Table of Content

15 November 2019, Volume 40 Issue 21
Basic Research
Estimation of Diffusion Coefficients of Nano-Components Migration from Nano-Metal/Metal Oxide-Polyolefin Food Packaging Film
ZHANG Ce, HU Changying, SHI Yujie, JIANG Ziwei
2019, 40(21):  1-6.  doi:10.7506/spkx1002-6630-20180908-085
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In order to investigate whether the migration of nano-components from polyolefin food packaging films into food simulants obeys Fick’s second law, the available experimental data were fitted to the Crank model to estimate the diffusion coefficients of nano-components migration from nano-metal/metal oxide-polyolefin food packaging films. The effects of temperature, polyolefin, nano-components and food simulants on the diffusion coefficient were analyzed. The results showed that the migration of nano-components into food simulants was consistent with Fick’s second law. The increase in temperature promoted the migration of nano-components, and the relationship between the diffusion coefficients and temperature was in accordance with the Arrhenius model. The structures of polyolefin had different effects on the diffusion coefficients; among three structures of polypropylene, nano-copper and nano-zinc oxide had the largest diffusion coefficient in isotactic polypropylene. Different concentrations of nano-components had different effects on their diffusion coefficients. The solubility differences between nano-components and food simulants and polyolefins affected the migration of nano-components into food simulants.
Stability and Antibacterial Activity of Nisin-Loaded Liposomes under Different pH Conditions
FU Mi, YU Jiali, GUO Liang, LI Yanhua, CHEN Jie, MENG Yuecheng
2019, 40(21):  7-13.  doi:10.7506/spkx1002-6630-20180923-243
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In order to improve the utilization efficiency of nisin and to achieve its long-lasting and sustained-release antibacterial properties, nisin-loaded liposomes were prepared with soy lecithin as the wall material by thin film evaporation-sonication method. The internal structure of nisin-loaded liposomes was analyzed by infrared spectroscopy. The effects of pH on the stability, encapsulation efficiency and sustained release rate were studied as well as the effect of heat treatment on bacteriostatic properties of nisin-loaded liposomes under different pH conditions. It was found that nisin was bound to lecithin inside by electrostatic interaction. The particle size of liposomes kept increasing and the regularity deteriorated and with decreasing pH. At the same time, the encapsulation efficiency and the release rate decreased, and the liposomes became unstable. A maximum encapsulation efficiency of 82.26% was obtained at pH 7.0. In addition, the system had the strongest sustained release ability at pH 6.0, and the total release rate was up to 96.49% after 6 days. Based on the minimum inhibitory concentration and the minimum bactericidal concentration, the antibacterial effect of nisin-loaded liposomes was little affected by pH and slightly inferior to that of free nisin monomers. However, nisin-loaded liposomes still had good antibacterial effect after high temperature treatment at 121 ℃ for 15 min, indicating that the system had good thermal stability. The time-killing kinetic curve showed that the nisin-loaded liposomes showed a good bactericidal effect in a slow-release way.
Antibacterial Mechanism of Fermentation Product from Bacillus megaterium L2 against Erwinia carotovora subsp. carotovora
ZHAO Jinyi, XIAO Yang, YANG Long, ZHANG Su, JI Yuyu, LI Zhu
2019, 40(21):  14-20.  doi:10.7506/spkx1002-6630-20181112-124
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Objective: To explore the inhibitory mechanism of the fermentation products of Bacillus megaterium L2 against Erwinia carotovora subsp. carotovora EC-1 as a major soft rot pathogen of Amorphophallus konjac K. Koch during storage. Methods: The fermentation products were extracted from freeze-dried Bacillus megaterium culture and separated by silica gel column chromatography under atmospheric pressure into 7 fractions (LE4-1-LE4-7). LE4-3, which exhibited potent antibacterial activity against strain EC-1, was analyzed for chemical composition by gas chromatography-mass spectrometry (GC-MS), and its antibacterial mechanism was studied by measuring the half maximal inhibitory concentration (IC50), the conductivity of cell suspension, nucleic acid and protein leakage, soluble total sugar concentration, total cell protein concentration, phosphorus metabolism and intracellular reactive oxygen species (ROS) level. Results: The major compounds of LE4-3 included ethyl phenylacetate (32.190%), ethyl linoleate (15.819%), and methyl phenylacetate (13.793%). Its IC50 value against strain EC-1 was (1.06 ± 0.01) mg/mL, and the antimicrobial mechanism may be achieved by damaging bacterial cell structure, affecting the integrity of the cell membrane, and inhibiting protein biosynthesis and energy metabolism. Therefore, fraction LE4-3 has promising application prospects for soft rot resistance in Amorphophallus konjac K. Koch during storage.
Structure and in Vitro Digestibility of Adzuki Bean (Vigna angularis) Starch-Lipid Complexes
GUO Hongwei, ZHAO Chengbin, WU Yuzhu, ZHANG Hao, ZHANG Suixin, LI Yan, XU Xiuying, LIU Jingsheng
2019, 40(21):  21-27.  doi:10.7506/spkx1002-6630-20181112-125
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Adzuki bean starch was complexed with four fatty acids (palmitic, stearic, oleic and linoleic acid), separately. After microwave-assisted pretreatment of the starch, starch-lipid complexes were prepared by water bath heating. The structures of the starch-lipid complexes were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). Their digestion characteristics in vitro were determined as well. The results showed that the volume of the four complexes, with?uneven?surfaces, increased when compared with the control starch under SEM. DSC analysis indicated that there was only one single peak in rice bean starch but three in each of these complexes, suggesting that the complexes were composed of type I and type II complexes. Gelatinization onset temperature, peak temperature, and conclusion temperature increased in the four complexes, which confirmed that the addition of fatty acids inhibited the gelatinization of the starch. Thermal enthalpy increased with the increase in the carbon chain length or the degree of unsaturation of fatty acids. The increase in enthalpy value was possibly related to the formation of resistant starch. FT-IR spectroscopy demonstrated the formation of complexes. Increased number of hydrogen bonds may increase the content of resistant starch. The complexes generated a diffraction angle of the V-type crystal structure accompanied by changes in crystal characteristics, which proved the existence of the complexes. The characteristic peak intensity of the complexes with palmitic, stearic or oleic acid was significantly higher than that of the complex with linoleic acid. As the intensity of the V-shaped characteristic peak increased, the resistant starch content increased. The relative content of rapidly digested starch in all complexes decreased, the relative contents of slowly digested starch and resistant starch increased, and the anti-digestibility of the starch decreased with the increase in the carbon chain length or unsaturation degree of fatty acids. The four fatty acids had different effects on the structure and in vitro digestion of adzuki bean starch. Among them, palmitic acid had the most significant effect. This study could provide useful information for further studies on the structural properties of starch-lipid complexes and their applications in resistant starch.
Effect of Heat Treatment on Emulsifying Properties and Raman Spectroscopic Characteristics of Enzymatically Modified Egg Yolk Liquid
XU Nan, ZHAO Ying, CHI Yujie
2019, 40(21):  28-34.  doi:10.7506/spkx1002-6630-20180925-270
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Egg yolk liquid is thermally sensitive and begins to denature at around 64 ℃, forming a gel. For this reason, heat treatment during processing can deteriorate the emulsifying properties of egg yolk liquid, limiting its application in the food industry. In this experiment, the effects of different heat treatments (at 60, 65 or 70 ℃ for 4 min) on emulsifying properties and protein structure of enzymatically modified egg yolk liquid were studied. The results showed that the emulsifying activity index (EAI) of egg yolk liquid decreased with the increase of heat treatment temperature, and the average particle size of the emulsion system formed increased. Under the same heat treatment condition, the EAI and emulsion stability index (ESI) of the modified egg yolk liquid were significantly higher than those of its unmodified counterpart (P < 0.05), and the particle size of the emulsion system formed with the modified egg yolk liquid decreased significantly, and the distribution of particle sizes was closer to the normal distribution. Raman spectral analysis showed that the secondary structure of proteins in the modified yolk liquid changed after heat treatment. With increasing heat treatment temperature up to 65 ℃, the relative content of α-helix structure increased significantly and the relative content of random coil structure decreased markedly (P < 0.05). Meanwhile, tryptophan and tyrosine residues and aliphatic hydrophobic groups were more exposed to the outside of protein molecules than the unmodified one. Partial least squares (PLS) was used to establish a model for describing the emulsifying properties of egg yolk liquid based on the Raman spectral data. It was found that changes in the conformation and secondary structure of proteins (especially low density lipoprotein) in egg yolk liquid had the greatest influence on the emulsifying properties of egg yolk liquid.
