Volume 31,Issue 4,2015 Table of Contents

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  • 1  The Apoptosis-inducing Effects of Kuding Tea Flavonoids on Human Oral Cancer HSC-3 Cells Through Caspase Activation
    ZHAO Xin WANG Rui PANG Liang QIU Li-hua
    2015, 31(4):1-7. DOI: 10.13982/j.mfst.1673-9078.2015.4.001
    [Abstract](1291) [HTML](0) [PDF 833.68 K](1113)
    Abstract:
    The apoptosis-inducing effects of Kuding tea flavonoids on human oral cancer HSC-3 cells through caspase activation (cysteinyl aspartate specific proteinase) were observed in this study. The MTT assay showed that Kuding tea flavonoids inhibited the growth of HSC-3 cancer cells at a concentration of 0~150 μg/mL; however, the flavonoids did not influence the proliferation of human oral keratinocyte cells (normal cells). Kuding tea flavonoids (concentration, 150 μg/mL) showed a better growth inhibitory effect (78.9%) on HSC-3 cancer cells compared to the soybean isoflavones capsule substance (42.8%) available in the market. Analysis of the mRNA expression in cancer cells showed that Kuding tea flavonoids upregulated caspase-3, caspase-8, caspase-9, Bcl-2 associated X protein (Bax), factor associated suicide (Fas), and Fas ligand (FasL) mRNA expressions, and downregulated the expressions of B-cell lymphoma-2 (Bcl-2), Bcl-xL, cellular inhibitor of apoptosis protein-1 (cIAP-1), and cIAP-2 mRNA, compared to the control. This increase and decrease in mRNA expression was observed to be correlated to the increase in concentration of Kuding tea flavonoids. These results demonstrated that Kuding tea flavonoids induced in vitro apoptosis in HSC-3 cancer cells via caspase activation.
    2  Neuroprotective Effects of Soybean Protein Isolate Hydrolysates against Neuronal Oxidative Damage in PC12 Neuronal Cells
    LIU Jing-bo LIU Wen-chao XU Meng-lei LIU Ji-yun LI Liang-yu
    2015, 31(4):8-12. DOI: 10.13982/j.mfst.1673-9078.2015.4.002
    [Abstract](1143) [HTML](0) [PDF 739.33 K](1154)
    Abstract:
    The neuro-protective effects of soybean protein isolate hydrolysates (SPIHs) against neuronal oxidative damage were investigated in a PC12 cell model in this study. Four hydrolysates with different molecular weights were obtained from soybeans (raw material) through enzymatic hydrolysis and membrane separation. The antioxidant properties of the SPIHs were also investigated. Subsequently, a neuronal oxidative damage model was constructed by stimulating PC12 cells with H2O2. SPIHs at appropriate concentrations were used to treat the damaged cells; the effect of SPIHs on cellular oxidative damage was evaluated using various biological indices. The results of these analyses indicated that low molecular weight SPIHs exhibited the most potent antioxidant activities, and caused a dose-dependent improvement in the neuronal cell viability, reduction in lactate dehydrogenase (LDH) release and malondialdehyde (MDA) formation, and suppression of intracellular accumulation of reactive oxygen species (ROS) (p < 0.05 or p < 0.01). Based on the results of this study, low molecular weight SPIHs were believed to protect neuronal cells against neuronal oxidative damage, and could be utilized as a functional component in functional food and health products to protect against neuronal oxidative damage.
    3  Effect of Flavonoids Extracted from Corn Silk (FESM) on Rats with Gouty Arthritis
    LIN He DONG Jin-xiang QIU Zhi-dong LV Guang-fu ZHANG Jing-zhuo CHANG Zhi-da LIN Zhe
    2015, 31(4):13-16. DOI: 10.13982/j.mfst.1673-9078.2015.4.003
    [Abstract](1381) [HTML](0) [PDF 651.97 K](1460)
    Abstract:
    The effect of flavonoids extracted from corn (Stigma Maydis) silk (FESM) on gouty arthritic rats was determined in this study. Rats in the treatment group were treated with different quantities of FESM (1, 0.5, and 0.25 g/kg) via gavage for 8 days; rats in the control and model groups were treated with the same amount of distilled water. On the fifth day, rats from the treatment and model groups were injected with sodium urate (2.5 mg/mL) in the right ankle joint cavity one hour after gavage, in order to induce gouty arthritis. The extent of swelling in the right ankle joint, and plasma interleukin 1α (IL-1α), IL-6, tumor necrosis factor-α (TNF-α), intercellular adhesion molecule 1 (ICAM-1), and matrix metalloproteinase-1 (MMP-1) contents were measured after 72 hours. The right ankle joint was also subjected to an histopathological examination. Rats belonging to the groups treated with high and moderate doses of FESM (1 and 0.5 g/kg) displayed significantly lower right ankle joint swelling (P < 0.01) and plasma IL-1α, IL-6, TNF-α, ICAM-1, and MMP-1 content (P < 0.05), compared to the rats in the control group. Therefore, FESM was believed to improve the degree of pathomorphological changes in the synovial tissue of the joints. These results indicated the beneficial effect of FESM on gouty arthritis.
    4  Grading of Beef Marbling by Using Invariant Moments and An Improved Support Vector Machine
    WU Yi-quan CAO Peng-xiang WANG Kai TAO Fei-xiang
    2015, 31(4):17-22. DOI: 10.13982/j.mfst.1673-9078.2015.4.004
    [Abstract](1326) [HTML](0) [PDF 752.25 K](1105)
    Abstract:
    The image processing techniques was used to improve the objectivity and degree of automation in the grading of beef marbling, in order to minimize the interference caused by human errors in the manual beef marbling grading process. This study proposed the use of a grading method for beef marbling that utilized the invariant moments, a gray level co-occurrence matrix, and a mixed kernel support vector machine (SVM), optimized by a chaotic bee colony. Firstly, the invariant moments and the statistical quantity of gray level co-occurrence matrix of the beef marbling image were computed in order to construct a feature vector. The training and testing samples of the beef marbling image were then inputted to a mixed kernel function SVM. Optimal recognition performance was attained by optimizing the penalty factor and kernel parameters of the mixed kernel function SVM using a chaotic bee colony algorithm. Finally, the samples to be graded were inputted to the SVM for classification and recognition, and the optimal grading results were obtained. A large number of experimental results revealed grading accuracies of 100% (Grade One), 93.3% (Grade Two), 93.3% (Grade Three), 96.7% (Grade Four), and 100% (Grade Five), based on the standard beef marbling image obtained by NY/T676-2010. The proposed method showed the highest grading accuracy compared to those of the methods developed utilizing gray moment and SVM, and the gray level co-occurrence matrix and the black propagation (BP) neural network; in addition, the obtained results were closest to the actual grading results obtained by the professional beef marbling grading division.
    5  Evaluation of the Anti-proliferative Activities of Major Fruits in China on Human Hepatic Carcinoma (HepG2) and Colon Adenocarcinoma (Caco-2) Cells
    LIU Dong WAN Hong-xia SUN Hai-yan
    2015, 31(4):23-28. DOI: 10.13982/j.mfst.1673-9078.2015.4.005
    [Abstract](1298) [HTML](0) [PDF 603.36 K](1225)
    Abstract:
    The total phenolic content and the anti-proliferative activities of the phenolic extracts against HepG2 and Caco-2 cells were determined by the Folin-Ciocalteu method and the methylene blue assay, respectively; the correlation between the total phenolic content and the anti-proliferative activity of the extracts was analyzed. The results of these analyses revealed that plum (Prunus salicina Lindl.) had the highest total phenolic content (1686.08 ± 96.94 ?mol gallic acid equivalent (GAE)/100 g of fresh fruit), whereas watermelon (Citrullus lanatus) (83.54 ± 2.10 ?mol GAE/100 g of fresh fruit) and hami melon (Cucumis melo var. saccharinus) (79.35 ± 0.76 mol GAE/100g of fresh fruit) had the lowest phenolic content among the 25 tested species. Among the fruit species with quantifiable anti-proliferative activities (half maximal effective concentration (EC50)), plum and guava (Psidium guajava Linn.) showed the strongest anti-proliferative activities against HepG2 cells (EC50 values: 18.99 ± 0.06 and 20.94 ± 0.09 mg/mL, respectively), whereas pears (Pyrus spp.) showed the weakest anti-proliferative activity against these cells (EC50 value: 389.63 ± 10.82 mg/mL). Plum also demonstrated the strongest anti-proliferative activity against Caco-2 cells (EC50 value: 8.73 ± 0.11 mg/mL), while the activity of pitava (Hylocereus undulatus Britt.) was observed to be the weakest (EC50 value: 388.07 ± 7.04 mg/mL). The anti-proliferative activities of fruits on HepG2 and Caco-2 cells were significantly correlated to their total phenolic content (R2 = 0.4147, p < 0.01; R2 = 0.4071, p < 0.05, respectively). This correlation indicates the high anti-proliferative effect of fruit polyphenols on cancer cells.
    6  Effects of Cyclocarya paliurus (Batal.) Iljinskaja Polysaccharides on Lipid Metabolism and Expressions of PPARα, FAS, and GLUT4 mRNA in Hyperlipidemic Rats
    LI Nan ZHAO Jing WU Ru YANG Zhan-wei WANG Wen-jun
    2015, 31(4):29-35. DOI: 10.13982/j.mfst.1673-9078.2015.4.006
    [Abstract](1493) [HTML](0) [PDF 966.47 K](1158)
    Abstract:
    The effects of Cyclocarya paliurus (Batal.) Iljinskaja polysaccharides (CPPs) on the expression of genes related to lipid metabolism were examined in hyperlipidemic rats. Hyperlipidemic rats were randomly divided into hyperlipidemia model control, simvastatin, C. paliurus (CP) water extract group, low-dose CPP, moderate-dose CPP, and high-dose CPP groups (16 rats per group), and all rats were continuously fed for eight weeks. After the experiment, the total antioxidant capacity (T-AOC) and the contents of catalase (CAT), glutathione peroxidase (GSH-Px), and maleic dialdehyde (MDA) in the liver were measured. The mRNA expression levels of PPARα, FAS, and GLUT4 in the liver and adipose tissue were investigated by quantitative real-time polymerase chain reaction (qRT-PCR) to explore the hypolipemic mechanism of CPPs. All CPP-treated groups, irrespective of dose, and the CP water extract group exhibited decreased MDA in the liver after treatment, and the most significant reduction was observed in the high-dose CPP group (53.47% decrease; P < 0.01). The T-AOC value and the contents of CAT and GSH-Px increased in all CPP-treated groups and the CP water extract group (P < 0.01), and the largest increases were 112.05%, 48.63%, and 6.17%, respectively. In addition, each CPP-treated group exhibited increased mRNA expression levels of PPARα and GLUT4 after treatment (P < 0.05, P < 0.01), and the highest increases in the liver were 19.45% and 35.50%, respectively. All CPP-treated groups had decreased FAS mRNA expression, and the largest declines observed in the liver and adipose tissue were 25.02% and 20.49%, respectively. These results indicated that CPP has inhibitory effects on lipid oxidation in the liver and regulates the expression of genes related to lipid metabolism, thus alleviating hyperlipidemia.
