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Volume 32,Issue 1,2016 Table of Contents

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    • 1  Maternal Lead Exposure Effects on the Expression of P2X7 Receptor in the Hippocampus of Mouse Pups
    LI Ning ,  LV Feng-shou ,  ZHANG Ping-an ,  QIAO Ming-wu ,  ZHAO Qiu-yan ,  SONG Lian-jun ,  LI Li
    2016, 32(1):1-5. DOI: 10.13982/j.mfst.1673-9078.2016.1.001
    [Abstract](1899) [HTML](0) [PDF 738.66 K](1711)
    Abstract:
    In order to investigate the effects of maternal lead (Pb) exposure on the expression of P2X7 receptor in the hippocampus of mouse offspring, female mice were administered Pb through their drinking water, from the first day of gestation until the pups were weaned, at 21 days of age. Lead acetate was dissolved in distilled deionized water at concentrations of 0.1%, 0.5%, or 1%. The control group received only distilled water. At postnatal day 21, blood and hippocampal Pb levels were determined by graphite furnace atomic absorption spectrometry, and the expression of P2X7 receptor in the hippocampus was examined by immunohistochemistry and western blotting. Blood and hippocampal Pb levels of all lead-exposure groups were significantly higher compared with the control group (P < 0.05). Additionally, the expression of P2X7 receptor was increased in Pb-exposed groups in comparison with the control group (P < 0.05). Maternal Pb exposure led to the Pb accumulation in mouse pups, and it increased Pb levels in the blood and hippocampus. Consequently, P2X7 receptor was overexpressed in the hippocampus of these pups, which may contribute to the dysfunction of hippocampal neurons, causing damage in the nervous system and neurotoxicity.
    2  Effects of Polysaccharides Extractedfrom Hovenia acerba Lindl. on Glycemia and Lipidemia in Diabetic Mice
    YE Wen-bin ,  FAN Liang ,  WANG Yu ,  ZHAO Qing-fang ,  GUO Shou-jun ,  YUN Han-bo
    2016, 32(1):6-12. DOI: 10.13982/j.mfst.1673-9078.2016.1.002
    [Abstract](2217) [HTML](0) [PDF 720.85 K](2195)
    Abstract:
    The effects of Hovenia acerba Lindl. polysaccharides (HAPs) on blood glucose and blood lipids in alloxan (ALX)-induced diabetic mice were investigated in the present study. A mouse model of diabetes was established by intraperitoneal injection of ALX. The ALX-induced diabetic mice were randomly assigned to one of eight groups, including three HAP-treated groups (low-, medium-, and high-doses), a metformin-treated group, a glibenclamide-treated group, an epinephrine-treated group, an untreated diabetic model group, and a normal control group that was not treated with ALX. The HAPs were administered intragastrically for four weeks and the effects of HAPs on the levels of fasting blood glucose (FBG), glycated hemoglobin (HbA1c), total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were investigated. The HAPs significantly reduced blood glucose in normal rats, markedly mitigated adrenaline-induced hyperglycemia, and effectively reduced serum FBG, HbAlc, TC, and TG, while increasing the concentration of HDL. These results suggest that HAPs can lower blood glucose and improve the metabolic disorders of blood lipids in ALX-induced diabetic mice.
    3  Protective Effect of Wheat Germ Peptide on Cultured SH-SY5Y Human Neuroblastoma Cell Line in an in vitro Cell Injury Model
    CHENG Yun-hui ,  LV Zhao-liang ,  SUN Wei ,  TANG Ji-qing ,  XU Zhou ,  WEN Li ,  YU Hui-xin ,  ZHANG Li
    2016, 32(1):13-21. DOI: 10.13982/j.mfst.1673-9078.2016.1.003
    [Abstract](1427) [HTML](0) [PDF 1.06 M](1467)
    Abstract:
    The protective effects of wheat germ peptide (RVF) on the SH-SY5Y human neuroblastoma cell line were investigated in this study. Starvation- and hydrogen peroxide (H2O2)-induced injury models were established by in vitro cell culturing of an SH-SY5Y human neuroblastoma cell line. The SH-SY5Y cells were treated with 40 RVFs at different concentrations and incubation times. The results showed significant nutritional functions only in the group pre-incubated with 200 μmol/L RVF for 12 h in a no-serum starvation-induced injury model and the group treated with 500 μmol/L RVF for 24 h in the 1% serum starvation-induced injury model, and no dose- or time-dependent relationships were found . In the H2O2-induced injury model, treatment with 200 μmol/L RVF increased cell survival rates by 25.05 and 21.90% in the methyl-tetrazolium (MTT) and sulforhodamine B (SRB) assays, respectively, in a time- and dose-dependent manner. The cell morphological analysis indicated that after RVF treatment, the SH-SY5Y cells gradually resumed a spindle or polygonal shape from a wrinkled, shrunken, and elongated shape, with enhanced cell adhesion. In the two injury models investigated in this study, RVF only showed a significant protective effect in the H2O2-induced injury model.
    4  Isolation and Identification of an Endophytic Fungus from Erythronium japonicum Decne and Inhibitory Effect of Secondary Metabolites on Carcinoma Cells
    LU Qun ,  Teigo Asai ,  Yoshiteru Oshima
    2016, 32(1):22-28. DOI: 10.13982/j.mfst.1673-9078.2016.1.004
    [Abstract](1160) [HTML](0) [PDF 765.79 K](1551)
    Abstract:
    An endophytic fungus was isolated from Erythronium japonicum Decne. Using a tissue separation method, and this fungus was identified by 28S rDNA sequencing and phylogenetic analysis. The strains were cultured in potato dextrose (PD) and yeast and malt extract (YM) media, and their secondary metabolites were analyzed using high-performance liquid chromatography (HPLC) and mass spectrometry (MS). This strain was cultivated on a large scale in YM medium, while the secondary metabolites were separated and purified using silica gel chromatography. The cytotoxicity of the compounds isolated from secondary metabolites was determined by MTT assay. The endophytic fungus from Erythronium japonicum Decne. was identified as Eupenicillium sp. NF2_PD013. HPLC and MS analyses indicated that there were more secondary metabolites of this endophytic fungus in YM medium with a higher yield than those in PD medium. The four chlorine-containing compounds obtained from the secondary metabolites in YM medium were identified as geodin, dihydrogeodin, 3’-chlorotrypacidin, and monochlorosulochrin. Geodin and 3’-chlorotrypacidin showed significant inhibitory effects on the proliferation of breast cancer cells MCF-7 and hepatocellular carcinoma cells HepG2.
    5  Evaluation of Hypoglycemic and Hypolipidemic Effects of Fine Dried Noodles with a Low Glycemic Index
    TIAN Bao-ming ,  ZHANG Lei ,  LIU Qing-qing ,  LIU Xiong
    2016, 32(1):29-36. DOI: 10.13982/j.mfst.1673-9078.2016.1.005
    [Abstract](843) [HTML](0) [PDF 886.62 K](1382)
    Abstract:
    The effects of fine dried noodles with a low glycemic index (GI) on glucolipid metabolism of streptozotocin (STZ)-induced diabetic rats were investigated. Based on the blood glucose level, thirty-two adult male Sprague-Dawley (SD) rats were randomly divided into four groups: ordinary dried noodle control group, ordinary dried noodle diabetic group, low GI dried noodle control group, and low GI dried noodle diabetic group. After a four-week feeding, the blood glucose and lipid indexes were determined. The results showed that the dietary fiber content in low GI noodles was relatively high, up to 16.04%. The low GI noodles increased body weight and the levels of serum insulin, hepatic glycogen, and muscle glycogen in diabetic rats. The low GI noodles also reduced food intake and glycosylated serum protein (GSP) levels, decreased fasting blood-glucose (FBG), decreased the relative weights of various organs, and improved impaired glucose tolerance. Additionally, low GI dried noodles reduced the levels of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) in serum while increasing the serum high-density lipoprotein cholesterol (HDL-C) level in diabetic rats. As a result, the liver total lipid and lipid concentrations were significantly decreased. The blood glucose and lipid indices of the two control groups were similar, indicating that the low GI dried noodles did not affect normal rats. This study demonstrates that low GI dried noodles have some beneficial effects in improving hyperglycemia and lipid metabolism disorders in diabetic rats, which is of importance for the prevention and treatment of diabetes.
    6  Extracellular Metabolic Profiling of Common Food-borne Pathogens
    LI Yu-dong ,  WU Qing-ping ,  ZHANG Ju-mei ,  WEI Xian-hu ,  ZHANG You-xiong ,  GUO Wei-peng
    2016, 32(1):37-43. DOI: 10.13982/j.mfst.1673-9078.2016.1.006
    [Abstract](1336) [HTML](0) [PDF 1.20 M](1851)
    Abstract:
    This study aims to determine the characteristic metabolites of common food-borne pathogens and develop fast and efficient techniques for food safety monitoring. In this study, the zymotic fluid of food-borne pathogens was freeze-dried and derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), followed by analysis using gas chromatography mass spectrometry (GC-MS). An NIST11 database search and classification were also performed, and the acquired data were analyzed using heatmapping and principal component analysis (PCA). The results showed that there were a large number of substances, such as organic acids, alcohols, and amines that were formed in the culture broth. Significant differences were observed between different bacterial species based on the types and relative metabolic contents. Many specific metabolites for each bacterial species were found, some of twhich have never been reported in other strains. The extracellular metabolic profiles of all bacteria were analyzed by heatmapping and PCA, and the results showed that the strains could be differentiated at 24 h; the differentiation effect of PCA was significantly enhanced after the removal of amino acid and sugars, and the optimal effect was found at 24 h. Our results show that extracellular metabolic profile analysis can be used to determine the biomarkers of food-borne pathogenic bacteria and distinguish between bacterial species. Further, some of the characteristic metabolites may be potential biomarkers of common food-borne pathogens.