Analysis and Comprehensive Evaluation of Textural Quality of Ripe Fruits from Different Varieties of Oriental Melon (Cucumis melo var. makuwa Makino)
PAN Haobin, LIU Dong, SHAO Qingxu, GAO Ge, QI Hongyan
2019, 40(21):  35-42.  doi:10.7506/spkx1002-6630-20181025-299
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Fruits from 10 varieties of oriental melon were measured for 8 textural indexes and 6 physicochemical indexes related to texture by a texture analyzer and conventional physicochemical analysis. Correlation analysis, factor analysis and systematic cluster analysis were used to establish a comprehensive evaluation method for the textual quality of oriental melon, which is expected to provide a theoretical basis for further exploration of the key factors determining the textural characteristics of oriental melon and the selection of fine varieties. A significantly positive correlation between texture profile analysis (TPA) hardness and gumminess, chewiness or puncture hardness (P < 0.01), between adhesive force and adhesiveness (P < 0.01), between cohesiveness and gumminess or chewiness (P < 0.05), between gumminess and chewiness (P < 0.01), and between puncture hardness and gumminess or hewiness were observed. In addition, there was a significantly negative correlation between protopectin and water content and TPA hardness, puncture hardness, chewiness or gumminess (P < 0.05), between water-soluble pectin content and puncture hardness (P < 0.05), and between cellulose content and cohesiveness (P < 0.05), but starch content exhibited a significantly positive correlation with adhesive force and adhesiveness (P < 0.05). Three principal factors were extracted by factor analysis based on eigenvalues greater than one, explaining cumulatively 89.40% of the total variance. According to their representative indexes, the principal factors were named as tough-hard factor, adhesive-soft factor and cohesive factor, accounting for 52.76%, 25.73%, and 10.91% of the total variance, respectively. From the comprehensive score model obtained, the textual quality of ‘Yumeiren’ and ‘Caihongqihao’ were superior, ‘Hongpimian’ and ‘Xiangshami’ were poor, and the other varieties were in the middle. Systematic cluster analysis divided the 10 oriental melon varieties according to their textual properties into 5 classes: I including ‘Qianyu’, ‘Baitangguan’, and ‘Tetianmibao’, with crisp and hard texture; II including ‘Hongdaobian’ and ‘Yangjiaomi’, with crisp texture; III including ‘Hualeiwang’, ‘Caihongqihao’, and ‘Yumeiren’, with tough and hard texture; IV including ‘Xiangshami’, with sandy and soft texture; and V including ‘Hongpimian’, with adhesive and soft texture.
Effects of Auricularia Powder on Dough Rheological Properties and Noodle Quality Characteristics
WANG Dan, ZHENG Huihua, JI Yang, FANG Donglu, ZHAO Liyan, CHEN Hui, HU Qiuhui
2019, 40(21):  43-50.  doi:10.7506/spkx1002-6630-20190608-079
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In order to study the effects of Auricularia polytricha powder versus Auricularia auricular-judae powder on the rheological properties of dough and noodle quality, the effects of the addition of either Auricularia power on the thermomechanical properties, starch gelatinization properties and rheological properties of dough were investigated as well as on the texture, cooking loss rate, color, and sensory and nutritional quality of cooked noodles. The results showed that both Auricularia powers significantly increased dough water absorption and protein weakening degree, and reduced dough development time (P < 0.05). Auricularia polysaccharide effectively prevented starch aging, and its ratio to glutenin affected the viscoelastic properties of dough. The sensory score of noodles with 20% A. polytricha or 10% A. auricular-judae was the highest, accompanied by a significant increase in the contents of protein and dietary fiber (P < 0.05). The total content of essential amino acids in noodles with Auricularia polytricha or A. auricular-judae increased by 32.28%, and 8.85%, respectively. The amino acid composition of noodles with A. polytricha was closer to the pattern recommended by the Food and Agriculture Organization and the World Health Organization.
Inhibitory Effect of Ozone on the Growth and Mycotoxin Production of Alternaria
JIANG Nan, WANG Liuqing, LI Zuliang, WANG Duo, WANG Meng
2019, 40(21):  51-57.  doi:10.7506/spkx1002-6630-20190402-020
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Alternaria spp. can easily infect crops, causing plant diseases. Furthermore, it can produce Alternaria toxins, mainly including tenuazonic acid (TeA), alternariol (AOH), and alternariol monomethyl ether (AME). The toxins pose serious risks to human health. Therefore, there is an urgent need for a highly efficient, safe and economical strategy to prevent and control the growth and mycotoxin production of Alternaria spp.. In this paper, we studied the effect of ozone on the growth of A. alternata and its ability to produce toxins in vitro. The results showed that the diameter of the colony was significantly lower after ozone treatment (P < 0.05). Moreover, ozone could significantly inhibit the production of TeA, AOH and AME. It could cause morphological variations of the spores and hyphae, which became massively wrinkled and fractured, as the observed by scanning electron microscopy (SEM). In addition, it showed strong inhibitory effects on the pathogenicity and toxigenicity of A. alternata on tomato fruit. The concentrations of TeA, AOH and AME decreased by 36.1%, 89.9% and 93.2%, respectively after treatment with 20 mg/L ozone, and their degradation rates showed a positive correlation with ozone concentration and treatment time. TeA could be completely degraded after being treated with 20 mg/L ozone for 30 min. The degradation rates of AOH and AME were up to 90% when both mycotoxins were exposed to 20 mg/L ozone for 120 min. In conclusion, ozone could be used to prevent and control agricultural products from being polluted by A. alternata and its mycotoxins.
Effect of Xanthan Gum on Bioaccessibility of Four Bamboo Leaf Flavonoids during Simulated in Vitro Gastrointestinal Digestion
LI Zhanming, CAI Hongli, LIANG Yi, MAO Hao, LIAO Hanxue, YU Yue, ZHOU Dongren
2019, 40(21):  58-64.  doi:10.7506/spkx1002-6630-20180920-214
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Objective: Flavone C-glycosides?of bamboo leaves are susceptible to degradation during gastrointestinal digestion, leading to low bioaccessibility. Given this background, this study evaluated the changes in the bioaccessiblity of four flavone?C-glycosides (orientin, isoorientin, vitexin, and isovitexin)?present in the 80% ethanol extract of bamboo leaves at various stages of simulated gastrointestinal digestion in the presence of xanthan gum. Methods: Simulated digestion was carried out in the presence and absence of xanthan gum. The changes in flavone C-glycoside concentrations were analyzed by ultra-high performance liquid chromatography (UPLC). Results: Addition of xanthan gum significantly attenuated the degradation of flavone C-glycosides during the digestion process. The?oral, gastric and intestinal?phases had different impacts on the bioaccessibility of flavone C-glycosides. Xanthan gum could significantly enhance the bioaccessibility of the four flavonoid C-glycosides, especially vitexin and isovitexin. The concentrations of isovitexin and vitexin in the xanthan gum group decrease by 62% and 59% after intestinal digestion, respectively, which were much lower than those (decrease by 84% and 80%) observed in the presence of xanthan gum. Conclusion: Xanthan gum can significantly improve the bioaccessibility of bamboo leaf flavone?C-glycosides during simulated in vitro digestion, suggesting promising applications for the development of functional products.
Changes in Antioxidant Activity of Crude Peptides from Mutton Ham at Different Processing Stages
WANG Yongqin, GUO Xin, MA Xuelian, YUAN Huchuan, ZHU Miaomiao, HUANG Liyuan, WANG Yuan, WANG Qingling
2019, 40(21):  65-71.  doi:10.7506/spkx1002-6630-20181103-036
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In this study, dry-cured mutton ham samples at different processing periods were taken in order to clarify the change in the antioxidant activity of endogenous antioxidant peptides during mutton ham processing. Crude peptides were extracted from these samples with phosphate buffer and the peptide content was determined. Subsequently, the antioxidant activity was evaluated by reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cation (ABTS) and hydroxyl radical scavenging capacity, and anti-lipid oxidation activity. The results showed that the peptide content of mutton ham were significantly increased during processing, and so did the antioxidant activity as manifested by a significant increase in reducing activity (P < 0.05) and an overall increase in ABTS cation and DPPH radical scavenging capacity, which reached the maximum values of 0.09 and 0.017 8 mmol/L at the end and the middle stage of maturity, respectively. The hydroxyl radical scavenging capacity showed a downward trend in general, and reached its maximum value during the drying period. Sodium dodecyl sulfate-polyacrylamide gel electrophoresisshowed that proteins in ham muscle were gradually degraded throughout the processing period producing small antioxidant peptides. This study provides reference for future studies on the antioxidant mechanisms of mutton ham peptides.