    7  Differential Prevalence of Spoilage Bacteria in Salmon Fillets during Refrigerated Storage and Identification of Predominant Spoilage Bacterial Species
    LI Ting-ting DING Ting ZOU Zhao-yang ZHOU Kai YI Shu-min LI Jian-rong
    2015, 31(4):36-41. DOI: 10.13982/j.mfst.1673-9078.2015.4.007
    [Abstract](1155) [HTML](0) [PDF 833.59 K](1409)
    Abstract:
    Chilled fresh salmon fillets were used for the study; the differential prevalence of spoilage bacteria during storage at 0 ℃ was analyzed by morphological observations and 16S rDNA sequence analysis. In addition, the specific spoilage bacteria were separated and identified using the VITEK 2 automated microbial identification system. The major spoilage bacterial species identified in salmon fillets stored at 0 ℃ during the start of storage (day 0) were Staphylococcus sp., Pseudomonas sp., Pediococcus sp., Micrococcus sp., Aeromonas sp., Carnobacterium sp., and Sphingomonas sp. The phase of spoilage bacteria gradually became unitary with the increase in storage time; a significant decrease was observed in the numbers of Staphylococcus sp., Pediococcus sp., and Micrococcus sp., whereas the Aeromonas sp. and Sphingomonas sp. disappeared completely over time. No significant changes were observed in the Carnobacterium sp; on the other hand, there was a gradual increase in the proportion of Pseudomonas sp., leading to its predominance during the end of the storage time. The sequences, amplified by polymerase chain reaction (PCR), were compared against the sequences present in the National Center for Biotechnology Information (NCBI) database; the phylogenetic tree constructed using the MEGA 5.05 software was used for analysis, and the automated microbial identification system was utilized for all measurements. These results identified Pseudomonas fluorescens to be the dominant spoilage bacterium in refrigerated salmon fillets.
    8  Impact Mechanism of Staphylococcus aureus Genomic Islands on Multi-drug Resistant Phenotype and Biofilm-forming Capacity
    DENG Yang LIANG Yan-rui MIAO Jian LI Lin LI Bing XU Zhen-bo
    2015, 31(4):42-50. DOI: 10.13982/j.mfst.1673-9078.2015.4.008
    [Abstract](1384) [HTML](0) [PDF 929.69 K](1175)
    Abstract:
    Staphylococcus aureus (S.aureus) has been long recognized as a common food-borne pathogen in food safety. To study their drug resistence, genomic island typing and biofilm-foming capacity, a toal of 127 clinical isolates of staphylococci strains from Guangzhou were subject to the investigation. A detection of Staphylococcus aureus was conducted with a Micro-broth dilution method to determine the strain susceptibility results from 26 kinds of antibiotics. S.aureus was further confirmed with the detection of specific 16S rRNA, femA, mecA genes by PCR. Ccr and mec complexes of S.aureus SCCmec genomic island elements were typed by multi-PCR. In this experiment, 107 drug-resistent staphylococci are all multi-drug resistant strains, and 76.1% (86/113) show resistance to nine kinds of antibiotics or more. 113 Staphylococcus SCCmec typing results: typeI (0 strains), typeII (12 strains), typeIII (73 strains), typeIV (10 strains), typeV (11 strains),5strains is not typing. In this paper, the correlation of genomic islands with Staphylococcus aureus drug-resistance phenotype and biofilm-forming capacity is analyzed and discussed. It provides a research base for further security control on a variety of food contamination caused by food-borne microorganisms.
    9  Effect of Glutamyl Endoproteinase Modification on Emulsifying Properties of β-conglycinin
    HOU Jun-jie YAN Jiang-yin YANG Xiao-quan
    2015, 31(4):51-57. DOI: 10.13982/j.mfst.1673-9078.2015.4.009
    [Abstract](1158) [HTML](0) [PDF 1.07 M](1387)
    Abstract:
    A soy β-conglycinin (7S) hydrolysate (7S-GE), obtained by the hydrolysis by the glutamyl endoproteinase (E.C. 3.4.21.19) at pH 7.5. The core region of 7S (7S-core) was prepared by filtered the 7S-GE through the micro-filter member with 10 kDa molecule cut-off. The emulsifying ability of 7S, 7S-GE and 7S-core were investigated using zeta-potential, droplet size and saturation surface load. The results showed that the emulsion formed by 7S-core had lower zeta-potential and significant higher droplet size and saturation surface load compared with the emulsion which formed by 7S and 7S-GE. The influence of pH, iron strength on the stability of the emulsions formed by 7S, 7S-GE and 7S-core were investigated. The results showed that the stability of the emulsion formed by 7S-core was decreased remarkably against the pH, iron strength. Higher creaming index and coalescence of oil droplet through the microscope were observed. This study demonstrated emulsifying ability and stability of 7S remarkably depended on the extension regions.
    10  Characterization of Antibiotic, Heavy Metal, and Benzalkonium Chloride Resistance of Plasmid-carrying Listeria monocytogenes
    ZHANG Hui BAO Hong-duo ZHOU Yan ZHANG Li-li WANG Ran
    2015, 31(4):58-62. DOI: 10.13982/j.mfst.1673-9078.2015.4.010
    [Abstract](964) [HTML](0) [PDF 639.52 K](986)
    Abstract:
    The major aims of this study included the characterization of plasmids carried by Listeria monocytogenes (Lm), and an in-depth analysis of the sensitivity of plasmid-carrying Lm towards antibiotics, the heavy metal cadmium, and benzalkonium chloride. The results of this study showed the presence of endogenous plasmids in 11 Lm strains. All Lm strains displayed average sensitivity to amoxicillin, erythromycin, and rifampicin (22/22), and 100% resistance to cefradine (22/22). Five strains showed intermediate resistance to vancomycin hydrochloride, while some strains were resistant to ciprofloxacin (17/22), neomycinsulphate (16/22), and tetracycline hydrochloride (9/22). The analysis of cadmium resistance showed the presence of plasmids in all strains resistant to the heavy metal cadmium (14/22). In contrast, only three of the plasmid-carrying Lm strains were determined to be resistant to benzalkonium chloride. All Lm strains were identified and lysed via the phage sterilization method. In summary, although the plasmid-carrying Lm isolates displayed increased drug-, benzalkonium chloride-, and cadmium-resistance, they were susceptible to phage action. Therefore, the results of this study indicate a novel method for the control of drug resistance and pollution by resistant-bacteria.
    11  Variations in the Expression of the L-lactate Dehydrogenase Gene during the Different Phases of Lactococcus lactis KLDS4.0325 Growth
    ZHOU Ying GAO Xiao-feng LIU Fei GU Chun-tao HUO Gui-cheng
    2015, 31(4):63-68. DOI: 10.13982/j.mfst.1673-9078.2015.4.011
    [Abstract](1255) [HTML](0) [PDF 1.00 M](1378)
    Abstract:
    The expressions of three L-lactate dehydrogenase genes at the mRNA transcription level during the different phases of Lactococcus lactis KLDS4.0325 growth were investigated in this study. Dynamic variations in the expressions of the three L-lactate dehydrogenase genes (ldh , ldhB, and ldhX) during the different growth phases were detected by fluorescence-based quantitative real time polymerase chain reaction (PCR), using the 16s rRNA gene as the internal standard. The growth curves of the strain were observed to be ‘S’-shaped, with the strains reaching the exponential phase of growth within 2~6 h of culture; subsequently, the cells remained in the stationary phase. The growth curve revealed the extremely strong vitality of the cells; the amplification efficiency curve of the 16s rRNA, ldh, ldhB, and ldhX genes indicated similar amplification efficiencies (close to 100%) of the reference and target genes. These results indicated that the fluorescence-based quantitative real time PCR method reflected the expression level of the target genes adequately. The ldh, ldhB, and ldhX genes were expressed to specific levels during the three time points (6 h, 9 h, and 12 h) of strain growth. In addition to the growth of the strain, the gene expression levels demonstrated a significant upward trend, with a continuous amplitude of increase; the highest expression level was observed at 12 h post-initiation. The levels of expression of the ldh gene significantly differed among the three time points; in addition, the expression of ldhB significantly differed from that of ldhX.
    12  Correlations between Phenolic Compounds Contents in Wheat Bran Fermented by Aspergillus Awamori and Three Types of Enzyme Activities
    DU Xiao-yan WU Hui ZHAO Chao-min MIN Tian TANG Yu-qian LI Xiao-feng LAI Fu-rao
    2015, 31(4):69-76. DOI: 10.13982/j.mfst.1673-9078.2015.4.012
    [Abstract](1188) [HTML](0) [PDF 887.73 K](1308)
    Abstract:
    In the present study, solid state fermentation of wheat bran was performed by three Aspergillus awamori strains (GIM3.266, GIM3.4, GIM3.5, respectively) at 28℃ for 8 days consecutively. Different forms of phenols in wheat bran were extracted and analyzed using the Folin-Ciocaltey method on a daily basis. The activities of xylanase, cellulase, and feruloyl esterase were also investigated during the fermentation process. It was showed that the contents of free phenolic compounds increased sharply after fermentation. The total phenolic content could reach 11561.30 μg/g wheat bran, increasing by 169% than the unfermented wheat bran. Besides, it was found that the activity of cellulose and xylanase increased during the early stage of fermentation, peaking at 156.70 U and 34123.00 U respectively. The activity of feruloyl esterase could reach a peak of 2642.60 U in the middle and later periods. In general, positive correlations were found between the contents of phenolic compounds and the activities of xylanase and feruloyl esterase, revealing that synergistic effects of these two enzymes during fermentation can lead to higher contents of phenolic compounds.
