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15 March 2020, Volume 41 Issue 5
Basic Research
Understanding the Formation Mechanism of Dark Cutting Beef Based on Sarcoplasmic Proteomics
WU Shuang, WANG Lei, YANG Xiaoyin, LUO Xin, LI Hang, ZHU Lixian, ZHANG Yimin
2020, 41(5):  1-7.  doi:10.7506/spkx1002-6630-20181231-368
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The present study explored the mechanism of the occurrence of dark cutting beef through comparing the sarcoplasmic proteomics of normal pH (5.59) and dark cutting beef (pH 6.54) at 45 min and 24 h post-mortem and analyzing the differentially expressed proteins. The results revealed that 20 differentially expressed proteins were identified. Of these proteins, 9 were metabolic enzymes, 4 were antioxidant proteins and 4 were chaperones. Compared with dark cutting beef, all energy-related enzymes (adenylate kinase 1, creatine kinase M chain, Phospholysine phosphohistidine inorganic pyrophosphate phosphatase, succinate-CoA ligase, UTP-glucose-1-phosphate uridylyltransferase, and S-adenosylhomocysteine hydrolase) except adenylate kinase 1 (which was overexpressed in dark cutting beef) at postmortem 24 h, and the glycometabolic enzymes (phosphoglucomutase 1 and myophosphorylase) were overexpressed in normal pH beef. All antioxidant proteins, and heat shock protein beta-1 and beta-2 were overexpressed in normal pH beef, while alpha-crystallin B chain was overexpressed in dark cutting beef. The development of dark cutting beef could be directly explained by lower abundances of glycometabolic enzymes and energy-related enzymes when compared to normal pH beef. Moreover, succinate-CoA ligase, heat shock protein beta-1 and alpha-crystallin could be employed as biomarkers to identify dark cutting beef.
Effect of Anthocyanins Extract from Lycium ruthenicum Murr. Fruit on Pancreatic Lipase Activity
ZHANG Jing, MI Jia, LU Lu, LUO Qing, YAN Yamei, RAN Linwu, JIN Bo, CAO Youlong
2020, 41(5):  8-14.  doi:10.7506/spkx1002-6630-20190620-234
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Objective: To investigate the inhibitory effect of anthocyanins from the fruit of Lycium ruthenicum Murr. on pancreatic lipase activity. Methods: The inhibitory activity of the anthocyanins on pancreatic lipase was determined by spectrophotometry. The interaction effect between them was studied by ultraviolet spectroscopy and fluorescence spectroscopy. Results: The anthocyanins had a certain inhibitory effect on pancreatic lipase activity. The half-maximum inhibition concentration (IC50) was (2.84 ± 0.45) mg/mL and the inhibition was reversible and competitive. Ultraviolet and fluorescence spectra showed that the anthocyanins could result in π→π* transition of peptide bond C=O groups in pancreatic lipase, a decrease the content of alpha-helix and quenching of endogenous fluorescence. Thermodynamic parameters analysis showed that the anthocyanins and pancreatic lipase interacted mainly through hydrogen bond and Van der Waals force. Conclusion: The anthocyanins from L. ruthenicum Murr. fruit can bind to pancreatic lipase and thereby inhibit its activity.
Antibacterial Mechanism of Antimicrobial Peptide Brevilaterin Combined with ε-Polylysine against Staphylococcus aureus
NING Yawei, SU Dan, FU Yunan, HAN Panpan, WANG Zhixin, JIA Yingmin
2020, 41(5):  15-22.  doi:10.7506/spkx1002-6630-20191009-055
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Staphylococcus aureus is a common foodborne pathogenic bacterium, and controlling S. aureus is of great importance for the improvement of food safety. Thus, using S. aureus as an indicator microorganism, the synergistic antibacterial mechanism of the antimicrobial peptide brevilaterin combined with ε-polylysine was investigated. Time-kill kinetics showed that brevilaterin and ε-polylysine had a synergistic antibacterial effect on S. aureus. Transmembrane proton potential kinetics indicated that ε-polylysine could disrupt the transmembrane pH gradient, but brevilaterin had no obvious effect. The combination of brevilaterin and ε-polylysine each at 1/4 minimal inhibitory concentration (MIC) synergistically damaged the transmembrane pH gradient. Flow cytometry combined with fluorescence microscopy was used to investigate the cell membrane integrity, and the results showed that 36.3% of the cells were damaged by brevilaterin at 1/4 MIC, while only 10.4% of the cells were destroyed by ε-polylysine at 1/4 MIC. Their combined use could synergistically damage the cell membrane integrity, resulting in 51.3% cell membrane damage. The ultrastructure of cells observed by transmission electron microscopy showed that the combined use of brevilaterin and ε-polylysine had a synergistic effect in disrupting cell morphology and causing leakage of cellular contents when compared with either alone. Sodium dodecylsulfate-polyacrylamide gel?electrophoresis suggested that ε-polylysine could inhibit bacterial protein synthesis or result in the degradation of proteins, while brevilaterin had no effect on protein synthesis. Agarose gel retardation electrophoresis showed that brevilaterin had no effect on bacterial DNA, and ε-polylysine and its combination with brevilaterin could lead to the retention of DNA, indicating that ε-polylysine could inhibit bacteria by binding with DNA. Therefore, the combination of brevilaterin and ε-polylysine could synergistically disrupt the membrane integrity, and exert a synergistic antibacterial effect through inhibition of respiratory chain dehydrogenase activity by brevilaterin, and destruction of transmembrane pH gradient by ε-polylysine as well as its binding with DNA.