    7  Molecular Mechanisms of Novel Synthetic Analogs of Tachyplesin against Pathogenic Escherichia coli F41
    XIE Hai-wei ,  YANG Xian-song ,  KE Chun-lin ,  XU Hui ,  GUO Yong
    2016, 32(1):44-51. DOI: 10.13982/j.mfst.1673-9078.2016.1.007
    [Abstract](1154) [HTML](0) [PDF 1.23 M](1547)
    Abstract:
    This study aimed to investigate the antibacterial activity and antibacterial kinetics of synthetic tachyplesins. The changes in the secondary structure of the synthetic peptides were investigated by circular dichroism (CD) spectroscopy, and the effect of synthetic peptides on the microstructure of cells was investigated by electron microscopy. The permeability of the cell membrane was investigated by leakages of K+ ion l and ultraviolet (UV)-absorbing materials, and the interaction between synthetic peptides and genomic DNA was investigated by DNA gel retardation experiment. The results showed that the antibacterial activity and antibacterial kinetics were different in different synthetic tachyplesins, and the antibacterial activity was related with the concentration of tachyplesins and the action time. The cellular microstructure of Escherichia coli was significantly changed by synthetic antimicrobial peptides Tac, TacW, and TacV causing leakages of K+ ions and UV absorbing materials, changes in cell membrane permeability, bacterial cell wall fractures, and cell collapse. At the same time, synthetic antibacterial peptides could bind to genomic DNA and lead to gel retardation. In conclusion, the action mechanism of synthetic tachyplesins is closely related to the ratio of amphiphilic amino acids and basic amino acids in tachyplesins structure. The molecular mechanisms involves multiple effects, including changes in membrane permeability and bacterial cell microstructure, genomic DNA binding, inhibition of replication and transcription, and formation of multiple targets.
    8  Comparison of Effectiveness and Properties of Raman Surface Signal Enhancement by Gold and Silver Nanoparticle Sols on Three β Agonists
    GAN Sheng ,  LAI Qing-niao ,  LI Zhi-cheng ,  HAN Ting ,  WU Chao-quan
    2016, 32(1):52-57. DOI: 10.13982/j.mfst.1673-9078.2016.1.008
    [Abstract](1977) [HTML](0) [PDF 1.08 M](2001)
    Abstract:
    The sodium citrate-reduction method was adopted to prepare gold nanoparticle sols (three sizes) and one silver nanoparticle sol as Raman surface enhancers, and their size, granularity, dispersity, and stability were determined by ultraviolet–visible spectroscopy (UV-Vis) and transmission electron microscopy (TEM). Raman signal enhancement effect was analyzed by testing three β agonists: clorprenaline hydrochloride, terbutaline sulfate, and bambuterol hydrochloride. The results demonstrated that gold and silver nanoparticle sols showed no interference in the enhanced Raman signals from the surface-enhanced Raman scattering of the three β agonists. The size of the gold nanoparticles had an impact on sol absorptivity, which could be adjusted easily by adding sodium citrate, while the size of the silver nanoparticles was not easy to control. The gold sol could remain stable for a long period, while precipitation could easily occur in the silver sol. However, after binding with the target molecules, the silver nanoparticles could produce stronger resonance phenomena and exhibit a stronger surface enhancement effect than the gold nanoparticles. Therefore, it was more effective on the Raman signal enhancement of target molecules.
    9  Mechanism of Plasmid-mediated Quinolone Resistance in Escherichia coli Isolated from Animal-derived Food
    JIANG Xiao-bing ,  ZHANG Jia-yang ,  WANG Yan-bo ,  YU Tao ,  JI Sheng-dong ,  MENG He-cheng ,  SHI Lei
    2016, 32(1):58-64. DOI: 10.13982/j.mfst.1673-9078.2016.1.009
    [Abstract](920) [HTML](0) [PDF 682.09 K](1290)
    Abstract:
    Escherichia coli was isolated from animal-derived food samples and the antibiotic susceptibility of isolated strains was investigated by agar dilution method. The distribution of plasmid-mediated quinolone resistance (PMQR) genes and mutations in the quinolone resistance-determining region (QRDR) were analyzed by the polymerase chain reaction (PCR) amplification and product sequencing. A total of 179 strains of E. coli were detected (27.7%) in 645 animal-derived food samples. The resistance of these isolates to 15 different antibiotics was observed, with high level of resistance to streptomycin, tetracycline, nalidixic acid, and trimethoprim/sulfamethoxazole. Fourteen strains were PMQR-gene positive, accounting for 7.8% of the test strains, and 11 of the PMQR-positive strains could transfer quinolone resistance to the recipient through conjugation. Mutations in QRDR were prevalent among the PMQR-positive isolates, which could be responsible for the high-level resistance to quinolone. Our results demonstrate that animal-derived food may act as a reservoir for drug-resistant strains and can be a channel for transfer of resistant genes to humans via the food chain, thus causing human infection and a possible outbreak of drug-resistant strains.
    10  Analysis of the Antifungal Activity of Pine Needle Extracts and Their Active Components against Citrus Blue Mold
    YANG Shu-zhen ,  JIANG Dan-dan ,  FAN Gang ,  ZHANG Qaing ,  LI Min ,  CHENG Yun-jiang ,  PENG Li-tao
    2016, 32(1):65-69. DOI: 10.13982/j.mfst.1673-9078.2016.1.010
    [Abstract](1126) [HTML](0) [PDF 617.83 K](1394)
    Abstract:
    Antifungal activity of the active components of extracts from the pine needles of Pinus massoniana against citrus blue mold (Penicillium italicum) were studied by using spore germination based assay. The results demonstrated that extraction solvents with different polarities caused differences in the antifungal activities of the extracts from pine needles of Pinus massoniana, and the extent of the antifungal activity of these extracts were in the following order: ethyl acetate extract, ethanol extract, dichloride methane extract, water extract, and petroleum ether extract. Twenty major chemical components were identified in the ethyl acetate extract by gas chromatography mass spectrometry (GC/MS), including α-pinene (28.73%), β-pinene (24.72%), β-myrcene (1.44%), β-caryophyllene (8.06%), camphene (1.63%), and β-cubebene (4.79%). The most prevalent components, α-pinene and β-pinene, exhibited the strongest antifungal activities against Penicillium italicum and were the main active components in Pinus massoniana against Penicillium italicum, followed by β-myrcene. Camphene, 3-carene, ocimene, and β- caryophyllene exhibited the weakest inhibitory effects on the spores of Penicillium italicum. Therefore, α-pinene and β-pinene are of significance for further study and development as safe and effective fumigants for the storage of citrus fruits after harvest.
    11  Preparation and Evaluation of the Stability of a Microalgae Oil-water Emulsion by Using Soybean Protein-chitosan Coacervate as an Emulsifier
    SUN Ying-en ,  YUAN Yang ,  YANG Xiao-quan
    2016, 32(1):70-76. DOI: 10.13982/j.mfst.1673-9078.2016.1.011
    [Abstract](1461) [HTML](0) [PDF 894.11 K](1674)
    Abstract:
    Microalgae oil is rich in polyunsaturated fatty acids, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), commonly added to liquid foods. However, microalgae oil is prone to oxidative deterioration during food processing, preservation, and digestion. In addition, it is difficult to add liposoluble microalgae oil to liquid foods. Therefore, improving the stability of microalgae oil is critical for its application in the food industry. Here, a microalgae oil-water emulsion was prepared using soybean protein isolate (SPI) and chitosan (CS) coacervate. Because the oxidative stability of emulsions depends greatly on their physical stability, the effects of cross-linking with microbial transglutaminase (mTGase) on the physical and oxidative stabilities of the microalgae oil-water emulsion were investigated. The results indicated that the optimum cross-linking effect of mTGase on SPI/CS coacervate was achieved under the following conditions: pH: 6.0; Cs to SPI ratio: 0.1 g/g; mTGase concentration: 25 U/g SPI. Cross-linking with mTGase significantly improved the physical and oxidative stabilities of the microalgae oil-water emulsion, as well as the emulsifying efficiency of microalgae oil. The microalgae oil emulsion product prepared using this method can be added to soy milk and other liquid protein drinks, thus enhancing the health benefits from DHA.
    12  Functional Action of a Chinese Herbal Compound in Improving Bowel Movement
    JIN Xin ,  GAO Qing ,  GE Ya-zhong
    2016, 32(1):77-81. DOI: 10.13982/j.mfst.1673-9078.2016.1.012
    [Abstract](1157) [HTML](0) [PDF 622.20 K](1647)
    Abstract:
    With development of the social economy and improvement of people’s standard of living, traditional dietary habits have been gradually changing. Consequently, constipation, a common disease affecting quality of life, has attracted considerable attention. Therefore, it is very important to discover safe and effective products that can improve bowel movement. This study aims to evaluate the functional action of a Chinese herbal compound in improving bowel movement. A mouse model of constipation induced using diphenoxylate was used in small intestinal motility and bowel evacuation experiments. Measurements included the first evacuation time, the number of fecal pellets in five hours, the weight of evacuation, the movement rate of ink in the small intestine, and the effect of the herbal compound on colonic substance P (SP), vasoactive intestinal peptide (VIP), and synaptophysin (SY). The results showed that compared with the control group, the groups treated with the Chinese herbal compound exhibited a shortened evacuation time, an increased number of fecal pellets, an increased weight of feces in five hours, an increased movement rate of ink, an enhanced small intestinal movement, an increased SP value, and a decreased VIP level. Therefore, the results demonstrate that the Chinese herbal compound can improve bowel movement in mice.
    13  Antimicrobial Mechanisms of Mistletoe (Viscum articulatum) Extracts Against Staphylococcus aureus
    ZHANG Xing-mei ,  XUE Qiao-li ,  XIAO Rong ,  ZHAO Ling-zhi ,  LIN Qi ,  HU Yong-jin
    2016, 32(1):82-88. DOI: 10.13982/j.mfst.1673-9078.2016.1.013
    [Abstract](954) [HTML](0) [PDF 855.97 K](1419)
    Abstract:
    The antibacterial effects and mechanisms of 95% ethanolic extracts of Viscum articulatum were studied. The result showed that 95% ethanolic extracts of mistletoe had significant antagonistic activity against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella typhimurium, and Micrococcus varians and had no effect on Bacillus subtilis and B. natto. The best antibacterial effect was observed in controlling Staphylococcus aureus (minimum inhibitory concentration (MIC): 0.1 mg/mL). Further studies showed that 95% ethanolic extracts increased the permeability of bacterial cell walls and membranes and caused the leakage of cellular contents such as soluble saccharides and proteins, thus increasing the conductivity. The observations from light microscopy, scanning electron microscopy, and transmission electron microscopy further demonstrated that the extracts could not only target the bacterial cell wall and membrane systems to destroy their normal structures, but also killed bacteria by inhibiting cell division. The results suggest that Viscum articulatum presents potential as a natural food additive.