    13  Rheological Properties of Cornstarch after Modification by Dry Heating with Soy Protein Isolate
    QIU Chao LI Xiao-jing ZHAO Mei XIONG Liu JI Na WANG Ya-hong SUN Qing-jie
    2015, 31(4):77-82. DOI: 10.13982/j.mfst.1673-9078.2015.4.013
    [Abstract](1208) [HTML](0) [PDF 929.53 K](1215)
    Abstract:
    The pasting and rheological properties and the microstructure of normal cornstarch (CS) and waxy cornstarch (WCS) mixed with soy protein isolate (SPI) were characterized before and after dry heating using a rapid visco analyser (RVA), a rheometer, and by scanning electron microscopy (SEM). Dry heating with SPI led to a significant increase in starch viscosity; the increase in viscosity of WCS was observed to be more pronounced than that of CS. There was a significant increase in the G′ and G′′ values and a corresponding decrease in the tan δ value of the dry heated mixtures, compared to those of untreated starch. This indicated an increase in gel network structure formation in pasted starch after dry heating; in fact, the gel network of heated pasted starch became more solid-like compared to that observed in untreated starch. The SEM images revealed the occurrence of starch accumulation after dry heating of starch with SPI; in addition, compared to CS/SPI, WCS/SPI was observed to form a larger lump. The accumulation of starch molecules suggested the occurrence of interactions between starch and SPI after dry heating; the interactions of WCS and SPI were more pronounced than those of CS and SPI. This simple heating process (with SPI) could be used as a promising method for the modification of WCS.
    14  Effects of Lactobacillus plantarum M616 on the Fermentation Characteristics of Sourdough
    WANG Jin-shui YANG Sen YIN Yan-li ZHANG Yan-jie FENG Jing-li ZHOU Xiao-pei
    2015, 31(4):83-87. DOI: 10.13982/j.mfst.1673-9078.2015.4.014
    [Abstract](1699) [HTML](0) [PDF 821.65 K](1235)
    Abstract:
    In the current work, the effect of sourdough fermentation by Lactobacillus plantarum M616 on pH, TTA, and sugar content were analyzed, and the rheofermentation properties of the sourdough were examined using an F3 Rheofermentometer and Chopin Alveograph. The results showed that L. plantarum M616 had suppressive effect on the growth of yeast and played an important role in the changes of pH and TTA. In addition, the degradation of starch by L. plantarum was higher than its absorption of reduced sugar, increasing the sugar content and sweetness of the resulting sourdough. The pH of sourdough decreased to 3.73 at the end of fermentation, which partly inhibited the growth of mold and other unwanted microorganisms. The growth and metabolism of L. plantarum M616 not only improved the dough viscosity and dough thews, but also relieved the decrease in dough tenacity. Among these features, the viscosity and thews were the most affected and increased by two-fold in sourdough compared with yeast-fermented dough.
    15  Regulation of the Recombinant Expression of a Rhizomucor miehei Lipase Gene in Aspergillus oryzae by Hydrogen Peroxide
    WU Xin-liang GUO Yong
    2015, 31(4):88-94. DOI: 10.13982/j.mfst.1673-9078.2015.4.015
    [Abstract](1028) [HTML](0) [PDF 461.99 K](1145)
    Abstract:
    Rhizomucor miehei lipase (RML) is an important microbial lipase with a wide range of industrial applications. The effect of hydrogen peroxide (H2O2) on RML expression in A. oryzae transformant ONL1 was explored in this study. The results of quantitative fluorescence polymerase chain reaction (QF-PCR) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicated that the RML activity of the cultivated A. oryzae ONL1 transformants was increased by five-fold after treatment with 10 mM H2O2 for two hours. The H2O2 treatment did not appear to affect the translation of RML mRNA, with the elevated expression of RML being attributed to the H2O2 regulation of RML transcription. Therefore, hydrogen peroxide might regulate melO promoter-controlled heterologous gene expression at the transcriptional level. Because of the highly volatile nature of H2O2, a prolonged cultivation time led to a lower effect on RML activity. High RML activity within a short cultivation time could be achieved by the continuous addition of H2O2 in the to maintain the concentration of 10 mM in culture medium. The results of the RML activity assay and QF-PCR analysis highlighted the following strategies for the regulation of melO promoter-controlled RML expression in A. oryzae: codon optimization of RML gene sequence, signal peptide optimization, and repeated batch culture.
    16  Analyzing the Changes in Sarcoplasmic Protein Phosphorylation with Respect to Postmortem Ageing Times in Mutton with Different Levels of Tenderness
    CHEN Li-juan LI Xin YANG Yang CHEN Li NI Na ZHANG De-quan
    2015, 31(4):95-101. DOI: 10.13982/j.mfst.1673-9078.2015.4.016
    [Abstract](1004) [HTML](0) [PDF 695.42 K](1004)
    Abstract:
    The major aim of this study was to investigate the changes in the levels of phosphorylation of sarcoplasmic proteins with respect to the postmortem ageing time in mutton with different levels of tenderness. Longissimus muscle samples of 40 sheep were collected at 0.5, 1, 4, 12, and 24 h postmortem, and were divided into two groups (high-level-of-tenderness and low-level-of-tenderness) based on the shear force and myofibrillar fragmentation index (MFI) at 24 h postmortem. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was combined with fluorescence staining in order to analyze the level of phosphorylation of sarcoplasmic proteins. The results of these analyses indicated that groups with different degrees of tenderness and postmortem times showed significantly different levels of sarcoplasmic protein phosphorylation within 24 h (postmortem). The highest levels of protein phosphorylation in the low-level-of-tenderness and high-level-of-tenderness groups were observed at 4 and 12 h postmortem, respectively. In addition, the global levels of sarcoplasmic protein phosphorylation observed in the low-level-of-tenderness group at 0.5, 1, and 4 h postmortem were significantly higher than those observed in the high-level-of-tenderness group. Therefore, the level of sarcoplasmic protein phosphorylation was significantly affected by the varying degrees of tenderness and the different postmortem times (P < 0.05); moreover, it was theorized that protein phosphorylation influences rigor mortis in postmortem muscles through glycolysis, thereby affecting muscle tenderness.
    17  Effect of Exogenous Melatonin on Ethanol Fermentation and Antioxidant Activity of Saccharomyces cerevisiae
    WANG Cheng ZHAN Ji-cheng LIU Xing-yan ZHAO Fang SUN Xiang-yu HUANG Wei-dong
    2015, 31(4):102-108. DOI: 10.13982/j.mfst.1673-9078.2015.4.017
    [Abstract](1311) [HTML](0) [PDF 1.04 M](1386)
    Abstract:
    The effect of exogenous melatonin on ethanol fermentation ability, major fermentation products, antioxidant system, and total antioxidant ability of Saccharomyces cerevisiae was investigated; in addition, the melatonin content in S. cerevisiae was determined. The results showed that fermentation ended on day 8 in the control group, while it continued until day 14 in the treatment groups; however, the total CO2 weight loss, residual sugar content, and alcohol content did not differ significantly between the control and melatonin treatment groups at the end of fermentation. There was a significant decrease in the production of trehalose and glycerol in the treatment groups (after day 8) compared to that observed in the control. The glycerol content in the groups treated with low, medium, and high concentrations of melatonin was observed to be lower by 7.57%, 12.29%, and 11.99%, respectively, compared to that in the control group, which attained a maximum level of 6.25 g/L on day 8. Low concentration melatonin treatment stimulated the activity of superoxide dismutase (SOD) and catalase (CAT) enzymes, and reduced the accumulation of malondialdehyde (MDA) during fermentation. The activity of the SOD was increased in the 0.01 and 1 mg/L melatonin treatment groups by 68.15% and 59.89%, respectively, compared to that in the control; conversely, the CAT activity in the low, medium, and high melatonin treatment groups was observed to increase by 2.85-, 2.87-, and 1.84-fold, respectively, compared to that in the control at the end of fermentation. MDA content in the high melatonin treatment group was 71.44% that of the control (at the end of fermentation). There was an increase in the antioxidant activity of the broth treated with melatonin corresponding to the increase in melatonin concentration. Melatonin concentration gradually decreased during fermentation to reach a steady state level towards the end of the process.
    18  Analysis of the Iron-binding Capacity and Characteristics of Hen Egg Ovotransferrin under Different Conditions
    DU Hua-ying WU Lei-yan ZHU Li-qin YANG Wu-ying JIANG Yan XU Ming-sheng
    2015, 31(4):109-114. DOI: 10.13982/j.mfst.1673-9078.2015.4.018
    [Abstract](1277) [HTML](0) [PDF 804.52 K](1129)
    Abstract:
    The binding capacity of hen egg ovotransferrin (OVT) to different concentrations of iron ions was studied under multiple pH conditions and NaHCO3 concentrations. The effects of iron saturation on the thermal denaturation temperature and structure of OVT were analyzed by differential scanning calorimetry (DSC) and circular dichroism (CD) spectrum analysis. The results showed that complete iron saturation was obtained at an approximate iron ion to OVT molar ratio of 2.2. OVT exhibited higher iron-binding capacity under neutral or slightly alkaline pH conditions. The iron-binding capacity of OVT also increased with the increase in NaHCO3 concentration; however, a steady-state level was reached at NaHCO3 concentrations exceeding 75 mmol/L. The thermal denaturation temperature of OVT increased corresponding to the increase in iron saturation, and was observed to be 63.41 ℃ and 83.29 ℃ for apo-ovotransferrin (apo-OVT) and holo-ovotransferrin (holo-OVT), respectively. Apo-OVT showed a more negative band in the far-ultraviolet CD spectrum compared to holo-OVT; the α-helical content of apo-OVT decreased by 4.4%, while that of β-sheet strands, β-turns, and other structures increased by 2.80%, 1.20%, and 12.90%, respectively. The tertiary structure of holo-OVT displayed an obvious change in the near-ultraviolet region of the CD spectrum.