Effect of Enzymatic Hydrolysis of Soymilk on the Microstructure and Physicochemical Properties of Dried Tofu
CHEN Fanfan, TENG Fei, HAN Song, WU Changling, ZHOU Yan, GUO Zengwang, WANG Zhongjiang, LI Yang
2020, 41(5):  23-30.  doi:10.7506/spkx1002-6630-20190215-070
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In order to study the effect of enzymatic hydrolysis of soymilk on the microstructure and physicochemical properties of dried tofu, changes in the surface hydrophobicity, protein thiol content and disulfide bond content of soymilk were evaluated after being hydrolyzed by flavourzyme and texture properties, microstructure, water state, water-holding capacity, in vitro digestibility and sensory characteristics of dried tofu were determined. The results showed that compared with untreated control, the surface hydrophobicity and disulfide bond content of soymilk hydrolyzed for 30 min increased by 1 904.5 and 0.18 μmol/g, respectively. The sensory quality of dried tofu was significantly improved at first and then deteriorated with increasing hydrolysis time, and the highest sensory score was reached at 30 min. Compared with the control, the microstructure of dried tofu made from hydrolyzed soymilk was tighter and more uniform, the hardness, springiness, chewiness, cohesiveness and resilience were also improved. The water-holding capacity and in vitro digestion rate were increased by 9.29% and 9.00%, respectively, and the water loss rate was reduced by 0.2% when the enzymatic hydrolysis time was 30 min. Enzymatic hydrolysis of soymilk could the increase its protein thiol content and surface hydrophobicity, and then affect the structural compactness and sensory characteristics of dried tofu. This study provides a preliminary theoretical basis for quality improvement of dried tofu and for the application of enzymatic hydrolysis in soybean products.
Predictive Modeling of the Nonbiological Stability of Chinese Yellow Wine
XIE Guangfa, LU Jian, SUN Junyong, LU Yin, PENG Qi, QIAN Bin, JIN Jianshun, WANG Lan, FU Zukang, LU Zhendong, LIU Caiqin
2020, 41(5):  31-38.  doi:10.7506/spkx1002-6630-20190219-106
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In order to establish a predictive model for determining the turbidity of Chinese yellow wine to estimate its shelf life, the chemical components related to the turbidity were investigated, including total polyphenols, catechins, sensitive polyphenols, total nitrogen, Lundin fractions, sensitive proteins and iron ions. A multivariate linear regression model for predicting the turbidity was developed. The results showed that the turbidity (Y1) of bottled wine was significantly correlated with the number of heating-cooling cycles required for an increase of 4 NTU in turbidity (X1), sensitive protein content (X2), total nitrogen content (X3), low molecular mass nitrogen content (X4) and medium molecular mass nitrogen content (X5). The linear regression equation developed was Y1 = 2.79 ? 0.485X1 + 0.663X2 + 0.327X3 + 1.577X4 ? 3.864X5. The measured turbidity of wine stored for 12 months was in good agreement with the predicted value, suggesting the prediction model has a good application potential.
Isolation, Purification, Structure Identification and Anti-tumor Activity of Anthocyanin from Kyoho Grape Skins
XUE Hongkun, TAN Jiaqi, LIU Chai, LIU Chenghai
2020, 41(5):  39-48.  doi:10.7506/spkx1002-6630-20190115-165
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The purpose of this study was to investigate the isolation, purification, structure and antitumor activity of anthocyanins from kyoho grape skins. Pigment-rich crude extract from kyoho grape skins was separated and purified sequentially by AB-8 macroporous resin, polyamide resin and Sephadex LH-20 column chromatography. The structure of the purified anthocyanins was identified by using ultra-high performance liquid chromatography combined with triple quadrupole time-of-flight mass spectrometry (UPLC-QTOF MSE), and their effects on the proliferation, invasion and apoptosis of HepG2 hepatocellular cells and A549 lung cancer cells were investigated by MTT assay, Transwell invasion assay and Annexin V-FITC/PI double labeling staining, respectively. The ultraviolet (UV)-visible (Vis) spectrum showed that the AB-8 purified sample had absorption peaks at 280, 520 and 330 nm, indicating that the major components of the sample were anthocyanins which might contain acylation groups. In the sample, some anthocyanins were adsorbed by polyamide resin, while Sephadex LH-20 column chromatography could allow good separation and purification of anthocyanins from kyoho grape skins. Three anthocyanin components (I, III and IV) were obtained in high yields ((0.108 ± 0.011)%, (0.053 ± 0.007)% and (0.038 ± 0.005)%) and purities (98.52%, 96.84% and 91.36%, respectively) and they were identified as cyanidin-3-rutinoside, malvidin-3,5-diglucoside-coumarin and malvidin-3-galactoside. The anthocyanin components could significantly inhibit the proliferation and invasion of HepG2 hepatoma cells and A549 lung cancer cells, and significantly increase the apoptosis of cancer cells. Their anti-tumor effects were ranked as follows: III > I > IV.
In Vitro Antioxidant Properties of Duck Lipids
LONG Xia, NING Junli, HUANG Xianzhi, DING Xiaowen
2020, 41(5):  49-56.  doi:10.7506/spkx1002-6630-20190119-231
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Objective: The antioxidant effect of duck lipids against the oxidation of the macromolecules lipid, protein and DNA was evaluated in vitro, with the aim of providing a basis for further study of its antioxidant capacity in vivo. Methods: The antioxidant effect was assessed by 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, ferric ion reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), the ability to inhibit β-carotene fading, the effect on the carbonyl content of bovine serum albumin (BSA), and DNA damage protection potential. Results: The half-maximum inhibitory concentration (IC50) for DPPH radical scavenging was (15.03 ± 0.53) mg/mL; when the concentration of duck lipids was 35 mg/mL, FRAP value was (241.87 ± 3.05) μmol/L, ORAC value was (2.59 ± 0.15) μmol TE/g, and the inhibition rate of β-carotene degradation was (67.29 ± 3.37)%. Duck lipids at lower concentrations could protect BSA, but at 6 mL/g increase the carbonyl content by (50.00 ± 3.21)%. The protection rate against DNA damage of duck lipids at 1 mg/mL was (43.27 ± 0.01)%. Conclusion: Duck lipids had good antioxidant activity.
