Volume 32,Issue 9,2016 Table of Contents

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  • 1  Procyanidins from Lotus Seedpod Induce Apoptosis in HepG2 Cells via Caspase-dependent Pathway
    DUAN Yu-qing XU Hui QU Wen-juan LUO Xiao-ping ZHAO Bin LI Pan ZHANG Hai-hui
    2016, 32(9):1-7. DOI: 10.13982/j.mfst.1673-9078.2016.9.001
    [Abstract](896) [HTML](0) [PDF 3.51 M](1393)
    Abstract:
    The possible mechanism of apoptosis induced by procyanidins from lotus seedpod (LSPCs) in human hepatoma HepG2 cells was investigated. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to study the inhibitory effect of LSPCs on HepG2 cell proliferation, morphological changes in apoptotic nuclei were observed via Hoechst 33258 staining, and the percentage of apoptotic cells was calculated by double-staining flow cytometry using Annexin V conjugated to fluorescein isothiocyanate and propidium iodide. DNA damage, mitochondrial membrane potential, and expression levels of apoptotic proteins were determined by comet assay, JC-1 staining, and western blot, respectively. The results indicate that after treatment with LSPCs, HepG2 cell proliferation was significantly inhibited; there were obvious signs of apoptosis, including high chromatin condensation level, nuclear fragmentation, and karyopyknosis; and the number of chromatin-condensed cells increased from 3.86% to 42.76% (p<0.01). The percentage of viable cells decreased significantly and the proportion of apoptotic cells increased from 5.32% to 67.05% (p<0.01). Treatment with LSPCs caused DNA damage, loss of mitochondrial membrane potential, an increase in the protein expression levels of cytochrome C, caspase-3, and caspase-9, in addition to upregulation of Bax protein expression and downregulation of Bcl-2 protein expression. However, the apoptosis inhibitor Z-VAD reduced the inhibitory effect of LSPCs on HepG2 cell proliferation, significantly reduced nuclear condensation, inhibited mitochondrial damage and caspase protein expression, and eventually inhibited LSPC-induced apoptosis. Thus, the results show that LSPCs trigger apoptosis in HepG2 cells via the mitochondria-mediated, endogenous caspase pathway.
    2  Hepatoprotective Effects of Bioactive Compounds from Rape Bee Pollen on L-02 Cells Injured by CCl4
    GAO Li-miao YU Bin XU Xiang PENG Ding-li GAO Peng-bo SUN Li-ping
    2016, 32(9):8-12. DOI: 10.13982/j.mfst.1673-9078.2016.9.002
    [Abstract](1051) [HTML](0) [PDF 631.27 K](1090)
    Abstract:
    Quercetin-3-O-β-D-glucosyl-(2→l)-β-glucoside (QMP), kaempferol-3,4'-di-O-β-D-glucoside (KMG), and kaempferol-3-O- β-D-glucosyl-(2→l)-β-D-glucoside (KMP) were isolated and purified from rape bee pollen. A model of CCl4-induced liver injury was established via in vitro cultivation of L-02 cells, and the protective effects of QMP, KMG, and KMP on L-02 cells with CCl4-induced injury were studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The contents of malondialdehyde (MDA), superoxide dismutase (SOD), and lactic dehydrogenase (LDH) were used as the characteristic indicators to study the hepatoprotective effect in terms of oxidative stress. The relative cell survival rate of QMP-treated cells (200 μg/mL) was 2.64 and 2.66 times as much as that of the model group, respectively, suggesting that QMP can effectively prevent CCl4-induced liver injury in L-02 cells, but the hepatoprotective effects of KMG and KMP were not significant. QMP, kaempferol, and quercetin could significantly reduce intracellular MDA levels; the MDA levels of 300 μM dose groups were 0.65, 0.60, 0.59 and 0.52 times as much as that of the model group, respectively; the corresponding LDH leakage rates were reduced by 23.82%, 27.69%, 30.11%, and 32.77%, respectively; the SOD contents were increased by 1.45, 1.61, 1.58, and 1.65, respectively. The results suggest that QMP possesses significant in vitro antioxidant activity and a hepatoprotective effect, the antioxidant activity is one of the mechanisms underlying its hepatoprotective effect. This study provides a basis for developing drugs to treat diseases associated with liver injury.
    3  Hematopoietic Effect of Fufang Pike Eel Skin Gelatin on Iron Deficiency Anemia
    NIU Hui-na HOU Hu ZHENG Hai-xue LI Ba-fang
    2016, 32(9):13-19. DOI: 10.13982/j.mfst.1673-9078.2016.9.003
    [Abstract](818) [HTML](0) [PDF 907.51 K](1346)
    Abstract:
    With the aim of developing a new kind of compound hematopoietic health product, the hematopoietic effect of Fufang pike eel skin gelatin (FEG) on iron deficiency anemia in rats was investigated. The pike eel skin gelatin was prepared using a hot water extraction method, and was combined with Angelica sinensis, Radix Paeoniae Alba, Rhizoma Chuanxiong, Astragalus membranaceus, Radix Polygoni Multiflori Preparata, Fructus Crataegi, and Radix Rehmanniae Preparata. A rat model of iron deficiency anemia (IDA) was established by feeding rats with a traditional low-iron diet and bleeding from the caudal vein. Then, the IDA rats were randomly divided into the following five groups (ten rats per group): model control group, FEG high and low dose groups (FEG-H and FEG-L), and Fufang donkey-hide gelatin high and low dose groups (PC-H and PC-L). After 30 d of administration by gavage, the hematopoietic effect was evaluated by measuring the concentrations of hemoglobin (Hb), serum iron (SI), ferritin (SF), and soluble transferrin receptor (sTfR), and performing red blood cell counts (RBC), hematoxylin and eosin (H & E) staining of liver tissues, and bone marrow smears. The results showed that high dose FEG could significantly improve the value of RBC (p<0.01), reduce the reticulocyte count (p<0.05) and the indices of liver (p<0.01), spleen (p<0.05), and kidney (p<0.01), and alleviate symptoms of bone marrow hyperplasia and liver tissue disorder. Additionally, high dose FEG enhanced Hb content from 77.21 g/L to 175.86 g/L, increased SI and SF concentrations by 2.9 and 0.6 times, respectively, and reduced sTfR concentration by 19.42%. Fufang pike eel skin gelatin could effectively improve the symptoms of IDA.
    4  Improvement in the Effectiveness of Staining Neutral Lipids in Coccomyxa subellipsoidea C-169 by Cytomics Technologies
    WEI Dong LI Lu
    2016, 32(9):20-27. DOI: 10.13982/j.mfst.1673-9078.2016.9.004
    [Abstract](1151) [HTML](0) [PDF 3.63 M](1089)
    Abstract:
    Using cytomics technologies, such as flow cytometry, fluorescence microplate reader, and confocal laser scanning microscope, the effects of algal cell concentration, nile red concentration, types and concentration of assistant solvents, staining temperature and time as well as shaking time on the relative content of neutral lipids in algal cells (expressed as average fluorescence intensity) were investigated. The effectiveness of staining neutral lipids in Coccomyxa subellipsoidea C-169 was improved. The results indicated that the optimal algal cell concentration for nile red fluorescence staining was 106 cells/mL, and the optimal dye concentration ranged from 0.05 to 0.2 μg/mL, which could avoid interference due to excessive fluorescence. The addition of 15~30% (V/V) glycerol could significantly improve the permeability of dye into the cells. Relatively high fluorescence intensity was detected at the staining temperatures ranging from 25 to 40 ℃, but no significant difference was found among them (p>0.05). The average fluorescence intensity of Coccomyxa subellipsoidea C-169 after staining was not significantly improved when the staining time was increased to over 10 min and the shaking time was increased to over 30 s. The systematically optimized staining procedure can significantly improve the accuracy of fluorescence detection of neutral lipids at the cellular level, and provides an effective method for rapid determination of the neutral lipid content in other microalgae using this fluorescence probe.
    5  Toxicity Reduction by (and Hepatoprotective Effects of) Carboxymethyl Pachymaran on 5-Fluorouracil-induced Liver Injury in Mice
    WANG Can-hong HE Xiao-shan ZHANG Li-jing HUO Xiao-wei LIU Dong-yu HAN Jia-yuan LI Li-yong CAO Li
    2016, 32(9):28-34. DOI: 10.13982/j.mfst.1673-9078.2016.9.005
    [Abstract](962) [HTML](0) [PDF 1.89 M](1094)
    Abstract:
    A mouse model of 5-Fu-induced liver injury was established, and peripheral-blood white blood cells (WBC), bone marrow nucleated cells (BMNC), visceral indexes, and alanine transaminase (ALT) and aspartate aminotransferase (AST) activities in serum were quantified after the drug was administered. The effects of CMP on mouse liver tissues were examined using histopathological sectioning of the liver tissues; protein expression levels of Keap1, Nrf2, GCL, NF-κB, p38, pp38, Bax, and Bcl-2 in liver tissues were measured by western blotting; and protein expression levels of NF-κB and pp38 were analyzed by immunohistochemistry. The results showed that compared with the normal group, 5-Fu increased the liver index, spleen index, ALT activity, and AST activity by 13.75%, 53.76%, 39.48%, and 62.81%, respectively. WBC and BMNC values were decreased by 7.15% and 50.81%, respectively; the expression levels of NF-κB, pp38, and Bax in liver tissues were significantly increased, but the expression level of Bcl-2 was decreased, indicating that the liver injury model was successfully established. The CMP treatment of this model decreased the liver index, spleen index, ALT activity, and AST activity by 12.40%, 31.45%, 20.83%, and 20.14%, respectively. WBC and BMNC values were increased by 17.12% and 46.77%, respectively. The expression level of Bcl-2 was significantly increased, while the expression levels of NF-κB, pp38, and Bax were reduced. CMP alone had no significant effect on the liver of normal mice, but effectively reduced the toxicity of 5-Fu and showed apparent hepatoprotective effects. The underlying mechanism is related to the regulation of NF-κB, p38 MAPK, and Bcl-2 signaling pathways.