    14  Interaction of Coomassie Brilliant Blue G-250 with Bovine Serum Albumin
    WANG Yong-gang ,  WANG Shi-wei ,  LI Yun-chun ,  LENG Fei-fan ,  MA Jian-zhong ,  WANG Xiao-li ,  ZHUANG Yan
    2016, 32(1):89-94. DOI: 10.13982/j.mfst.1673-9078.2016.1.014
    [Abstract](1233) [HTML](0) [PDF 893.59 K](1830)
    Abstract:
    The interaction of Coomassie brilliant blue G-250 (CBBG-250) with bovine serum albumin (BSA) was investigated by the methods of ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD), and molecular modeling technique. The UV-Vis results showed that BSA could interact with CBBG-250 to form a CBBG-BSA complex in a molar ratio of 1:1 with increasing BSA concentrations. At different temperatures, the apparent binding constant (Ka) values were 5.03 ? 104 (298 K), 3.04 ? 104 (303 K), 2.84 ? 104 (308 K), and 1.99 ? 104 L/mol (313 K), respectively, which decreased with increasing temperatures. The whole process was enthalpically and entropically driven, and the enthalpy (△H) and entropy changes (△S) were 45.32 kJ/mol and 139.18 J/(mol?K), respectively, indicating that the hydrogen bonds and Van der Waals forces played a dominant role in the molecular interaction. FT-IR was used to study the changes in characteristic amide bands (I and II) of α-helix in BSA before and after the interaction. The results showed that amide band I shifted from 1650 cm-1 to 1710 cm-1, amide band II shifted from 1573 cm-1 to 1544 cm-1, and the α-helical structure content was reduced. CD measurements and molecular docking technique further verified the changes in BSA structure and the content of α-helical structure decreased from 42.15% to 1.27%.
    15  Effect of Frozen Storage at Constant Temperature on the Molecular Chain Structure of Hydrated Gluten by Small-angle X-ray Scattering (SAXS)
    ZHAO Lei ,  WANG Xing-xing ,  HU Zhuo-yan ,  LI Bing ,  LIU Guo-qin ,  LI Lin
    2016, 32(1):95-99. DOI: 10.13982/j.mfst.1673-9078.2016.1.015
    [Abstract](916) [HTML](0) [PDF 708.72 K](1359)
    Abstract:
    Frozen flour products have been rapidly developed in the food industry, while some key scientific issues on the effects of the frozen storage process on the quality of flour products remain unclear. In this study, the effects of frozen storage (-18 ℃) on the molecular chain configuration, root mean square radius of gyration (Rg), and molecular weight of hydrated gluten were studied by small-angle X-ray scattering (SAXS). The results showed that before frozen storage, gluten molecules had a relatively loose chain structure in a 500 mM acetic acid solution, possessed a mass fractal structure (mass fractal dimension (Dm): 2.05), and a network structure. With elongated storage time, Dm value tended to decrease, indicating a gradually loose chain structure of gluten protein polymers. The Rg value and average molecular weight of gluten also tended to decrease with increasing frozen storage time and the change of Rg was positively correlated with that of Dm. These results demonstrated that depolymerization occurred during the frozen storage process due to the ice recrystallization, resulting in breaks in gluten molecule chains and a loose network structure.
    16  Digestion Properties of Sodium Alginate-high Amylose Corn Starch-conjugated Linoleic Acid Ternary Complex
    ZHAO Yang ,  CHEN Hai-hua ,  WANG Yu-sheng ,  HUANG Juan ,  SHANG Meng-shan
    2016, 32(1):100-105. DOI: 10.13982/j.mfst.1673-9078.2016.1.016
    [Abstract](1126) [HTML](0) [PDF 863.88 K](1314)
    Abstract:
    Digestion properties were investigated for sodium alginate-high amylose corn starch–conjugated linoleic acid ternary complex (AG-HACS-CLA). The in vitro digestion properties of AG-HACS-CLA were measured by the hydrolysis curve method, the crystal structure of AG-HACS-CLA was determined by X-ray diffractometer and Fourier-transform infrared spectrometer analyses, and the relationship between the digestion properties and crystal structure of the complex were explored. The results showed that before gelatinization and pasting, AG-HACS-CLA was a low glycemic index food with a predicted glycemic index (pGI) of 47.06, while the gelatinized and pasted AG-HACS-CLA was a medium glycemic index food with a pGI of 58.27. The in vitro digestion properties of AG-HACS-CLA were influenced by the type of crystal and degree of crystallization, and the resistant starch content of AG-HACS-CLA was related to the microcrystal phase. A V-type crystal with a high degree of order was formed after the complexation of starch with CLA, so that the proportion of the microcrystal phase in AG-HACS-CLA increased by 3.5%, compared to the sample without addition of CLA. Compared to the natural HACS, with a B-type crystal structure, AG-HACS-CLA exhibited better structural stability and greater resistance to digestion. AG prevented the formation of intermolecular hydrogen bonds in AG-HACS-CLA. The proportion of AG-HACS-CLA in the microcrystal phase was decreased by 7.1% and the content of resistant starch in AG-HACS-CLA was decreased by 20% compared to that of the sample without addition of AG.
    17  Structural Characteristics and Antioxidant Activity of Polysaccharides from Glycyrrhiza glabra L. Leaf
    LIN Lian-zhu ,  JIAO Ming
    2016, 32(1):101-110. DOI: 10.13982/j.mfst.1673-9078.2016.1.017
    [Abstract](993) [HTML](0) [PDF 654.40 K](1511)
    Abstract:
    A crude water-soluble polysaccharide (GC C) was obtained from Glycyrrhiza glabra L. Leaf by water extraction. DEAE-Sepharose fast flow column chromatography was used to separate and purify GC C to obtain one neutral polysaccharide (GC I) and two acidic polysaccharides (GC II and GC III). The strongest 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC) were detected in GC I, which was therefore selected for structural characterization. The molecular weight, monosaccharide composition, and glycosidic linkages of GC I were determined by high performance gel permeation chromatography (GPC), infrared spectroscopy (FT-IR), 1-phenyl-3-methyl-5-pyrazolone (PMP) precolumn derivatization-high performance liquid chromatography (HPLC), and methylation-gas chromatography mass spectrometry (GC-MS). It was found that GC I consisted of two polysaccharides with average molecular weights of 980 kDa and 20 kDa. The FT-IR spectra showed the characteristic peaks of the polysaccharides were in the frequency range of 4000-500 cm-1. Monosaccharide composition analysis indicated that GC I contained mannose, rhamnose, glucose, galactose, and arabinose, The residues of →2)-Araf-(1→, →6)-Galp-(1→ and →6)-Glcp-(1→ showed thehighest amounts in GC I.
    18  Rheological Properties of Thermal Gels Prepared from Whey Protein-β-glucan Maillard Products
    XU Jing ,  QI Bao-kun ,  ZHAO Qing-shan ,  JIN Hua ,  ZHANG Xiao-song ,  JIANG Lian-zhou
    2016, 32(1):111-115. DOI: 10.13982/j.mfst.1673-9078.2016.1.018
    [Abstract](890) [HTML](0) [PDF 654.92 K](1423)
    Abstract:
    Protein/polysaccharide conjugates obtained by Maillard reaction (MR) have good emulsifying properties. However, only few reports are available on the use of MR protein/polysaccharide gel systems. Whey protein isolate (WPI) and barley β-glucan (BGL) with different molecular weights (20~210 ku) were used to prepare WPI-BGL Maillard products by dry heat processing in this study. Browning intensity was measured by spectrophotometry, the structure was analyzed by fluorescence spectra, and the effect of MR on the rheological properties of WPI-BGL thermal gel was explored. The results showed that the browning intensity was highest for WPI-BGL20, the ionic strength affected the rheological properties of WPI-BGL gel, the fluorescence intensity of WPI-BGL samples was lower than that of WPI, and the MR between WPI and BGL resulted in a significant change in structure and a decrease in gel storage modulus (G'). This was possibly due to the suppression of disulfide bond formation between protein molecules and hydrophobic interactions in WPI-BGL systems, leading to weakening of the WPI-BGL gel. G' of the WPI-BGL gel reduced gradually with a decrease in BGL molecular weight, indicating that a greater extent of MR results in a weaker conjugate gel.
    19  Separation, Purification and Biological Activity Evaluation of Antimicrobial Peptides from Tenebrio molitor
    ZHANG Jian-xin ,  SUN Chang-jiang
    2016, 32(1):116-121. DOI: 10.13982/j.mfst.1673-9078.2016.1.019
    [Abstract](912) [HTML](0) [PDF 729.06 K](1562)
    Abstract:
    Antibacterial peptides were prepared by hydrolysis of the proteins from Tenebrio molitor using alkaline protease. The antibacterial peptides were further separated and purified. Five fractions were obtained from the dynamic adsorption of the protease hydrolysate on macroporous adsorption resin and gradient elution. Theantibacterial activity, thermostability, and molecular weight of different fractions of the peptides were compared. The antimicrobial susceptibility test indicated that the ethanol-eluted fraction exhibited the strongest antimicrobial activity. This fraction was further separated into two subfractions (H-1 and H-2) by preparative high-performance liquid chromatography (HPLC). The H-2 subfraction showed relatively strong antimicrobial activities on E. coli, Salmonella and Staphylococcus aureus, with a minimum inhibitory concentration (MIC) of 0.512 mg/mL. The thermostability tests indicated that H-2 was heat stable and could maintain a relatively strong antimicrobial activity after being heated to 121 ℃ for 20 minutes. The liquid chromatography–mass spectrometry (LC-MS) results indicated the molecular weight of H-2 was 756.82 Da. The results of this study provide a scientific basis for efficient separation and purification of antibacterial peptides from Tenebrio molitor and provide data supporting the application of antibacterial peptides from Tenebrio molitor as food preservatives.