Food Engineering
Analysis of Mass and Heat Transfer Characteristics of Potato and Oat Composite Noodles during Combined Heat Pump-Hot Air Drying
QU Zhanping, REN Guangyue, ZHANG Yingmin, DUAN Xu, ZHANG Ledao
2020, 41(5):  57-65.  doi:10.7506/spkx1002-6630-20190228-221
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In this study, potato-oat composite noodles were dried by a new combined heat pump-hot air drying technique. Low-field nuclear magnetic resonance (LF-NMR) and scanning electron microscopy were used to analyze the drying characteristics and the heat transfer characteristics during the drying process. The results showed that higher heat pump temperature, water content at the conversion point or hot air temperature could result in higher drying efficiency and increased diffusion of moisture. The Midilli model was suitable for describing the drying behavior of noodles. Under different drying conditions, the effective water diffusion coefficient was 3.82 × 10-10–5.12 × 10-10 m2/s. The results of LF-NMR showed that the total water content decreased continuously during the drying process, and the peak of weakly bound water shifted to the left, indicating that the content of weakly bound water decreased to the greatest extent, accompanied by a simultaneous decrease in the degree of freedom; weakly bound water was mostly transformed to free water along with tightly bound water. When the equilibrium moisture was reached, bound water was relatively more abundant than free water. The moisture content on a dry basis exhibited a significantly positive correlation with peak area (P < 0.01). Magnetic resonance imaging showed that the density of protons in the middle of noodles was the largest, and protons migrated outside as the drying progressed. The microstructure became denser, and tightly bound water more tightly combined with macromolecules, thus resulting in the formation of a more intact gluten network structure.
Effect of Air Discharge Treatment on Physiological Metabolism and Cell Membrane of Fusarium oxysporum
LIU Mengdie, LI Caiyun, LI Jie,, YAN Shoulei, WANG Qingzhang
2020, 41(5):  66-72.  doi:10.7506/spkx1002-6630-20190225-181
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Lotus root is apt to be spoiled by Fusarium oxysporum due to its rich nutrition. In order to explore a method to inhibit the spoilage microbe, the effect of air discharge treatment on substance and energy metabolism in Fusarium oxysporum was studied, and we further investigated the cell membrane damage caused by air discharge at the cellular level. Three treatments were set up by using ozone at 6.87 mg/m3 or/and negative ions at 5 × 106 ions/cm3, respectively, and untreated Fusarium oxysporum was regarded as the control group. Results showed that after air discharge treatment, the metabolic balance of Fusarium oxysporum mycelium was destroyed, and consequently sugar and protein accumulated. Respiratory intensity and ATP synthesis decreased significantly (P < 0.05). Moreover, the cell membrane permeability increased, the integrity was destroyed, the fluidity significantly decreased (P < 0.05), and the membrane potential increased significantly (P < 0.05). Compared with the single treatments, the combined treatment was more effective in destroying cell membrane structure. In conclusion, air discharge exerted bacteriostatic effect by changing the cell membrane permeability and integrity of Fusarium oxysporum, and inhibiting catabolism, consequently decreasing ATP supply and finally affecting cell viability.
Freeze-Thaw Stability of Sonicated Soybean Lipophilic Protein-Hydroxypropyl Methylcellulose Stabilized Emulsions
ZHONG Mingming, LIAO Yi, QI Baokun, FANG Lin, SUN Yufan, XIE Fengying, LI Yang,
2020, 41(5):  73-79.  doi:10.7506/spkx1002-6630-20190130-390
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In this paper, the freeze-thaw stability of emulsions stabilized by soybean lipophilic protein (SLP) treated with different ultrasonic powers and hydroxypropyl methylcellulose (HPMC) was studied and the underlying mechanism was evaluated from the perspective of structure-activity relationship. The results showed that the degree of aggregation of emulsions subjected to two freeze-thaw cycles was reduced with the increase of ultrasonic power, and the composite emulsion with SLP sonicated at 400 W and HPMC was the most stable. The oil release rate of sonicated SLP-HPMC emulsions was significantly lower than that of unsonicated SLP-HPMC emulsion (P < 0.05). Sonication treatment changed the secondary structure of SLP; the highest contents of β-sheet and β-turn in sonicated SLP were observed at 400 W ultrasonic power, and the loose structures of β-sheet and β-turn contributed to increased protein flexibility and to higher susceptibility to structural changes and unfolding, affecting the interfacial stability and consequently the freeze-thaw stability of the SLP-HPMC composite emulsion.