    6  Effects of the Total Flavonoids from Citrus aurantium on Proliferation and Apoptosis of 3T3-L1 Cells
    HAO Yun-fang YANG Li JIANG Jian-guo
    2016, 32(9):35-40. DOI: 10.13982/j.mfst.1673-9078.2016.9.006
    [Abstract](684) [HTML](0) [PDF 970.25 K](943)
    Abstract:
    The impact of the total flavonoids of Citrus aurantium (TFC) treatment on proliferation and apoptosis of 3T3-L1 cells was studied. After 3T3-L1 cells were cultured and treated with TFC in different concentrations for 24 h, the effect of TFC on cell proliferation was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological changes of 3T3-L1 cells were observed under an inverted microscope, the cell apoptotic rate was determined by Annexin V-EGFP/PI double staining, and propidium iodide (PI) staining was used to measure the effect of TFC on cell cycle. The intracellular reactive oxygen species (ROS) level was measured using a ROS assay kit, and the mRNA expression level of apoptosis-related genes was determined by fluorescence quantitative real-time polymerase chain reaction (RT-PCR). The results showed that high concentrations of TFC (300 and 400 μg/mL) could significantly inhibit the proliferation of 3T3-L1 cells; the inhibition rates on cells were 38% and 63%, respectively, and the morphological characteristics of 3T3-L1 cells were changed. The ROS concentration in cells was also increased significantly. The apoptosis experiments indicated that TFC could induce early and late apoptosis of 3T3-L1 cells; the early apoptosis rates for the treatments with 100 μg/mL, 200 μg/mL and 300 μg/mL TFC for 24 h were 4.6%, 15.7% and 22.5%, respectively, and the late apoptosis rates were 14.4%, 8.3% and 32.2%, respectively. The cell cycle results showed that the G0/G1 phase ratio of the treated 3T3-L1 cells decreased from 58.9% to 51.4%%, the ratio of corresponding S phase was increased slightly, and the ratio of the cells in G2/M phase was not significantly changed. The increase in the ratio of pro-apoptotic gene bax and anti-apoptotic gene bcl-2 and the increase in the mRNA expression of apoptosis-related genes p21 and p53 promoted apoptosis in 3T3-L1 cells.
    7  Effects of the Aging Time after Slaughter on Changes in the Intracellular Environment of Different Parts of Yak Meat
    JIA Qing CHEN Cheng HAN Ling SUN Zhi-chang ZHANG Ju-hui YU Qun-li
    2016, 32(9):41-46. DOI: 10.13982/j.mfst.1673-9078.2016.9.007
    [Abstract](720) [HTML](0) [PDF 2.66 M](1253)
    Abstract:
    The relationship between intracellular changes in the muscle cells and meat tenderness in different yak parts during different periods of the postmortem aging process was explored. Yak meat was treated with air cooling (0~4 ℃, air speed 0.5 m/s), and the front triceps brachii muscle (TB), central longissimus muscle (ML), and rear semimembranosus muscle (SM) were taken between two hours and five days after slaughter. The pH value, extracellular space area of muscle cells, mitochondrial morphological changes, and activity of the energy factor were measured. Moreover, Ac-DEVD-CHO, a specific inhibitor of caspase-3, was added to perform sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) protein electrophoresis. The results suggested that within 12 h to 24 h postmortem, a significant reduction in the pH of ML (pH=5.17±0.4, p<0.01) was detected. At 24 h postmortem, the extracellular space area of SM was significantly increased by 48.75% (p<0.05) compared with that of the sample at 12 h postmortem. At five days postmortem, significant mitochondrial fusion occurred in ML, and some mitochondrial crests remained in TB. At three days postmortem, the adenosine triphosphate (ATP) content of ML was significantly decreased by 79% compared to the samples at 24 h postmortem, and almost fell to the lowest level (p<0.01). At 12 h postmortem, the protein degradation in TB and ML was significantly inhibited by the caspase-3 specific inhibitor, and an apparent 30 ku protein band was detected in ML. The result showed that the aging process postmortem, the environmental changes in the muscle cells of different parts of yak, and the changes in the quality of yak meat are synchronized.
    8  Changes in Physicochemical Properties of Jujube (Zizyphus jujuba) Fruit cv. Jinsixiaozao during Growth and Maturity Stages
    DING Sheng-hua WANG Rong-rong LI Gao-yang FU Fu-hua LV Hui-ying HUANG Lv-hong
    2016, 32(9):47-55. DOI: 10.13982/j.mfst.1673-9078.2016.9.008
    [Abstract](794) [HTML](0) [PDF 1017.92 K](1249)
    Abstract:
    The dynamic changes in color, chlorophylls, soluble sugars, metabolic activity, organic acids, and free amino acids in jujube fruit cv. jinsixiaozao during six different growth and maturity stages (S1~S6) were studied in order to understand fruit metabolism. The results indicated that as growth and maturity progressed, the chlorophyll content decreased and the fruit color changed from green into red in jujube fruit. The contents of fructose and glucose gradually increased, while the sorbitol content decreased gradually. Sucrose was not detected at early growth stages, but it accumulated at the late maturity stage and showed the highest content. Jujube fruit cv. jinsixiaozao is a sucrose accumulation-type fruit and sucrose phosphate synthase is the key enzyme for accumulating sucrose. Jujube fruit cv. jinsixiaozao is also a malic acid-type fruit, malic acid accumulated along with fruit maturation, and the citric acid content showed a declining trend after the initial increase. Asparagine and proline were synthesized in large amounts during fruit maturation, and are the two main amino acids in mature jujube fruits. The total soluble sugars, ratio of sugar to acid, and total free amino acids of jujube fruit at the S6 stage were the highest among all growth stages. So S6 can be considered as the suitable harvest stage for fresh edible jujube fruits cv. jinsixiaozao.
    9  Aerobic Respiration in Lactococcus lactis based on Gene Expression
    LIU Fei LI Bai-liang DU Jin-cheng YU Shang-fu DING Xiu-yun XU Min HUO Gui-cheng
    2016, 32(9):56-61. DOI: 10.13982/j.mfst.1673-9078.2016.9.009
    [Abstract](739) [HTML](0) [PDF 985.98 K](1457)
    Abstract:
    The homology of genes coding for respiratory chain and cytochrome oxidase activity of Lactococcus lactis strains that can or cannot undergo aerobic respiration were compared to provide a foundation for determining the necessary conditions for aerobic respiration in Lactococcus lactis. Firstly, growth curves of the two selected strains, KLDS4.0325 and KLDS4.1102, were determined under fermentation and aerobic respiration conditions. Secondly, the genomic DNA of strain KLDS4.1102 was extracted, and its respiratory chain-encoding genes were amplified by polymerase chain reaction (PCR), followed by DNA sequencing. Finally, the sequences of genes coding for the respiratory chain of KLDS4.0325 were downloaded from the GenBank database, the homology of genes coding for the respiratory chain in the two Lactococcus lactis strains was compared by DNAMAN software, and the cytochrome oxidase activities of these two strains were determined. The biomass and pH of KLDS4.0325 undergoing aerobic respiration increased significantly, but KLDS4.1102 presented a consistent growth trend between the two physiological conditions. The homology analysis of the genes coding for respiratory chain of two strains showed that KLDS4.1102 possessed a complete respiratory chain, while cytochrome oxidase activity could not be detected in KLDS4.1102. This finding suggests that KLDS4.1102 cannot undergo respiratory metabolism normally, possibly because some gene cannot be expressed normally, leading to abnormal cytochrome oxidase function.
    10  Effect of Varying β-Conglycinin/Glycinin Ratios on the Emulsifying and Interfacial Properties of Soybean Proteins
    CHEN Shuo TANG Chuan-he
    2016, 32(9):62-68. DOI: 10.13982/j.mfst.1673-9078.2016.9.010
    [Abstract](791) [HTML](0) [PDF 1.50 M](1851)
    Abstract:
    The effect of soybean protein composition (different ratios of 7S globulin (β-conglycinin) and 11S globulin (glycinin)) on the emulsifying and interfacial properties of oil-in-water (O/W) emulsions was evaluated. The results indicated that manually extracted 7S and 11S globulins were in their native state. With increasing 11S content, the emulsifying activity index, absolute value of ζ-potential, protein concentration, content at the O/W interface, emulsifying activity, and stability were reduced, and the overall particle size distribution, droplet flocculation index, and droplet coalescence index of the emulsion were increased. According to the results of emulsifying properties, 7S globulin contributed more towards the overall emulsification ability of soybean proteins than the 11S globulin did. Electrophoresis images of interfacial proteins indicated that all subunits of the two globulins could be adsorbed at the O/W interface, and changes in the contents of all subunits were in accordance with the proportion of proteins in the sample. With increasing 11S content, the emulsion microstructure changed from a clear spherical shape into irregularly flocculated aggregates. In general, diffusion, adsorption, and rearrangement rates of the 11S globulin at O/W interface were higher than that of 7S globulin, and the rearrangement rates of all protein samples with different 11S contents at O/W interface were higher than the adsorption rates. These results suggest that emulsifying and interfacial adsorption properties of soybean globulins can be regulated to some extent by altering the protein composition.