    20  Determination of Antioxidant Activity and the Contents of Polyphenols and Flavonoids of Apples by Simulated Gastrointestinal Digestion
    PENG Meng-xue ,  CONG Yan-li ,  LIU Dong
    2016, 32(1):122-128. DOI: 10.13982/j.mfst.1673-9078.2016.1.020
    [Abstract](1623) [HTML](0) [PDF 1.10 M](1784)
    Abstract:
    Three cultivars of apples (Fuji, Gala, and Granny Smith apples) were used as raw materials for the investigation. Bioactive substances were extracted by in vitro gastrointestinal digestion and organic solvent extraction method. The antioxidant activity, as well as polyphenol and flavonoid contents in the extract, were determined, and patterns in the changes and correlations among these three were analyzed. The results showed that after simulated gastrointestinal digestion, antioxidant activity and polyphenol and flavonoid contents of apples increased significantly (P < 0.05). The amount of released polyphenol reached a maximum level and remained stable during the one-hour gastrointestinal digestion. During gastric digestion, the maximum amount of released polyphenol was 1.36~1.76 times higher than that before gastric digestion. During intestinal digestion, the maximum amount of released polyphenol was 1.34~2.08 times higher than that before intestinal digestion. Apple polyphenols are mainly composed of free polyphenols, and the content of polyphenols in the organic solvent extract was more than that after the simulation of gastrointestinal digestion (P < 0.05). At the simulated gastric digestion phase, a strong correlation (r = 0.74~0.99，P < 0.05) was noted among antioxidant activity and polyphenol and flavonoid contents. However, at the intestinal digestion phase, the correlation among antioxidant activity and flavonoid and polyphenol contents was low (r = -0.47~0.47, P < 0.05). Simulating gastrointestinal digestion may cause changes in the content and structure of polyphenols, leading to increases in antioxidant activity and polyphenol and flavonoid contents.
    21  Effect of Bean Starches on the Gel Properties of Silver Carp Surimi
    YU Yong-ming ,  MA Xing-sheng ,  YI Shu-min ,  SHAO Zhen ,  XU Yong-xia ,  LI Jian-rong
    2016, 32(1):129-135. DOI: 10.13982/j.mfst.1673-9078.2016.1.021
    [Abstract](1113) [HTML](0) [PDF 1.29 M](1918)
    Abstract:
    The effect of pea starch, green bean starch, and potato starch on the gel properties of silver carp surimi were investigated in this study. The changes of gel strength, water holding capacity (WHC), cooking loss, transverse relaxation time (T2), and microstructure of the surimi gel in the presence of different amounts of added starches were analyzed. The results showed that the addition of 8% or 10% potato starch or green bean starch significantly increased the gel strength and WHC of silver carp surimi gel, and reduced cooking loss. The results of low field nuclear magnetic resonance (LF-NMR) showed that starches had a greater impact on transverse relaxation times (T23, T24) than on transverse relaxation times (T21, T22) of surimi gel. Especially, the addition of 10% potato starch or green bean starch significantly decreased T23 and T24 of the surimi gel and weakened the mobility of immobilized water. Compared with potato starch or green bean starch, pea starch significantly improved the gel properties of silver carp surimi with an added amount of only 4%, while cooking loss, T23, and T24 were significantly reduced. With an addition of 10% potato starch, 10% green bean starch, or 4% pea starch, a highly uniform and compact gel network structure was formed in silver carp surimi.
    22  Effects of Peach Kernel Protein Isolates on the Physical and Oxidative Stability of Water-in-oil Emulsions
    YI Jian-hua ,  SUN Yi-fei ,  ZHU Zhen-bao ,  DONG Wen-bin ,  HUANG Xin
    2016, 32(1):136-142. DOI: 10.13982/j.mfst.1673-9078.2016.1.022
    [Abstract](1039) [HTML](0) [PDF 942.33 K](1400)
    Abstract:
    A water-in-oil (W/O) emulsion was prepared using a microfluidizer, with walnut oil rich in polyunsaturated fatty acids as the oil phase. Peach kernel protein isolates (PKPIs) were added to the aqueous phase, and the emulsion was stored in the dark at 45?C. The particle size distribution, mean particle size, and other physical properties were measured on alternate days, and the primary oxidation products (lipid hydroperoxides) and secondary oxidation product (headspace hexanal) were determined in order to evaluate the influence of aqueous phase PKPI on the stability of W/O emulsions. The results showed that the application of PKPIs could reduce the emulsion droplet size and improve the physical stability of W/O emulsions. Additionally, PKPIs show antioxidant activity; at the concentration range of 0.1~0.4 wt%, the physical and oxidative stability of W/O emulsions increases with the increasing PKPI concentrations. Aqueous phase pH had a significant effect on the oxidative stability of emulsions. The antioxidant activity of PKPI at aqueous phase pH 7.0 was higher than that at pH 3.0. Calcium ionic strength of aqueous phase also had an important impact on the stability of PKPI W/O emulsions. When the concentration of CaCl2 was in the range of 100-200 mM, the physical stability of the emulsions increased with increasing ionic strength. At low levels of calcium ionic strength of aqueous phase in the emulsion (≤10 mM CaCl2), a high ionic strength was able to suppress the antioxidant activity of PKPI. At a high level of calcium ionic strength (≥ 100 mM CaCl2), a high ionic strength was able to accelerate lipid oxidation in the emulsions.
    23  Effect of Red Koji on the Antioxidant Properties of Guangdong Hakka Rice Wine
    ZHAO Wen-hong ,  MO Yi-can ,  HONG Ze-chun ,  WU Hu-lian ,  HUANG Min-xin ,  LI Bin
    2016, 32(1):143-150. DOI: 10.13982/j.mfst.1673-9078.2016.1.023
    [Abstract](987) [HTML](0) [PDF 943.98 K](1661)
    Abstract:
    In order to determine the effect of red koji on the antioxidant properties of Guangdong Hakka rice wine, the differences in the total phenolic content, total antioxidant capacity, hydroxyl radical (?OH), and 2,2-diphenyl-1-picrylhydrazyl (DPPH?) radical scavenging abilities, as well as the reducing power of the Guangdong Hakka rice wines developed using different formulations of koji were analyzed in this experiment. The results showed that the highest total phenolic content (183.78 μg/mL) was found in rice wine using a combination of red koji, wheat koji, and Chinese yeast and was significantly different from that of the wine developed using red koji only. The inhibitory rate on the self-oxidation of linoleic acid in rice wines using a combination of red koji, wheat koji, and Chinese yeast, a combination of wheat koji and Chinese yeast, and red koji alone were 52.3%, 38.3%, and 25.8%, respectively; the corresponding half maximal inhibitory concentration (IC50) values for DPPH? radical scavenging ability were 75.33 μL, 195.79 μL, and 113.58 μL, respectively. Rice wine using a combination of red koji, wheat koji, and Chinese yeast exhibited the highest reducing power, which was close to that of butylated hydroxytoluene (BHT) and was significantly different from that of wine prepared from only wheat koji and Chinese yeast. Increased addition of red koji led to an increase in the antioxidant activity of Hakka rice wine; however, red koji did not affect the anti-lipid peroxidation effect of Hakka rice wine. Thus, the antioxidant activity of rice wine using a combination of red koji, wheat koji, and Chinese yeast was higher than that of rice produced using a combination of wheat koji and Chinese yeast and red koji alone, and red koji had a certain influence on the antioxidant activity of Guangdong Hakka rice wine.
    24  Stability of Antioxidant Peptides Extracted from Pseudosciaena crocea Viscera
    LI Zhi-yu ,  ZHANG Chong ,  TIAN Yu-ting ,  ZHENG Bao-dong
    2016, 32(1):151-158. DOI: 10.13982/j.mfst.1673-9078.2016.1.024
    [Abstract](1073) [HTML](0) [PDF 947.85 K](1459)
    Abstract:
    The stability of the antioxidant activity of antioxidant peptides extracted from Pseudosciaena crocea viscera were studied under different conditions. Peptides with strong antioxidant activity were selected by size exclusion chromatography (SEC), and the antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH?) radical scavenging rate and Fe2+ chelating capacity as indexes. Under conditions of neutral pH, room temperature, low NaCl concentration, and appropriate amounts of K+,Ca2+, and Al3+, the antioxidant activity of the antioxidant peptides from Pseudosciaena crocea viscera was generally stable, and DPPH? radical scavenging rate and Fe2+ chelating capacity were 88.5% and 66.7%, respectively. With high NaCl concentration, high temperature, additions of K+, Ca2+, and Al3+, and long-duration ultraviolet irradiation, the antioxidant activity of the antioxidant peptides from Pseudosciaena crocea viscera was reduced by 30%. Furthermore, at acidic pH and additions of glucose, fructose, and lactose at 70 ℃, the DPPH? radical scavenging activity of the antioxidant peptides from Pseudosciaena crocea viscera was increased to approximately 90%; while alkaline conditions were conductive for the Fe2+ chelating capacity, indicating that treatments have different impacts on different antioxidant indicators. In addition, pepsin digestion treatment had no significant impact on the antioxidant activity of antioxidant peptides from Pseudosciaena crocea viscera, and further chymotrypsin digestion significantly decreased the antioxidant activity stability of the peptides. Therefore, appropriate processing and storage are critical for maintenance of the stability of the antioxidant peptides extracted from Pseudosciaena crocea viscera.
    25  Preparation of a Starch-based Carrier for a Gastric Floating Controlled-release Delivery System and Its in vitro Release Behavior
    ZHANG Hui ,  HUANG Xiao-yi ,  HUANG Yan-ran ,  CHEN Ling
    2016, 32(1):159-163. DOI: 10.13982/j.mfst.1673-9078.2016.1.025
    [Abstract](854) [HTML](0) [PDF 735.16 K](1267)
    Abstract:
    Carboxymethyl groups were introduced into starch molecules to obtain a starch-based gastric floating drug carrier. The influence of degree of substitution (DS) of the carboxymethyl group on the structure and performance of the starch-based gastric floating drug carrier was investigated systematically. The results showed that, with increasing DS of the carboxymethyl group and decreasing crystallinity of carboxymethyl starch, the swelling property decreased after the initial increase; when the DS was 0.8, the swelling index of carboxymethyl starch increased by ten times compared with that of the native starch. Based on this result, a gastric floating drug delivery system was prepared with vitamin B1 as a functionally active substance and carboxymethyl starch as the carrier material. The in vitro release behavior of vitamin B1 gastric floating tablets was evaluated in simulated gastric fluid. The results revealed that the carboxymethyl starch based gastric floating tablets had good floating and sustained-release properties. When the carboxymethyl starch with a DS of 0.08 was used as the carrier, the tablets could maintain floating in gastric fluid for 8 h with a floating lag time of less than 2 min. The in vitro drug release kinetics suggest that the carboxymethyl starch based gastric floating system can extend the vitamin B1 release time to 6 h, and the release behavior follows zero order kinetics.
