/L betaine and 20 mmol/L Mg2+, completed within 50 min in a 63°C isothermal water bath. Compared to PCR detection, the LAMP method can be completed in a shorter time period with higher specificity. The sensitivity threshold was approximately 20.4 copies for the aph gene and was similar to that of the PCR method. The positive detection rate of the aph gene was 84.2% for 38 Staphylococcus aureus isolates.
    51  Development and Application of a High-resolution Method to Determine Trans Fatty Acids in Commercially Available Edible Oil
    YANG Zhan-dong YANG Ji-guo LI Ke-liang GE Ya-zhong NING Zheng-xiang
    2015, 31(7):331-335. DOI: 10.13982/j.mfst.1673-9078.2015.7.051
    [Abstract](1024) [HTML](0) [PDF 689.24 K](1704)
    Abstract:
    A high resolution method to determine trans fatty acids was established, and was used to examine the content and types of trans fatty acids in commercially available edible oil. Good chromatographic separation of four trans linoleic acid isomers, eight trans linolenic acid isomers, and 37 common fatty acids could be achieved using a high-polarity HP-88 gas chromatography (GC) column under optimized chromatographic conditions. Moreover, the peaks of trans fatty acids and common cis fatty acids did not overlap in the same detection conditions; thus, a high-resolution analysis of fatty acid (including trans fatty acid) composition was possible. The main brands of commercially available edible oil products all contain trans fatty acids. Blended oil, peanut oil, and soybean oil contained 2~3% trans fatty acids (the trans linolenic acid content was between 1.5~2%); corn oil and sunflower oil contained 0.7~2% trans linoleic acid; rice oil contained the highest trans fatty acid content, close to 4%. Additionally, the trans fatty acid content in camellia oil and olive oil were generally below 0.5%. The types of trans fatty acid isomers in each oil sample also differed.
    52  Phosphatidylcholine in Health Supplement Capsules Detected by Ultra-performance Liquid Chromatography and Verified by Mass Spectrometry
    WANG Bin CHEN Yi-guang WEN Shao-kai WU Chu-sen CHEN Wei-li LI Hong-yan WU Yu-luan LUO Hai-ying
    2015, 31(7):336-341. DOI: 10.13982/j.mfst.1673-9078.2015.7.052
    [Abstract](904) [HTML](0) [PDF 739.29 K](1300)
    Abstract:
    A new method was established to detect phosphatidylcholine in health supplement capsules, using ultra-performance liquid chromatography (UPLC) and the result was further verified using UPLC-tandem mass spectrometry (UPLC-MS/MS). The capsule contents were diluted before being tested or went through liquid-liquid-partitiondepuration. The analytes were separated using a BEH HILIC column and isocratic elution with methanol and isopropanol as the mobile phase. The analyte quantitates were detected by a photodiode array (PDA) detector and further verified by UPLC-MS/MS operated using electrospray ionization cation (ESI+)-muti-reaction monitoring( MRM). The detection limit was 0.001 mg/mL and linear range was between 0.005 and 0.100 mg/mL. The mean addition recovery rate of 6 concentrations was 83.3%, with a mean, relative standard deviation of 4.5%. Health supplement capsule marked 11.4 g/100 g was tested using this method with parallel determination results of 8.93 g/100 g and 8.76 g/100 g and the relative standard deviation of 3.02% and 0.60%, respectively. The results showed that the method is accurate, fast, and suitable for the determination and verification of phosphatidylcholine in health supplement capsules.
    53  Simultaneous Detection of 11 Mycotoxins in Aquatic Products using Multifunctional Column Clean-up and Ultrahigh-performance Liquid Chromatography-tandem Mass Spectrometry
    LI Xiang-li TAN Gui-liang LIANG Bo LIU Yao
    2015, 31(7):342-346. DOI: 10.13982/j.mfst.1673-9078.2015.7.053
    [Abstract](1061) [HTML](0) [PDF 631.13 K](1226)
    Abstract:
    A novel method to simultaneously detect 11 kinds of mycotoxins (aflatoxin B1 [AFB1], aflatoxin B2 [AFB2], aflatoxin G1 [AFG1], aflatoxin G2 [AFG2], aflatoxin M1 [AFM1], ochratoxin A [OTA], zearalenone [ZEN], deoxynivalenol [DON], 3-acetyldeoxynivalenol [3-AcDON], 15-AcDON, and fusarenon-X [Fus-X]) in aquatic products was developed, using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with multiple reaction monitoring (MRM). The samples were extracted with acetonitrile-water (84:16, V/V), purified using a multifunctional clean-up column (MycoSpin 400), and separated by a chromatographic column (Waters Acquity UPLCTM BEH C18; 100 × 2.1 mm i.d., 1.7 μm) using (0.01% formic acid-0.05% ammonia-H2O)/methanol as mobile phase. The quantitative and qualitative analyses were conducted in MRM mode with a mass spectrometer and an external standard. The results indicated that 11 mycotoxins showed good linear relationship within their respective linear response ranges, the correlation coefficients were > 0.9918, the limit of quantitation (LOQ) was 0.1 to 20.0 μg/kg, and the average recoveries (n = 3) were from 62.8% to 115.3%, with values of relative standard deviation (RSD) ranging between 2.6% and 19.0%. The developed method with the facile pretreatment, good purification effect, high sensitivity and reproducibility can be used for rapid detection of trace levels of multiple mycotoxins in aquatic products.