    11  Effect of Distilled Spirit on the Structural Changes of Myofibrillar Protein from Zhedong Goose Meat
    LUO Hong-lin PAN Dao-dong SUN Yang-ying CAO Jin-xuan WU Zhen ZENG Xiao-qun
    2016, 32(9):69-76. DOI: 10.13982/j.mfst.1673-9078.2016.9.011
    [Abstract](655) [HTML](0) [PDF 1.73 M](1167)
    Abstract:
    Raman spectroscopy was applied to study the structural changes caused by the volume fraction of distilled spirit on myofibrillar proteins extracted from Zhedong goose breast meat. The results indicated that increasing the volume fraction of the distilled spirit caused the solubility of myofibrillar protein to increase (p<0.05) and the surface hydrophobicity to decrease (p<0.05). As evidenced by scanning electron microscopy, a good gel property and a uniform microstructure were obtained when the volume fraction of the distilled spirit was low; however, with increasing volume fraction of the distilled spirit, the gel network pore size was increased and the water-holding capacity of proteins was decreased significantly (p<0.05). The increase in the volume fraction of distilled spirit caused conversions among the three conformations of the disulfide bond. For the control group, the main amide I Raman band was found at 1655 cm-1, with an α-helix of 40.45%. At a 2% volume fraction, the main band was found at 1668 cm-1 (random coil), the relative contents of the α-helix and β-sheet decreased significantly (p<0.05), and the random coil content increased significantly (34.40%) (p<0.05). This indicates that distilled spirit can affect the structure and gel properties of myofibrillar protein.
    12  Characterization of a Thermostable Manganese Superoxide Dismutase from a Deep-sea Thermophilic Bacterium
    DENG Dun ZHANG Yun SUN Ai-jun LIANG Jia-yuan HU Yun-feng
    2016, 32(9):77-83. DOI: 10.13982/j.mfst.1673-9078.2016.9.012
    [Abstract](833) [HTML](0) [PDF 1.29 M](1149)
    Abstract:
    An SOD gene (SODBa3) was cloned from the genome of Bacillus sp. SCSIO 15121 that was originally isolated from the sediment of the South China Sea. SODBa3 contains 609 base pairs (bp) and corresponds to 202 amino acid residues. The pET28a (+)-SODBa3 expression vector was constructed in this study, and heterologous expression of soluble SODBa3 was achieved in Escherichia coli BL21 (DE3). Enzymatic properties of the recombinant SODBa3 were then studied; the optimal pH and reaction temperature were 8.0~8.5 and 60 ℃, respectively, and the specific activity of SODBa3 was 3215.6 U/mg. The results showed that the activity of SODBa3 was sensitive to CH3Cl-C2H5OH but was not affected by hydrogen peroxide, indicating that SODBa3 is a Mn2+-dependent enzyme. The thermostability of SODBa3 was also studied by circular dichroism spectroscopy and by examination of changes in the activity of SODBa3 at various temperatures. The results revealed that SODBa3 was relatively stable during treatment at 40~70 ℃ for one hour, and the residual activity was 50% after incubation at 100 ℃ for one hour. The metal ion tolerance experiment indicated that 5 mM Mn2+ had stimulating effects on SODBa3 activity; SODBa3 showed good tolerance to 10% ethanol and dimethyl sulfoxide (DMSO), and the residual activities were 112.56%±9.77% and 98.55%±6.47% of the control activity, respectively. These findings indicate that microbial SODBa3 has high potential for utilization in the industry.
    13  Screening and Fermentation Characteristics of a Lactic Acid Bacterial Strain in Acid Camel Milk
    XIONG Lei ZHAO Jian-xin FAN Da-ming LIU Xiao-ming YAN Bo-wen WANG Li-yun CHEN Wei ZHANG Hao
    2016, 32(9):84-89. DOI: 10.13982/j.mfst.1673-9078.2016.9.013
    [Abstract](680) [HTML](0) [PDF 692.57 K](1320)
    Abstract:
    Five strains of lactic acid bacteria (LAB) were isolated and identified in Xinjiang naturally fermented camel milk, including three strains of lactobacilli (Lactobacillus helveticus, Lactobacillus plantrum, and Lactobacillus kefiri) and two strains of Pediococcus acidilactici (Pediococcus acidilactici and Pediococcus pentosaceus). These LAB strains showed good growth in the culture medium, where the viable cell count reached 109 colony-forming units (CFU)/mL after 16 h of cultivation. Traditional yogurt starter culture was inoculated in camel milk and incubated at 42 ℃ and the results showed effective acid production, where optimum acid production was achieved with 0.1% traditional yogurt starter culture. The isolated LAB strains were prepared as fermenting agents combined with traditional yogurt starter culture. The combination using Lactobacillus helveticus exhibited optimal synergistic effect and acid-generating efficiency. After six hours of fermentation, the pH value reached approximately 4.5, with acidity value of 85 oT. Furthermore, the fermented camel milk showed higher sensory quality and a higher sensory evaluation score compared with fermented camel milk samples prepared using combinations of other strains. Therefore, the fermenting agent combination of 0.1% traditional yogurt starter with Lactobacillus helveticus strains can be used for acid camel milk fermentation.
    14  Effect of Grapefruit Essential Oil Content on Properties of Composite Film and Shelf Life of Agaricus bisporus
    ZHUANG Yan QIN Yu-yue LI Bing WU Yan LI Wen-hui
    2016, 32(9):90-99. DOI: 10.13982/j.mfst.1673-9078.2016.9.014
    [Abstract](683) [HTML](0) [PDF 1.44 M](998)
    Abstract:
    The effect of various concentrations (0%, 5%, 7.5%, 10%, and 12.5% V/m) of grapefruit essential oil (GEO) was studied on the on thermal, structural, mechanical, gas barrier, and antimicrobial properties of polylactic acid (PLA)/GEO composite film. By reducing the intermolecular force of polymer chains, GEO improved the flexibility of the composite film and showed a certain plasticization effect on the films. The presence of GEO decreased the crystallinity of PLA phase. The water vapor barrier properties of the films significantly decreased with increasing GEO content. Additionally, the incorporation of GEO in the PLA polymer matrix improved the antimicrobial activity of packaging films. PLA packaging films with or without GEO were used for preservation of button mushroom (Agaricus bisporus). The results indicate that PLA/GEO composite film is more effective in retaining the firmness, reducing the microbial count, and maintaining a high overall acceptability of mushrooms than pure PLA and low-density polyethylene (LDPE) films. Therefore, the results suggest that PLA/GEO composite film is a useful packaging material for extending the shelf life of button mushrooms.
    15  Anti-photoaging Activity of Extract A from a Traditional Chinese Medicine Formula and its Mechanism of Action
    GAO Qing JIN Xin GE Ya-zhong JI De-sheng YOU Li-jun
    2016, 32(9):100-106. DOI: 10.13982/j.mfst.1673-9078.2016.9.015
    [Abstract](728) [HTML](0) [PDF 2.31 M](1115)
    Abstract:
    Because ultraviolet light (UV) can cause various skin diseases, scientists have been paying increasing attention to the study of skin care. The anti-photoaging effect of an extract A from a traditional Chinese medicine formula was studied on UV-irradiated rats. The morphology and ultrastructure of the skin tissues were determined by pathological analysis and electron microscopy, respectively. Immunohistochemical analysis and the fluorogenic quantitative polymerase chain reaction were used to determine the skin tissue matrix metalloproteinase 1 (MMP-1), MMP-2, MMP-9, and Ia antigen expression levels, as well as the gene expression levels of skin collagen type I and collagen type III, and connective tissue growth factor and transforming growth factor β1 (TGF-β1). Compared with the model control group, rats in the low-, medium- and high-dose extract-A-treated groups showed mitigated dermal interstitial vasodilation, inflammatory cell infiltration, fibroblast hyperplasia, dermal elastic fiber degeneration, and focal accumulation, with decreases in skin thickness of the epidermis and the number of dermal fibroblasts of the irradiated skin. Extract A also improved the ultrastructure of the irradiated skin, and reduced the expression of TGF-β1 while improving that of collagen type III. Therefore, extract A of this traditional Chinese medicine formula possesses strong anti-photoaging activity.
    16  Comparsion of Structural Characteristics and Functional Properties of Different Commercial Soy Protein Isolates
    YANG Feng LIU Xue REN Xian-e HUANG Yong-chun
    2016, 32(9):107-115. DOI: 10.13982/j.mfst.1673-9078.2016.9.016
    [Abstract](866) [HTML](0) [PDF 1.15 M](1796)
    Abstract:
    The structural characteristics and functional properties of twenty commercial soy protein isolate samples were studied and correlations between structural characteristics and functional properties were also analyzed. The mean particle size (MPS) of these samples ranged from 16.73 to 388.27 nm, the Zeta potential (ZP) ranged from -19.90 to -32.00 mV, and the surface hydrophobicity (H0) ranged from 234.63 to 493.00. The contents of exposed sulfhydryl groups (SH), free SH, and disulfide bonds (SS) ranged from 3.59 to 11.15 μmol/g, 4.68 to 13.37 μmol/g and 6.02 to 15.47 μmol/g, respectively, and the protein solubility (PS) values ranged from 9.64 to 41.07%. The emulsifying activity index (EAI) and emulsifying stability index (ESI) values ranged from 14.94 to 46.10 m2/g and 13.61 to 59.13 min, respectively. Foaming capacity (FC) and foaming stability (FS) values ranged from 28.97 to 98.50% and 60.41 to 98.03%, respectively. Water holding capacity (WHC) and fat absorption capacity (FAC) ranged from 3.50 to 20.43 g water/g protein and 4.08 to 5.66 g oil/g protein, respectively. There were significant differences in structural characteristics and functional properties among some samples (p<0.05). Correlation analysis of the structural characteristics and functional properties of these samples indicated that PS and FC were positively correlated to MPS and the absolute value of ZP. Positive correlations were also observed between EAI and the absolute value of ZP, between ESI and MPS, and between FS and the contents of exposed SH and free SH, respectively. While negative correlations were observed between EAI and SS content, between FC and the content of free SH, and between WHC and MPS, respectively.