    26  Line Intercept Histogram-based Arimoto Entropy or Arimoto Gray Entropy for Food Image Segmentation
    WU Yi-quan ,  LONG Yun-lin
    2016, 32(1):164-169. DOI: 10.13982/j.mfst.1673-9078.2016.1.026
    [Abstract](964) [HTML](0) [PDF 748.24 K](1278)
    Abstract:
    In food production, the numerous kinds of foods produced have to meet the applicable national food safety standards. Therefore, methods for food image segmentation should be rapid with high accuracy and high universality. In food image segmentation methods based on the threshold of two-dimensional Arimoto entropy or two-dimensional Arimoto gray entropy, the algorithm is highly complex. Hence, it is difficult to meet real-time requirements. To solve this problem, a method using line intercept histogram-based Arimoto entropy or Arimoto gray entropy for food image segmentation was proposed. First, the line intercept histogram was defined, which was followed by building of the line intercept histogram of images according to this definition. Finally, Arimoto entropies or Arimoto gray entropies of different gray levels in this line intercept histogram were calculated. When the maximum entropy was reached, the corresponding grayscale was determined to be the optimal image segmentation threshold. Several experiments were performed on different kinds of food images by using this method. Compared with the existing segmentation methods based on one-dimensional and two-dimensional Arimoto entropy and Arimoto gray entropy, the method proposed here can achieve better performance by increasing algorithm speed and improving segmentation results.
    27  Computational Fluid Dynamics Simulation of Storage Temperature Field in a Non-ventilated Underground Granary
    WANG Zheng-qing ,  YING Peng ,  ZHENG Jia-huan
    2016, 32(1):170-174. DOI: 10.13982/j.mfst.1673-9078.2016.1.027
    [Abstract](968) [HTML](0) [PDF 683.65 K](1417)
    Abstract:
    The storage temperature field of an underground granary is an important factor affecting the quality of stored grain and the surrounding environment. In this study, Gambit software was used to build a 3-dimensional model of an underground granary. The model was meshed and variations of the grain heap temperature field under non-ventilated conditions during the storage process were studied using computational fluid dynamics (CFD) numerical simulation method. The mass conservation equation, momentum equations, and wall heat transfer equations in CFD software were optimized by writing and importing the user-defined function (UDF). Variations in the temperature field at a non-ventilated underground granary were obtained by iterative calculation and CFD software simulation. The results demonstrated a continuous heat and mass transfer between grain heaps and surrounding building structures, as well as between the grain heaps, with an increase in grain storage time in the underground granary. Additionally, the final temperature drew close to the constant local underground temperature. The results show that an underground granary is an economically feasible alternative for grain storage as well as provide a reference for the control of temperature of underground granaries and mechanical ventilation for grain heaps.
    28  Effects of Different Cooking Methods on Lipid Oxidation and Volatile Compound Profile of Pork
    WANG Rui-hua ,  JIANG Wan-zhou ,  WANG Qian ,  CHEN Jian-chu ,  YE Xing-qian ,  LIU Dong-hong
    2016, 32(1):175-182. DOI: 10.13982/j.mfst.1673-9078.2016.1.028
    [Abstract](1070) [HTML](0) [PDF 1.02 M](1535)
    Abstract:
    The effects of boiling, roasting, microwave heating, and frying in soybean oil, peanut oil, or sunflower oil on lipid oxidation and the volatile compound profile of pork were evaluated. The obtained results indicate that cooking may promote lipid oxidation in pork, and all the investigated cooking methods increased peroxide value (POV) and 2-thiobarbituric acid (TBA) value of pork. The pork samples treated with different cooking methods showed significant differences (P < 0.05) in the degree of lipid oxidation; the highest degree of lipid oxidation was found after roasting, followed by microwave heating, boiling, and frying. Gas chromatography-mass spectrometry (GC-MS) analyses identified 68 volatile compounds in cooked pork, mainly aldehydes, aliphatic hydrocarbons, alcohols, ketones, and esters, and the contents of total volatile compounds ranged from 221.09 (pork fried in soybean oil) to 1084.61 (boiled pork) AU×106/g. The major volatile compounds were aldehydes, ranging from 73.78% (pork fried in sunflower oil) to 78.79% (roasted pork). Hexanal was determined to be the most abundant compound. TBA value correlated significantly with aldehydes, alcohols, and total volatile compounds (P < 0.05), while the correlation between volatile compounds and POV value was not significant (P > 0.05). Principal component analysis (PCA) can effectively distinguish pork samples cooked with different cooking methods.
    29  Effect of Different Manufacturing Processes on the Rheological Properties and Microstructure of Accelerated-ripened Cheddar Cheese
    ZHANG Jian-qing ,  WANG Ying ,  JING Xue-lian ,  ZHANG Li-ping ,  LI Xiao-dong
    2016, 32(1):183-187. DOI: 10.13982/j.mfst.1673-9078.2016.1.029
    [Abstract](882) [HTML](0) [PDF 878.36 K](1372)
    Abstract:
    Three accelerated ripening methods were used to prepare cheddar cheese samples. Sample 1 was a non-accelerated-ripened control cheddar. Samples 2, 3, and 4 were prepared by addition of a ripened cheese slurry; using a mixture of ripened cheese slurry and encapsulated enzyme; and with encapsulated enzyme alone. A rheometer and scanning electron microscope (SEM) were used to study the qualities of the samples. The frequency sweep test results indicated that with increasing frequency, the complex viscosity η* values of the four samples decreased significantly while the storage modulus G′and loss modulus G″values increased significantly (P ＜ 0.01). At the same scanning frequency, the rank order of the complex viscosity values of the samples was as follows: sample 1 > sample 3 > sample 2 > sample 4. The temperature sweep test showed that the G′and G″values of all of the samples decreased significantly with increasing temperature (P ＜ 0.01). The damping factor (tanδ) values of all samples decreased after the initial rise, indicating that the temperature change had a significant effect on the G′and G″values of all of the accelerated-ripened cheese samples during the dynamic scanning. The transition temperatures of sample 1, sample 2, sample 3, and sample 4 were 37.5 ℃, 32.5 ℃, 35 ℃, and 32.5 ℃, respectively. The SEM images showed a large amount of large mechanical openness in samples 1 and sample 3, with less mechanical openness in sample 2. There was almost no mechanical openness in sample 4, indicating that sample 4 had a better texture after accelerated ripening.
    30  Cytochrome C Oxidase Subunit I sequence as a DNA Barcode to Identify Common Meat Species
    WANG Shuang ,  LI Yong-bo ,  MA Chao-feng ,  ZHANG Wei ,  TIAN Chen-xi ,  ZHOU Wei ,  ZHANG Yan
    2016, 32(1):188-193. DOI: 10.13982/j.mfst.1673-9078.2016.1.030
    [Abstract](2241) [HTML](0) [PDF 673.20 K](1956)
    Abstract:
    To detect adulteration in four common meat species and related meat products, and determine if the products are consistent with the label description, a DNA barcoding technique was established in this study. The cytochrome c oxidase subunit I (COI) gene was used as the target gene to identify four types of animal-derived foods. Genomic DNA from cattle, sheep, pig, and duck was extracted and used as template and six pairs of universal primers were designed based on the conserved regions of the COI gene. Polymerase chain reaction (PCR) amplification was performed using these six pairs of universal primers as well as seven pairs of universal primers obtained from the literature. The sequencing results were aligned using basic local alignment search tool (BLAST) analysis of the GenBank database, to evaluate the identification and detection capabilities of each DNA barcode. The COI-A sequence was found to be optimal, showing 100% amplification efficiency in four species. A total of 20 batches of meat product samples were analyzed using the primer COI-A and approximately 90% samples were found to be consistent with their label descriptions. Amplification failed for one batch of beef-ball sample due to low meat content, while duck-derived material was detected in a second batch, indicating adulteration. DNA barcoding technique is rapid and effective, and the COI-A sequence selected in this study can be applied to directly identify beef, lamb, pork, and duck as well as related meat products. The results of this study provide a reference for species identification of other common animal-derived foods.
    31  Effect of Different Solvents on the Extraction and Activities of Taro Proteins
    TONG Jing-jing ,  ZHANG Xiao-yuan ,  LAI Fu-rao ,  WU Hui ,  YU Wen-wen
    2016, 32(1):194-202. DOI: 10.13982/j.mfst.1673-9078.2016.1.031
    [Abstract](1132) [HTML](0) [PDF 785.88 K](1613)
    Abstract:
    The proteinsamino acid composition, the total sugar, total phenol and the contents of water, salt, ethanol, tris(hydroxymethyl)aminomethane (Tris) and isoelectric point precipitation extracts of Zhangxi taro were determined. The antioxidant capacity, coagulating activity and trypsin inhibitory activities of the five extracts were analyzed, in order to obtain a taro protein extract with relatively high activity. The results from the experiment on antioxidant activity showed that all extracts had certain 2,2′-azino-bis (3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS)?and hydroxyl radical scavenging capacities, and the Tris extract exhibited relatively strong scavenging capacities for both radicals. All taro extracts showed agglutinating activity against rabbit erythrocytes, but no coagulation activity against sheep erythrocytes. The specific hemagglutinating activities of the five extracts were as follows: salt extract (3.24 × 103 HU/mg) > Tris extract (2.88 × 103 HU/mg) > isoelectric point precipitation (1.86 × 103 HU/mg) > water extract (1.41×103 HU/mg) > ethanol extract (0.98×103 HU/mg). Among the five extracts, ethanol extract had no trypsin inhibitory activity. Salt extract, water extract, and Tris extract had higher trypsin inhibitory activities, and the corresponding values were 134 TIU/mg, 130.51 TIU/mg, and 113.30 mg/TIU, respectively. In conclusion, the Tris extract contained more proteins with high activity among the five extracts, as well as more protein bands than the others.