    19  Regulation of Rice Fatty Acid Oxidation and Microorganisms by Clove Essential Oil Microcapsule Preservative
    LIU Xiang-jun GAO Kai GAO Yu-min LIU Xia LI Xi-hong WU Si LIU Da-miao
    2015, 31(4):115-120. DOI: 10.13982/j.mfst.1673-9078.2015.4.019
    [Abstract](1302) [HTML](0) [PDF 749.95 K](1067)
    Abstract:
    Microcapsule preservative was achieved with β-cyclodextrin and chitosan as the wall material and clove essential oil as the filling material using the envelope method and in-situ polymerization. The surface morphology and release rate of the microcapsule preservative at different temperatures (0, 15, and 30 ℃) were tested. Rice was treated with or without the preservative (0.2 g) at 0, 15, and 30 ℃ to regularly determine quality indices related to rice fatty acid oxidation and microorganisms. SEM characterization analysis showed that the microcapsules were irregular in shape, and the release speeds varied according to the following order 30 > 15 > 0 ℃. Moreover, the apparent degrees of regulation by this preservative on rice fatty acid oxidation and microorganisms was as follows: 30 > 15 > 0 ℃. After storage for 6 months at 30 ℃, the LOX-3 value of rice with this preservative was 2.5 times that of the control group; the fatty acid value of rice with the preservative was 1.9 times that of the control; the total acidity of the control was 2.3 times that of the preservatives; and the total bacteria and total mildew counts in rice with the preservative were more than three times lower than those of the control. Therefore, at 30 ℃, this preservative had the most significant regulatory effects on rice fatty acid oxidation and microorganisms.
    20  Delayed Senescence in Harvested ‘Younai’ Plums Induced by 1-MCP Treatment and Its Relation to Energy Metabolism
    LI Hui LIN Yi-xiong LIN He-tong YUAN Fang LIN Yi-fen CHEN Yi-hui
    2015, 31(4):121-127. DOI: 10.13982/j.mfst.1673-9078.2015.4.020
    [Abstract](1136) [HTML](0) [PDF 893.68 K](1415)
    Abstract:
    The effect of 1-methylcyclopropene (1-MCP) treatment on the senescence of harvested ‘Younai’ (Prunus salicina Lindl. cv. Younai) plums and its relation to energy metabolism was investigated in this study. Harvested ‘Younai’ plums were treated with 0 (control) and 1.2 μL/L 1-MCP for 12 h, and stored at 25 ± 1 ℃. The cell membrane permeability, ATP, ADP, and AMP content, NAD kinase (NADK) activity, and NAD, NADH, NADP, and NADPH expression was analyzed in the control and sample plums during storage. The results of these analyses revealed that MCP-1 treatment slowed the increase in cell membrane permeability, promoted ATP accumulation during the late stage of fruit storage (12~18 days), and delayed the decrease in the level of energy charge during the whole storage period (compared to the control samples). In addition, 1-MCP treatment resulted in the maintenance of a relatively high NADK activity, a reduction in NAD and NADH content, and an increase in the NADP and NADPH content in the 1-MCP treated-‘Younai’ plums. Based on these results, it was concluded that the MCP-1 treatmentinduced the maintenance of the integrity of the cell membrane structure, and the delay in the senescence of harvested ‘Younai’ plums was correlated with the maintenance of a higher level of energy charge.
    21  In vitro Monitoring of the Probiotic Activity of Tea Catechins on Human Intestinal Flora
    YANG Yang ZHANG Xin WENG Pei-fang WU Zu-fang
    2015, 31(4):128-136. DOI: 10.13982/j.mfst.1673-9078.2015.4.021
    [Abstract](1123) [HTML](0) [PDF 976.95 K](1329)
    Abstract:
    Recently, tea catechins have been reported to have certain regulatory effect on intestinal microecology. In this study, high purity (>98%) of EGCG, EGCG3’’Me, ECG and ECG3’’Me were prepared from Guangdong Oolong tea by puri?cation procedures of macroporous resins. Then, the regulation effects of EGCG, EGCG3’’Me, ECG and ECG3’’Me on intestinal microecology in vitro were evaluated by monitoring the bacterial populations and analyzing the concentrations of short-chain fatty acids (SCFA) at different fermentation times (0, 6, 12 and 24 h). The results showed that tea catechins had significant proliferate effect (P<0.05) on beneficial bacteria (Bifidobacterium spp. and Lactobacillus/Enterococcus spp.), significant inhibitory effect (P<0.05) on Bacteroids-Prevotella group and Clostridium histolyticum group, while they did not affect the population of total bacteria (P>0.05). The total SCFA concentrations in cultures with tea catechins were significant higher (P<0.05) than that of the control in each fermentation time point. Moreover, the metabolites of tea catechins during the fermentation were also identified. Together, these results suggest that tea catechins, including methylated tea catechins have potential prebiotic-like activity by modulating intestinal microbiota and generating SCFA, contributing to the improvements of host health.
    22  Bioactive Compounds and Antioxidant Activity of Different Varieties of Soybean Cultivars
    ZHOU Meng MA Yu-rong HUANG Hui-hua
    2015, 31(4):137-143. DOI: 10.13982/j.mfst.1673-9078.2015.4.022
    [Abstract](1060) [HTML](0) [PDF 765.90 K](1806)
    Abstract:
    The characteristics of ten soybean cultivars that are widely grown in South China were examined. Soy flours were prepared, and the total phenolic content (TPC), total flavonoid content (TFC), isoflavone content, and antioxidant activity (based on 2,2-diphenil-1-picrylhydrazyl [DPPH] radical scavenging capacity, ferric ion reducing antioxidant power [FRAP], and oxygen radical absorbance capacity [ORAC]) were measured. The correlations between bioactive compound contents and antioxidant activity were analyzed. Bioactive compound contents and antioxidant activity were significantly influenced by soybean genotype. The TPCs of soybean cultivars ranged from 3.18 to 4.47 mg GAE/g, and the highest and lowest contents were detected in cultivars HC5 and HC6, respectively. The TFCs ranged from 0.27 to 0.39 mg CE/g, and the highest and lowest contents were detected in cultivars HC3 and HC2, respectively. The isoflavone contents ranged from 720.24 to 1,285.47 μg/g, and the highest and lowest contents were detected in cultivars HX3 and HC6. Cultivars HX1 and GXD2 exhibited the highest DPPH and lowest FRAP values, respectively, while the highest and lowest ORAC values were observed in cultivars HX5 and HX9, respectively. DPPH and FRAP were positively correlated with TPC and TFC, respectively, while ORAC was negatively correlated with isoflavone content. Based on this comprehensive evaluation, HC5, HX1, and HX9 were much richer in bioactive compounds than the other cultivars, while HX1 and HX5 had higher antioxidant activity and can be used as raw materials for the production of high-quality soy-based foods.
    23  Variations in the Antioxidant Activities of Four Crude Polyphenolic Extracts from Barley during the Germination Process
    ZHAO Pei ZHAO Ning FAN Qiao-ning QUAN Mei- ping HE Meng-fei CHEN Jia-hui JIN Xiao-yan TIAN Cheng-rui
    2015, 31(4):144-150. DOI: 10.13982/j.mfst.1673-9078.2015.4.023
    [Abstract](1259) [HTML](0) [PDF 857.11 K](1223)
    Abstract:
    The content of four kinds of polyphenolic extract and the variations in their antioxidant activities during germination were investigated in Ganbei 4 barley. The antioxidant activity was evaluated based on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and ferric reducing activity. Simultaneously, the contents of monomeric phenolic acids from the crude polyphenolic extracts (four types) were determined by high-performance liquid chromatography (HPLC). The results of these analyses revealed the significant influence of malting on the content and types of crude polyphenolic extracts and monomeric phenolic acid, as well as on their antioxidant activities. The proportion of free phenolic acids was observed to be the highest in raw barley than that in germination process.. These values showed a significant decrease during the steeping process; subsequently, the values showed a remarkable increase during the late stage of germination. Correlation analysis revealed a close relation between the ferric-reducing ability, DPPH and ABTS radical scavenging abilities of the four crude polyphenols and their compositions. Monomeric phenolic acids, which were closely related to crude polyphenols, were also observed to significantly affect the antioxidant activities of crude polyphenols. Ferulic acid, catechin, and p-coumaric acid were identified as the major active phenolic acid components of Ganbei 4 barley.
    24  The Radical Production and Oxidative Properties of Rice Protein under Microwave Radiatio
    HU Bo FAN Da-ming Wusgal LIAN Hui-zhang ZHANG Hao CHEN Wei
    2015, 31(4):151-156. DOI: 10.13982/j.mfst.1673-9078.2015.4.024
    [Abstract](1138) [HTML](0) [PDF 781.91 K](1031)
    Abstract:
    The relationship between radical production and oxidative properties of rice protein under microwave irradiation was investigated. Electron spin resonance (ESR) studies proved that the radicals produced in the microwaved rice protein samples were carbon-centered. Comparative studies revealed that radicals were not only produced in thermally treated materials, but also in small quantities in native samples of rice protein. Under microwave irradiation, the ESR signals for radicals gradually increased with the reduction of water activity as well as with the increase of microwave power. With the increase of irradiation time, the intensities increased, and the rate of increase of intensities of radical signals also increased. By measuring the surface hydrophobicity and the contents of carbonyl, sulfhydryl, and free amino groups, it was found that the internal hydrophobic side-chains of the protein were exposed and some of the peptide bonds were broken. Combined with the production of radicals during microwave irradiation, it was proposed that when microwaved to over 80 °C, the increase rate of production of carbon-centered radicals would be significantly higher, and was consistent with oxidation characteristics.
    25  Characteristics of Carbon Dioxide Production by Insect and Fungus Growth in Stored Wheat
    GUO Li-hui ZHAI Huan-chen CAI Jing-ping
    2015, 31(4):157-163. DOI: 10.13982/j.mfst.1673-9078.2015.4.025
    [Abstract](832) [HTML](0) [PDF 858.33 K](1005)
    Abstract:
    In the present work, the characteristics of carbon dioxide (CO2) produced by insects and fungi were studied under different wheat storage conditions with varying temperatures and moisture contents. The findings could be useful for determining the storage safety of wheat. The results showed that storage temperature had the most dramatic effects on the rate of CO2 production by fungi during growth. When the storage temperature rose from 20 ℃ to 25 ℃, the CO2 production rate increased by ten-fold. Gas was mainly produced by insects in wheat with moisture in the safe range, while fungi were the main producers in high-moisture wheat. In terms of CO2 production characteristics, there was a linear relationship between insect density and CO2 production quantity (r > 0.99), and gas production by fungi appeared accelerated. The gas production rate increased by 5.96-fold when fungal counts in wheat did not change significantly (p > 0.05) during early storage. In large-scale wheat warehouse experiments, the gas production rate of insects was stable, and the CO2 concentration fluctuation rate was 13% at 25 days in the 4-m-deep area of the wheat bulk, at which insects carried out their activities. In comparison, the changes in CO2 concentrations were 37-fold at locations 0.5 m from mold spots. Therefore, the harmful activities of insects and fungi in stored wheat could be sensitively monitored by CO2 detection.