Differences in Myofiber Characteristics and Meat Quality of Different Yak Muscles
YANG Yuying, ZHANG Yimin, MAO Yanwei, LIANG Rongrong, DONG Pengcheng, YANG Xiaoyin, ZHU Lixian, LUO Xin, ZHANG Wenhua, CAO Hui
2019, 40(21):  72-77.  doi:10.7506/spkx1002-6630-20181025-296
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The meat quality of three yak muscles: Longissimus lumborum (LL), Psoas major (PM) and Semimembranous (SM) was compared by considering their myofibril characteristics as well as quality traits (Warner-Bratzler shear force, sarcomere length, meat color, cooking loss rate and pH). The myofiber characteristics were measured by histochemical analysis and quantitative real-time polymerase chain reaction. Meanwhile, the correlation between meat quality traits and myofiber characteristics was analyzed. A significant difference was observed among yak muscles in meat quality traits. PM muscle had higher pH, a* value and better tenderness than the other muscles. However, the water-holding capacity (WHC) of LL was better than the other muscles. Similarly, there was a significant difference in myofiber characteristics among the muscles (P < 0.05). PM had higher number of type I fiber (50.8%) and higher relative mRNA expression of MYH7 but significantly lower fiber diameter (P < 0.05) than the other muscles. The percentage of the number of type I fiber was highly correlated with meat quality traits; it was negatively correlated with shear force, but it was positively correlated with sarcomere length and cooking loss. The area of type I fiber was negatively correlated with L* value (P < 0.05). These results suggest that the quality of yak meat could be improved by increasing the proportion of type I fiber in muscles.
Effect of Particle Size of Excipient Emulsion and Blanching on Bioaccessibility of β-Carotene from Spinach
YUAN Xi, LIU Xiaojuan, CAO Yong
2019, 40(21):  78-87.  doi:10.7506/spkx1002-6630-20180926-273
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Vegetables are the primary carotenoid contributors in the human diet. The relatively low bioaccessibility of carotenoids limits their potential health benefits. In recent years, studies have shown that the particle size of excipient emulsion and processing methods are the important factors affecting the bioaccessibility of carotenoids in vegetables. Therefore, the effect of different particle sizes (200, 500 nm and 10 μm) of excipient emulsion and processing methods (raw and blanching) on the bioaccessibility of β-carotene from spinach were studied using a simulated gastrointestinal tract (GIT) model. The results showed that physical properties (particle size and ζ-potential), microstructure, oil digestibility and bioaccessibility of β-carotene in small-particle-size (~200 nm d3,2) emulsion/spinach mixed system during simulated GIT digestion were significantly different from those in large-particle-size (~10 μm d3,2) emulsion/spinach mixed system (P < 0.05) but not from those in medium-particle-size (~500 nm d3,2) emulsion/spinach mixed system (P > 0.05). The bioaccessibility of β-carotene in the mixed systems containing small- and medium-particle-size emulsions was 28.78% and 28.65%, which was significantly higher than that in the one containing large-particle-size emulsion (12.80%) (P < 0.05). The bioaccessibility of β-carotene during the simulated digestion of spinach in the presence of small-particle-size excipient emulsion was significantly affected by the processing method used (15.66% in blanched spinach, vs 28.78% in raw spinach) (P < 0.05). These results indicate that controlling the particle size of the excipient emulsion and selecting a reasonable way to process fruits and vegetables is of great significance for improving the bioaccessibility of β-carotene in fruits and vegetables.
Effect of Pullulan on the Structure and Rheological Properties of Starches from Three Rice Varieties
CAO Chuan, SHEN Mingyu, XU Li, WEI Dongmei, ZHOU Yibin
2019, 40(21):  88-93.  doi:10.7506/spkx1002-6630-20181103-034
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In the present study, debranched starches (DBS) from three rice varieties were prepared by treatment with pullulanase with the aim to investigate the effect of enzymatic hydrolysis on starch structure and rheological properties. The results showed that the crystallinity of rice starch decreased and the amorphous region increased after pullulanase treatment. The chain length distribution showed that the fine structures of the three rice starches were similar, the hydrolysis reaction was more effective for shorter side chains, and glutinous rice starch was more easily digested. There was no significant difference in the Fourier transform infrared spectra of debranched and raw rice starch except that the stretching vibration peak of ?OH was relatively enhanced. Upon the addition of pullulanase, the viscosity of starch paste decreased steeply especially for glutinous rice starch, which was more easily hydrolyzed than the other two rice starches. The rheological properties indicated that the starch granules became intermeshing and loosely arranged after hydrolysis. Moreover, the mobility was increased, and the solubility and water-holding capacity were enhanced. Glutinous rice starch was more sensitive to pullulanase treatment than the other rice starches. To conclude, debranching can improve starch gel properties and enhance starch fluidity .
Absorption and Accumulation of As(III) and As(V) in Lentinus edodes Fruit Bodies from Culture Medium
TANG Qingqiang, CAO Xiaogang, XIA Linbing, CHEN Jinli, ZHANG Fengzhen, LUO Shunyu, WANG Danhong,
2019, 40(21):  94-99.  doi:10.7506/spkx1002-6630-20180903-030
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This study was done to evaluate the absorption and accumulation of highly toxic inorganic arsenic (As) species in the fruit bodies of Lentinus edodes from the culture medium added with different amounts of arsenite (As(III)) or arsenate (As(V)) during two consecutive crop years. High performance liquid chromatography coupled with inductivity coupled plasma mass spectrometry (HPLC-ICP-MS) was used to detect the contents of five As species in Lentinus edodes and the corresponding culture medium. The results showed that the accumulation coefficients of As(III) and As(V), when added at levels of 0.3–10 mg/kg, in Lentinus edodes ranged from 0.36 to 0.84 and from 0.82 to 7.53, respectively, and at addition levels of 0.33–0.38 mg/kg, the accumulation in Lentinus edodes could be fitted to the following equations: y = ?1.138 9x2 + 0.921 6x ? 0.004 for As(III), and y = ?9.024 3x2 ? 4.388 1x + 0. 838 7 for As(V), where x and y were the contents of As(III) or As(V) in the culture medium and the fruit bodies, respectively. The yield of Lentinus edodes was reduced even to reach zero with increasing concentration of As(III) or As(V) in the culture medium. The critical value was 0.33 mg/kg for both As species. The content of As(III) in the culture medium gradually decreased with cultivation time, while the content of As(V) increased slightly. The content of organic arsenic in the fruit bodies of Lentinus edodes increase with the addition of As(III) or As(V), which may be related to the transformation of As(III) into As(V) or organic arsenic during the growth of Lentinus edodes.
Food Engineering
Fluidized Bed Drying Properties and Kinetic Modelling of Nutritious Reconstituted Porridge
LI Yupeng, ZHAO Yilin, ZHAO Chengbin, WU Yuzhu, XU Xiuying, CAO Yong, ZHANG Hao, LIU Jingsheng
2019, 40(21):  100-106.  doi:10.7506/spkx1002-6630-20181022-240
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An experimental study was conducted to investigate the drying characteristics of nutritious reconstituted porridge (prepared from a mixture of corn, red bean, buckwheat, oats and millet (3.5:3.0:2.0:0.7:0.8, m/m) with added water by twin screw extrusion) on a fluidized bed dryer. The effects of airflow rate, inlet air temperature and water addition on the dry basis moisture content and drying rate of nutritious reconstituted porridge were explored. The water loss characteristics during the drying process were obtained. Based on the experimental data, a kinetic model was established, and it was statistically tested. The results showed that the Page model was the best model for describing the fluidized bed drying of nutritious reconstituted porridge, and the fitting equation was ln(?ln MR) = ?4.064 63 + 0.014 14T + 0.069 85v + 0.327 5H + (0.570 96 + 0.000 976 25T ? 0.009 68v ? 0.265 5H)ln t, where T was inlet air temperature (℃), v was airflow rate (m/s), and H was the amount of water addition (%). This equation could better describe the drying process and accurately predict the dry basis moisture content and drying rate at each of its stages.