    32  Preparation of Polyurethane-based Sustained Release Thermal Sensitive Plastic Wrap by Phase Inversion and Its Application
    XIAO Kai-jun ,  CAI Sheng ,  TANG Xu ,  ZHAN Ting ,  DONG Hao
    2016, 32(1):203-209. DOI: 10.13982/j.mfst.1673-9078.2016.1.032
    [Abstract](865) [HTML](0) [PDF 800.38 K](1351)
    Abstract:
    Polyurethane-based sustained release thermosensitive plastic wrap was prepared using phase inversion, with carvacrol and synthetic polyurethane as the antimicrobial preservative and the raw material, respectively. The phase transition temperature, vapor permeability, release properties, and antibacterial effects of the polyurethane-based sustained release thermosensitive plastic wrap were measured by using a differential scanning calorimeter, Fourier transform infrared spectrometer, and X-ray diffractometer, and its application in Cantonese-style bakery packaging was studied. The results showed that carvacrol and polyurethane formed a film by physical blending, and the phase inversion temperature of this film was 47.9 ℃. Following an increase in the temperature from 40 ℃ to 50 ℃, the vapor permeability and sustained release of the wrap were dramatically increased. The vapor permeability rate increased from 158.01 g×m-2×24 h to 469.50 g×m-2×24 h, and the sustained release rate increased from 1.06% to 3.28%. Furthermore, the composite film showed a significant inhibitory effect against Escherichia coli, Bacillus subtilis, and mold. When used for the preservation of bread, croissants, moon cake, and other food items, polyurethane-based sustained release thermosensitive plastic wrap showed excellent antimicrobial effects and it was able to extended the product shelf life two to four times.
    33  Quality Evaluation Modeling of Dried Shark Fin Products Based on Principal Component Analysis
    XIAN Yan-ping ,  DONG Hao ,  LUO Dong-hui ,  ZHAO Mou-ming ,  GUO Xin-dong
    2016, 32(1):210-217. DOI: 10.13982/j.mfst.1673-9078.2016.1.033
    [Abstract](1151) [HTML](0) [PDF 779.95 K](1762)
    Abstract:
    The δ13C value, δ15N value, and contents of 23 metal elements and 17 amino acids in 13 dried shark fin products were determined by elemental analysis-isotope ratio mass spectrometry (EA-IRMS), inductively coupled plasma-mass spectrometry (ICP-MS) and automatic amino acid analysis. A total of 15 indexes, including δ13C value, δ15N value, aspartic acid (ASP), threonine (THR), proline (PRO), leucine (LEU), lysine (LYS), Mg, Ca, Cr, Mn, Fe, Cu, Zn and Ba, were selected to establish a quality evaluation model for dried shark fin products by the principal component analysis method. For this model, five eigenvalues (λ1 = 3.793, λ2 = 3.626, λ3 = 2.290, λ4 = 1.662, λ5 = 1.281) greater than 1 were obtained. The first five common factors were extracted from SPSS and their variance contribution rate reached 84.343%, indicating the quality of dried shark fin products can be adequately reflected by the selected first five factors. The quality of 51 dried shark fin products was evaluated by the established model. The results showed that the comprehensive scores of genuine dried shark fin samples ranged from 71.9498 to 564.9416, while those of fake and artificial dried shark fins ranged from 607.9568 to 644.1284 and 648.014 to 798.5972, respectively. Therefore, the quality evaluation model established in this study can rapidly and effectively assess the quality of dried shark fin products.
    34  Inoculation of Staphylococcus and Micrococcus to Improve the Oxidative Stability of Cantonese Sausages
    ZHANG Da-lei ,  CHEN Wei-wei ,  LI Jie-feng ,  JIANG Ai-min
    2016, 32(1):218-223. DOI: 10.13982/j.mfst.1673-9078.2016.1.034
    [Abstract](1005) [HTML](0) [PDF 783.44 K](1292)
    Abstract:
    The aim of this study was to investigate the mechanism of extending the shelf life of Cantonese sausages by bacterial inoculation. Strains Staphylococcus H33B and Micrococcus X142B originally isolated from Cantonese sausages based on their protease, lipase, and nitrite reductase activities were used to inoculate the sausages. First, the contents of peptides with different molecular weights in each treatment group were determined. Subsequently, four common antioxidant assays were employed to determine the antioxidant activities of the peptides (<5 ku), and finally, the values for fat oxidation, protein oxidation, and metmyoglobin content were determined. The results showed that the bacterial inoculation could not only significantly increase the content of small-molecule peptides (MW < 5 ku) in the sausage but also enhance the antioxidant activities of the peptides in the treatment group. Additionally, bacterial inoculation could reduce the extent of oxidation in the Cantonese sausages during storage, and the most significant effect was observed in the product inoculated with mixed bacteria. These results indicate that the inoculation of some kinds of bacteria into Cantonese sausages can reduce the extent of oxidation, thus extending their shelf life.
    35  Influence of Storage Temperature and Spice Extracts on Microfloral Changes in Vacuum-packaged Sausage
    HAN Qi ,  KONG Bao-hua ,  YAO Lai-bin ,  SUN Fang-da
    2016, 32(1):224-229. DOI: 10.13982/j.mfst.1673-9078.2016.1.035
    [Abstract](925) [HTML](0) [PDF 681.69 K](1303)
    Abstract:
    Sausages with or without additional spice extracts were vacuum packed and stored at room temperature (20 ℃) or 4 ℃, to study the effect of storage temperature and addition of spice extracts on changes in microflora of vacuum-packaged sausages. Both, traditional culture and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) methods were used in this study. The results from traditional plate culture method revealed that the total bacterial count as well as that of Lactobacillus sp., Pseudomonas sp., Staphylococcus sp., and Brochothrix thermosphacta showed a dramatic increase (P < 0.05), and the number of microorganisms in the sample stored at 20 ℃ was greater than that stored at 4 ℃ (P < 0.05). The addition of spice extracts significantly reduced the number of microorganisms in the sausage samples under the same storage condition (P < 0.05). PCR-DGGE results showed that Lactobacillus sp., Pseudomonas sp., Brochothrix thermosphacta, and Staphylococcus sp. were the dominant spoilage bacteria during storage, similar to the results from the traditional plate culture method.
    36  Effect of Characteristic Xinjiang Oil Coatings on the Preservation of Eggs
    WANG Qing-ling ,  WEI Chang-qing ,  KONG Shuang ,  ZHANG Lei ,  LU Shi-ling
    2016, 32(1):230-234. DOI: 10.13982/j.mfst.1673-9078.2016.1.036
    [Abstract](1045) [HTML](0) [PDF 633.83 K](1341)
    Abstract:
    The effects of different coating agents on the preservation of eggs were compared by studying the changes in the internal qualities (weight loss, yolk moisture content, Haugh unit (HU), yolk index, and albumen pH) of coated eggs stored at 22 ℃ for 50 days. The results showed that weight loss, moisture content, and pH of albumen increased significantly (p < 0.05), whereas the yolk index and HU decreased dramatically during storage. With increasing storage time, the impact of coating agents on the egg internal quality was more significant. After 50 days of storage, the weight loss of oil-coated and emulsion-coated eggs (<3%) was significantly lower than that of noncoated (18%) and chitosan-coated eggs (11.2%). The yolk index and HU of noncoated and chitosan coated eggs decreased significantly during storage, whereas freshness was maintained in oil-coated eggs. Moreover, the albumen pH of noncoated and chitosan-coated eggs considerably increased from 8.51 to 9.07 and 8.92, respectively, while the pH of oil-coated eggs slightly decreased. In addition, no significant difference in yolk moisture content was observed among the different types of coating agents. This study demonstrates that the oils used in this experiment, especially linseed oil, exhibit significant protective effects on the internal quality of eggs.
    37  Quality Changes in Different Varieties of Taro Treated by Microwave Vacuum Drying
    WEI Qiu-yu ,  ZHANG Zhong-yuan ,  LI Da-jing ,  JIANG Ning ,  JIN Bang-quan ,  LIU Chun-quan
    2016, 32(1):235-241. DOI: 10.13982/j.mfst.1673-9078.2016.1.037
    [Abstract](1199) [HTML](0) [PDF 862.34 K](1871)
    Abstract:
    Changes in the nutritional composition of eight different varieties of taro (Colocasia esculenta (L.)Schott) before and after microwave vacuum drying were analyzed, and the changes in color, hardness, crispness, expansion rate, microstructure, sensory quality and other quality parameters of dried products from different taro varieties were studied. The results showed that the moisture content of fresh taro corm ranged from 61.33~82.94%, and the highest moisture content was found in Fenghua taro. The starch content of fresh taro corm ranged from 15.87~30.25%, and the highest starch content was found in Xiangsha taro. The highest sucrose content (2.6 g/100 g) and the highest soluble protein content (1455 mg/100 g) were observed in Lipu taro and Hongxiang taro, respectively. Except for sucrose, other nutritional components were significantly reduced in the dried taro products, and starch content showed the highest decrease. The differences in the quality of dried taro slices among different varieties were significant after microwave vacuum drying. Among them, Lipu taro, Longxiang taro, Fenghua taro, Pinlang taro, and Xiangsha taro had high brightness values and small color change values, and the color of the products was well maintained. Longxiang taro and Wugu taro exhibited a high expansion rate, an apparent internal porous structure, moderate hardness, and good crispness. Sensory evaluation showed that Longxiang taro, Fenghua taro, and Wugu taro had better color, shape, texture, and sensory quality, and their acceptable levels were significantly higher than those of the other taro varieties.
    38  Effect of Whole Wheat Flour on the Qualities of Youtiao Dough and Youtiao Product
    LI Ling ,  WANG Li ,  QIAN Hai-feng ,  ZHANG Hui ,  QI Xi-guang
    2016, 32(1):242-249. DOI: 10.13982/j.mfst.1673-9078.2016.1.038
    [Abstract](988) [HTML](0) [PDF 691.46 K](1344)
    Abstract:
    The effect of whole wheat flour (WWF) on the rheological and pasting properties of youtiao dough and the quality (expansibility, color, texture, and oil content) of youtiao product were investigated in this study. The results showed that with increasing ratio of WWF in the basic formula of youtiao dough to replace refined wheat flour (RWF), the dough development time was decreased from 16.03 min to 11.33 min and the dough stabilizing time declined from 18.23 min to 10.23 min, whilethe water absorption rate was increased from 64.87% to 76.33%. The pasting properties of youtiao mixed powder were also significantly affected by WWF. Especially, the viscosity peak decreased from 1160 to 990.7 (RVU). As for youtiao product, the specific volume of youtiao product using 100% WWF substitution was only 3.01 cm3/g. Meanwhile, the addition of WWF darkened the surface color of youtiao and the value of L* was decreased from 73.42 to 57.89, while the moisture content increased from 28.04% to 34.09%. Additionally, the texture of youtiao product was significantly influenced by WWF. In particular, the hardness of youtiao with 100% WWF substitution was five times of the control (11958.38 g vs 2490.45 g). The total oil content in youtiao produced with RWF was 19.60%, while the total oil content in youtiao produced with 100% WWF was only 11.25%. The analyses showed that the WWF substitution rate was positively correlated (r = 0.869) with the moisture content of youtiao and was negatively correlated with specific volume (r = 0.995), surface oil content (r = 0.942), and structure oil content (r = 0.951). WWF addition can be used to produce a type of fried WWF products with low oil content and high nutritional value.