Effect of Heat Treatment on Physicochemical Properties of Chinese Yam Flour
SU Xiaojun, LU Chengte, WANG Feng, GUO Shiyin, LI Wenjia, LI Qingming
2020, 41(5):  80-86.  doi:10.7506/spkx1002-6630-20190307-087
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The effects of different heat treatments: steaming at atmospheric pressure (SAP) and boiling at atmospheric pressure (BAP) on the physicochemical properties of Chinese yam flour were analyzed by rapid viscosity analysis (RVA), rheometry, Fourier transform infrared (FTIR) spectroscopy and scanning electronic microscopy (SEM). The results showed that the wettability and dispersibility were improved by both heat treatments, which decreased from 7.77 and 4.68 min to 2.11 and 0.52 min after 30 min of SAP, respectively. After heat treatment, the pasting temperature, peak viscosity, minimum viscosity, breakdown value, and final viscosity decreased, while the iodine blue value increased with the increase in heat treatment time. The apparent viscosity of heat-treated yam flour declined steeply and then tended to stable with increasing shear rate, exhibiting shear thinning. Heat treatment destroyed the structure of yam flour, decreased the degree of structural orderliness and resulted in an irregular appearance. It was also found that the change of color caused by atmospheric boiling was smaller than that caused by atmospheric steaming, while the change of solubility caused by atmospheric steaming was smaller than that caused by atmospheric boiling. After steaming, the solubility increased from 16.05 to 17.89 g/100 g. The solubility of SAP treated sample was higher than that of the sample subjected to BAP for the same durations. The boiling treatment resulted in a significant decrease in the contents of functional components; that is, the contents of polysaccharides, total polyphenols, total flavones and allantoin decreased from 2.67, 0.076, 0.084, 0.445 g/100 g to 1.75, 0.070, 0.071 and 0.288 g/100 g after 30 min, respectively, while the steaming treatment resulted in losses of total polyphenols and flavonoids, which decreased from 0.076 and 0.084 g/100 g to 0.055 and 0.061 g/100 g after 30 min, respectively. Compared with BAP, SAP was a better processing method for cooked Chinese yam flour.
Effect of Microfluidization on the Structure and Function of Wild Black Bean Protein
WU Haitao
2020, 41(5):  87-92.  doi:10.7506/spkx1002-6630-20181229-358
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The effects of microfluidization applied at different pressures (0, 42.5, 89.0, 123.5, 152.0 and 175.5 MPa) on the structure and solubility of black bean protein isolate (BBPI) from wild black beans were studied. The results showed that microfluidization enhanced the hydrophobic interaction between wild BBPI molecules and caused breakdown of unstable aggregates into soluble proteins. However, high shearing strength at pressure exceeding 123.5 MPa resulted in reaggregation of the soluble proteins. The emulsifying activity of BBPI increased initially and then decreased with increasing pressure, while the emulsion stability did not change significantly (P > 0.05). Raman spectroscopy analysis showed that compared with native BBPI, the contents of α-helical and β-sheet decreased in all simples subjected to microfluidization. Microfluidization resulted in partial unfolding of the proteins and exposure of tryptophan residues on the protein surface as demonstrated by a decrease in the intensity of tryptophan band at 760 cm-1, but it significantly increased the intensity of tyrosine band, indicating that the microenvironment around tyrosine residues was altered. The Raman intensity increased as the homogenization pressure increased, resulting in conformational transformation of disulfide bond from t-g-t to g-g-t.
Nutrition & Hygiene
RNA-seq Transcriptomic Analysis of Phycocyanin in Regulating the Inhibition of Non-small Cell Lung Cancer Cells
HAO Shuai, LI Shuang, WANG Jing, WU Tingting, ZHANG Jiawen, WANG Chengtao
2020, 41(5):  93-101.  doi:10.7506/spkx1002-6630-20181227-325
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Phycocyanin is a natural food colorant used in many food industries in China. It is also a natural functional food protein with good antitumor capacity. In the present study, the high-throughput RNA-seq analysis showed that phycocyanin affected the expression levels of 2 532 genes, including 1 491 up-regulated ones and 1 041 down-regulated ones. GO analysis showed that these differentially expressed genes mainly participated in cell proliferation, apoptosis and cytokine responses. Cluster analysis showed that proliferation-related genes such as Cdk2, Cdc25, PCNA and TLR4 were down-regulated, whilst p27 and p21 were up-regulated after phycocyanin treatment. Meanwhile, apoptosis-related genes such as Bcl-2 and NKD1 were significantly down-regulated, whereas CCT6 and GBP2 were significantly up-regulated. KEGG pathway analysis showed that PI3K-Akt signaling was one of the important pathways through which phycocyanin participated in regulating H460 cells. By revealing the potential mechanism of action of phycocyanin in non-small cell lung cancer H460 cells, the present study may provide a theoretical foundation for the development of targeted therapeutics against non-small cell lung cancer and of functional food factors against tumor cells.
Alkylresorcinols from Wheat Bran Induced Autophagy and Apoptosis of HepG2 Cells
GUO Yazhou, YANG Xiaoming, LI Yueying
2020, 41(5):  102-107.  doi:10.7506/spkx1002-6630-20190102-016
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In this study, two alkylresorcinol homologues C19:0 and C21:0 were isolated by preparative chromatography from wheat bran, and their autophagy and apoptosis-inducing effect on HepG2 cells was studied. The results showed that the structures of alkylresorcinol C19:0 and C21:0 were validated by liquid chromatography-mass spectrometry (LC-MS). Cytotoxicity tests showed that the alkylresorcinols (ARs) at concentrations ranging from 10 to 320 μg/mL could significantly inhibit the growth of HepG2 cells in a dose-dependent manner (P < 0.05, P < 0.01, P < 0.001). Compared with the control group, cell apoptosis rates in the experimental group significantly increased (P < 0.01); the protein expression of cleaved caspase3, Bax/Bcl-2, beclin-1 and LC3II increased but the protein expression of p62 decreased (P < 0.01) after 24 h treatment at 160 μg/mL. Therefore, it was suggested that the alkylresorcinols could induce autophagy in HepG2 cells, and induce apoptosis by activating the caspase-3 pathway, thus inhibiting the growth of HepG2 cells.