    17  Physicochemical Properties of Wheat Flour with Different Particle Size Ranges
    SONG Yan-yan WANG Yuan-hui CHEN Jie
    2016, 32(9):116-120. DOI: 10.13982/j.mfst.1673-9078.2016.9.017
    [Abstract](993) [HTML](0) [PDF 521.28 K](1840)
    Abstract:
    Particle size is an important index used to evaluate the quality of flour, as it influences the properties of wheat flour and its products. In order to study the specific effect of particle size on flour quality, four commercial flours were classified into four particle size ranges (140~160 mesh, 160~180 mesh, 180~200 mesh, and 200 mesh and above) by sieving. The distributions of the four commercial flours across the different size ranges were studied, and a laser particle size analyzer was used to scan the particle size distribution of flour in each range. The gluten index and the contents of moisture, ash, damaged starch, crude protein, wet gluten, and dry gluten of all ranges of flour were measured, and the change in the composition and differences in the physicochemical indices of all ranges of flour were analyzed. The results showed that a small particle size led to a high content of damaged starch. The physicochemical properties of the flour samples in the ranges of 160~180 mesh (96~80 μm) and 180~200 mesh (80~75 μm) were significantly different from those in other ranges, and variance analysis showed significant differences in the damaged starch content, crude protein content, dry gluten content, wet gluten content, and gluten index among the flours with different particle sizes.
    18  Effect of Tartary Buckwheat Protein on the Growth and Bile Salts Tolerance of Probiotics
    ZHOU Xiao-li LU Yuan ZHOU Yi-ming XIAO Ying
    2016, 32(9):121-126. DOI: 10.13982/j.mfst.1673-9078.2016.9.018
    [Abstract](705) [HTML](0) [PDF 1008.27 K](1085)
    Abstract:
    The effect of water-soluble tartary buckwheat protein on the growth and bile salt tolerance of probiotics (Lactobacillus plantarum and L. acidophilus) was explored in an in vitro intestinal environment. The results demonstrated that the addition of different concentrations of tartary buckwheat protein (1, 3 and 5 mg/mL) increased the optical density value (OD600) of L. plantarum culture broth by 12.33%, 25.84% and 35.31%, respectively, and that of L. acidophilus culture liquid by 15.37%, 26.66% and 30.57% respectively. In addition, tartary buckwheat protein increased the tolerance of L. plantarum and L. acidophilus to bile salts (sodium cholate and sodium glycyl cholate) significantly (p<0.05). The OD600 values of L. plantarum culture broth increased 1.64 and 8.67 times and that of L. acidophilus culture broth increased 4.11 and 8.30 times in sodium cholate and sodium glycyl cholate, compared with that of control, respectively. Further in vitro culture experiments demonstrated that the effect of buckwheat protein significantly promoted the growth of intestinal Lactobacilli (p<0.05). In conclusion, tartary buckwheat protein improves the growth of Lactobacillus in bile acid salts and the intestine, indicating scope for the application of tartary buckwheat protein in food.
    19  Effect of Malic Acid on the Stability of Anthocyanins in Blackcurrant Juice
    ZHAO Yu-hong JIA Lin-na BAO Yi-hong ZHANG Li-gang
    2016, 32(9):127-134. DOI: 10.13982/j.mfst.1673-9078.2016.9.019
    [Abstract](783) [HTML](0) [PDF 982.89 K](1023)
    Abstract:
    Anthocyanins are the main pigments and are very important bioactive components in blackcurrant juice. The stability of anthocyanins was affected by soluble solid concentration, storage temperature, pH, and copigments. Blackcurrant juice was used as the raw material in this study, and the effects of malic acid on the chemical stability and degradation kinetics of the anthocyanins in blackcurrant juice samples with various soluble solid concentrations were investigated under different storage temperatures and pH values. The total anthocyanin contents of samples were determined using the pH-differential method, and the Arrhenius equation was used to fit the pattern of the degradation. The results indicated that the degradation rate constant (k) and the residual rate of anthocyanins in juice with 0.08% malic acid were decreased and increased, respectively, at a temperature of 4 ℃, pH of 3.0, and a solid concentration of 10 °Brix. Under the above conditions, the degradation half-life (t1/2) of anthocyanins increased from 51 d to 141 d, and the thermal degradation activation energy (Ea) increased from 51 kJ/mol to 61 kJ/mol with the addition of malic acid. Degradation of anthocyanins in blackcurrant juice during storage followed first-order reaction kinetics. Malic acid has certain copigmentation effects on blackcurrant juice under the conditions of low temperature, low pH, and low soluble solid concentration, and can enhance the stability of anthocyanins.
    20  A Model for the Inhibition of Listeria monocytogenes by Lactobacillus plantarum, Established using a Modified Jameson-effect Model
    DONG Qing-li ZHANG Wen-min SONG Xiao-yu XU Chao-qun LIU Zhi-feng YUAN San-ling LIU Qing
    2016, 32(9):135-140. DOI: 10.13982/j.mfst.1673-9078.2016.9.020
    [Abstract](853) [HTML](0) [PDF 735.00 K](1053)
    Abstract:
    The inhibitory effect of Lactobacillus plantarum on the growth of Listeria monocytogenes was investigated, and a model for demonstrating this inhibition was constructed using a modified Jameson-effect model. A Lac. plantarum pure culture and a mixed culture of Lac. plantarum and Lis. monocytogenes were obtained using the dilution method, and were cultivated in thermostat incubators at 7 ℃, 14 ℃, 21 ℃, 28 ℃, and 35 ℃, respectively. Samples were collected periodically and the bacterial count was recorded. The Lis. monocytogenes pure culture data were obtained from the ComBase database. Based on the data of the mixed culture, the Baranyi model was selected as the primary model and was used for fitting to estimate the maximum growth rate (μmax) and lag phase (λ). Subsequently, the modified Jameson-effect model was employed to establish the model for the inhibition of Lis. monocytogenes by Lac. plantarum, and validation of the model was performed. Lac. plantarum did not grow at 7 ℃ and exhibited a significant inhibitory effect on Lis. monocytogenes at 14 ℃, 21 ℃, 28 ℃, and 35 ℃. Validation of the inhibition model showed that the mean square error (MSE), bias factor (Bf), and accuracy factor (Af) values were in a range of 0.07~0.10, 0.98~1.04, and ~1, respectively, indicating that the modified Jameson-effect model could effectively predict the growth of Lis. monocytogenes in the presence of Lac. plantarum as an inhibitor.
    21  Kinetic Modeling of Plasticizer Migration from Starch-based Film in Food Simulants
    ZHU Jie LI Xiao-xi LI Lin
    2016, 32(9):141-146. DOI: 10.13982/j.mfst.1673-9078.2016.9.021
    [Abstract](744) [HTML](0) [PDF 690.80 K](1182)
    Abstract:
    Esterified starch, with a high degree of substitution, and triacetin were used as the matrix and the plasticizer, respectively, to prepare a starch-based film. Thermogravimetric analysis (TGA) was employed to detect the changes in plasticizer content in the starch-based films when the film was exposed to different food simulants. The migration of plasticizer from the starch-based film was analyzed using the overall kinetic and the diffusion models. The results indicated that in 4% acetic acid system with a weak affinity towards the starch-based film, the whole plasticizer migration obeyed first-order kinetics; the short-term plasticizer migration obeyed the Fick’s second law; and the following migration obeyed the non-Fickian model of diffusion. In 65% aqueous ethanol and n-hexane systems with a stronger affinity towards starch-based films, the plasticizer migration did not obey the Fick’s law and the effect was more obvious for the long-term migration. Collectively, the results indicated that because of the different affinities between food simulants and film matrix, the plasticizer migration through the swelling layer towards food simulants exhibited different kinetic characteristics, which changed due to the effect of the interaction between films and simulant systems.
    22  Model Optimization for the On-line Inspection of Internal Apple Quality by Shortwave Near-infrared Spectroscopy
    GUO Zhi-ming HUANG Wen-qian CHEN Quan-sheng PENG Yan-kun ZHAO Jie-wen
    2016, 32(9):147-153. DOI: 10.13982/j.mfst.1673-9078.2016.9.022
    [Abstract](865) [HTML](0) [PDF 1.19 M](2024)
    Abstract:
    The critical part in the application of near-infrared (NIR) spectroscopy for the on-line inspection of internal fruit quality is to build quantitative analysis models with good robustness and high accuracy. A system based on shortwave NIR spectroscopy for on-line inspection of apple quality was developed. The spectra were collected in diffusion reflectance mode within the wavelength range of 500~1100 nm, and the conveyor belt speed was fixed to five samples per second. After the band intensity was normalized, genetic, successive projection, and ant colony optimization (ACO) algorithms were employed to select characteristic variables, following which the respective corresponding partial least square (PLS) models were constructed, and the spectral variable search mechanisms of these three methods were analyzed. Compared with the full spectral model, the predictive models built on the variable selection methods all exhibited better predictive performance with fewer variables, improved computational speed, and enhanced robustness. The best predictive performance was found in the model built using ACO-PLS, where the correlation coefficient of the prediction set was 0.9358 and the root mean square error of prediction was 0.2619 oBx. The results of this study demonstrate that NIR combined with variable selection methods can build an efficient model for the on-line determination of the apple soluble solid content, and has great potential for industrial application.