    39  Effect of Sucrose Treatment on Flavonoid Content and Antioxidant Activity of Sedum aizoon Leaves
    HU Yue ,  WANG Hong-fei ,  DONG Shuan-quan ,  CHENG You-sheng ,  XU Feng ,  SHAO Xing-feng ,  LI He-sheng
    2016, 32(1):250-255. DOI: 10.13982/j.mfst.1673-9078.2016.1.039
    [Abstract](834) [HTML](0) [PDF 763.83 K](1406)
    Abstract:
    Young twigs from Sedum aizoon L. were incubated in media containing various concentrations of sucrose (5, 10, 20, 30, and 40 mmol/L). The medium containing 20 mmol/L sucrose exhibited a relatively good flavonoid accumulation during the incubation, with the flavonoid content (wet weight) of Sedum aizoon L. cultured in this medium being 1.58 times greater than that of the control group. This medium was selected to study the antioxidant capacity of Sedum aizoon L. Sucrose treatment significantly increased the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and total phenolic content. The sucrose-treated group had higher activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD) than the control group due to the impact of exogenous sucrose. In addition, the phenylalanine ammonia-lyase (PAL) activity for the sucrose-treated group was higher than that of the control group. These results indicate that sucrose treatment enhances flavonoid content and antioxidant activity. These results provide a new approach and a theoretical basis for flavonoid accumulation using Sedum aizoon L.
    40  Effects of Hot Air Drying and Microwave Drying on Characteristics and Quality of Germinated Brown Rice
    XU Chuo-wei ,  ZHANG Lu ,  ZHAO Si-ming ,  XIONG Shan-bai ,  XIE Meng-meng ,  ZHANG Pei
    2016, 32(1):256-260. DOI: 10.13982/j.mfst.1673-9078.2016.1.040
    [Abstract](1080) [HTML](0) [PDF 619.38 K](1527)
    Abstract:
    Germinated brown rice (GBR) was dried using hot air or microwaves and effects the drying characteristics, main nutritional content, enzymatic hydrolysability, hardness, and color of the dried GBR were analyzed. Drying mathematical models were established to provide a basis for the prediction of microwave drying and the control of drying conditions. The drying model based on Fick's laws of diffusion and Page equation fit the hot air drying and microwave drying curves of GBR well. The drying rate constant and moisture effective diffusivity increased with the increase in hot air temperature or microwave power per gram. The activation energy of hot air drying of GBR was 55.76 kJ/mol. Drying conditions significantly affected the content of main nutritional content, enzymatic hydrolysability, and hardness. The contents of reducing sugar, free amino acid and γ- aminobutyric acid of GBR treated by microwave drying were relatively low. Browning reaction during the drying process changed the color of the GBR to yellow, while the redness value after microwave drying was higher than that after hot air drying.
    41  Comparison of Non-volatile Components of Fish Sauces Prepared with Different Fast Fermentation Processes
    CHEN Zhi-yao ,  ZHANG Ye-hui ,  TANG Dao-bang ,  LIU Xue-ming ,  CHEN Zhi-yi
    2016, 32(1):261-265. DOI: 10.13982/j.mfst.1673-9078.2016.1.041
    [Abstract](961) [HTML](0) [PDF 654.88 K](1555)
    Abstract:
    Sea fish was used as raw material in four fast fermentation processes, including enzymatically hydrolyzed fish with a mixture of soybean meal and koji (E-SFS), enzymatically hydrolyzed fish with a mixture of peanut meal and koji (E-PFS), whole fish with a mixture of soybean meal and koji (SFS), and whole fish with a mixture of peanut meal and koji (PFS). The effects of the different processes on the non-volatile components and sensory properties of fish sauce were investigated. The results showed that the contents of non-salt soluble solids, total nitrogen, and crude fat were significantly different（p < 0.05）among the four samples, with the values being in the following order: E-SFS > E-PFS > PFS > SFS. The content of total nitrogen in all samples met the first-grade requirement for commercial fish sauce. Analysis of free amino acids (FAAs) showed that the highest amount of total FAAs was found in E-SFS, the highest proportion of umami FAAs was found in E-SFS and E-PFS, and the highest proportion of bitter FAAs was found in in SFS and PFS. The sensory quality of the samples was closely related to the interactions among the non-volatile components of each substance. The sensory evaluation revealed that E-SFS had the strongest umami flavor, while PFS exhibited the strongest fishy smell, but with the highest overall acceptability.
    42  Determination of Triazine and Phenylurea Herbicides in Milk Samples Using Ionic Liquid Vortex-assisted Surfactant-enhanced Emulsification Microextraction
    HUANG Zhi-hong ,  SONG Mao-hong ,  WANG Su-li ,  YUANG Guang-yao ,  LIU Min
    2016, 32(1):266-271. DOI: 10.13982/j.mfst.1673-9078.2016.1.042
    [Abstract](941) [HTML](0) [PDF 1.03 M](1662)
    Abstract:
    An ionic liquid vortex-assisted surfactant enhanced emulsification microextraction (IL-VASEME) procedure was developed and validated to determine the levels of triazine and phenylurea herbicides in milk using high-performance liquid chromatography (HPLC). 1-Hexyl-3-methylimidazolium hexafluorophosphate (C6MIMPF6) was used as the extraction solvent and was dispersed in the milk solution samples with a vortex. Meanwhile, a surfactant, used as the emulsifier, enhanced the speed of the mass-transfer of analytes from the aqueous phase to the IL and prevented the IL from sticking to the centrifuge tube wall. Acetic acid and Na2SO4 were used to remove proteins and fats, thus eliminating the interference with the analytes. Additionally, the effects of the type and volume of IL, type and concentration of the surfactant, vortex extraction and centrifugation time, ion pair concentration, and sample pH on the extraction efficiency were investigated. Under the optimal conditions, a good linearity was found in the range of 1–400 μg/L, and the correlation coefficients ranged from 0.9963 to 0.9998. The limit of detections (LODs) (0.018–0.095 μg/L) and limit of quantifications (LOQs) (0.10–0.38 μg/L) of the method were calculated based on the signal-to-noise ratios of three and ten of the lowest extractable concentration, respectively. The proposed method was used to determine six herbicides in low fat milk, pasteurized plain milk, pure milk, and fresh milk, and the recovery experiments were performed at three concentration levels, while the recoveries and relative standard deviations (RSDs) ranged from 70.34% to 100.02% and from 2.06% to 9.95%, respectively.
    43  Speciation Analysis of Calcium, Iron, and Zinc in the Oral Liquid Containing Polygonatum and Enzymes
    CHEN An-hui ,  CHEN Shang-long ,  WU Yong-hua ,  SHAO Ying ,  LI Ji-wu ,  LIU Shu-bin ,  ZHENG Xiu-wen
    2016, 32(1):272-277. DOI: 10.13982/j.mfst.1673-9078.2016.1.043
    [Abstract](812) [HTML](0) [PDF 760.60 K](1466)
    Abstract:
    A method was developed for the speciation analysis of metal elements in the oral liquid containing Polygonatum and enzymes. The suspended or soluble metals in the oral liquid were isolated by using a 0.45-μm microporous membrane. The inorganic and organic metal species were purified with a D101 macroporous adsorption resin, and the protein-bound and polysaccharide-bound metals were separated from the organic metal species by acetone and absolute ethyl alcohol extractions, respectively. Microwave digestion-high resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was used to determine calcium, iron and zinc in different species. The results showed that there were high contents of calcium (318.80 ± 5.38 μg/mL), iron (17.93 ± 0.28 μg/mL), and zinc (3.50 ± 0.06 μg/mL) in the oral liquid containing Polygonatum and enzymes, and most of these metal elements were soluble. Organic metal species were dominant among the soluble metal elements, with organic calcium, iron, and zinc elements accounting for 54.11%, 49.74%, and 55.40%, respectively, of the corresponding total metal elements in the oral liquid. Protein-bound calcium, iron, and zinc accounted for 16.24 ± 0.39%, 12.42 ± 0.22%, and 13.21 ± 0.29%, respectively, of the corresponding total metal elements in the oral liquid. Polysaccharide-bound calcium, iron, and zinc accounted for 25.07 ± 0.50%, 18.47 ± 0.28%, and 4.35 ± 0.29%, respectively, of the corresponding total metal elements in the oral liquid, showing that the polysaccharide-bound zinc content was lower than that of the other metal species. The proposed method shows a high practical value, providing a scientific basis for the speciation analysis of metal elements and illustrating fundamental data for further study on the functions of the oral liquid containing Polygonatum and enzymes.
    44  Dual-amplified Colorimetric Immunoassay Based on PtNPs-PV for Detection of Ractopamine at Ultra-trace Level in Meat Samples
    CHEN Shu-xian ,  LIU Jing ,  FU Tian ,  PAN Dao-dong ,  SUN Yang-ying ,  CAO Jin-xuan ,  ZENG Xiao-qun ,  WU Zhen
    2016, 32(1):278-283. DOI: 10.13982/j.mfst.1673-9078.2016.1.044
    [Abstract](1303) [HTML](0) [PDF 868.87 K](1335)
    Abstract:
    A colorimetric immunoassay for the detection of ractopamine (RAC) residues in pork is presented in this study. This method combined the high selectivity of antigen-antibody specific binding and the signal-amplification effect from the complex of colloidal platinum nanoparticles (PtNPs) and the PowerVision (PV) agent. It could detect RAC residues at ultra-trace levels specifically and sensitively. The secondary antibodies and a large amount of horseradish peroxidase (HRP) contained in the PV agent can specifically bind with antibodies and catalyze the substrate 3,3'-diaminobenzidine (DAB) to generate colored precipitates. PtNPs can also catalyze DAB to produce colored precipitates and complexes, thereby, achieving a double amplification effect. The amount of RAC residues in the sample can be calculated by measuring the changes in the absorbance of DAB precipitation. Under the optimized assay conditions, this method exhibited a high detection sensitivity and a good correlation in the range of 0.05~20 ng/mL with R2 = 0.992 And the detection limit was 0.025 ng/mL. This approach showed many advantages,including high sensitivity, selectivity, and accuracy as well as rapid detection,which can meet the requirement of onsite surveillance of RAC residues in pork.