    54  Simultaneous Detection of Eleven Water-soluble Vitamins in Infant forMulae Using Liquid Chromatography–mass Spectrometry
    MIAO Lu MO Jia-lin ZHOU Hong-jian LI De-yong SU Jun GAN Ning-jun
    2015, 31(7):347-353. DOI: 10.13982/j.mfst.1673-9078.2015.7.054
    [Abstract](975) [HTML](0) [PDF 908.14 K](1318)
    Abstract:
    A novel method to simultaneously detect 11 water-soluble vitamins in infant formulae using high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) was established. The sample was pre-treated, followed by the separation using a Waters Acuity UPLC HSS T3 (2.1 × 100 mm, 1.8 μm) column by gradient elution, with 0.1% formic acid in methanol and 10 mol/L ammonium formate solution (pH = 3.5) as the mobile phase, in conjunction with electrospray ionization multiple reaction monitoring (MRM). The results showed that each sample could be analyzed within five minutes, detecting 11 water-soluble vitamins as well as exhibiting a good linear relationship (r ≥ 0.999) and a detection limit between 0.02 and 3.00 ng/mL. The recovery rate was tested at three levels with five repeats at each level. The results showed that the average recovery rate ranged between 88.0% and 110.0%, with relative standard deviation of < 5%. This method was rapid, simple, accurate, and sensitive, and could simultaneously analyze multiple vitamins within a wide concentration range. This method can therefore help to improve analytical efficiency and reduce cost of food testing laboratories, for the detection of water-soluble vitamins in infant formulae.
    55  Changes in Flavor Compounds of Silver Carp Surimi during Rinsing
    MA Hai-jian SHI Wen-zheng FU Qiang WANG Zhi-he
    2015, 31(7):354-360. DOI: 10.13982/j.mfst.1673-9078.2015.7.055
    [Abstract](873) [HTML](0) [PDF 996.89 K](1166)
    Abstract:
    Changes in the content of flavor nucleotides and free amino acids of silver carp surimi during the rinsing process were studied and volatile compounds were analyzed using electronic nose and gas chromatography–mass spectrometry (GC-MS). The results showed that inosinic acidIMP content reduced significantly after the first and second rinsing, whereas adenosine monophosphate AMP content after the third rinsing was significantly less than the unwashed surimi. The amount of free amino acids reduced significantly after the first, second, and third rinsing, while umami amino acid and sweet amino acid content reduced during the overall rinsing process. Additionally, the rinsing process affected the aroma of silver carp surimi. The results from the electronic nose principal component analysis showed that the aroma of surimi after the second rinsing was similar to that of dehydrated surimi, while that of the other groups were effectively distinguishable. Furthermore, the types of volatile compounds in unwashed surimi after the first, second, and third rinsing, and dehydration were 30, 27, 21, 15, and 18, respectively. These included mostly carbonyl compounds and alcohols such as hexanal, heptanal, nonanal, 1-hexanol, and 1-octen-3-ol, as detected by GC-MS.
    56  Comparison between Volatile Compounds in Fast, Factory Dry-smoked and Traditional Air Dry-smoked Xiang-xi Chinese Bacon
    ZHONG Yi-ru ZHOU Hui LOU Ai-hua LUO Qing-wen LIU Cheng-guo
    2015, 31(7):361-371. DOI: 10.13982/j.mfst.1673-9078.2015.7.056
    [Abstract](975) [HTML](0) [PDF 1.02 M](1351)
    Abstract:
    The main volatile compounds in traditional Xiang-xi Chinese bacon produced by rapid dry-smoking in a factory and traditional air dry-smoking were analyzed. Solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to determine the volatile compounds. Samples were obtained at end of curing, 2 and 6 days after drying and smoking for factory products, and after 5, 15, and 30 days for traditional dry-smoked products. The differences between finished products in the volatile flavor compounds were also compared. In total, 73 and 76 distinct volatile compounds were identified from factory products and traditional air-dried products, respectively. The main compounds in Xiang-xi Chinese bacon were esters, acids, aldehydes, ketones, phenols, and hydrocarbons. The main compounds in finished factory products were phenols (62.50%), aldehydes (8.95%), and hydrocarbons (5.08%), and in air-dried finished bacon were phenols (14.80%), esters (0.91%), and hydrocarbons (0.68%). The variation and relative contents of volatile compounds were higher in factory products than that in air-dried products.
    57  Volatile Components of Instant Oolong Tea Powder
    JIN Qiao-li JIANG Ze-dong NI Hui CHEN Feng HUANG Gao-ling YANG Yuan-fan
    2015, 31(7):372-379. DOI: 10.13982/j.mfst.1673-9078.2015.7.057
    [Abstract](1269) [HTML](0) [PDF 817.19 K](1228)
    Abstract:
    Instant tea powder is an important processed product of tea. Previous studies have reported in-depth investigations regarding the processing technology used for instant tea powder, however, only few studies are available on the quality of instant tea powder. The volatile components of instant oolong tea powder were analyzed using gas chromatography-mass spectrometry (GC-MS) combined with solid-phase micro-extraction (SPME). The results showed that the optimal SPME conditions included using the 50/30-μm Divinylbenzene-Carboxen-Polydimethylsiloxane DVB-CAR-PDMS adsorption fiber at 70℃ for 40 min. GC-MS analysis identified 39 volatile components, consisting mainly of linalool, trans-ocimene, cis-linalool oxide, and trans-linalool oxide, at concentrations of 16422.8, 3407.8, 2549.7, and 2163.1 μg/kg, respectively. Based on the analysis of odor activity value (OAV), the compounds mainly contributing to the aroma and their corresponding odor activity values were: linalool, 2,737,138; cis-linalool oxide, 360,522; trans-linalool oxide, 424,950; trans-β-ocimene, 56,796; and benzene acetaldehyde, 31,708. The above results together indicated that the main volatile components and aroma contributors were linalool, trans-β-ocimene, cis-linalool oxide, and trans-linalool oxide. These results provide reference data for the evaluation of the volatile components contributing to the aroma quality of instant oolong tea powder.

    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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