    23  Simulation Analysis of a Single-station Jujube Pit-removing Machine
    LIU Jiang-long ZHANG Shu-juan ZHOU Jing-bo YANG Yi
    2016, 32(9):154-160. DOI: 10.13982/j.mfst.1673-9078.2016.9.023
    [Abstract](918) [HTML](0) [PDF 1.03 M](1654)
    Abstract:
    Currently available triple-station jujube pit-removal machines require frequent changes of different sizes of fixtures when red jujubes of different size and variety are processed. This leads to poor adaptability, low work efficiency, and other issues. In order to solve these problems, a single-station pit-removal machine was designed based on an elastic fixture and the principle of rotational axis positioning, with a consideration of the dimensions of all kinds of jujubes and the parameters of their pits. The project included designing a novel fixture, the main transmission system, and the structure of key components. The axial positioning of red jujubes was achieved by the rotation of the lower fixture in the direction of the axis, while the design of the elasticity frame allowed the fixture to adapt to different sizes of red jujubes, thus avoiding the step of changing fixtures. A prototype model of single-station jujube pit-removal machine was built using UG software and appropriately simplified based on the structures of the components and the working principle of the pit-removal system. Subsequently, the pattern of movement and the stress conditions during operation was simulated by ADAMS virtual prototype software. Finally, a simulation with the single-station jujube pit-removal machine was carried out to validate its rationale. The results indicated that the pit-removal rate was 95%, the production yield was 91.5%, and the average rate of pulp loss was 3.75%. This jujube pit-removal machine satisfies the requirement of actual production and the pit removal rate was up to 21600 fruits per hour, which is higher than that of existing jujube pit-removal machines.
    24  Inactivation Effect of Radio Frequency Heating on Polyphenol Oxidase and the Analysis of Kinetics
    ZHOU Liang-fu LEI Yu-jie LI Yu-kun CHEN Xiang-wei NIU Hai-yue WANG Yun-yang
    2016, 32(9):161-166. DOI: 10.13982/j.mfst.1673-9078.2016.9.024
    [Abstract](1175) [HTML](0) [PDF 634.74 K](1473)
    Abstract:
    In order to investigate the pattern of polyphenol oxidase (PPO) inactivation by radio frequency (RF) heating, the effects of the electrode gap and the electrical conductivity of phosphate-buffered saline (PBS) on the heating rate and inactivation of PPO were studied, and the data were fitted to different models to determine the inactivation kinetics. The results showed that both the electrode gap and conductivity affected the RF heating rate. The larger the electrode gap was, the slower was the rate of temperature increase. When the electrical conductivity was 0.1 S/m, the rate of temperature increase was the fastest. At the electrode gap of 120 mm, conductivity of 0.1 S/m, and RF heating duration of 105 s, the PPO inactivation rate was 91.88%. The first-order kinetics model, Weibull model, and log-logistic model were used to fit the inactivation curve of PPO. The fitness of the three models was evaluated by using a series of indices, including the accuracy factor (Af), bias factor (Bf), root mean square error (RMSE), and correlation coefficient (R2). The curve did not show compliance with first-order kinetics, whereas both the Weibull and log-logistic models could fit the inactivation curve well. The consistencies between measured and predicted values of the three models were examined and the log-logistic model provided the best fitness for the PPO inactivation curve under RF heating.
    25  Drying Characteristics of Cantonese Almond Cookie Based on Fractal
    RUAN Zheng HONG Man-xing LIANG Lan-lan LI Bian-sheng
    2016, 32(9):167-173. DOI: 10.13982/j.mfst.1673-9078.2016.9.025
    [Abstract](680) [HTML](0) [PDF 1.42 M](895)
    Abstract:
    A tunnel drying equipment was used to simulate the industrial tunnel oven and determine the drying characteristics of Cantonese almond cookie. Scanning electron microscopy (SEM) followed by image analysis were done to determine the pore microstructure of almond cookie. The effect of particle size on the drying properties and quality of Cantonese almond cookie was explored based on fractal theory. The results showed that the almond cookie with low moisture content had an internal porous structure and an apparent fractal feature. The smaller the particle size was, the more complex the pore structure was. Under the same baking temperature of 100 ℃ or 120 ℃, the drying rate of almond cookies made of 140-mesh powder were significantly higher than that of almond cookies made of 60-mesh and 100-mesh powders. Texture property analysis (TPA) indicated that with a decrease in particle sizes (60 mesh→100 mesh→140 mesh), the hardness, cohesiveness, and chewiness of almond cookies decreased significantly (p<0.05). According to the sensory evaluation, the almond cookie made of 140-mesh powder had better quality than those made of 60 mesh and 100 mesh. Therefore, the drying rate and quality of Cantonese almond cookie can be improved by reducing particle size within a certain range during the production of almond cookie powder.
    26  Characteristic Wavelength Selection-based Prediction of Soluble Solids Content of Hami Big Jujubes using the Hyperspectral Imaging Technology
    SUN Jing-tao MA Ben-xue DONG Juan YANG Jie XU Jie JIANG Wei
    2016, 32(9):174-179. DOI: 10.13982/j.mfst.1673-9078.2016.9.026
    [Abstract](849) [HTML](0) [PDF 1.84 M](1285)
    Abstract:
    Prediction of soluble solids content (SSC) of dried Hami big jujubes was studied by means of the hyperspectral imaging technology in this work. Many spectral preprocessing methods were used to preprocess the raw spectra, and the partial least squares (PLS) models were established based on the raw spectra and preprocessed ones. The comparison and analysis showed that the best preprocessing result was achieved by the mean centering (MC) algorithm. MC-pretreated spectra were screened by the synergy interval partial least squares (si-PLS) method, and the characteristic wavelengths of SSC of Hami big jujubes were selected using a combination of a genetic algorithm (GA) and competitive adaptive reweighted sampling algorithm (CARS). The selected wavelength variables were used to build a PLS predictive model for SSC of Hami big jujubes. The results indicated that 16 characteristic wavelengths were selected and accounted for only 2% of full spectral variables in the MC-CARS-GA-si-PLS model. The performance of the newly built PLS model was better than that of the PLS model based on the full spectrum. The correlation coefficient of the prediction set (Rp), the root mean square error of prediction (RMSEP), and the relative prediction deviation (RPD) of this model were 0.93, 0.48, and 2.721, respectively. The results show that this PLS predictive model based on the wavelength selection not only is simpler but also enhances the predictive ability of such models, and can serve as a reference for quantitative analysis and study of fruits and dried fruits by the hyperspectral imaging technology.
    27  Effects of a Pulsed Electric Field on DPPH Radical-scavenging Activity and Structure of Antioxidant Peptide MMCTD
    ZHANG Ming-di XING Jie LI Xing-fang LIANG Rong LIN Song-yi
    2016, 32(9):180-185. DOI: 10.13982/j.mfst.1673-9078.2016.9.027
    [Abstract](755) [HTML](0) [PDF 734.53 K](1232)
    Abstract:
    The antioxidant peptide Met-Met-Cys-Thr-Asp (MMCTD) obtained in the previous study was analyzed in this work, and 2,2-diphenyl-1-picrylhydrazyl (DPPH?) radical-scavenging capacity served as an indicator of antioxidant activity. Mid-infrared spectroscopy (MIR), circular dichroism (CD) spectroscopy, zeta-potential, and nuclear magnetic resonance (NMR) were used for an in-depth analysis of the effects of a pulsed electric field (PEF) on the antioxidant activities of peptide MMCTD. The results showed that when the electric field intensity was 5 kV/cm and pulse frequency was 2400 Hz, the DPPH radical-scavenging capacity reached a peak value (94.27%±0.03%, mean±SD) and the zeta-potential of peptide MMCTD being treated was reduced to 10.85±0.98 mV. The MIR and NMR results revealed that after the PEF treatment, the functional groups of peptide MMCTD were not changed, but the chemical environment of the hydrogen ion (proton) was changed. The CD analysis indicated that the proportion of the β-sheet in the secondary structure decreased from 13.7% to 0%, and the relative amounts of the β-turn and random coil increased significantly. These changes not only preliminarily reveal that PEF can enhance the antioxidant activity of peptide MMCTD by changing the secondary structure and surface charge distribution but also lay the foundation for identification of the mechanism underlying the enhancement of antioxidant activity by PEF.
    28  Improving the Functional Properties of Chicken Protein in Maillard Reaction by Hydrolysis
    FU Jia-yin BAI Wei-dong LIU Yao-ru WANG Qin
    2016, 32(9):186-195. DOI: 10.13982/j.mfst.1673-9078.2016.9.028
    [Abstract](779) [HTML](0) [PDF 1.42 M](1335)
    Abstract:
    Various enzymes were used to hydrolyze chicken breast meat to produce enzymatic hydrolysates and xylose for Maillard reaction. The effect of the substrates obtained from different enzymatic hydrolysis methods on the Maillard reaction products (MRPs) (content of peptides, amino acids, sugars, and other reaction substrates, as well as content and antioxidant capacity of MRPs) were investigated and the correlation among all measured indicators were analyzed. The results indicated that the degree of hydrolysis (DH) significantly affected the properties of MRPs and the peptides produced by enzymatic hydrolysis showed higher reactivity for Maillard reaction. The hydrolysate with higher DH showed greater sugar consumption and increased MRP content, with higher antioxidant capacity. With the same initial concentration, ferric-reducing/antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH?) scavenging ability of the MRPS from eight-hour hydrolysate were twice and seven times higher than those of the MRPS from two-hour hydrolysate. The properties of enzymatic hydrolysates were significantly improved by the Maillard reaction, with two-fold maximum increase in soluble peptide content, one-fold maximum increase in soluble amino acid concentration, and 40-fold maximum increase in antioxidant capacity. Based on the correlation between the measured indices, sugar consumption reflects the extent of Maillard reaction to a certain degree, which in turn, improves the decomposition of peptides to generate amino acids.