Allergenicity Reduction of Shrimp Tropomyosin by High Hydrostatic Pressure Treatment Combined with Enzymatic Hydrolysis and Its Linear Epitope Residues
HU Zhihe, WANG Lijuan, XUE Lu, LIU Ping, JIA Ying, LU Dingqiang
2019, 40(21):  107-114.  doi:10.7506/spkx1002-6630-20190304-036
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The objective of this work was to compare the differences in the allergenicity and linear epitope residues of trypsin hydrolysates of tropomyosin (TM) prepared under normal and high pressure conditions and to discuss the reason why allergenicity reduction of hydrolyzed TM is enhanced under high pressure. The allergenicity was detected by indirect enzyme-linked immunosorbent assay (iELISA), and the secondary and tertiary structures were investigated by infrared and fluorescence spectroscopies. Optimal hydrolysis conditions under normal and high pressure were determined based on the binding capacity of hydrolysate to antibody (OD492 nm). Mass spectrometry (MS) was used for detecting the amino acid sequences of hydrolytic fragments. The results showed that trypsin activity was enhanced after treatment for 30 min under 200 MPa at 40 ℃. The allergenicity of high-pressure treated TM decreased with increasing pressure from 100 to 600 MPa, and it was related to changes in the relative content of β-turn structure and in tertiary structure. The allergenicity of TM was reduced by 89% and 98% after 30 min hydrolysis with 3 000 U/g of trypsin at 40 ℃ under normal pressure and 200 MPa, respectively. The percentage of fragments containing 8–16 amino acid residues in the hydrolysates was 76.8% and 93.3%, respectively, and the linear epitopes were reduced by 60.0%–66.7% and 88.9%–90.0%, respectively. Therefore, high pressure treatment could promote the enzymatic hydrolysis of TM, facilitating the elimination of linear epitopes and reducing the allergenicity of hydrolyzed products.
Effect of Ultra-High Pressure on the Myofibrillar Protein Structure and Gel Properties of Hairtail Surimi
CHEN Yanting, LIN Lu, GAO Xing, LUO Huabin, ZHANG Jinjie, LOU Qiaoming, XU Dalun, YANG Wenge
2019, 40(21):  115-120.  doi:10.7506/spkx1002-6630-20181021-223
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This study investigated the effect of ultra-high pressure (UHP) treatment on gel characteristics and myofibrillar protein structure in hairtail surimi. Changes in the gel strength, whiteness, texture properties and microstructure and the content and molecular conformation myofibrillar protein were measured after UHP treatment at different pressures for different times or heat treatment. The results showed that UHP could induce the formation of a network structure in surimi gel, and improve texture parameters, gel strength and whiteness compared to the control group. Scanning electron microscopy showed that the gel network structure of surimi treated with 350 MPa for 8 min (350-8 group) was close to that of the heat-induced group. UHP treatment reduced the content of myofibrillar protein in the surimi gel, and led to the gradual disappearance of the two negative grooves in the circular dichroism (CD) spectrum of myofibrillar protein. Meanwhile, the relative content of α-helix structure decreased, but the random coil and β-sheet contents increased to varying degrees. The random coil content of myofibrillar protein in the 350-8 group was close to that in the heat-induced group. Conclusion: Appropriate UHP treatment (at 350 MPa for 8 min) significantly affected the gel characteristics and the secondary structure of myofibrillar protein from surimi, promoted the formation of gel network and improved the quality of surimi gel.
Effect of Ultrasound-Assisted Curing on Drying Rate and Physicochemical Characteristics of Beef Jerky
LIU Meng, YANG Zhen, SHI Zhijia, WANG Wei, QIAO Xiaoling, WANG Shouwei
2019, 40(21):  121-126.  doi:10.7506/spkx1002-6630-20181204-046
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Ultrasound has a variety of physical and sonochemical effects, which can lead to physicochemical changes in foods. This study evaluated the effects of ultrasound-assisted curing on water loss, the concentrations of soluble substances and myoglobin in NaCl solution, drying rate, lipid oxidation, tenderness and microstructure of beef jerky. The results showed that the application of ultrasound during the curing process increased water loss significantly (P < 0.05), which had a positive correlation with ultrasound power and processing time. The water loss of beef slices treated at 0.60 W/cm2 ultrasound intensity for 60 min was the highest (6.93%), while the control without ultrasound treatment absorbed 6.14% water. Ultrasound processing promoted protein dissolution from beef significantly (P < 0.05), but excessively high ultrasound intensity could lead to a decrease in protein dissolution. Ultrasound treatment significantly promoted myoglobin dissolution and lipid oxidation (P < 0.05), and the effect was positively correlated with ultrasonic power and processing time. Additionally, the shear force of beef slices decreased significantly (P < 0.05) after ultrasound treatment at 0.30 or 0.60 W/cm2 for 60 min, but there was no significant difference under the other conditions investigated. Histological observation with hematoxylin-eosin staining confirmed that ultrasound treatments for 30 and 60 min at 0.60 W/cm2 could cause different degrees of damage to beef muscle fibers. In conclusion, the application of ultrasound in beef jerky processing can reduce the product hardness and shorten the drying time without any significant adverse effects.
Effects of Different Heat Treatments on the Quality of Largemouth Bass
XIANG Yafang, XIONG Guangquan, QIAO Yu, LIAO Li, WANG Lan, WU Wenjin, DING Anzi, LI Xin, SHI Liu
2019, 40(21):  127-135.  doi:10.7506/spkx1002-6630-20181018-200
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In order to prolong the shelf life of prepared largemouth bass products and to delay the quality deterioration during storage, largemouth bass pieces were subjected to three heat treatments (boiling in water, steaming, vacuum low temperature cooking (sous-vide)) and subsequently stored at 12 ℃ for 5 days. The total number of colonies, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value, juice loss rate, color, texture characteristics, water distribution, and odor profile were analyzed during the storage period. The results showed that during the storage process, the juice loss rate of sous-vide treated fish pieces was below 2%, and the loss of immobilized water was inhibited at the end of storage. The total number of colonies and TVB-N content were smaller in sous-vide-treated samples than in boiled and steamed samples, and sous-vide could significantly inhibit the spoilage and deterioration of largemouth bass during storage. Sous-vide treatment had little effect on the hardness and chewiness compared with boiling and steaming (P > 0.05). Using electronic nose technology, the quality of largemouth bass during storage could be identified and the results were consistent with TVB-N content. In conclusion, sous-vide can delay the deterioration of fish freshness, providing a new processing technology for the preservation of largemouth bass.
Nutrition & Hygiene
Regulation of Cholesterol Metabolism by Sulfated Polysaccharides from Morchella angusticeps Peck
TANG Yuwan, ZHANG Yueqiao, LI Yao, LEI Lin, LI Fuhua, ZHAO Jichun, WU Surui, MING Jian
2019, 40(21):  136-142.  doi:10.7506/spkx1002-6630-20190318-217
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Polysaccharide extracted from Morchella angusticeps Peck (PMEP) has been proved to have a hypocholesterolemic effect. This study aimed to compare the cholesterol-lowering activity of PMEP and its sulfated derivative (SPMEP) in rats fed on a high-cholesterol diet. Results showed that PMEP at high dose and SPMEP could decrease serum total cholesterol by 15% and 23%, respectively, indicating that SPMEP had a stronger cholesterol-lowering potency than PMEP (P < 0.05). PMEP and SPMEP down-regulated the expression of hepatic 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase and up-regulated the expression of cholesterol-7α-hydroxylase (P < 0.05). Besides, both of them could decrease liver cholesterol, while significantly increasing the excretion of total fecal and intestinal bile acids (P < 0.05). Therefore, the cholesterol-lowering activity of PMEP in rats can be enhanced after being sulfated.
Dietary Pollution Status and Exposure Risk Assessment of Short-Chain Chlorinated Paraffins
CHEN Huiling, SHEN Jinshan, WANG Xueguang, YANG Lixin
2019, 40(21):  143-149.  doi:10.7506/spkx1002-6630-20170411-154
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Short chain chlorinated paraffins (SCCPs) are a class of complex organic compounds with 10?13 carbon atoms. At present, there is insufficient published data on the pollution status of SCCPs in foodstuffs. In order to solve this problem, the contents of SCCPs and the distribution of SCCP homologues in 81 samples of 9 kinds of foodstuffs collected from 9 cities in northern China in 2016 were determined by on-line gel permeation chromatography-gas chromatography-negative chemical ion source-mass spectrometry (GPC-GC-NCI-MS). The results indicated that the contents of SCCPs in all samples were in the range of 2.30?496.49 ng/g (wet basis). In addition, the homologue distribution of SCCPs was dominated by lower chlorinated (Cl6?Cl7) C10-/C12-SCCPs. The risk associated with dietary exposure to SCCPs was between 1.1 and 3.8; although it was lower than 100, acceptable, this did not mean that there was no risk for human health. The findings obtained in this study can provide important data for understanding SCCP pollution status in Chinese diets and their influences on human health.