    26  Effect of Fructose-treatment on the Quality, Shelf-life, and Antioxidant Capacity of Picked Broccoli
    TANG Yue-chang XU Feng DONG Quan-quan CHEN You-sheng SHAO Xing-feng WANG Hong-fei
    2015, 31(4):164-169. DOI: 10.13982/j.mfst.1673-9078.2015.4.026
    [Abstract](1006) [HTML](0) [PDF 929.70 K](1144)
    Abstract:
    This study aimed to delay the yellowing of broccoli florets by treating with fructose at different concentrations (0, 4%, 6%, 10%, 12%, 14%, and 16%); in addition, the antioxidant activity and quality of the fructose-treated broccoli was determined. The results of this analysis revealed that treatment with 12% fructose effectively prolonged the shelf life of broccoli; fructose-treatment notably inhibited the decrease in hueangle (H) and increase in lightness (L*) values, and reduced the rate of degradation of chlorophyll in broccoli. The fructose-treated broccoli showed lower peroxidase (POD) activity, while retaining higher superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and ascorbate peroxidase (APX) activities, compared to the control broccoli. Fructose treatment also enhanced the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical-scavenging activity and total phenolic content of broccoli. In summary, fructose treatment effectively delayed senescence in picked broccoli, and inhibited the deterioration in broccoli quality. These results provide the theoretical basis for a novel technique for the preservation of picked broccoli.
    27  Development and Properties of a Polypyrrole-based Electrochemical Biosensor for Cholesterol Detection
    ZHANG Xiu-hua WAN Kai LIANG Zhen-xing JIN Feng PIAO Jin-hua
    2015, 31(4):170-174. DOI: 10.13982/j.mfst.1673-9078.2015.4.027
    [Abstract](874) [HTML](0) [PDF 836.93 K](1240)
    Abstract:
    A novel, current-based cholesterol biosensor was produced by electrochemical polymerization of pyrrole monomers, using cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) as catalysts. Polypyrrole (PPY) was prepared by electrochemical polymerization and the microstructure of the PPY film was characterized by scanning electron microscopy (SEM). The electrochemical characteristics and anti-interference capacity of the biosensor were evaluated by cyclic voltammetry (CV). The results of this analysis revealed that the PPY film obtained after 300 polymerization circles had optimum sensor performance. The biosensor displayed optimal operation at a pH of 8.0 and showed good detection performance at cholesterol oxidase and horseradish peroxidase concentrations of 30 and 20 mg/mL, respectively. The biosensor displayed a linear range of 2.0 × 10-6 to 1.6 × 10-4 mol/L and an apparent Michaelis-Menten constant ( ) of 5.6 × 10-6mol/L. The biosensor also exhibited excellent anti-interference activity after the addition of glucose, ascorbic acid (AA), and uric acid (UA), which affected the current by 8.1%, 8.5%, and 10.8%, respectively. The cholesterol biosensor exhibited good selective response to cholesterol, and can, therefore, be used in the determination of cholesterol content.
    28  Isolation and Identification of the Antiviral Active Ingredients of Inonotus obliquus
    HUANG Ji-guo LV Jing YU Xiong-tao HAN Yuan-yuan XIE Yi-zhen PAN Hong-hui
    2015, 31(4):175-180. DOI: 10.13982/j.mfst.1673-9078.2015.4.028
    [Abstract](1528) [HTML](0) [PDF 725.89 K](1174)
    Abstract:
    The chemical composition, structure, and antiviral activity of ethyl acetate extracts of Inonotus obliquus was identified and analyzed. Inonotus obliquus is an edible and medical fungus with diverse and complex structures and a wide range of biological activities; in addition, this fungus has a low toxicity to humans and is rich in secondary metabolites. Inonotus obliquus fruit bodies were dried, ground, and sequentially extracted at room temperature using ethyl acetate, methanol, and water. Ten compounds were isolated from the ethyl acetate extract of Inonotus obliquus using various chromatographic techniques. Various modern spectroscopic methods of analysis and the data available in literature were used to identify the following compounds: betulin (1), inotodiol (2), 3-hydroxy-lanosta-8,24-dien-21-al (3), 3β-hydroxytirucallic acid (4), ergosterol-5,8-peroxide (5), 3β-hydroxy-5α,8α-epidioxyergosta-6,9,22-triene (6), di(n-butyl) phthalate (7), 5-dehydroergosterol (8), pentacosanoic acid (9), and lignoceric acid (10). Among these, compounds 6 and 7 were isolated from Inonotus obliquus for the first time. Furthermore, the cytotoxicity and anti-HSV-1 activity of the isolated compounds 1–8 were also investigated. Compound 3 showed the strongest anti-HSV-1 activity, with a half maximal inhibitory concentration (IC50) of 98 μM; on the other hand, compound 7 exhibited the strongest cytotoxicity, with a 50% cytotoxic concentration (CC50) of 24 μM. This study provides a scientific basis for the future development of anti-HSV drugs from Inonotus obliquus.
    29  Growth Characteristics of Vibrio parahaemolyticus Biofilm on Glass Surfaces and Biofilm Detachment under Ultrasound Treatment
    WU Qian DENG Xi MA Yue TANG Shu-ze
    2015, 31(4):181-185. DOI: 10.13982/j.mfst.1673-9078.2015.4.029
    [Abstract](1271) [HTML](0) [PDF 637.39 K](1068)
    Abstract:
    The growth characteristics of Vibrio parahaemolyticus biofilms on glass surfaces, the effects of environmental factors during biofilm formation, and biofilm detachment under ultrasound treatment were investigated. The morphology of V. parahaemolyticus biofilms on the glass surface was observed by crystal violet staining, biofilm biomass was measured using an enzyme-linked immunosorbent assay (ELISA) plate reader at 595 nm, and the extent of biofilm detachment was measured by counting colony-forming units (CFU) using the plate count method. V. parahaemolyticus biofilms formed on the glass surface, and could be directly observed using crystal violet staining. The reticular structure formed by the V. parahaemolyticus biofilm became denser with increasing cultivation time. The optimum parameters for V. parahaemolyticus biofilm formation with respect to biomass were determined using the plate reader. For a culture medium salinity of 3%, a rotation speed of 70 r/min, and an incubation time of 24 h, the number of bacteria in the mature V. parahaemolyticus biofilm was 2.56 × 107 CFU/cm2. Optimal biofilm detachment was obtained under pulsed ultrasound treatment (30-s sonication at intervals of 30 s) applying a frequency at 50 kHz for four minutes, and the viability of bacteria was maintained under these conditions.
    30  Screening and Identification of Aroma-producing Microorganisms in Luzhou-flavor Daqu
    MING Hong-mei GUO Zhi ZHOU Jian CHEN Meng-en XU De-fu YAO Xia
    2015, 31(4):186-193. DOI: 10.13982/j.mfst.1673-9078.2015.4.030
    [Abstract](1558) [HTML](0) [PDF 725.29 K](1611)
    Abstract:
    Aroma-producing microorganisms were screened from traditional Luzhou-flavor daqu microbial resources. The relationship between aroma-producing microorganisms and flavoring substances in Luzhou-flavor daqu was also investigated. Functional aroma-producing microorganisms were identified using various molecular biology techniques. Multiple strains of bacteria (22) and yeast (6) were isolated and purified from the various fermentation stages of Luzhou-flavor daqu by traditional microbial separation. The bacterial and yeast strains were separately cultured in wheat solid growth medium, and tested for single-strain aroma production. The individual strains X19 and J3 were observed to produce rich flavors post-fermentation by a sensory evaluation (smell test). The volatile components present in the fermentation products of the two strains were identified by headspace solid phase micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS). This analysis identified a number of flavor substances in the fermentation products of the two strains. Among these, pyrazine, phenylethanol, and guaiacol were identified as important flavor substances present in Luzhou-flavor daqu. Therefore, the two strains were primarily identified as the functional aroma-producing microorganisms present in Luzhou-flavor daqu. Morphological observation and molecular biology identification analyses have identified the X19 and J3 strains as types of Bacillus licheniformis and Wickerhamomyces anomalus, respectively.
    31  Kinetics Governing the Inhibitory Effect of 3-hydroxy-4-methoxycinnamic Acid on Tyrosinase-catalyzed Reactions
    GONG Sheng-zhao CHEN Qing-sheng XU Meng-yi FENG Ai-juan
    2015, 31(4):192-196. DOI: 10.13982/j.mfst.1673-9078.2015.4.031
    [Abstract](1307) [HTML](0) [PDF 769.49 K](1181)
    Abstract:
    The kinetics governing the inhibitory effect of 3-hydroxy-4-methoxycinnamic acid on the activities of monophenolase and diphenolase in tyrosinase were studied using an enzymological kinetic analysis method, in a Na2HPO4-NaH2PO4 buffer system (pH = 6.8) at 30 ℃. The 3-hydroxy-4-methoxycinnamic acid was observed to efficiently inhibit tyrosinase monophenolase and diphenolase activities. Approximately 0.13 mmol/L and 0.39 mmol/L 3-hydroxy-4-methoxycinnamic acid caused a 50% rate inhibition (IC50) in monophenolase and diphenolase activities, respectively; these values were much lower than that of arbutin (IC50 = 5.3 mmol/L for diphenolase activity). The presence of 3-hydroxy-4-methoxycinnamic acid also prolonged the lag period of monophenolase; the presence of 0.20 mmol/L 3-hydroxy-4-methoxycinnamic acid resulted in a lag period of 4.3 min, compared to the 1.1 min lag period of monophenolase in the absence of 3-hydroxy-4-methoxycinnamic acid. The inhibition of diphenolase by 3-hydroxy-4-methoxycinnamic acid appeared to be reversible. This indicated that the inhibitor suppresses the enzyme activity, resulting in a reduction in catalysis efficiency, as opposed to removing the effective enzyme, which leads to a reduction in enzyme activity. The Lineweaver-Burk plot demonstrated the competitive inhibition of tyrosinase by 3-hydroxy-4-methoxycinnamic acid, with a maximum reaction rate (vm) and inhibition constant (KI) of 64.5 μmol/min and 0.11 mmol/L, respectively.