Protective Effect and Mechanism of Fibrinolytic Enzyme from Lyophyllum ulmarium on Alcohol-Induced Injury in Vascular Endothelial Cells
LI Fangfang, CONG He, SHEN Minghua
2020, 41(5):  108-114.  doi:10.7506/spkx1002-6630-20190301-010
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Objective: To investigate the protective effect and mechanism of fibrinolytic enzyme from Lyophyllum ulmarium (LUFE) on alcohol-induced injury in human umbilical vein endothelial cells (HUVECs). Methods: Cell viability was evaluated by the methyl thiazolyl tetrazolium assay and the activity of lactate dehydrogenase (LDH) in cell-free culture supernatants was determined. The activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA) were measured by colorimetry. The apoptosis changes of HUVECs were detected with acridine orange/ethidium bromide staining. The level of reactive oxygen species (ROS) and mitochondrial transmembrane potential (Δφm) were evaluated by dihydrorhodamine123 and rhodamine 123 staining, respectively. The protein expression of Bax, Bcl-2, cytochrome c, cleaved cysteinyl aspartate specific proteinase (caspase)-9 and cleaved caspase-3 was determined using Western blot assay. Results: Compared with the model group, LUFE could increase the survival rate, decrease the contents of LDH and MDA, and increase the activity of SOD and GSH-Px in HUVECs. LUFE could also reduce intracellular ROS production, increase mitochondrial transmembrane potential and inhibit apoptosis induced by alcohol. LUFE could down-regulate the expression of cytochrome c, cleaved caspase-9 and cleaved caspase-3, and up-regulate the expression of Bcl-2. Conclusion: LUFE has a protective effect on alcohol-induced injury of HUVECs, which may be related to its antioxidant capacity and its ability to regulate the mitochondrial signal pathway.
Anti-obesity Effect and Mechanism of Konjac Mannooligosaccharides
WEN Yongping, ZHU Di, SUN Jian, YAN Qiaojuan, JIANG Zhengqiang
2020, 41(5):  115-121.  doi:10.7506/spkx1002-6630-20190926-323
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Objective: To evaluate the inhibitory effect of konjac mannooligosaccharides (KMOS) on obesity and chronic inflammation in high-fat diet (HFD)-induced obese mice and to decipher the underlying molecular mechanisms. Methods: Ten-week-old healthy male C57BL/6J mice were randomly divided into 7 groups. After 12 weeks of continuous feeding, body mass, body fat, blood lipids, and oxidative stress indicators were detected. The indicators associated with lipid metabolism and their gene expression in adipose and liver tissues were analyzed. Results: KMOS effectively reduced body mass by 36.36% and body fat mass by 52.13%, improved blood lipid abnormality, and significantly inhibited the release of inflammatory factors and increased antioxidant enzyme activities (P < 0.05). Moreover, KMOS significantly reduced fat cell volume and inhibited lipid metabolism-related indicators and gene expressions in liver and adipose tissues (P < 0.05). Conclusion: KMOS can prevent obesity, and inhibit chronic inflammation and oxidative stress induced by obesity, which provides a scientific basis for the development of KMOS as functional dietary supplements against obesity and other chronic diseases.
Effect of Casein Glycation on Immunoenhancing Activity of Tryptic Caseinate Digest in Immunosuppressed Mice
SHI Jia, LIU Wanning, FU Yu, ZHAO Xinhuai
2020, 41(5):  122-127.  doi:10.7506/spkx1002-6630-20181213-163
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This study aimed to assess the potential effect of casein glycation via the Maillard reaction on in vivo immunoenhancing efficacy of tryptic casein digest in immunosuppressed mice. Glycated casein was prepared by the Maillard reaction of casein with lactose. Glycated and native casein were digested with trypsin to generate glycated casein digest and casein digest, respectively. Mice were treated with cyclophosphamide at 80 mg/kg mb for 3 days to induce immunosuppression, and then were given the two digests, separately at dose levels of 100, 200, and 400 mg/kg mb for 25 days. Afterwards, immune organ (spleen and thymus) indices, serum biochemical indices, immunoglobulin (IgM, IgA, and IgG) levels, lymphocyte proliferation capacity, and natural killer (NK) cell viability were evaluated. Results indicated that the immune status of mice in the model group was lower than that in the control group treated with normal saline as manifested by a significant decrease in immune organ indices, serum biochemical indices, serum Ig levels, spleen lymphocyte proliferation index and NK cell viability (P < 0.05). Compared with the immunosuppressed mice, spleen and thymus indices, serum IgM, IgA and IgG levels, spleen lymphocyte proliferation index, and NK cell viability increased by 35.9%–66.4%, 50.5%–62.9%, 21.6%–30.4%, 27.1%–41.8%, 37.2%–45.1%, 34.2%–51.1%, and 32.1%–90.7% in the mice treated with casein digest at the medium and high doses, and by 27.7%–51.9%, 39.2%–52.6%, 19.1%–29.0%, 21.8%–35.3%, 30.1%–41.6%, 32.9%–41.6%, and 27.3%–81.1% in the mice treated with glycated casein digest at the medium and high doses, respectively. Both digests were able to attenuate the decrease in immune indices of immune suppressed mice induced by cyclophosphamide, while casein digest showed higher immuno enhancing efficacy than glycated casein digest. Therefore, casein glycation via the Maillard reaction could decrease the immunoenhancing activity of its tryptic digest on mice.
Rice Vinegar Residue Reduces Adipocyte Size and Hyperlipidemia by Inhibiting Lipids Absorption in Hamsters
TONG Litao, JU Zhiyuan, GENG Donghui, WANG Lili, ZHOU Xianrong, ZHOU Sumei
2020, 41(5):  128-134.  doi:10.7506/spkx1002-6630-20181114-155
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Rice vinegar residue, a by-product of rice vinegar making, is wasted in enormous quantity, which has been believed to have potential effects in the regulation of lipid metabolism. This study aimed to investigate the effects of rice vinegar residue on lipid metabolism in hypercholesterolemic hamsters. Rice vinegar residue at doses of 200 and 500 mg/(kg mb·d) and rice vinegar at 200 mg/(kg mb·d) were separately given by gavage to hamsters for 30 days. Both rice vinegar residue and rice vinegar significantly lowered the concentration of low-density lipoprotein cholesterol in plasma (P < 0.05), reduced the average size of adipocytes in white adipose tissues, and increased the fecal concentrations of triglycerides, total cholesterol and bile acids (P < 0.05). Moreover, vinegar residue disrupted solubilization of intestinal cholesterol into micelles (P < 0.05), as well as inhibited its binding to cholate (P < 0.05). On the other hand, vinegar residue had no inhibitory effect on lipase activity. Eventually, we conclude that rice vinegar residue has potential beneficial effects on lipid metabolism and obesity by preventing the absorption of cholesterol in the intestine and promoting the excretion of fecal lipids and cholesterol synthesis in the liver, which may be related to the combination between vinegar residue and cholate.