Residues and Safety Evaluation of Fluazinam in Green Chinese Onion (Allium fistulosum L. var. giganteum Makion) and Shallot (Allium ascalonicum)
ZHU Xiaodan, JIA Chunhong, WANG Dong, JING Junjie, HE Min
2019, 40(21):  150-155.  doi:10.7506/spkx1002-6630-20180930-343
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To ascertain the dissipation and residues of fluazinam in green Chinese onion (Allium fistulosum L. var. giganteum Makion) and shallot (Allium ascalonicum), six independent field trials with 39.5% (V/V) fluazinam suspension were conducted during the crop year of 2017 in Beijing, Shandong, Inner Mongolia, Jiangsu, Sichuan and Ningxia of China. Fluazinam was extracted from samples with acetonitrile and subsequently cleaned-up with primary secondary amine, graphite carbon and octadecyl carbon sorbents prior to analysis by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS). The quantification was performed by the external standard method. The results showed that the half-lives of fluazinam in green Chinese onion and shallot were 1.2 and 8.7 d, respectively. The final residues of fluazinam in them were < 0.010–0.308 and 0.100–5.738 mg/kg, respectively. There is no maximum residue limit (MRL) established in China for fluazinam in green Chinese onion and shallot. The MRLs set by Europe, Japan and Korea are 0.01, 0.1 and 3.0 mg/kg, respectively. According to the MRLs of Europe and Japan, the residues of fluazinam in green Chinese onion and shallot were unsafe. In this context, China should speed up the formulation of MRLs for fluazinam in green Chinese onion and shallot. This work will be useful for developing MRLs for fluazinam and ensuring the safe application of fluazinam in the future.
Photoinduced Toxicity and Mechanism of Action of Dibutyl Phthalate
LI Zhijun, BAO Haiying
2019, 40(21):  156-162.  doi:10.7506/spkx1002-6630-20180923-250
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Dibutyl phthalate (DBP) is naturally occurs ubiquitously in medicinal and edible jelly fungi, and its potential harm to the environment and organisms has increasingly become a major concern. In this study, the photoinduced toxicity of DBP was studied and its mechanism of action was investigated. The metabolism and distribution of DBP in the plasma and liver of rats intragastrically administered with it were detected by high performance liquid chromatography (HPLC). Moreover, the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione (GSH) and superoxide dismutase (SOD) activity in rat liver and kidney were determined, and the pathological sections of liver and kidney were observed. Pharmacokinetics showed that sunlight could promote the transformation of DBP into mono-n-butylphthalate (MBP), and MBP content in the liver and kidney was higher than that in other organs. MBP could significantly increase ROS and MDA levels and decrease GSH level and SOD activity in rat liver and kidney, providing evidence that MBP could induce lipid peroxidation in rat liver and induce early liver injury. The pathological sections showed that light could enhance the damage of MBP to rat liver and kidney cells. Therefore, DBP is a potentially harmful phototoxic substance in male rats. In conclusion, much attention should be paid to its application in foods and packaging materials.
Dietary Supplementation with Black Garlic Powder Exerts Immunostimulatory Activity in Cyclophosphamide Induced BALB/c Mice
YANG Ming, QIN Ye, HAO Junyu, WU Tao, LIU Rui, SUI Wenjie, ZHANG Min
2019, 40(21):  163-170.  doi:10.7506/spkx1002-6630-20180927-291
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The present study aimed to investigate the immunostimulatory activity of black garlic powder on immunosuppressed BALB/c mice. Cyclophosphamide was injected to establish an immunosuppressed model. Then, the effect of black garlic powder at doses of 100, 300 and 900 mg/kg on splenic and thymus index, the transformation of splenic lymphocytes, delayed type hypersensitivity, quantity of antibody-producing cells, half hemolysis value (HC50), carbon clearance rate, interleukin (IL)-8 and IL-12 gene expression levels in splenic cells of mice were investigated. The results indicated that all three doses of black garlic powder significantly improved thymus index, antibody production, splenic lymphocyte proliferation and the expression of IL-8 and IL-12 in splenic cells when compared with the model control (MC) group (P < 0.05). In addition, compared with the MC group, black garlic powder at the middle and high doses could significantly enhance splenic index and delayed-type hypersensitivity response (P < 0.05). Moreover, compared with the MC group, black garlic powder at the high dose effectively improved serum hemolysin level and mononuclear macrophage phagocytosis activity (P < 0.05). Thus, black garlic powder appears to be an excellent candidate to improve immune function in BALB/c mice.
Effect of Low-Molecular-Mass Seleno-aminopolysaccharide on Histomorphology and Expression of Tight Junction Proteins in Immunocompromised Mice
TANG Zhen, GU Lixia, XIANG Xingwei, WEN Zhengshun, QU Youle, ZHENG Bin, SONG Houhui
2019, 40(21):  171-176.  doi:10.7506/spkx1002-6630-20180927-303
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The purpose of this study was to investigate the effect of low-molecular-mass seleno-aminopolysaccharide (LSA) on the histomorphology and the expression of the tight junction proteins zonula occludens-1 (ZO-1) and occludin in the ileum of immunocompromised mice. The immunosuppressive mouse model was established by intraperitoneal injection of cyclophosphamide (CPA). The thymus index and spleen index were calculated. Pathological changes in the spleen and jejunum were observed by hematoxylin-eosin staining. The expression of tight junction proteins in the ileum were analyzed by real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The results showed that the spleen and thymus index were significantly increased in the LSA groups (P < 0.05) when compared with the CPA group. The spleen structure was clear with an obvious boundary between the red and white pulps and the area of white pulp was increased in the 0.6 and 0.9 mg/(kg mb·d) LSA groups when compared with the CPA group. In addition, the morphology of jejunum villi was more ordered than that of the model group. The mRNA expression of ZO-1 and occludin was significantly increased in the 0.6 mg/(kg mb·d) LSA group (P < 0.05). To sum up, LSA had immunomodulatory effects and could be beneficial for intestinal health.
Bioactivity of Total Flavonoids Extracted from Kunlun Chrysanthemum Flowers (Coreopsis tinctoria)
JING Siqun, ZHAI Hongyue, SU Leping, REN Zhiyan, WANG Yinna, YAN Liangjun
2019, 40(21):  177-187.  doi:10.7506/spkx1002-6630-20181028-319
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In this study, the antioxidant and antibacterial properties of total flavonoids from Kunlun chrysanthemum flower (KCTF) were evaluated together with its protective effect on liver injury induced by carbon tetrachloride in mice and anti-proliferative effect on tumor cells. The antioxidant capacity was measured by free radical scavenging capacity in vitro, as well as superoxide dismutase activity and malondialdehyde content in vivo. Moreover, the anti-proliferative activity was determined using HeLa cells and esophageal cancer Eca-109 cells. Results indicated that KCTF had significant antioxidant activity and inhibited the growth of both Gram-positive and Gram-negative bacteria. However, KCTF had no significant hepatoprotective effect. KCTF possessed potent inhibitory activity with average half-inhibitory concentration (IC50) values of (133.60 ± 0.12) and (192.00 ± 0.08) μg/mL for HeLa and Eca-109 cells, respectively. Therefore, KCTF may have potential application in functional food industries due to its antioxidant, bacteriostatic and anti-proliferative effects.
Packaging & Storage
Effects of Three Plant-Derived Antimicrobial Agents on Shelf-Life and Bacterial Diversity of Freshwater Swap Shrimp Meat (Macrobrachium nipponense) during Storage
WU Haihong, LIU Fang, JIN Panpan, SUN Zhilan, XU Weimin
2019, 40(21):  188-195.  doi:10.7506/spkx1002-6630-20181101-017
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In this study, the effects of three plant-derived antimicrobial agents (carvacrol, thymol and perillyl alcohol) on the shelf-life and spoilage bacterial diversity of freshwater swamp shrimp meat were analyzed by traditional plate counting and Illumina Miseq high-throughput sequencing. The results showed that all the three agents could significantly prolong the shelf-life of shrimp meat stored at 4 or 10 ℃, and carvacrol and thymol were more effective than perillyl alcohol. Through high-throughput sequencing analysis, it was found that the major bacterial flora significantly changed after storage. The proportions of Arcobacter, Shewanella and Aeromonas, dominant in the samples during the early storage period, were reduced to very low levels during the later period, and Streptococcus, Brochothrix, Carnobacterium, Psychrobacter, Flavobacterium, and Pseudomonas became the dominant bacteria at the end of storage. The growth of Brochothrix, Carnobacterium, Psychrobacter, and Flavobacterium could be inhibited by the antimicrobial agents, making Pseudomonas the dominant bacteria in the treated samples. Based on the above results, these antimicrobial agents can significantly prolong the shelf-life of shrimp meat by inhibiting the growth of many dominant spoilage bacteria.