    32  Effect of Whole Barley Flour Addition on Dough Properties and Quality of Bread
    LI Zhen DONG Ying YU Lai-ting SHI La-ni
    2015, 31(4):197-202. DOI: 10.13982/j.mfst.1673-9078.2015.4.032
    [Abstract](1410) [HTML](0) [PDF 877.35 K](1352)
    Abstract:
    High gluten-wheat flour (10%~60%, w/w) was substituted with whole barley flour (hereinafter referred to as barley flour), and, subsequently, the effect of the substitution on dough properties and bread quality was investigated. The results revealed that the addition of barley flour effected a corresponding decrease in the content of wet gluten in barley-wheat mixed flour from 36.43% (control) to 11.43% (with 60% barley flour). In addition, the water absorption capacity increased, while the dough development time, time for stability, C2 value (weakening value), dough extensibility, and maximum resistance significantly decreased with increase in the concentration of barley flour. Meanwhile, dough microstructures were observed to change with the addition of barley flour, displaying coarser structures. The addition of barley flour in the range of 20%~60% resulted in the breakdown of the gas chamber walls; in fact, intact gas chamber structures could hardly be found. The specific volume, springiness, and sensory quality of the bread decreased, while the hardness increased with addition of barley flour. Moreover, a decrease in the area of gas chambers, an increase in the hole area, and a decrease in slice brightness were observed. The addition of 10%~20% barley flour imparted an acceptable overall sensory quality to the bread. However, the quality of bread baking decreased significantly with addition of excess barley flour (30%~60%), with the complete disappearance of the sponge-like texture of bread.
    33  The Effects of Different Storage Conditions on the Physical and Chemical Properties of Heat-moisture-treated Castanea henryi Starch
    XIE Tao TANG Zheng-hui KANG Ling-tao YANG Chun-feng GAO Juan
    2015, 31(4):203-209. DOI: 10.13982/j.mfst.1673-9078.2015.4.033
    [Abstract](932) [HTML](0) [PDF 1.05 M](1018)
    Abstract:
    Starch from Castanea henryi was recrystallized by heat-moisture treatment; in addition, the effect of different storage conditions on the physical and chemical properties of recrystallized starch was studied. Storage at 4 ℃ was observed to exert a significant influence on the in vitro digestion kinetic parameters of recrystallized starch; in addition, storage at this temperature resulted in the formation of starch with greater resistance, with the average degree of polymerization reaching the maximum limit on the 14th day. The type of crystal showed a gradual change from type A (on day 0) to type V on the 3rd and 7th day, and type B on the 14th and 21st day, with significant alterations in the relative crystallinity. Storage at 25 ℃ also had a substantial effect on the in vitro digestion kinetic parameters, resulting in the formation of starch that could be digested faster. The maximum average degree of polymerization was achieved on day 3; the crystal type from day 0 (type A) was retained over time, and the changes in relative crystallinity were not obvious, excluding the appearance of a low-temperature melting zone. The melting enthalpy of crystallized starch stored at 25 ℃ was substantially reduced compared to that stored at 4 ℃; in addition, the reduction in melting peak temperature was observed to be more prominent. Storage at 4/25 ℃ also had a significant effect on the in vitro digestion kinetic parameters, resulting in the formation of starch that was slowly digested. This resulted in a relatively rapid increase in the average degree of polymerization up to the 7th day. The crystal type was altered from type A on day 0 to type V on the day 3, type B on the 7th and 14th days, and type V on the 21st day. Rapid changes in relative crystallinity were observed. In addition, the peak and conclusion temperatures of the high temperature melting zone decreased by large amounts compared to the 4 ℃ storage condition.
    34  Effects of Cryogenic Freezing by Liquid Nitrogen on the Quality and Microstructure of Silver Pomfret (Pampus argenteus)
    LU Jun YU Hai-xia YANG Shui-bing JIANG Qing-qing LIU Wen-juan DONG Kai-cheng HU Ya-qin
    2015, 31(4):210-216. DOI: 10.13982/j.mfst.1673-9078.2015.4.034
    [Abstract](1871) [HTML](0) [PDF 1.08 M](1119)
    Abstract:
    Silver pomfret (Pampus argenteus) was pretreated with liquid nitrogen (LN2) by spray freezing (central point temperature of -40°C in 20 min), followed by freezing storage at -18°C. For the control, samples with similar sizes in the same batch were pretreated by plate freezing (central point temperature of -20°C in 6 h) or frozen directly using a freezer (central point temperature of -18°C in 20 h). Control samples were subsequently stored at -18°C, similar to LN2 samples. The results showed that the pH values of the LN2-frozen samples, plate-frozen samples, and freezer-frozen samples reached minima at 6.42, 6.35, and 6.11, respectively, on the 105th day; the salt-soluble protein contents were 6.71, 3.24, and 1.38 mg/g, respectively, and the Ca2+-ATPase activities were 1.73 × 10-3, 0.76 × 10-3, and 0.56 × 10-3 μmol/(min?mg), respectively. The increases in K values and total volatile base nitrogen were limited with lower prefreezing temperatures. Texture profile analysis (TPA) showed that the hardness, springiness, and resilience of frozen fish meat decreased significantly (P < 0.05) with prolonged storage time. In contrast, a low prefreezing temperature may result in slower changes in these indices. Microstructure observations showed that LN2-frozen samples appeared the most similar to the fresh material, with a narrow gap between the myofibrils and excellent cell integration after storage for 150 days. The results indicated that the LN2 spray method was the best of the three tested methods for maintenance of the quality of silver pomfret.
    35  The Separation of Oxyresveratrol from Mulberry Root and Its Effect on Steady-state Embedding and Inhibition of Tyrosinase Activity
    LIU Guo DU Jie LIU Fei XU Hong CHEN Ha TANG Jian HUA Yang-lin LIU Guang-rong CAO Yong
    2015, 31(4):217-221. DOI: 10.13982/j.mfst.1673-9078.2015.4.035
    [Abstract](1215) [HTML](0) [PDF 599.84 K](1178)
    Abstract:
    Oxyresveratrol is a 2'-hydroxyl derivative of resveratrol (a trans-stilbene); it is an important natural bioactive product with whitening, anticancer, antioxidant, hepatoprotective, anti-inflammatory, and anti-aging functions. In this study, high-performance liquid chromatography (HPLC) was used to detect oxyresveratrol in mulberry root, and its extraction, separation, steady-state embedding, and inhibitory effects on tyrosinase activity were examined. The extraction rate of oxyresveratrol was 94.32% for the following conditions: 80% ethanol as the extraction solvent, an extraction temperature of 70 ℃, an extraction duration of 1.5 h, a liquid to solid ratio of 4:1, and independent extraction of three times. The steady-state embedding rate of oxyresveratrol was 98.91% for the following conditions: a solid content of 40%, an inlet temperature of 190 ℃, an atomizing disk speed of 16,000 r/min, and a feed speed of 1.78 L/h. The oxyresveratrol standard and oxyresveratrol microcapsule samples both had inhibitory effects on tyrosinase activity, and the strength of inhibition was dose-dependent.
    36  The Effect of Heat Treatment on the Vitality and Pathogenicity of Citrus Fungi
    LIN Li-ping CHEN Yu-long ZHU Li-qin LIU Ji-luan LI Yu-mei WU Guo-ping
    2015, 31(4):222-227. DOI: 10.13982/j.mfst.1673-9078.2015.4.036
    [Abstract](972) [HTML](0) [PDF 766.65 K](1109)
    Abstract:
    This study investigated the effect of heat treatment on the vitality and pathogenicity of citrus pathogenic fungi after harvest. The vitality of the fungi was tested by heat-treatment of the fungal spore suspension as well as fungal spore suspension with navel orange skin at 52 ± 1 ℃ for 10 min. Fungal spore viability indices, such as the mortality, morphology, suspension supernatant conductivity value, and OD260nm of five strains of fungus (marked A, B, C, D, and E) were examined after the two heat treatments, respectively. The pathogenicity of strain A (as an example) was determined by analyzing and comparing the changes in disease incidence in navel oranges, caused by contamination with fungal spores heat treated with or without navel orange skin. The results of these analyses revealed that heat-treatment without orange skins resulted in a decrease in fungal spore vitality, while not affecting its pathogenicity. However, simultaneous heat and navel orange peel treatment caused great structural damage to the pathological fungal spores, affecting a significant decrease in its vitality and pathogenicity, compared to fungal spores that were only subjected to heat-treatment. The mortality of strain A spores increased from 48% to 72%; in addition, the emergence time of typical disease lesions in navel oranges was delayed from 4 days to over 7 days.
    37  Development of Monoclonal Antibodies against Helicobacter pylori and Their Applications to Immunological Assays
    MA Jian NI Chao WANG Hai-ying NING Zheng-xiang
    2015, 31(4):228-233. DOI: 10.13982/j.mfst.1673-9078.2015.4.037
    [Abstract](930) [HTML](0) [PDF 649.72 K](1308)
    Abstract:
    Helicobacter pylori (Hp) is a gram-negative, microaerophilic bacterium found in the human stomach and duodenum, and long-term H. pylori infection is linked to the development of gastritis, gastric and duodenal ulcers, and stomach cancer. H. pylori infection is mainly acquired during childhood, and its spontaneous clearance is rare. Its prevalence among adults can be effectively reduced by early diagnosis and antibiotic therapy. In this study, a standard H. pylori strain (ATCC 43504) was cultured in vitro, the lysate was used as an antigen to immunize BALB/c mice, and a hybridoma cell line was prepared using conventional techniques. In total, 21 hybridoma cell lines that stably secreted anti-H. pylori monoclonal antibodies (mAbs) were obtained based on indirect enzyme-linked immunosorbent assay (ELISA) screening and multiple rounds of limiting dilution subcloning. Ascites were prepared and mAbs were purified using ammonium sulfate precipitation methods. The pairing of mAbs and sample detection were conducted by colloidal gold immunochromatographic assays (GICAs), and multiple mAb pairs with high sensitivity and specificity were obtained. Among them, the limits of detection (LODs) of the lysates from two antibody pairs consisting of capture (mAb 2-18E1) and detection (mAb 2-9H5 and mAb 2-17E9) antibodies were 25 ng/mL. These results indicated that the GICA method can provide a basis for the development of reagents to detect H. pylori antigens.