    45  Comparison of Two Methods for Glycated Hemoglobin (HbA1c) Measurement
    LI Jun-min ,  YANG Ying ,  DONG Xu-wan ,  LI Shan ,  WANG Ju-fang ,  CAO Cheng-xi
    2016, 32(1):284-289. DOI: 10.13982/j.mfst.1673-9078.2016.1.045
    [Abstract](980) [HTML](0) [PDF 845.51 K](1863)
    Abstract:
    The level of glycated hemoglobin (HbA1c) in the blood is a standard measure of the long-term glycemic status of the human body. High-performance liquid chromatography (HPLC) is the standard reference method for HbA1c measurement as designated by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Gel-capillary isoelectric focusing (cIEF) with a stable pH gradient of 20 mmol/L NaOH (catholyte solution) and 20 mmol/L sulfuric acid (anolyte solution) and gels containing ampholytes have outstanding separation power. In this study, HPLC has been compared to gel-cIEF for the measurement of HbA1c. HPLC and gel-cIEF were used to measure the HbA1c values of 46 randomly selected blood samples. Correlation analysis revealed that the two methods showed a good correlation. The HPLC method was prone to interference by hemoglobin variants and exhibited low specificity. The gel-cIEF method was not affected by hemoglobin variants and showed high specificity. In conclusion, gel-cIEF can be used as an alternative method to HPLC for the standard detection of glycated hemoglobin.
    46  Flavor Precursor Compounds of Green Coffee Beans from Different Geographical Origins in Yunnan Province
    DONG Wen-jiang ,  ZHANG Feng ,  ZHAO Jian-ping ,  HU Rong-suo ,  LU Min-quan
    2016, 32(1):290-296. DOI: 10.13982/j.mfst.1673-9078.2016.1.046
    [Abstract](1074) [HTML](0) [PDF 601.03 K](1580)
    Abstract:
    The composition and content of flavor precursor compounds in green coffee beans from Dehong, Baoshan, Lincang, and Pu-erh were analyzed using one-way analysis of variance (ANOVA) and principal component analysis (PCA). Thus, the differences in green coffee beans from different geographical origins were studied interms of flavor precursor compounds. The highest and lowest levels of total amino acid content were found in Dehong coffee (10.31%) and Baoshan coffee (9.07%), respectively, while the protein and amino acid contents of Dehong coffee were similar to those of Baoshan coffee.. The fat and fatty acid contents of Dehong and Lincang coffee samples were lower than those of Puer and Banshan coffee samples, while the highest and lowest levels of monosaccharide content were found in Pu-erh coffee (17.21%) and Baoshan coffee (15.95%), respectively. PCA and ANOVA results indicated that fatty acid content of Pu-erh samples and amino acid content of Baoshan coffee were significantly different from those of samples from other regions. Additionally, monosaccharide, protein, and fat contents of Lincang samples were significantly different from those of Baoshan samples. Most samples were clustered in the 2-dimensional score plot drawn based on these properties. This study provides a theoretical reference for Yunnan coffee roasting.
    47  Determination of Six Small-molecule Compounds in Polyethylene Terephthalate (PET) Used for Food Packaging by GC-MS
    HUANG Zhan-yan ,  WANG Zhi-wei
    2016, 32(1):297-303. DOI: 10.13982/j.mfst.1673-9078.2016.1.047
    [Abstract](1010) [HTML](0) [PDF 749.69 K](1429)
    Abstract:
    A method for determination of six small-molecule compounds in food packaging material polyethylene terephthalate (PET) was developed in this study, using gas chromatography coupled with mass spectrometry. Methylene chloride ultrasonic-assisted extraction and dissolution methods in a mixed solvent of phenol/1,1,2,2-tetrachloroethane were compared and optimized. The extract was separated using a HP-5MS column, the analytes were detected by mass spectrometer, and retention time and peak area were used for qualitative and quantitative analyses, respectively. The results showed that the optimum conditions for methylene chloride ultrasonic extraction were as follows: solid to liquid ratio (m:V) 1:15, extraction time 30 min, and extraction cycle one time. A good linearity was found for six small-molecule compounds in the range of 0.05~2 mg/L, with the coefficients of determination greater than 0.9980. The limit of detection and the limit of quantitation were 0.1~25 μg/L and 1~25 μg/L, respectively. The recovery rates of spike concentrations of 200, 500, and 1000 μg/L were between 71.99% and 109.99%, relative standard deviations (RSDs) were between 0.01~8.20%; the intra-day and inter-day precisions were less than 4.74% and 5.86%, respectively. This method was used for the determination of six small-molecule compounds in 25 different types of commercial PET materials used for food packaging. Toluene, butylated hydroxy toluene (BHT), or di-(2-ethylhexyl) phthalate (DEHP) were detected in five samples, and the highest contents of toluene, BHT, and DEHP found, were 308.11 mg/kg, 500.31 mg/kg and 482.57 mg/kg, respectively. The advantages of this method include simple pre-treatment procedure, good separation, and high sensitivity, and this method can be used for routine determination of six small-molecule compounds found in PET materials.
    48  Polycyclic Aromatic Hydrocarbon Accumulation Patterns and Related Health Risk Assessment of Aquatic Products in Ningbo
    WANG Bao-feng ,  WENG Pei-fang ,  DUAN Qing-yuan ,  ZHONG Hui-ying ,  CHAI Li-yue ,  SU Qing ,  WU Zu-fang ,  ZHANG Xin
    2016, 32(1):304-312. DOI: 10.13982/j.mfst.1673-9078.2016.1.048
    [Abstract](1252) [HTML](0) [PDF 720.52 K](1474)
    Abstract:
    The content of polycyclic aromatic hydrocarbons (PAHs) in 29 different aquatic products consumed by residents of Ningbo from 2013 to 2014 was determined using gas chromatography-mass spectrometry (GC-MS) to analyze seasonal accumulation patterns. The PAH exposure dose in the aquatic products consumed by Ningbo residents and the resultant health risk were evaluated. The results showed that thetotal contents of 16 PAHs (wet weight) were 46.31 ± 40.19 (spring), 46.01 ± 22.20 (fall), 31.93 ± 19.13 (winter), and 26.62 ± 24.41 ng/g (summer). The average dose of exposure to PAHs of the urban and rural populations via consumption of contaminated aquatic products were 4584.01 ± 1212.68 and 3523.81 ± 932.21 ng/d, respectively. The incremental lifetime cancer risks for urban and rural populations were 5.27 ± 5.78 × 10-5 (urban) and 2.94 ± 1.81 × 10-5 (rural), respectively, which were higher than the acceptable risk (1.0 × 10-6) and lower than that suggested by the United States Environmental Protection Agency (1.0 × 10-4). These results indicate that there is a potential risk of cancer to Ningbo residents consuming local aquatic products, requiring urgent attention. The uncertainty coefficient of variation of cancer risk associated with PAHs for the rural area (0.20) was higher than that for the urban area (0.16). ED is an important factor that should be controlled to reduce health risks．
    49  Quality of Drainage Water from Different Processing Steps in a Mandarin Canning Plant
    WU Dan ,  CHEN Jian-chu ,  HONG Ji-guang ,  YE Xing-qian ,  LIU Dong-hong ,  WANG Ya-jun ,  ZHOU Jian-feng
    2016, 32(1):313-319. DOI: 10.13982/j.mfst.1673-9078.2016.1.049
    [Abstract](976) [HTML](0) [PDF 710.16 K](1534)
    Abstract:
    Drainage water from the mandarin canning plants is a type of fruit and vegetable processing wastewater . Since large amounts of organic matter are present in the drainage water from mandarin canning plants, this water was collected separately and analyzed in this study for the first time. The sensory, physicochemical, and microbiological indicators of water quality were studied. The result showed that there are significant differences in the water quality between different processing steps during mandarin canning. The drainage water samples could be classified as mildly, moderately, or severely polluted, based on the comprehensive analysis of the water quality. The drainage water from the third rinsing, sorting/grading, conveying, sterilization, and cooling processing steps could be classified as mildly polluted water, with a small number of visible suspended solids, and the chemical oxygen demand (COD) values were between 31.30 mg/L and 110.35 mg/L. The drainage water from the first and second rinsing processing steps was classified as moderately polluted water, with an increased amount of visible suspended solids, and COD values between 500.40 mg/L and 1515.40 mg/L. The drainage water from acid treatment and alkali treatment processing steps was severely polluted, with a large number of visible suspended solids, and COD values between 6827.80 mg/L and 13207.10 mg/L. The processing steps of the third rinsing, sorting/grading, conveying, sterilization, and cooling accounted for 65% of the total water consumption, and they resulted in mildly polluted drainage water, which could be potentially reused.
    50  Highly Specific Quantitative Estimation of Almond Kernel Protein in Almond Protein Beverag
    ZHANG Shi-wei ,  LAI Xin-tian ,  WANG Shi-feng ,  FENG Long-hu ,  TANG Dong ,  YANG Guo-wu
    2016, 32(1):320-325. DOI: 10.13982/j.mfst.1673-9078.2016.1.050
    [Abstract](921) [HTML](0) [PDF 762.62 K](1343)
    Abstract:
    A new method was established to quantitatively estimate almond kernel protein in almond protein beverage using competitive enzyme-linked immunosorbent assay (ELISA). Subsequently, two-dimensional electrophoresis (2-DE) was used to compare the proteomic differences between almond kernel and apricot kernel. Amino acid sequences of apricot pruning protein were determined and a Pru-1 subunit fragment with a mass of 27 kDa and pI (isoelectric point) of 5.5 to 8.0 was identified, extracted, purified, and used as an antigen to prepare a specific monoclonal antibody. This was used to establish the highly specific ELISA method to detect almond kernel protein. With almond soluble protein as standard, the half-maximal inhibitory concentration (IC50) of this new method was found to be 10.3 μg/mL and linear detection range was from 2.0 to 100 μg/mL (R2 = 0.991). The method exhibited good specificity and had no cross-reactivity with the proteins of test apricot kernels and other edible plant seeds. In the pre-treatment procedure, 7 M urea with 0.5% dithiothreitol (DTT) was used as sample extraction solution. The limit of detection for plant protein beverage was 300 μg/mL, with relative standard deviation lessthan10%. The average recoveries of pasteurization, ultra high-temperature sterilization, and autoclave sterilization were 97%, 93%, and 84%, respectively.
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    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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