Quercetin Inhibited Protein and Lipid Oxidation and Improved Quality Properties of Minced Pork during Chilled Storage
JIA Na, ZHANG Fengxue, WANG Letian, SUN Jia, LIU Dengyong
2019, 40(21):  196-202.  doi:10.7506/spkx1002-6630-20181025-287
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The objective of this study was to explore the effect of quercetin on protein and lipid oxidation and quality characteristics of minced pork during chilled storage. The thiobarbituric acid reactive substances (TBARS) value, total protein thiol content, protein carbonyl content, surface hydrophobicity, color, cooking loss and texture of minced pork with added quercetin at different levels (0, 0.05, 0.10 and 0.20 g/kg) were measured. The results showed that the TBARS value was significantly reduced with the addition of quercetin at all investigated concentrations (P < 0.05). The addition of 0.10 and 0.20 g/kg quercetin significantly inhibited the loss of total sulfhydryl group content and the increase of surface hydrophobicity on Day 9 of storage. The addition of 0.20 g/kg quercetin remarkably suppressed the formation of carbonyl compounds from Day 1 to 6 (P < 0.05). The redness value was effectively increased with the addition of 0.10 g/kg quercetin when the quercetin addition was 0.10 g/kg. When the concentration of quercetin was 0.05 and 0.10 g/kg, the cooking loss was significantly reduced on Day 6 and 9 (P < 0.05). Moreover, quercetin remarkably increased the elasticity, hardness and chewiness of minced pork during storage (P < 0.05). Therefore, when quercetin is used as an antioxidant in meat and meat products, the effect of its addition amount on meat quality should be considered.
Effect of Pre-Harvest Spraying of Diethyl Aminoethyl Hexanoate on Membrane Lipid Metabolism in Pericarp of Longan Fruits during Postharvest Storage
LIN Yixiong, LIN Hetong,, CHEN Yihui, WANG Hui, LIN Yifen,
2019, 40(21):  203-210.  doi:10.7506/spkx1002-6630-20181224-283
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In order to investigate the effect of pre-harvest spraying of diethyl aminoethyl hexanoate (DA-6) on membrane lipid metabolism in the pericarp of longan fruit during postharvest storage, ‘Fuyan’ longan (Dimocarpus longan Lour. cv. Fuyan) were sprayed with 10 mg/kg DA-6 or distilled water (as the control) once at 70, 90 and 110 days after full bloom. The fruit were harvested at 120 days, and they were selected, cleaned and dried prior to packaging in 0.015 mm thick polyethylene bags (50 fruits per bag, 50 bags per group) and subsequent storage at (28 ± 1) ℃ and 85% relative humidity. The results showed that compared with the control fruit, pre-harvest spraying of DA-6 could retard the increase in cell membrane permeability, reduce the activity of membrane lipid-degrading enzymes such as lipoxygenase (LOX), lipase and phospolipase D (PLD), maintain higher contents of phosphatidylcholine (PC) and phosphatidylinositol (PI), higher index of unsaturated fatty acids (IUFA) and relative degree of unsaturation of fatty acids (U/S), but lower content of phosphatidic acid (PA) in the pericarp of harvested longan fruit during storage. Therefore, pre-harvest spraying of DA-6 could delay the degradation of unsaturated fatty acids (oleic acid (C18:1), linoletic acid (C18:2) and linolenic acid (C18:3)) of cellular membrane lipids, which were beneficial to maintain the cellular structure. From these results, it could be concluded that improved longan fruit storability by pre-harvest spraying of DA-6 may be related to effectively alleviated membrane lipid metabolism in the pericarp of longan fruit during postharvest storage.
Preparation and Characterization of Eugenol-Chitosan Food Packaging Film through Supercritical Solution Impregnation
TANG Chuan, YANG Ming, LU Xuan
2019, 40(21):  211-215.  doi:10.7506/spkx1002-6630-20181123-271
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Supercritical solution impregnation (SSI) was employed to prepare eugenol (EG)-loaded chitosan film (CSF) for active food packaging. The effects of impregnation pressure and depressurization rate on the loading capacity (LC) of EG-CSF were investigated, and the properties of EG-CSF such as morphology, water uptake (WU), water vapor permeability (WVP), and antibacterial activity were characterized. The results showed that the LC increased with the elevation of impregnation pressure, but decreased with the increase of depressurization rate, and the maximum LC of 6.02% were achieved at 20 MPa and 1 MPa/min. The WU and WVP of EG-CSF decreased after undergoing the SSI process. EG-CSF had good antibacterial activity against Staphlycoccus aureus, Pseudomonas aeruginosa and Escherichia coli. The eugenol-loaded chitosan film prepared by SSI could be promising for application in active food packaging.
Effect of Light Exposure Treatment on the Quality of Fresh-Cut Green Bell Pepper (Capsicum annuum L.) during Shelf Display
ZHANG Tingting, SHI Yue, HE Zhaojun, MA Yue, WANG Yubin, ZHAO Xiaoyan, ZHANG Chao,,
2019, 40(21):  216-221.  doi:10.7506/spkx1002-6630-20181009-056
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The effect of white, red, blue and green light exposure and dark treatments on the quality of fresh-cut green bell pepper (Capsicum annuum L.) was evaluated. After 5 days of shelf display, the percentage mass loss, color, relative conductivity, malondialdehyde (MDA) content and flavor of fresh-cut green bell pepper were compared among light and dark treatments. Green light exposure led to the lowest percentage mass loss (3.75%) while having little effect on soluble solids content, the degree of damage caused by water soaking, and color difference. The color difference was 3.22 compared with fresh fruit, which was significantly lower than that observed for white light exposure (P < 0.05). Moreover, no significant difference was observed between the effects?of white and green light exposure on the flavor of fresh-cut green pepper (P > 0.05). Therefore, green light exposure was beneficial to maintain the quality of fresh-cut green pepper during shelf display.
Effect of L-Cysteine Treatment on the Quality of ‘Qingcui’ Plum Fruit during Storage at Room Temperature
LING Yang, DENG Lili, YAO Shixiang, ZENG Kaifang
2019, 40(21):  222-228.  doi:10.7506/spkx1002-6630-20190328-358
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In order to investigate the effect of exogenous L-cysteine treatment on the storage quality of ‘Qingcui’ plum fruit (Prunus salicina Lindell), the fruit were soaked in L-cysteine solutions at 0, 100, 500 and 1 000 mg/L for 10 min, separately, and then stored at 20 ℃ and 85%-90% relative humidity. The results showed that L-cysteine at all three concentrations could reduce the natural infection incidence and disease index of ‘Qingcui’ plum fruit during storage at room temperature. Treatments with 500 and 1 000 mg/L L-cysteine could inhibit the yellowing and softening process, delay the decrease in the contents of total soluble solid, titratable acid and ascorbic acid, and inhibit the increase in mass loss, relative electrical conductivity and malondlaldehyde (MDA) content. The effect was found to be better at 1 000 mg/L L-cysteine concentration. Meantime, 1 000 mg/L L-cysteine treatment increased the contents of endogenous cysteine, glutamate, aspartate and proline. Therefore, exogenous L-cysteine treatment at optimal concentration can effectively delay the senescence and quality loss of ‘Qingcui’ plum fruit after harvest.
Application of Crude Bacteriocin of Lactobacillus plantarum JY-22 in Preservation of Silver Carp Meatballs
CUI Tianqi, DU Hong, Lü Xinran, GUO Chao, BAI Fengling, YI Shumin, DING Haochen, HUANG Jianlian, LI Jianrong
2019, 40(21):  229-235.  doi:10.7506/spkx1002-6630-20181019-207
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The efficacy of crude bacteriocin of Lactobacillus plantarum JY-22 was evaluated in preserving the quality of silver carp meatballs inoculated with Bacillus licheniformis or Bacillus cereus. The product quality and safety were evaluated by sensory, physicochemical and bacteriological indicators. The results showed that the addition of JY22 bacteriocin could improve the sensory quality of fish meatballs and effectively inhibit the growth of Bacillus in fish meatballs. On the 21st day of storage, JY-22 bacteriocin at a concentration of 0.6 minimum inhibitory concentration (MIC) reduced the viable cell count of fish meatballs inoculated with Bacillus licheniformis or Bacillus cereus alone by 1.92 (lg (CFU/g)) and 1.00 (lg (CFU/g)), respectively. JY-22 bacteriocin slowed the decrease in pH during the storage of fish meatballs and reduced the whiteness, but it had little effect on the elasticity. JY-22 bacteriocin at 0.6 MIC could extend the shelf life of the product by at least 3 days. To conclude, JY-22 bacteriocin could effectively control the growth and reproduction of Bacillus in fish meatballs, and preserve the product quality.