    29  Degradation of Deoxynivalenol in Flour by Ozone and Ultraviolet Light and their Effects on Flour Quality
    YU Yi-gang MA Han-ruo HOU Rui TANG Yu-qian XIAO Xing-long
    2016, 32(9):196-202. DOI: 10.13982/j.mfst.1673-9078.2016.9.029
    [Abstract](808) [HTML](0) [PDF 757.27 K](1760)
    Abstract:
    In order to decrease the deoxynivalenol (DON) content of flour, contaminated flour samples were treated by ozone and ultraviolet (UV) light and the effect of these treatment conditions on DON degradation was studied; the protein content, wet gluten content, and whiteness of flour before and after treatment were compared. Additionally, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was employed to study the cytotoxicity of DON and the degradation products in LO2 cell line. The results showed that when the DON-contaminated flour was treated with 45 mg/L ozone and 16.00% (m/m) moisture for 60 min at room temperature, the DON degradation rates for the flour samples with initial DON contents of 2.35, 2.84, 4.09, and 4.95 mg/kg reached 46.59%, 40.71%, 38.96%, and 35.40%, respectively. When the DON-contaminated flour was treated with 1200 μW/cm2 UV and 12.00% (m/m) moisture for 60 min, the DON degradation rates of the above same flour samples reached 39.89%, 40.32%, 36.68%, and 30.32%, respectively. After the two treatments, the protein content, wet gluten content, and whiteness of flour showed no significant difference as compared to those of control group. The results of MTT assay indicated that DON exhibited a strong cytotoxicity on LO2 cells, and the cell viability was reduced by 62.02% after 48 h of DON treatment. The products of UV and ozone degradation with the same initial DON concentration reduced the cell viability by 17.50% (p<0.05) and only 2% (p>0.05), respectively. DON in the flour could be degraded effectively in a short time using the method described in this study, which showed no significant impact on the flour quality. The degradation products of both the methods exhibited a significantly reduced cytotoxicity to LO2 cells.
    30  The Influence of Low-temperature Radio Frequency Plasma Treatment on Quality of Peanut Oil
    LIU Zhen WANG Shi-qing XIAO Jun-xia XIONG Xu-bo ZHANG Yan JIANG Wen-li
    2016, 32(9):203-208. DOI: 10.13982/j.mfst.1673-9078.2016.9.030
    [Abstract](692) [HTML](0) [PDF 631.96 K](1037)
    Abstract:
    Peanut oil was treated with low-temperature radio frequency plasma, and the plasma in an excited state may cause changes in the physicochemical properties of oil. Acidity, iodine content, peroxide content, vitamin E (VE), oxidation stability, and the concentration of trans-fatty acids of peanut oil were used as indicators to assess the influence of the aflatoxin removal process using low-temperature radio frequency plasma on quality of peanut oil. The results showed that after the peanut oil samples were treated with plasma at 100, 200, or 300 W for 10 min, the acidity values were reduced to 0.28, 0.25, and 0.26 mg KOH/g, respectively, and there were significant differences (p<0.05). The iodine value did not change substantially within 10 min, and the differences were not significant (p>0.05). Within the range of the experimental treatment, peroxide content of peanut oil was always below 6 mmol/kg. High-performance liquid chromatography (HPLC) analysis indicated that VE and trans-fatty acid contents were affected by the plasma treatment only slightly. The use of low-temperature radio frequency plasma to remove aflatoxin B1 (AFB1) is not only safe and effective but also maintains the quality of peanut oil.
    31  Comparison of the Physicochemical Characteristics of Gardenia Fruit Oils Obtained by Various Methods
    LI Hao-yang WANG Fei-yun LIU Hua-min WANG Xue-de QIN Guang-yong
    2016, 32(9):209-215. DOI: 10.13982/j.mfst.1673-9078.2016.9.031
    [Abstract](864) [HTML](0) [PDF 523.58 K](1527)
    Abstract:
    Three types of oil samples were obtained from gardenia fruit using n-hexane extraction, subcritical low-temperature butane extraction, and supercritical carbon dioxide extraction, respectively. The effect of the three extraction methods on the oil quality was investigated by comparing the main physicochemical indices, fatty acid composition, phytosterol content, oryzanol content, vitamin E content, and oxidative rancidity time. The results showed that the peroxide values, acid values, saponification values, and iodine values of the three gardenia fruit oils ranged between 9.38~17.30 mmol/kg, 4.06~14.28 mg KOH/g, 186.07~198.91 mgKOH/g, and 116.43~130.16 g I2/100 g, respectively. The results of gas chromatography (GC) suggested that the main fatty acids present in the samples were linoleic acid, oleic acid, and other unsaturated fatty acids, and their relative contents accounted for 76.04~78.00% of the total content of phytocompounds present in the oils. The contents of phytosterol and vitamin E in gardenia fruit oils ranged between 0.85~3.48% and 17.06~29.80 mg/100 g, respectively. The gardenia fruit oil obtained using supercritical carbon dioxide extraction showed the best color quality and the lowest amount of solvent residue, but the highest acid value. The oil extracted by n-hexane had the highest phytosterol content and a relatively good antioxidant activity. The oil obtained from subcritical butane-extraction had the lowest acid value and the highest content of vitamin E. This study reveals a theoretical basis for the selection of extraction and refining methods of gardenia fruit oils, and shows a certain value on application.
    32  Effects of Moisture Content and Heating Temperature on Texture and Sensory Qualities of Pork
    ZHANG Li-yan HU Jia-ying
    2016, 32(9):216-223. DOI: 10.13982/j.mfst.1673-9078.2016.9.032
    [Abstract](833) [HTML](0) [PDF 668.95 K](1733)
    Abstract:
    Using pork tenderloin as a raw material, the effects of moisture content and heating temperature on the properties of pork products were investigated on the basis of sensory evaluation, instrumental analysis, and the results of low-field nuclear magnetic resonance (LF-NMR) analysis. The results revealed that sensory hardness, sensory tightness, and sensory chewiness of pork decreased with the increasing moisture content, whereas sensory springiness was slightly improved, but there were no significant differences among the dried samples heated at 100 ℃ (p>0.05). Hardness, chewiness, the shear force, and other textural properties showed a significant negative correlation with the moisture content of the pork products (p<0.01). The soft and loose texture and reduced hardness of the meat heated at 121 ℃ could be improved by reducing its water content (<36%). The results of LF-NMR indicated that with the increasing degree of drying, the transverse relaxation time (T2) values of hydration water, immobilized water, and free water decreased, and the shift of relaxation time of water in the T21 state was more significant with the increasing heating temperature. Compared with air drying, high-temperature heating had more significant effects on the moisture distribution of pork. Immobilized water was found to be closely related to textural properties. Thus, quality of meat products may be changed by controlling the concentration of immobilized water.
    33  Effect of Hot-air Drying on the Epidermal Cuticle of Hami Jujube
    WEI Yu-long YU Ning XU Ming-qiang CHEN Kai WANG Ping LI Huan-rong PANG Huan-ming
    2016, 32(9):224-233. DOI: 10.13982/j.mfst.1673-9078.2016.9.033
    [Abstract](761) [HTML](0) [PDF 2.67 M](1024)
    Abstract:
    Fresh hami jujube fruits were hot-air dried at five different temperatures (35, 40, 45, 50, and 55 ℃) to study the effect of hot-air drying on their epidermal cuticle. The morphology, thickness distribution, and lipid-soluble substances in the cuticle of Hami jujube were studied using scanning electron microscopy (SEM), paraffin sections, and gas chromatography-mass spectrometry (GC-MS). The results showed that restructuring occurred in the epidermal cuticle of jujube during the drying process, becoming more significant with increasing temperature, and that the restructuring process also changed the cuticle thickness. There were changes in the content of lipid-soluble substances in the jujube fruits when dried at different temperatures. At 35 and 40 ℃, the contents of cuticular hydrocarbons, alcohols, and ketones increased, while the contents of acids and aldehydes decreased; at 45, 50 and 55 ℃, the contents of ketones, phenols, aldehydes, and esters increased, while the contents of hydrocarbons and acids decreased. A high drying temperature led to a decrease in the content of medium- and long-chain lipid-soluble substances, and an increase in short-chain lipid-soluble substances. These changes in the contents of lipid-soluble substances might be major factors influencing the changes in cuticular structures.