    38  Extraction and Purification of Globulin from Juglans mandshurica Maxim and Characterization of Its Functional Properties
    WANG Xiao-fei MIN Wei-hong ZHU Yun-ming LIU Chun-lei WU Dan CUI Ling-yu LIU Jing-sheng
    2015, 31(4):234-241. DOI: 10.13982/j.mfst.1673-9078.2015.4.038
    [Abstract](1008) [HTML](0) [PDF 929.34 K](1266)
    Abstract:
    Globulin is a major protein component of walnuts (Juglans mandshurica Maxim) from the Changbai mountain. The walnut is rich in proteins; therefore, it must be further developed and processed for appropriate utilization of the protein resources. Walnut globulin was extracted by optimized Osborne method, and purified by ion-exchange chromatography. Walnut globulin was subjected to a preliminary structural analysis; subsequently, its functional properties were comprehensively compared (and analyzed) against those of soy protein isolates (SPI), in order to provide a theoretical basis for its application in food processing. The prepared globulin contained 80.71% protein content. Anion-exchange chromatography showed four peaks; the relative molecular weights corresponding to these peaks were concentrated in the ranges 14.3~27.0 kU, 18.0~21.0 kU, 30.0~37.0 kU, and 44.3~59.0 kU, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The essential amino acid content of the prepared globulin conformed to the Adult Standard Recommendation of the FAO/WTO. The differential scanning calorimetry (DSC) spectrogram of the prepared globulin revealed two endothermic peaks, indicating denaturation temperatures of 98.08°C and 155.33°C, corresponding to enthalpy values of 13.06 J/g and 764.80 J/g, respectively. The Fourier transform-infrared (FT-IR) spectrum revealed that the prepared globulin mainly consisted of alpha helical secondary structures. The functional properties of the prepared globulin, excluding foamability and water absorption (which were significantly lower than those of SPI), were observed to be comparable to those of SPI.
    39  The Effects of Thermal Sterilization on the Quality of Tinned Tuna
    WANG Liang LIU Dong-hong
    2015, 31(4):242-247. DOI: 10.13982/j.mfst.1673-9078.2015.4.039
    [Abstract](995) [HTML](0) [PDF 1001.11 K](1481)
    Abstract:
    A heat penetration test was conducted on tinned tuna in brine (185 g) in this study. The heat penetration parameters were determined at six different temperatures (110, 116, 119, 121, 124, and 127 ℃), using a lethality value of F0 = 8 min from the center of the tin. The results of this study showed that a higher sterilization temperature could significantly shorten sterilization time (P < 0.05). The sterilization time was reduced by 58.94%, 60.98%, 71.14%, 74.19%, and 78.46%, when sterilization temperatures of 116, 119, 121, 124, and 127 ℃ were applied, respectively (compared to the time required for sterilization at 110 ℃). Higher sterilization temperatures at the same lethality caused a significant reduction in the cook value (C) and C to F0 value (P < 0.01). The increase in sterilization temperature caused a gradual increase in L* value (P < 0.01), from 58.76 at 110 ℃ to 71.30 at 127 ℃. On the other hand, the a* and b* values displayed decreasing trends. The hardness of the tuna samples increased with the increase in sterilization temperature (P < 0.05), from 472.57 g at 110 ℃ to 796.03 g (maximum) at 127 ℃. On the other hand, the total volatile basic nitrogen value (TVB-N) decreased with increasing sterilization temperature (P < 0.05), from 25.56 mg/kg sample (at 110 ℃) to15.63 mg/kg sample (at 127 ℃). Thiobarbituric acid (TBA) content was also significantly affected by the sterilization temperature (P < 0.05), with a minimum value of 0.92 mg MDA/kg sample observed at 110 ℃ and a maximum value of 2.26 mg MDA/kg sample observed at 127 ℃. These results indicated that the quality of tinned tuna could be improved by the utilization of a relatively high sterilization temperature.
    40  Effect of Harpin Treatment Combined with Carboxymethyl Chitosan-alginate Composite Coating on Hami Melon Preservation
    ZHOU Yan XIE Jing ZHOU Ran LI Nian wen
    2015, 31(4):248-252. DOI: 10.13982/j.mfst.1673-9078.2015.4.040
    [Abstract](982) [HTML](0) [PDF 841.59 K](1200)
    Abstract:
    The effect of harpin treatment combined with a carboxymethyl chitosan-sodium alginate composite coating on Hami melon preservation was compared with that of the composite coating alone. At room temperature (19 ± 2 ℃), Hami melons were immersed in 90 mg/L harpin for three minutes and coated with a composite coating agent composed of 0.5% carboxymethyl chitosan, 1% sodium alginate, 0.5% glycerol, 0.6% Tween 80, and 0.5% cinnamic aldehyde. Hami melons treated with the composite coating alone were used as the controls, and untreated Hami melons were used as the blank controls. The quality of Hami melon was evaluated based on Vc content, firmness, peroxidase (POD) activity, malondialdehyde (MAD), total yeast and mold counts, and electronic nose results. The composite coating combined with harpin treatment resulted in a reduced loss of Vc, a similar firmness, an effectively inhibited increase in MAD, and a different scent compared with that of the composite coating group. However, the effects of harpin treatment on POD activity and the inhibition of yeast and mold in pulp did not differ significantly among groups (P > 0.05). The harpin treatment combined with carboxymethyl chitosan-alginate composite coating had a better effect on preservation than did the control group and extended the storage life of Hami melon.
    41  Effects of Vacuum Freeze-drying on the Quality of the Oyster Ostrea rivularis
    GAO Jia-long SHEN Jian ZHANG Chao-hua QIN Xiao-ming
    2015, 31(4):253-257. DOI: 10.13982/j.mfst.1673-9078.2015.4.041
    [Abstract](1015) [HTML](0) [PDF 605.32 K](1082)
    Abstract:
    Oysters are abundant in China, and a large number are processed as dried products However, the dried oysters prepared by traditional methods have poor rehydration characteristics and are low value-added products. To produce a high-quality dried oyster, fresh oyster meat was processed by vacuum freeze-drying, and the rehydration characteristics, texture, and contents of protein, fat, and various flavor components were studied. The eutectic point and melting point of the fresh oyster Ostrea rivularis were -25 ℃ and -17.5 ℃, respectively. Fresh oysters were pre-frozen at temperatures of -30 ℃ to -35 ℃ for two hours, and were then vacuum freeze-dried for 15 hours to produce a dried product with a cold trap temperature of -40 ℃ and a vacuum pressure of 20 Pa. Compared with the control product (commercial dried oyster), the freeze-dried product exhibited better rehydration capacity, and could be rehydrated completely within 20 minutes with a rehydration ratio of 3.68. The texture of freeze-dried oysters was better than that of the control product, and the contents of protein and various flavor components were higher than those of the control. Therefore, vacuum freeze-drying can not only decrease protein loss, but maintains the texture and flavor of oysters, indicating that this method can be used to produce high-quality dried oysters.
    42  Dynamic Discriminant Models for the Detection of Subtle Bruising in Huping Jujube Constructed Based on Their Visible/near-infrared Spectral Data
    WANG Bin ZHANG Shu-juan ZHAO Cong-hui
    2015, 31(4):258-263. DOI: 10.13982/j.mfst.1673-9078.2015.4.042
    [Abstract](1176) [HTML](0) [PDF 981.41 K](1094)
    Abstract:
    This study aimed to identify a rapid effective method to distinguish intact and subtly bruised Huping jujubes by the dynamic collection of their near infrared (NIR) spectral data. A combination of the Savitzky-Golay (S-G) and multiplicative scatter correction (MSC) methods were used for the preprocessing of spectral data. Full spectrum (FS) data obtained after preprocessing, major component data extracted by principal component analysis (PCA), and characteristic wavelength data extracted by successive projections algorithm (SPA) were used as input variables for the construction of models by partial least squares discriminant analysis (PLS-DA), or using the least squares-support vector machine (LS-SVM). The accuracy of these models in discriminating between the four types of intact and subtly bruised Huping jujubes was determined. The results of these analyses revealed the obvious advantages of PCA use for the extraction of the major components of Huping jujubes; in addition, this (PCA) data fulfilled all practical requirements for the accurate discrimination of all four types of subtly bruised samples. The PCA-LS-SVM model demonstrated optimal accuracy in the discrimination of four types of subtly bruised and intact Huping jujubes (100%, 86%, 100%, 100%, and 100%, respectively), , resulting in a total discrimination accuracy of 97.2%). In conclusion, this study provides a new theoretical basis for the dynamic discrimination of subtly bruised Huping Jujube.
    43  The Effect of Different Drying Temperatures on the Transformation of Polyphenols and Volatile Aroma Components in Pu-erh Tea
    LIU Tong-xun TAN Meng-zhu
    2015, 31(4):264-271. DOI: 10.13982/j.mfst.1673-9078.2015.4.043
    [Abstract](1560) [HTML](0) [PDF 960.99 K](1446)
    Abstract:
    Acceleration of the fermentation of pu-erh tea by the addition of alanine and xylose was analyzed; in addition, the effect of different drying temperatures (air-drying at, and drying at 40 ℃, 60 ℃, 80 ℃, 100 ℃, and 120 ℃) on the quality and volatile aroma components of Pu-erh tea following pile fermentation were explored in this study. Drying at different temperatures was observed to have different effects on the transformation of polyphenols. The tea polyphenol, catechins and theabrownins content in Pu-erh tea was higher in the low-temperature drying group (below 60 ℃) than in the other groups; however, the polyphenol content was significantly lower in the high-temperature drying group (above 80 ℃) than in the other groups. Analysis of the volatile aroma components of Pu-erh tea revealed similarities in the major aroma components in each temperature group; these included (+)-cyclosativene, hexanal, heptanal, 5-methyl furfural, benzaldehyde, phenylacetaldehyde, and natural nonylaldehyde. The aroma components of Pu-erh tea dried at low-temperatures (air-drying, 40 ℃ and 60 ℃) showed a relatively high percentage of olefins, while tea dried at high temperatures (80 ℃, 100 ℃, and 120 ℃) displayed relatively higher aldehyde content. The low-temperature drying group displayed a relatively higher percentage of benzene-related and heterocyclic aroma components than the high-temperature drying group; the highest percentage was observed in the air-drying group. In general, the quality of air-dried Pu-erh tea was determined to be the best, and good quality Pu-erh teas were those dried at temperatures below 60 ℃.