Recent Advances in the Application of Emulsion Gels as Fat Replacers in Meat Products
FENG Yangyang, XU Jingxin, YU Dong, KONG Baohua, LIU Qian
2019, 40(21):  236-242.  doi:10.7506/spkx1002-6630-20181119-224
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With the increasing interest of consumers in the relationship between diet and health, how to replace animal fat, containing a large amount of saturated fatty acids, in meat products has become a hot topic in the field of meat science. However, simply reducing the use of animal fat could significantly reduce the flavor, tenderness and juiciness of meat products. Recently, more and more research has focused on the potential application of emulsion gels as animal fat replacers in meat products due to their unique structures and functional properties. This article provides an extensive review of the literature on the preparation, quality characteristics and application in low-fat meat products of emulsion gels in order to establish a good theoretical basis for the application of emulsion gels to replace animal fat in meat products and to provide innovative technical support for the development of value-added low-fat health and nutritious meat products.
Recent Progress in Molecular Typing and Virulence Mechanism of Cronobacter
YAN Rui, NIU Bing, YANG Jielin
2019, 40(21):  243-250.  doi:10.7506/spkx1002-6630-20181126-291
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Cronobacter, an acute bacterial pathogen, has attracted extensive attention for causing several fatal outbreaks in neonatal intensive care units including meningitis and necrotic enterocolitis. In recent years, the diversity of the genus Cronobacter has been well described, and various detection and typing methods have been developed. The commonly used methods include biotyping, pulsed field gel electrophoresis typing and DNA sequence-based genotyping such as single locus sequencing, O-serotyping, multilocus sequence typing, single nucleotide polymorphism typing and clustered regularly interspaced short palindromic repeats (CRISPR)-cas array profiling. The 7 species of Cronobacter vary in virulence and outer membrane proteins and vesicles play a significant role in cellular pathological alterations caused by infection with Cronobacter. Sialic acid may be useful in clinical practice. To date, no consistent conclusions have been drawn regarding the virulence mechanism of Cronobacter. An array of virulence factors have been revealed by gene sequencing, but they still need further validation. The improved typing methods not only are essential for the development of Cronobacter spp. taxonomy, but also lay the foundation for exploring the virulence mechanism of Cronobacter spp..
Bioactivity and Mechanism of Action of Natural Non-Protein Amino Acids: A Review of Recent Literature
XU Kai, BI Jingjing, ZHANG Jihao
2019, 40(21):  251-259.  doi:10.7506/spkx1002-6630-20181004-004
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As an important category of natural bioactive substances in foods and medicine, non-protein amino acids are characterized by abundant sources, varietal diversity and complex mechanism of action. Based on an extensive review of the literature, this article summarizes some non-protein amino acids that have a great impact on humans and have been investigated intensively so far. It reviews the biological sources, bioactivities and mechanisms of action of these amino acids. The aim is to present the application potential of such natural compounds in several fields such as agriculture, environmental science, food science, medicine and life science.
Recent Advances in Understanding the Effect of Heat Treatment on α-Lactalbumin Denaturation and Its Interaction with Other Milk Proteins
ZHAO Xuan, LI Xiangying, QIN Yusi, CHEN Di, WANG Cunfang
2019, 40(21):  260-265.  doi:10.7506/spkx1002-6630-20181021-226
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In this paper, the effect of heat treatment on the denaturation of α-lactalbumin (α-La) and its interaction with other milk protein components as well as the influencing factors are reviewed. The thermal stability of α-La can be affected by Ca2+ binding. It cannot self-aggregate after denaturation, but can form aggregates with β-lactoglobulin (β-Lg) and serum albumin (SA). Aggregates of α-La/β-Lg produced by high temperature short time (HTST) treatment can be used to produce protein drinks with low viscosity, low turbidity and high solubility. Aggregates of α-La/SA have a good gel structure. α-La/β-Lg aggregates can also combine with κ-casein on the surface of casein micelles, forming polymers that are beneficial to shorten the fermentation process and improve the gel structure of yogurt. The combination of α-La with immunoglobulin G allows reduced allergenicity of milk with HTST, ultra-pasteurization and ultra-high temperature treatments. A suitable heat treatment should be selected in practice to improve the production efficiency.
Inhibitory Mechanism of Plant Polyphenols on Protein Oxidation and Their Application for Shelf-Life Extension of Meat Products: A Literature Review
LI Wenhui, LIU Fei, LI Yingbiao, RAN Lidan, HOU Ran, ZHONG Yuanyuan, DONG Juan
2019, 40(21):  266-272.  doi:10.7506/spkx1002-6630-20180408-090
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Protein oxidation and microbial contamination are the main causal factors of the deterioration and spoilage of meat and meat products during storage. One of the effective methods to prevent the deterioration of meat and meat products is adding plant polyphenols, which have good antioxidant and antibacterial activities. The classes of plant polyphenols and their inhibitory mechanisms on protein oxidation and microbial contamination in meat and meat products are summarized in this paper. It describes four ways that plant polyphenols inhibit protein oxidation: reactive material scavenger, non-free radical derivative scavenger, transition metal ion chelating agent and ferrimyoglobin reducing agent. Plant polyphenols prolong the shelf-life of meat and meat products by interacting with bacterial cell wall components and cell membranes, preventing and controlling the formation of biofilm, synthesizing biological macromolecules and consequently inhibiting bacterial enzyme activities. The application of plant polyphenols in inhibiting protein and lipid oxidation and microbial growth in meat products is reviewed and future research prospects are discussed.
A Review of Recent literature on Butyrate-Producing Bacteria in the Human Intestine and Health-Promoting Functions of Their Metabolite Butyrate
GAO Wenwen, MENG Xiangchen
2019, 40(21):  273-279.  doi:10.7506/spkx1002-6630-20181010-086
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A plenty of butyrate-producing bacteria are colonized in the human intestine, and their major metabolite is butyrate, which plays an important role that cannot be ignored for the host. This article outlines the major types of butyrate-producing bacteria in the intestine and their symbiosis with probiotic lactic acid bacteria like Bifidobacterium. Moreover, the biosynthesis pathway of butyrate and its effects on intestinal health and animal growth are reviewed. We expect this review will provide a theoretical basis for further research on butyrate-producing bacteria and the development of related functional products.
Analysis of Events of Ingestion of Food-Borne Stimulants by Mistake and Current Status of Relevant Regulations and Standards in China and Abroad
LI Xiaoman, ZANG Mingwu, WANG Shouwei, LI Dan, ZHANG Kaihua, ZHANG Zheqi
2019, 40(21):  280-287.  doi:10.7506/spkx1002-6630-20190225-175
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The prevention and control of food-borne stimulants are an important part of the work of sports competition management institutions and food supply service. This paper outlines the sources and classification of food-borne stimulants, and analyzes the positive cases of food-borne stimulants that were ingested by mistake in China and abroad from 2008 to 2018, with focus on product types, reasons for accidental ingestion, and positive components and classification as well as the major characteristics. Finally, recent progress in regulations and standards concerning food-borne stimulants is summarized, which will provide novel ideas for strengthening the detection, prevention and management of food-borne stimulants in China.
Recent Advances in Understanding Neuroprotective Effect of Apigenin
SUN Shengnan, ZHANG Youyuan, JIN Shaojin, ZHU Yunfeng, XU Cuicui, MA Ying, LU Weihong
2019, 40(21):  288-294.  doi:10.7506/spkx1002-6630-20181114-156
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Apigenin, a member of the flavone family, is ubiquitous in fruits, vegetables, beans and tea. Apigenin can pass through the blood-brain barrier and has a strong ability to protect the nervous system and attenuate relevant diseases. This review focuses on the neuroprotective mechanism of apigenin and its role in improving neurological diseases from antioxidant and anti-inflammation perspectives, which will provide new ideas and evidence for the potential application of apigenin in treating neurological diseases.