    34  Influence of Frozen Storage Temperature on Quality and Microstructure of Frozen Pork Dumpling Filling
    HUANG Li KONG Bao-hua ZHANG Han-jie HAN Qi ZHAO Xin-xin
    2016, 32(9):234-240. DOI: 10.13982/j.mfst.1673-9078.2016.9.034
    [Abstract](877) [HTML](0) [PDF 1.85 M](1504)
    Abstract:
    The effect of different frozen storage temperatures on quality properties and microstructures of frozen pork dumpling fillings to reveal the mechanism underlying the changes in their quality was evaluated. Freshly prepared dumplings were frozen at -25 ℃ and then stored for 0 d, 30 d, 60 d, 90 d, or 180 d at -7 ℃, -18 ℃, and a temperature fluctuating between -7 ℃ and -18 ℃, respectively. The a*-value, b*-value, and the gel properties of myofibrillar protein were measured at an interval of 30 d, and the scanning electron microscopy (SEM) and paraffin sectioning of the dumpling filling were also performed. The results showed that with increasing frozen storage time, a*-value and b*-value of the dumpling filling was reduced significantly (p<0.05), the first peak storage modulus values (G′) of myofibrillar protein gel decreased, and Tanδ at the final heating stage increased. The SEM and paraffin section results indicated that the samples stored at -18 ℃ had a relatively fine and smooth texture, showing a lower degree of protein denaturation in the minced meat matrix. However, the texture of the samples stored at -7 ℃ and -7 ℃/-18 ℃ became coarse; the degree of protein denaturation and the emulsifying properties of the minced meat matrix increased and decreased, respectively; and there was a significant fat exudation. This finding indicated that a high (-7 ℃) storage temperature and a fluctuating storage temperature (-7 ℃/-18 ℃) caused deterioration of the dumpling quality. Therefore, a low-temperature and a short-term storage are necessary for the retail sales, transportation, and storage of frozen dumplings, in order to maintain a good quality.
    35  Effects of Different Thawing Methods on the Quality Attributes of Frozen Lentinus edodes Cubes
    ZHANG Yu ZHAO Jin-hong DING Yang NIE Ying ZHU Zhen TANG Xuan-ming
    2016, 32(9):241-247. DOI: 10.13982/j.mfst.1673-9078.2016.9.035
    [Abstract](856) [HTML](0) [PDF 602.10 K](1154)
    Abstract:
    Different thawing methods (air ambient temperature thawing; refrigerator thawing; microwave thawing at 119, 259, and 280 W; and high-pressure thawing at 100, 150, and 200 MPa) were tested for their effects on the thawing time and quality attributes (color, drip loss, hardness, total phenolic content, and ion permeability) of frozen Lentinus edodes cubes. Both microwave thawing and high-pressure thawing could significantly shorten the thawing time of the frozen samples compared with air or refrigerator thawing, with the thawing time decreasing with increasing microwave power or processing pressure. The sample thawed by high pressure exhibited a dramatic decrease in color and hardness and a pronounced increase in ion permeability, thus resulting in a dramatic decrease in the quality of Lentinus edodes. However, microwave thawing significantly improved the quality attributes of the mushroom samples in terms of color (total color difference reduced by 19.9~44.1%), hardness (increased by 18.9~38.0%), drip loss (reduced by 45.7~42.0%), and total phenolic content (increased by 21.1~25.2%) compared with air ambient temperature thawing. The result suggests that microwave thawing at 259 W is the best method for thawing Lentinus edodes cubes with the highest sensory score (7.1). This study indicates that microwave thawing can significantly enhance both the thawing rate and quality attributes for Lentinus edodes, and shows a certain value to the processing of this mushroom species.
    36  Effects of Adsorption on Polycyclic Aromatic Hydrocarbon Removal and Flavor Retention in Sesame Oils during the Refining Process
    LIU Yu-lan SHI Long-kai LIU Yan AN Jun ZHANG Dong-dong
    2016, 32(9):248-253. DOI: 10.13982/j.mfst.1673-9078.2016.9.036
    [Abstract](847) [HTML](0) [PDF 418.40 K](1066)
    Abstract:
    The effects of adsorption on flavor, removal of polycyclic aromatic hydrocarbons (PAHs), and contents of three lipid components of sesame oil during the refining process were studied. The PAH removal efficiencies of three tested adsorbents were in the descending order of Norit activated carbon>WY2 activated carbon>activated clay. The contents of benzo[a]pyrene (B[a]P) in the adsorbed sesame oils was lower than the limit of the national standard GB 2716-2005 of China (B[a]P<10 μg/kg). The contents of B[a]P and PAH4 in the adsorbed sesame oils treated with 0.2% Norit activated carbon and 0.5% WY2 activated carbon were lower than or were close to the limits set by EU No 835/2011 (B[a]P content: <2 μg/kg; PAH4 content: 10 μg/kg). Their B[a]P contents were 0.83 and 1.50 μg/kg, respectively, and their PAH4 contents were 4.85 and 10.94 μg/kg, respectively. Meanwhile, the inherent flavor loss was low, and the retention rates of sesamin, sesamolin, and vitamin E were high. The comprehensive assessment of the removal of PAHs, and the retentions of flavor and beneficial lipid components in sesame oils indicated that 0.5% WY2 activated carbon was the most suitable adsorbent.
    37  Preparation and Characterization of Starch Nanoparticles Prepared using Short Glucan Chains Debranched for Different Times
    JIANG Sui-sui YANG Jie CHANG Ran-ran XIONG Liu SUN Qing-jie
    2016, 32(9):254-259. DOI: 10.13982/j.mfst.1673-9078.2016.9.037
    [Abstract](1013) [HTML](0) [PDF 1.19 M](1566)
    Abstract:
    Using waxy maize starch as the raw material, short glucan chain samples were prepared by enzymatic hydrolysis with different debranching times, and starch nanoparticles (SNPs) were prepared through self-assembly of the prepared chains at 4 ℃. Transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter analysis (DSC), and high-performance size-exclusion chromatography (HPSEC) were used to characterize the structure and morphology of SNPs. The TEM and DLS results showed that the SNPs were spherical or ellipsoidal particles, with a diameter of 30~150 nm, and that the size increased with increasing enzymatic hydrolysis time. X-ray diffraction results showed that all of the SNPs displayed the same typical B-type structure, and the relative crystallinity was above 40%. Compared with other glucan chains debranched for different times, the sample obtained from a six-hour enzymatic hydrolysis exhibited the narrowest molecular weight (MW) distribution, and produced SNPs with the highest peak for pasting temperature (Tp) and enthalpy (ΔH). The effects of different enzymatic hydrolysis times on the properties of SNPs were studied, and these findings could provide the theoretical basis for the preparation of SNPs using enzymatic hydrolysis and starch retrogradation.
    38  Distribution of Mycotoxins in Milling and Wet Processing of Scabby Wheat
    HE Hui-hui LI Li HAN Xiao-xian ZHENG Xue-ling BIAN Ke
    2016, 32(9):260-266. DOI: 10.13982/j.mfst.1673-9078.2016.9.038
    [Abstract](1100) [HTML](0) [PDF 744.92 K](1298)
    Abstract:
    Wheat scab not only leads to loss of grain but also poses a high risk of contamination by various mycotoxins. To study the distribution of four kinds of mycotoxins in scabby wheat after milling and wet processing, infected wheat was milled into flour in the laboratory, after which crude starch and gluten were obtained by wet separation. Content of deoxynivalenol (DON), aflatoxin B1 (AFB1), zearalenone (ZEN), and ochratoxin A (OTA) in flour and separated products was measured by enzyme-linked immunosorbent assay (ELISA). The results showed that milling and wet processing had a significant influence on the distribution of mycotoxins. After grinding, the content of DON, AFB1, and ZEN in break flour and reduction flour were significantly lower than that in raw grain, ranging from 1.38% to 16.24%, 20.47% to 71.77%, and 26.71% to 69.51%, respectively. The products of wet processing showed DON content ranging from 4.88% to 12.11% of that obtained in corresponding straight flour. While AFB1 and OTA were concentrated and enriched in the products, their concentration was 2.55 and 3.65 times that in straight flour, respectively. The content of ZEN in crude starch was approximately 12.70% to 15.83% of that in straight flour, while wheat gluten concentration increased 4.11 times that in corresponding straight flour. The results from this study indicates that appropriate wheat treatment methods, such as grinding and wet processing, should be selected for wheat processing according to the fungal infection type and severity of scabby wheat during industrial production.
    39  Analysis and Evaluation of Nutritional Composition of Yangtze River- coilia Meat at Different Ovarian Development Stages
    TENG Jing TAO Ning-ping LI Yu-qi
    2016, 32(9):267-274. DOI: 10.13982/j.mfst.1673-9078.2016.9.039
    [Abstract](918) [HTML](0) [PDF 698.07 K](957)
    Abstract:
    The nutritional components in the meat of Yangtze River-Coilia at different ovarian development stages (stage II, stage III, stage IV, and stage V) were studied and evaluated in this paper. The crude fat content declined significantly; the moisture and crude protein contents increased significantly (p<0.05), and the ash content decreased after the initial increase from stages II to V. These results indicated that fat was the main energy source during ovarian development. Given that fatty acids are the first to be decomposed for energy, mono-unsaturated fatty acid levels showed a downward trend during all stages of ovarian development. However, the fatty acids with the highest contents were C16:1 and C18:1 at different ovarian-development stages, indicating that they may be the principal metabolic fuels. The contents of the n-3 unsaturated fatty acids, especially those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), decreased significantly from stages II to V (p<0.05). In contrast, amino acid contents increased significantly from stages II to V (p<0.05), but the amino acid composition was relatively stable. The contents of total essential amino acids accounted for 39.65~40.93% of total amino acids, the ratios of total essential amino acids to total non-essential amino acids were in the range of 59.07~60.35%, and the amino acid scores were all higher than 100, indicating that meat of Yangtze River-Coilia can serve as a good source of amino acids. At different stages of ovarian development, the K content was the highest, followed by Na and Ca. Among the microelements tested, Cu and Mn levels were significantly decreased from stages II to V (p<0.05).