Effect and Underlying Mechanism of Mulberry Leaf Alkaloid on Improving D-Galactose-Induced Oxidative Damage in Mice
YANG Zhongmin, WANG Zuwen, HUANG Xianzhi, DING Xiaowen
2020, 41(5):  135-142.  doi:10.7506/spkx1002-6630-20190226-195
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Objective: To investigate the improving effect of mulberry leaf alkaloid (MLA) on D-galactose (D-Gal)-induced oxidative damage in mice, and to illustrate its underlying mechanism from the perspective of the animal’s own antioxidant defense system. Methods: An oxidative stress model was induced by D-Gal. Ten normal mice were served as the normal control. The model mice were randomly divided into model control, positive control (glutathione at 200 mg/kg mb) and low-, medium- and high-dose MLA treatment groups (50, 100, and 200 mg/kg mb). After intragastric administration for 4 consecutive weeks, body mass, food intake and food utilization of the mice were measured. The levels of 8-iso-prostaglandin F2α (8-iso-PGF2α), protein carbonyl (PCO), advanced oxidation protein products (AOPP), 3-nitrotyrosine (3-NT), 8-hydroxy-2’-desoxyguanosine (8-OH-dG), 5-hydroxy-2’-deoxycotosine (5-OH-dC) in plasma were measured by enzyme-linked immunosorbent assay test kit. The activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px), and the levels of metallothionein (MT) and thioredoxin (Trx), as well as total antioxidant capacity (TAC) in plasma were measured by using commercial test kits. Results: Compared with the model control group, body mass, food intake and food utilization of mice in the high-dose MLA group were significantly increased. The plasma contents of 8-iso-PGF2α, PCO, AOPP, 3-NT, 8-OH-dG, and 5-OH-dC in the medium- and high-dose MAL groups were significantly decreased (P < 0.05), and the activities of T-SOD and GSH-Px, the contents of MT and Trx, and TAC value were significantly increased (P < 0.05); all these effects were dose-dependent. In the high-dose group, the contents of 8-iso-PGF2α, PCO, AOPP, 3-NT, 8-OH-dG, and 5-OH-dC were significantly reduced by 83.46%, 35.43%, 61.70%, 63.65%, 65.02%, and 57.90%, respectively (P < 0.05). In addition, T-SOD, GSH-Px, MT, Trx, and TAC increased by 1.47, 2.96, 1.74, 1.37 and 1.63 times, respectively (P < 0.05), all of which reached the normal levels (P > 0.05). Conclusion: Mulberry leaf alkaloid can effectively improve lipid, DNA and protein oxidative damage in mice. The underlying mechanism may be related to regulating antioxidant enzyme activities and non-enzyme antioxidant contents, and enhancing the antioxidant defense system.
Screening for Self-Stabilizing System for Mixed Congee with Low Glycemic Index and Evaluation of Its GI in the Human Body
LIU Yifeng, DUAN Shenglin, LIU Jia, WANG Chengxiang, MA Shuhong, HOU Zhanqun, MA Fujun, YUAN Peng, XIA Kai, WEN Jian, HAN Xiaofeng
2020, 41(5):  143-151.  doi:10.7506/spkx1002-6630-20181207-093
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In this paper, in order to develop a self-stabilizing and low glycemic index (GI ≤ 55) mixed congee, the effects of soup and cereal materials on the rheological properties of (such as viscosity and elasticity) mixed congee were studied. Starch, Psyllium seed husk, konjak mannan, millet, glutinous millet, and oat were selected as main raw materials to make congee, which form a self-stabilizing system without artificial additives. At the same time, the results of GI test in the human body showed that the postprandial blood glucose of low GI mixed congee increased and decreased more smoothly than that of glucose. Therefore, low GI mixed congee was capable of stabilizing postprandial blood glucose (GI = 51.8), indicating that the mixed congee is a low GI food. In addition, using an intelligent electronic bionic device, the odor and taste of low GI mixed congee were compared with those of 9 mixed congees sold on the market. The results showed that low GI mixed congee had better taste, and its odor could be distinguished from that of the commercial mixed congees.
Inhibitory Effects of Six 5,7-Dihydroxyflavones on M1 Polarization of Macrophages
ZHENG Mengfei, LIU Jian, QU Wei
2020, 41(5):  152-158.  doi:10.7506/spkx1002-6630-20190124-309
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Purpose: The aim of this study was to evaluate the inhibitory effects of six flavonoids (luteolin, quercetin, myricetin, apigenin, kaempferol and chrysin) on M1 polarization of RAW264.7 macrophages and to delineate the structural determinants involved in their activity. Methods: Lipopolysaccharide (LPS) at 100 ng/mL was used to stimulate RAW264.7 macrophages to establish an inflammation model. Cell proliferation activity was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. The expression of CD274 and CD38 was detected by flow cytometry. The expression of proteins involved in the inflammatory signaling pathway was detected by Western blotting. The expression levels of M1-type macrophage marker genes were detected by real-time polymerase chain reaction (PCR). Results: All these flavonoids had no significant effect on cell proliferation at 20 μmol/L, but inhibited the expression of CD274 and CD38, with luteolin, apigenin and chrysin being more effective than quercetin, myricetin and kaempferol. The inhibitory activity of luteolin on activation of the nuclear factor κB signaling pathway was stronger than that of apigenin and quercetin, while the other flavonoids had no significant effect. The inhibitory effect of luteolin, apigenin and chrysin on the mRNA expression of inducible nitric oxide synthase (iNOS) was stronger than that of the other three compounds, and the inhibitory effect of luteolin, quercetin and apigenin on the mRNA expression of interleukin-1β (IL-1β) and monocyte chemotactic protein 1 (MCP1) was stronger than that of the other compounds. Conclusion: Hydroxylation at position 3 on the C ring is not conducive to the inhibition of flavonoids on macrophage polarization, while hydroxylation at positions 3’ and 4’ on the B ring are beneficial to enhance their activity.