Recent Advances in Understanding of the Potential Impact of Probiotics on Type II Diabetes
YAN Fenfen, LI Na, LI Bailiang, YUE Yingxue, SHI Jialu, ZHAO Li, HUO Guicheng
2019, 40(21):  295-302.  doi:10.7506/spkx1002-6630-20181029-331
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The gut microbiota play an important role in metabolism, maintaining human health and developing disease. In recent years, a series of studies on the gut microbiota have demonstrated that the intestinal flora is closely related to the occurrence and development of some metabolic syndromes (obesity, diabetes, and high blood pressure), allergic reactions, and neurodegenerative diseases. The relationship between the intestinal flora and human health has become a research hotspot, but the relationship between the gut microbiota and these diseases and the pathogenic mechanisms are still unclear. At present, 16S rRNA and macrogenomic analysis of intestinal flora structure and metabolites reveal the correlation between intestinal microorganisms and diabetes mellitus. As a special group of intestinal symbiotic bacteria, probiotics play an important role in regulating gastrointestinal homeostasis, nutrient metabolism and energy balance. Potential therapeutic strategies targeting the gut microbiota for diabetes have their unique advantages. This paper summarizes the recent progress in the application of probiotics in the prevention and treatment of diabetes, which will provide useful information for further research on diabetes.
Biofilm Formation and Control of Listeria monocytogenes Based on Quorum Sensing: A Review
LIU Yunge, LUO Xin, DONG Pengcheng, ZHU Lixian, MAO Yanwei, LIANG Rongrong, YANG Xiaoyin, HAN Guangxing, ZHANG Yimin
2019, 40(21):  303-310.  doi:10.7506/spkx1002-6630-20181114-166
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The biofilm structure of Listeria monocytogenes endows this bacterium with high antimicrobial resistance, making it difficult to effectively remove its biofilm during food processing. Quorum sensing (QS) is closely related to physiological characteristics of bacteria, such as biofilm formation, virulence invasiveness and stress response. In this article, the characteristics of L. monocytogenes biofilm are summarized. Emphasis is put on the formation mechanism from the perspective of quorum sensing (autoinducer-2 system and autoinducing peptide system). The currently available approaches for controlling L. monocytogenes biofilm are reviewed as well as studies on plant extracts as quorum sensing inhibitors. The aim of this review is to provide new ideas for the prevention and control of biofilm formation of L. monocytogenes.
Recent Progress in the Relationship between Polysaccharide Receptor and Macrophage Phagocytosis
ZHAO Li, JIN Zhouyu, JING Bo, SONG Hui
2019, 40(21):  311-316.  doi:10.7506/spkx1002-6630-20181127-309
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In recent years, polysaccharides have been widely used as immunomodulators in the regulation of macrophage surface receptor-mediated immunoregulation. Polysaccharide receptors on the surface of macrophages have become a research hotspot. Macrophages belong to immune cells and participate in mediating inflammation, repairing tissue damage, and recognizing and phagocytizing pathogens. The phagocytosis of macrophages begins with the recognition of endocytosis, which is closely related to macrophage surface receptors. Studies have shown that polysaccharides can promote macrophage phagocytosis, but the underlying mechanism is yet unclear. In this review, we explore the relationship between polysaccharide receptors on the macrophage surface and macrophage phagocytosis, which will provide useful information for future studies of polysaccharide-activated cell phagocytosis.
Recent Advances in Application of Near-Infrared Spectroscopy for Quality Detection in Fresh Poultry Meat
HE Hongju, ZHU Yadong, WANG Hui, MA Hanjun, CHEN Fusheng, LIU Xi, JIA Fangfang, KANG Zhuangli, LIU Hong, ZHU Mingming, ZHAO Shengming, WANG Zhengrong, LIU Suhan
2019, 40(21):  317-323.  doi:10.7506/spkx1002-6630-20181119-218
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Near-infrared spectroscopy (NIRS), a fast, non-destructive and green detection technology, is widely used in poultry meat research, where a high-precision and stable mathematical model for predicting the quality of unknown meat samples is built by relating spectral information to the reference values of quality indicators. Compared with traditional methods, NIRS has many advantages such as no pretreatment, more abundant information and faster data calculation, which indicates a great potential of NIRS for application in the detection of meat products. This paper reviews the recent progress that has been made in the application of NIRS in the detection of physical properties, chemical composition and microbial spoilage in raw poultry meat. The efficacies of NIRS combined with different chemometric algorithms for mathematical modelling in evaluating poultry meat quality are summarized. The shortcomings and future development trends of NIRS in poultry quality detection are also proposed. This review can provide data support and a theoretical basis for improving the application of NIRS in meat quality detection and for developing portable NIRS equipment.
Recent Progress in the Application of Lipidomics in Food Safety and Quality
HU Qian, ZHANG Jiukai, HAN Jianxun, XING Ranran, LIU Qing, CHEN Ying
2019, 40(21):  324-333.  doi:10.7506/spkx1002-6630-20181031-380
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Lipid composition varied among different foods. Lipids affect food quality, nutrition and hygiene. As important sources of energy and nutrients, lipids are directly related to the development and progression of many chronic diseases such as cardiovascular and cerebrovascular diseases, cancer, Alzheimer’s disease and diabetes. In-depth studies on lipid nutrition can affect not only food quality and safety, but also many fields such as clinical medicine and agro-pastoral production. Technologies for lipid separation and detection have recently developed rapidly, leading to the birth of lipidomics as an emerging subject for the analysis of lipids. As one of the most important branches of metabolomics, lipidomics has been widely used in the study of food lipids. This paper presents a brief description of the process of lipidomics research with focus on the application of lipidomics in food composition analysis, quality identification, authentication, geographical tracing and safety evaluation. Finally, the limitations for the application of lipidomics in the field of food safety and quality are analyzed. It is hoped that this review can provide useful information for the application of lipidomics in food safety and quality management.
A Review of the Modification, Functional Characteristics and Application in Food Preservation of Lysozyme
SUN Hao, SHI Yugang, ZHU Chenmin, ZHANG Runrun, CHEN Jianshe, Rammile ETTELAIE
2019, 40(21):  334-342.  doi:10.7506/spkx1002-6630-20181121-257
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Lysozyme (LZ) is a ubiquitous natural and nontoxic antibacterial agent that can dissolve selectively microbial cell walls and disrupt their physiological activity, and it is widely used in the food industry. The antibacterial action of native LZ is limited to Gram-positive bacteria, and it has almost no impact on Gram-negative bacteria. Hence, it is of great significance to adjust the molecular structure of LZ and expand its bacteriostatic spectrum. This review provides a detailed summary of the recently reported methods used to modify LZ (chemical modification, physical and biological modification, as well as nanosizing), the functional properties (enzymatic activity, stability and emulsifying properties) of modified LZ, and its inhibitory effect and mechanism of action against harmful microbes, as well as the application of modified LZ in the field of food preservation. The promising strategies for molecular modification of LZ and the potential application of LZ combined with nanotechnology and material science are also presented.
Recent Advances in Understanding the Role and Mechanism of Action of Tartary Buckwheat in Regulating Glucolipid Metabolism
XIAO Jie, WANG Xi, HOU Can, NIU Xinghe, DONG Zhizhong, YING Jian
2019, 40(21):  343-349.  doi:10.7506/spkx1002-6630-20181024-274
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Currently, tartary buckwheat is increasingly becoming a research hotspot due to its role in regulating glucolipid metabolism. The major chemical composition of tartary buckwheat includes multiple amino acids, fatty acids, vitamins, and flavonoids. Tartary buckwheat can be used as an alternative to reduce blood glucose and lipid levels and to improve insulin resistance. Flavonoids and proteins in tartary buckwheat have been recognized to be related to the improvement of glucolipid metabolism, which can improve glucose metabolism via inhibiting α-glucosidase activity and enhancing insulin sensitivity and improve lipid metabolism via bile salt absorption and regulating lipid metabolism pathways. This paper summarizes the material basis and mechanism for the regulation of tartary buckwheat on glucolipid metabolism and discusses future research directions and application prospects. It is expected to provide an impetus for further research and application of tartary buckwheat and provide new insights into the prevention and early treatment of obesity, hyperlipemia and diabetes.
A Literature Review of the Application of Enzymes in Processing of Plant-Based Foods for Elderly People
LI Shuangjiao, ZHAO Jing, XIAO Rong
2019, 40(21):  350-356.  doi:10.7506/spkx1002-6630-20181011-089
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Under the current global aging trend, China’s market for foods for elderly has great potential. However, the current market cannot satisfy the demands of surging elderly population in the future. Plant-derived foods can meet the demands of the elderly in terms of nutrition and taste, and are an important part of the dietary structure of the elderly. The enzymatic technology provides a powerful means for the special production of plant-derived foods for elderly people. In this article, the effects of endogenous enzymes on plant-derived foods, the use of exogenous enzymes for quality control of food raw materials, and combined with the application of new food processing technology in the field of plant-derived food processing, which will provide new ideas and directions for the development of plant-based foods.