    44  Establishment of Real-time Fluorescence Quantitative PCR for Gluconobacter using SYBR Green I
    LI Yue-hua ZHOU Wei YANG Lan ZHANG Jing-jing WANG Shuang LIU Tao ZHANG Yan ZHANG Wei
    2015, 31(4):272-276. DOI: 10.13982/j.mfst.1673-9078.2015.4.044
    [Abstract](1043) [HTML](0) [PDF 811.46 K](1202)
    Abstract:
    PCR primer was designed according to 16S rRNA conserved sequence of Gluconobacter from the GenBank, and a rapid and sensitive fluorescence quantitative PCR using SYBR Green Ι for Gluconobacter detection in fermented dairy products was established. The established method was then used for the specific detection of a panel of three Gluconobacter strains and 18 non-Gluconobacter strains, with the reliability of the results verified by agarose gel electrophoresis. The results showed that the primers were highly specific. Melting curve analysis of the PCR amplification product showed that primer dimers were present in the amplification product. However, nonspecific amplification could be excluded using the peak time of the melting curve. The standard curve based on Gluconobacter detection using the established method had good correlation (R2 = 0.9968). The minimal detection limit was 75 CFU/mL in the sensitivity test. The established method also successfully detected Gluconobacter in five artificially contaminated samples. These results indicated that the SYBR Green Ι fluorescence quantitative PCR method used herein exhibited high sensitivity and was easy to use. Therefore, this method is suitable for the qualitative detection of Gluconobacter strains in fermented dairy products.
    45  Rapid Determination of Total Fatty Acids, Saturated Fatty Acids, and Unsaturated Fatty Acids in Infant Formula using Near-infrared Spectroscopy
    MU Tong-na ZHUANG Sheng-li ZHAO Yu-qi WU Yan-tao YU Xiao-jin SUN Ting
    2015, 31(4):278-281. DOI: 10.13982/j.mfst.1673-9078.2015.4.045
    [Abstract](987) [HTML](0) [PDF 741.29 K](1177)
    Abstract:
    A near-infrared mathematical model for the detection of the total fatty acid (TFA), saturated fatty acid (SFA), and unsaturated fatty acid (UFA) contents in infant formula was established using Fourier near-infrared (NIR) spectroscopy combined with partial least squares (PLS) regression prediction. The reliability of the model was verified by cross-validation and external validation. Different wavelengths and different correction algorithms, including smoothing, vector normalization, first derivative, second derivative, and multiple scatter correction (MSC), were used to process the NIR spectra. The correction model correlation coefficients (R2) for TFA, SFA, and UFA contents were 0.9337, 0.9374, and 0.9020, respectively. The coefficient residual predictive deviations (RPDs) were 3.63, 3.65, and 2.90, respectively. These data demonstrated that this NIR mathematical model had good predictive performance. Twenty collected infant formula samples were predicted using the established model. Paired sample t test analysis showed that the chemically measured and predicted values of TFAs, SFAs, and UFAs had no distinct statistical differences.
    46  Effects of Various Heat Treatments on Volatile Compounds in Oatmeal
    GU Jun-qiang ZHONG Kui ZHOU Su-mei TONG Li-tao LIU Li-ya ZHOU Xian-rong WANG Li
    2015, 31(4):282-288. DOI: 10.13982/j.mfst.1673-9078.2015.4.046
    [Abstract](988) [HTML](0) [PDF 802.57 K](1434)
    Abstract:
    The impacts of various heat treatments on volatile compounds in oatmeal were examined using an electronic nose to analyze the flavor of oatmeal samples that were microwaved, baked, and steam cooked. Principle component analysis (PCA) was employed, and qualitative and quantitative analyses of the volatile compounds in oatmeal were conducted using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). Samples exposed to different heat treatments had distinct characteristics based on the electronic nose and PCA. The contributions of the first and second principal components were 61.33% and 23.19%, respectively, which contained sufficient sensory information to differentiate samples. A total of 61 volatile compounds were identified in the oatmeal samples, and only six were common among the heat treatments, indicating a significant effect of heat treatment method on flavor components. The main volatile compounds in the untreated oatmeal samples were alkenes (37.78%), aldehydes (14.30%), and naphthalenes (14.16%). Numerous aldehydes were produced in the oatmeal samples treated by microwaves and steaming, accounting for 62.05% and 80.65% of their compounds, respectively. Numerous aldehydes (33.95%), pyrazines (38.82%), and pyrimidines (20.12%) were produced after baking, resulting in a strong flavor associated with baking.
    47  A Real-time PCR Method for the Detection of Shark-origin Components in Shark Fin Products
    WANG De-lian LIU Dong-hong XU Li-zhu ZENG Guo-quan GAO Li-hai ZHANG Hui CHEN Sui XIAN Yan-ping GUO Xin-dong
    2015, 31(4):289-293. DOI: 10.13982/j.mfst.1673-9078.2015.4.047
    [Abstract](1334) [HTML](0) [PDF 730.94 K](1187)
    Abstract:
    Specific primers and probes were designed using a portion of the shark mitochondrial genome to establish a novel method for the detection of components of shark-origin in shark fin products, in order to determine product quality. The results of this study indicated that this method had good species specificity, as well as a high sensitivity of 0.01 ng/?L DNA concentration or 0.1% (m/m) weight. This method was then combined with a detection method developed for the identification of plant-origin genes; this combined method was used to examine 25 shark fin products available in the market (randomly chosen). The results of this analysis revealed the presence of shark-origin components (and not plant-origin components) in 18 samples, and of plant-origin components (and not shark-origin components) in the remaining 7 samples; this indicated that the latter 7 samples were imitation fin products prepared using plant ingredients. The method established in this study is fast, sensitive, and simple, and suitable for the rapid detection of shark-origin components in shark fin products available in the market.
    48  Ultrasound-assisted Homogeneous Ionic Liquid Microextraction Coupled with HPLC for the Detection and Extraction of Tanshinone from Radix Salvia miltiorrhiza
    WANG Zhi-bing ZHANG Hong-yu XUE Jin ZHANG Feng-qing
    2015, 31(4):294-300. DOI: 10.13982/j.mfst.1673-9078.2015.4.048
    [Abstract](1126) [HTML](0) [PDF 976.86 K](1096)
    Abstract:
    An ultrasound-assisted homogeneous ionic liquid microextraction tandem high performance liquid chromatography (UA- HILME-HPLC) method was developed and applied to the determination of four tanshinones (dihydrotanshinone, tanshinone I, cryptotanshinone, and tanshinone IIA) expressed in Radix Salvia miltiorrhiza. A water-soluble ionic liquid and water were used as the extraction solvent and extraction media, respectively. The target analytes were extracted using the ultrasound technique. The ion-pairing agent was added to this extraction solution, resulting in the formation of a water-insoluble ionic liquid, which was separated by centrifugation. The separated ionic liquid section was subjected to HPLC analysis. The results of this analysis identified the optimal experimental conditions for UA-HILME to be: 140 μL of the [C8MIM][BF4] extraction solvent, 1 mL of 0.6 mol/L NH4PF6 ion-pairing agent, pH of the sample solution at 5.0, an initial extraction temperature of 50 ℃, 5 min ultrasound extraction time, and 200 W ultrasonic power. All target compounds showed a good linear relationship (r > 0.9996) in the linear range. The observed limits of detection and quantification were 0.02~0.04 μg/mL and 0.07~0.13 μg/mL, respectively. The intra-day and inter-day precision (RSD) was lower than 3.23% and 4.57%, respectively. The spiked sample recovery rate ranged from 83.50% to 96.23%. This method combined the processes of extraction, concentration, purification, and separation, does not require any volatile organic solvents, and shows good results despite a short extraction time and small sample size. Therefore, this method could be widely applied to the extraction and analysis of active components in medicinal plants.
    49  The Contribution of Chicken Peptides Towards the Generation of Meat Flavor Compounds via Maillard Reaction
    LIU Jian-bin KANG Le LIU Meng-ya HE Cong-cong SONG Huan-lu
    2015, 31(4):301-310. DOI: 10.13982/j.mfst.1673-9078.2015.4.049
    [Abstract](1320) [HTML](0) [PDF 945.27 K](1300)
    Abstract:
    This study established eight model reaction systems using chicken peptides, in order to investigate their contribution towards the generation of meaty flavor compounds. Chicken peptides caused an increase in pyrazine content (by 14744.1 μg/L), which imparted a nutty and roasted aroma to a Maillard reaction system, consequently increasing the meaty flavor of the system. In addition, studies with Cys-added Maillard reaction systems, such as the Cys-xylose system, revealed that chicken peptides significantly promoted the generation of sulfur-containing aroma-active compounds, such as thiophenes and furan mercaptans. The concentration of pyrazines in a chicken peptide-Leu-xylose system was higher than that in a combination of the Leu-xylose and peptide-xylose reaction systems; this further indicated that the addition of Leu could promote the generation of pyrazines in the chicken peptide-xylose system. The influence of pH on the reaction systems was also studied by building model systems with differing pH conditions. A low pH (< 5.0) condition in the Maillard reaction system containing chicken peptides was observed to inhibit the generation of pyrazines. Combined with the quantitative data of non-volatile compounds, chicken peptides distributed in the 200–500u region were concluded to contribute to the generation of a meaty flavor in food via a Maillard reaction at high pH.
    50  A Study Examining Changes in Polycyclic Aromatic Hydrocarbon (PAH) Content of Edible Oils upon Frying
    SHI Long-kai LIU Yu-lan WANG Ying-hui ZHANG Dong-dong
    2015, 31(4):311-315. DOI: 10.13982/j.mfst.1673-9078.2015.4.050
    [Abstract](1097) [HTML](0) [PDF 709.05 K](1345)
    Abstract:
    Dough sticks were experimentally fried in soybean oil, rice bran oil, and palm oil. The effect of various frying time on the polycyclic aromatic hydrocarbons (PAHs) present in edible oils was studied by measuring PAH content in the oil after frying. The results showed a clear increase in the content of Bap, PAH4, and PAH16 with increase in frying time. When fried for 32 h, soybean oil showed an increase in the content of Bap, PAH4, and PAH16 (μg/kg) from 1.58, 6.88, and 18.73 (initially) to 3.93, 10.35, and 56.10, respectively. The Bap, PAH4, and PAH16 content (μg/kg) of rice bran oil increased from 2.52, 6.50, and 25.53 to 3.10, 10.34, and 100.71, respectively, and that of palm oil increased from 1.67, 8.60, and 25.23 to 2.26, 10.95, and 59.98, respectively, upon frying for 32 h. The extent of increase was different for each component during the high temperature frying process. The PAHs showing the highest and lowest (quantities) increment in soybean, rice, and palm oils were acenaphthene and benzo[b]fluoranthene, acenaphthene and benzo[g,h,i]pyrene, fluorine and benzo[b]fluoranthene, respectively. Furthermore, a greater increase in the content of light-weight PAHs compared to that of heavy-weight PAHs was observed.

    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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