    40  Analysis of Volatile Flavor Compounds in Ten Commercial Chicken Flavors
    ZHAO Mou-ming CAI Yu CAO Yong FENG Yun-zi
    2016, 32(9):275-286. DOI: 10.13982/j.mfst.1673-9078.2016.9.040
    [Abstract](834) [HTML](0) [PDF 492.20 K](1323)
    Abstract:
    In order to study the aroma compositions of commercial chicken flavors, headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to analyze ten commercial products. A total of 131 compounds were identified with various types of the same compound, such as sulfur-containing compounds (29), terpenes (28), and aldehydes (25), followed by esters, furan(one)s, ketones, pyrazines, phenols, acids, and alcohols. Significant differences in the aroma composition were observed among these different chicken flavors. The flavor with the most complex aroma composition was used as the representative sample to study the aroma profiles of chicken flavor using gas chromatography-olfactometry (GC-O), and thirty aroma-active compounds were detected. The representative aroma-active compounds and their corresponding aroma types were classified as follows: meat-like flavors (2-methyl-3-furyl) disulfide and 2-[(methyldithio) methyl] furan), characteristic fat flavors ((E,E)-2,4-heptadienal and (E,E)-2,4-nonadienal), alliaceous flavor (dimethyl trisulfide and diallyl disulfide), spicy flavor (4-methoxybenzaldehyde and 4-ethyl-2-methoxyphenol), roasted flavor (3-(methylthio) propanal), caramel-like flavor (2,4-dihydro-2,5-dimethyl-3(2H)-furanone and 2,5-dimethyl-4-hydroxy-3(2H)-furanone), sour flavor (acetic acid), and milk flavor (2,3-butanedione).
    41  Characteristic Flavor Compounds in Chicken Bouillon by Gas Chromatography-mass Spectrometry and -Olfactometry
    TIAN Huai-xiang WU Xuan QIN Lan CHEN Chen YU Hai-yan
    2016, 32(9):287-294. DOI: 10.13982/j.mfst.1673-9078.2016.9.041
    [Abstract](935) [HTML](0) [PDF 808.75 K](1721)
    Abstract:
    Volatile components from chicken bouillons were extracted by headspace solid-phase microextraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS). Subsequently, odor-specific magnitude estimation (OSME) method using gas chromatography-olfactometry (GC-O) and odor activity value method (OAV) were used to determine the characteristic flavor components and conclude their contributions on the overall flavor. The relationship between sensory attributes and volatile compounds analyzed by GC-MS were established using partial least squares regression (PLS). The results identified 105 flavor compounds in chicken bouillons, including 13 sulfides, 26 alkanes, 18 aromatic compounds, 11 ketones, four alcohols, 15 alkenes, six aldehydes, ten heterocyclic compounds, and two esters. Among these, 32 flavor compounds showed good correlation with sensory attributes according to the PLS models. Additionally, GC-O analysis detected 23 aroma components. The characteristic flavor compounds in chicken bouillon identified by OSME method and OAV method included 2-propene-1-thiol, allyl methyl sulfide, 3,3'-thiobis-1-propene, 3-(allyldisulfanyl)-1-propene, caryophyllene, and (E,E)-2,4-decadienal. The results indicate that GC-MS, GC-O, and OAV methods coupled with PLS method can effectively and comprehensively evaluate the characteristic flavor components of chicken bouillons.
    42  An Electrochemical Immunosensor for Rapid Quantification of Benzo(a)pyrene in Grain- and Oil-related Foods
    WANG Rui-xin FENG Ya-jing LI Xiu-que LI Shu-guo
    2016, 32(9):295-301. DOI: 10.13982/j.mfst.1673-9078.2016.9.042
    [Abstract](714) [HTML](0) [PDF 1.32 M](1207)
    Abstract:
    A nanoimmunosensor for rapid quantification of benzo(a)pyrene (BaP) in food was constructed by modifying the glassy carbon electrode (GCE) with 2.0 G polyamidoamine (PAMAM), graphene (GS), and a 1-butyl-3-methylimidazolium tetrafluoroborate composite film and by immobilizing the antibody against polycyclic aromatic hydrocarbons (PAHs) on the surface of the GCE. On the basis of the specific immune reaction between the anti-PAH antibody and antigen, the effects of the immune response on the immunosensor response current were studied by cyclic voltammetry and differential pulse voltammetry using K3[Fe(CN)6] as the probe in phosphate buffer (pH=7.0) containing 1 mmol/L K3[Fe(CN)6] and 0.1 mmol/L KCl. At optimized experimental parameters, the peak response current of the immunosensor decreased with the increasing BaP concentration, and the response current showed a linear relation with the concentration of BaP in the range 0.1–100 ng/mL, with a detection limit of 0.03 ng/mL (S/N=3). The prepared anti-PAH/PAMAM/GS/IL/GCE immunosensor showed excellent stability and reproducibility. The newly developed method was applied to analysis of BaP content in peanut and rapeseed oil samples, and the recovery rate was in the range of 94.46~103.36%. The results were generally consistent with those obtained by high-performance liquid chromatography (HPLC) method; therefore, the proposed method is feasible for rapid quantification of BaP in grain- and oil-related foods.
    43  Detection of SudanⅠin Food using Magnetic Molecularly Imprinted Polymer Microspheres
    ZHAO Chen JIA Guang-feng LU Wen-zong REN Yu-miao GONG Qiang
    2016, 32(9):302-307. DOI: 10.13982/j.mfst.1673-9078.2016.9.043
    [Abstract](1011) [HTML](0) [PDF 705.06 K](976)
    Abstract:
    A novel method (magnetic surface molecular imprinting technique) for the detection of Sudan I in food was investigated. A silica-wrapped magnetic nanoparticle was utilized as the carrier and on its surface the magnetic surface molecular imprinted polymer was synthesized. The magnetic properties, morphological features, adsorption properties, and specificities of the prepared Sudan I magnetic molecularly imprinted polymers were determined by ultraviolet (UV) spectrophotometry, infrared (IR) spectrometry, and transmission electron microscopy. The results showed that the imprinted sites of the magnetic surface imprinted polymer were located on the surface of the magnetic carrier, and the binding capacity with the target substance was shown to be improved. With the presence of an external magnetic field, the magnetic surface molecularly imprinted polymers easily reached adsorption equilibrium, magnetic separation was achieved, and nonspecific adsorption was reduced, thus improving the adsorption and selectivity capacity for Sudan I. Furthermore, the recovery of Sudan I in pepper was measured to be more than 80%, indicating that the magnetic surface molecular imprinting technique can be used as a novel method for the rapid and efficient detection of Sudan I in food.
    44  A Real-time Fluorescence Loop-mediated Isothermal Amplification Method to Detect Enterobacter sakazakii in Milk Powder
    LI Li-li YE Lei ZHANG Huang CAO Wei-wei DENG Zi-xin SHI Lei
    2016, 32(9):308-313. DOI: 10.13982/j.mfst.1673-9078.2016.9.044
    [Abstract](885) [HTML](0) [PDF 696.63 K](1225)
    Abstract:
    In order to rapidly detect Enterobacter sakazakii in milk powder, a real-time fluorescence loop-mediated isothermal amplification (RealAmp) method was developed. Three sets of loop-mediated isothermal amplification (LAMP) primers targeting the Enterobacter sakazakii 16S rRNA sequence were designed. With a DEAOU-308C thermostat fluorescence detector, the specificity of the primers was examined using a standard strain of Enterobacter sakazakii. The sensitivity and detection limit on genomic DNA were also determined with a standard strain of Enterobacter sakazakii, followed by measuring the sensitivity and detection limit of this assay for artificially contaminated skimmed milk powder and whole milk powder, and a comparative experiment was performed on 20 commercial milk powder samples using the RealAmp method and national standard method. The results showed that the primer set 16S-11 had the best amplification efficiency, showed no cross-reactivity with common pathogens, and the sensitivity of RealAmp for detecting Enterobacter sakazakii genomic DNA, artificially contaminated skimmed milk powder, and whole milk powder reached 102 CFU/mL, 102 CFU/mL, and 103 CFU/mL, respectively. The detection limit of RealAmp in detecting Enterobacter sakazakii genomic DNA, artificially contaminated skimmed milk powder, and whole milk powder reached 103 CFU/mL, 103 CFU/mL ,and 104 CFU/mL, respectively. The results of 20 commercial milk powder samples obtained by the RealAmp method were consistent with those from the national standard culture method. The results suggest that this RealAmp assay is suitable for the rapid detection of Enterobacter sakazakii in milk powder.
    45  Research Progress on Magnetic Microbead-based Electrochemical Immunoassays
    KANG Huai-bin MA Hong-yan LI Fang CHEN Jun-liang ZHANG Rui-hua ZOU Liang-liang
    2016, 32(9):314-323. DOI: 10.13982/j.mfst.1673-9078.2016.9.045
    [Abstract](777) [HTML](0) [PDF 3.01 M](1661)
    Abstract:
    Magnetic microbeads, which possess a huge specific surface area and high dispersion capability, can capture biomolecules and form stable immune complexes that can be rapidly separated as a result of the superparamagnetism of the magnetic microbeads. The sample pretreatment is simple, and the target compounds can be rapidly detected without complex pretreatment steps such as pre-concentration or purification. Moreover, because the electrochemical analysis technique is ultrasensitive, its coupling with magnetic microbeads provides a novel detection system. In recent years, active research programs have been undertaken in this field and important progress has been achieved. Miniaturized electrochemical immunoassay systems with high sensitivity, rapid detection, and simple operation have been developed and can be used in food analysis, environmental evaluation, clinical diagnostics, etc. In this review, the most recent research progresses in electrochemical immunoassay technology using magnetic microbeads as a solid phase are summarized, especially in terms of immunoassays using magnetic electrodes, immunoassays in a droplet using a rotating disk electrode, and magnetic-microbead-based immunoassays using enzyme labels and nanoparticle tags. Additionally, the future work in this field is discussed.

    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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