Protective Effects of Flavonoids from Millet Bran on H2O2-Induced Oxidative Stress Injury in HepG2 Cells
GUO Zengwang, FAN Naijing, TIAN Haizhi, TENG Fei, LI Meng, LI Yang, WANG Zhongjiang, JIANG Lianzhou
2020, 41(5):  159-165.  doi:10.7506/spkx1002-6630-20190101-013
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In this paper, we aimed to study the protective effect and mechanism of flavonoids from millet bran (FMB) on H2O2-induced oxidative damage in HepG2 cells by determining cell proliferation rate, intracellular reactive oxygen species (ROS) level, antioxidant enzymes activities and the expression of apoptosis-related proteins. The experiment was divided into normal group, oxidative stress model group, and low-, medium- and high-dose FMB treatment groups. The results showed that FMB significantly alleviated cell growth inhibition induced by H2O2 in HepG2 cells, decreased the levels of intracellular ROS and malondialdehyde (MDA), and increased the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), as well as down-regulated the expression of bax, p53, and caspase-3 (P < 0.05). Consequently, FMB could protect HepG2 cells against H2O2-induced oxidative damage, and its underlying mechanism may be related to inhibiting the expression of apoptosis-related proteins, regulating the cellular redox system, scavenging intracellular ROS, and increasing the activities of intracellular antioxidant enzymes.
Comprehensive Nutrition Evaluation of Infant Formula Based on Principal Component Analysis with Mahalanobis Distance
ZHANG Xue, GE Wupeng, XI Menglu, YANG Li, HE Rui, CUI Xiuxiu
2020, 41(5):  166-172.  doi:10.7506/spkx1002-6630-20190305-051
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This study aimed to scientifically evaluate the main nutritional ingredients of infant formula in order to provide a technical basis for the development and optimization of new infant foods. Gas chromatography, high performance liquid chromatography and ion chromatography were used to detect the three macronutrients proteins, fats and carbohydrates as well as fatty acids, amino acids, lactose and oligosaccharides in infant formula. From the multi-index system, six principal components were extracted and the Mahalanobis distance (MD) was used to measure the nutritional coincidence degree between infant formula and breast milk, and a comprehensive nutritional evaluation was carried out. The results showed that: 1) The compositions and contents of the macronutrients in nine infant formula samples were similar to those in breast milk, but there was a significant difference in some individual components (P < 0.05); 2) Among the tested infant formula samples, goat milk sample D scored highest for Mahalanobis distance (MD = 90.15), followed by goat milk sample F (MD = 86.96), and bovine milk samples H and I showed lower MD scores (82.32 and 82.11, respectively). Accordingly, MD scores for goat milk infant formula were generally higher than those for bovine milk infant formula; 3) MD scores were most affected by fatty acids, and the effect of carbohydrates was the least. The interaction between various nutrients also had an effect. This method can be considered a scientific and reasonable method for the nutritional evaluation of infant formula using multiple nutritional indicators.
Anti-fatigue Effect and Molecular Mechanism of Black Ginseng Polysaccharides in Mice
LIU Xinglong, ZHAO Yingchun, CHEN Xueyan, SHE Xinxin, SADIA Khatoon, JIANG Ying, XIE Huiyong, JIANG Bainan, ZHENG Yinan, LIU Wencong, DING Chuanbo
2020, 41(5):  173-179.  doi:10.7506/spkx1002-6630-20190311-135
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Objective: To investigate the effect of black ginseng polysaccharides (BGP) on alleviating physical fatigue in mice and to explain the underlying mechanism. Methods: A mouse model of muscle fatigue was established by weight-bearing swimming and the mice were orally administered simultaneously with BGP at 50, 100 or 200 mg/(kg mb·d) for 28 days. Exhaustive swimming time was recorded. Then, the levels of blood lactic acid (BLA), blood urea nitrogen (BUN) and serum interleukin-6 (IL-6) as well as the contents of glycogen and malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in liver were measured. The expression of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) was evaluated by using Western blot; the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and atherosclerosis peroxisome proliferator activated receptory α (PPARα) in skeletal muscle was analyzed by reverse transcription quantitative real-time polymerase chain reaction. Results: Compared with the weight-bearing swimming control group, BGP significantly prolonged exhaustive swimming time (P < 0.05), and it significantly decreased the levels of BLA, BUN and IL-6 and MDA content in liver (P < 0.05), improved the activities of SOD and GSH-Px and the content of glycogen (P < 0.05), inhibited the expression of IL-1β and TNF-α, and increased the expression levels of PGC-1α and PPARα compared with the non-weight-bearing swimming control group (P < 0.05). Conclusion: BGP have good anti-fatigue effect by regulating the expression of PGC-1α and PPARα genes in skeletal muscle and inhibiting inflammatory reaction in liver.
Packaging & Storage
Screening for Antifungal Agents of Clinical Drugs against Penicillium expansum on Postharvest Pear Fruit
ZHANG Shixin, PENG Litao, FAN Ming, YANG Shuzhen, YAN Deng
2020, 41(5):  180-185.  doi:10.7506/spkx1002-6630-20190305-053
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Penicillium expansum is an important pathogen causing decay and deterioration of postharvest fruits. Effective control of P. expansum is important for reducing postharvest fruit losses. “Repurposing drugs” may provide a fast and effective way of finding antifungal agents. In this study, spore germination method was used to determine antifungal activity and 26 clinical drugs targeted to cell membrane functions and energy metabolism were evaluated for their inhibition on P. expansum. The results showed that miconazole, clotrimazole, bifonazole, ketoconazole, 5-fluorocytosine, natamycin, and ebselen had significant inhibitory effects on P. expansum, with median effective concentration (EC50) below 2 μg/mL, and the EC50 of inexpensive bifonazole was 0.04 μg/mL. Further it was found that bifonazole could significantly inhibit the growth of P. expansum mycelium. The antifungal activity of bifonazole was not significantly affected by temperature (25, 50 and 75 ℃), neutral and weakly alkaline environment, or metal ions such as K+, Mg2+, Na+ and Ca2+, but significantly reduced by UV irradiation. The effect of bifonazole on blue mold inoculated onto pear fruit was also investigated, and the results showed that bifonazole treatment significantly reduced the lesion diameter (P < 0.05) and effectively inhibited postharvest blue mold of pear fruit. Thus, it is feasible to develop antifungal agents from clinical drugs for postharvest preservation of fresh fruits, and bifonazole has potential application in postharvest disease control of pear fruit.
Effect of Active Modified Atmosphere on the Inhibition of Gilbertella persicaria
LIU Shasha, ZHANG Yuxiao, WANG Liang, YUN Liping, CHEN Yong, ZHANG Xinhua, GUO Yanyin
2020, 41(5):  186-192.  doi:10.7506/spkx1002-6630-20190217-080
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The objective of this study was to investigate the effect of active modified atmosphere (MA) on the growth of Gilbertella persicaria in order to reduce postharvest fungal diseases during the storage of fruits and vegetables. In this study, four treatments were set up: 80% O2 + 20% CO2, 90% O2 + 10% CO2, 100% O2 and natural air (control), and Gilbertella persicaria was sealed in each of the four gas atmospheres and cultured at (20.0 ± 0.5) ℃. The amount of spores, conductivity, DNA release of spores, enzyme activities associated with defense against reactive oxygen species (ROS), and cell wall degrading enzymes in Gilbertella persicaria were evaluated. The results showed that active MA was effective in controlling the growth of Gilbertella persicaria through the synergy between O2 and CO2. With the increase of CO2 content, greater damage was observed to Gilbertella persicaria. The MA of 80% O2 + 20% CO2 caused the greatest damage to this strain and inhibited the production of spores. Additionally, active MA reduced the activities of superoxide dismutase (SOD), peroxidase (POD) and cell wall degrading enzymes and increased DNA release of spores and membrane permeability. The results of this study provide a theoretical basis for reducing the pathogenicity of Gilbertella persicaria in fruits and vegetables during storage and for inhibiting it by active MA.
Effect of High Relative Humidity Storage on Postharvest Yellowing and Sugar Metabolism of Broccoli Heads
ZHAO Ziying, JIA Wenru, ZUO Xiaoxia, JIN Wenyuan, JIN Peng, ZHENG Yonghua
2020, 41(5):  193-199.  doi:10.7506/spkx1002-6630-20190710-138
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In order to investigate the effect of high relative humidity (RH) storage on delaying postharvest yellowing of broccoli heads and to explore its relationship with sugar metabolism, broccoli heads were stored at (4.0 ± 0.5) ℃ in either a dry-fog humidity controlled cold room with 95%–98% RH or a normal cold room with 70%–75% RH for 36 days. Samples were taken at 6-day intervals during the storage period to measure the parameters of interest. The results showed that high RH storage could significantly delay the increase in mass loss rate and yellowing index of broccoli, inhibit the activity of chlorophyllase and Mg-dechelatase (MDCase), and maintain high contents of chlorophyll a, chlorophyll b and total chlorophyll. Meanwhile, compared with low RH storage, high RH storage increased the activity of sucrose-phosphate synthase (SPS), reduced the activity of sucrose acid invertase (SAI), glucokinase (GK) and UDP-glucose pyrophosphorylase (UGPase), and maintained high contents of glucose, fructose and sucrose. These results suggest that high RH storage?can maintain high soluble sugar content by regulating sugar metabolism-related enzyme activity and thereby delaying the yellowing of broccoli heads.
Correlation between Changes in Water Mobility and Fatty Acid Profile of Tuna during Cold Storage
WANG Xinyun, XIE Jing
2020, 41(5):  200-206.  doi:10.7506/spkx1002-6630-20190303-017
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In this study, changes in the water mobility of tuna meat were analyzed by low-field nuclear magnetic resonance (LF-NMR) and were correlated with changes in the fatty acid profile. The results of transverse relaxation time T2 indicated that T21 (trapped water) decreased, and T22 (free water) increased gradually with storage time. pH decreased at first and then increased, 2-thiobarbituric acid (TBA) value showed an increasing trend, and water activity (aw) and water content continuously decreased, indicating that the quality of tuna deteriorated. Correlation analysis showed that T2b was significantly negatively correlated with C18:0 and eicosapentaenoic acid content (P < 0.05). T21 was significantly positively correlated with docosahexaenoic acid content (P < 0.01). T22 was significantly positively correlated with C18:0 (P < 0.01) and C18:1n9c (P < 0.05) contents. Therefore, LF-NMR can be considered useful to detect changes in the fatty acid composition of tuna during cold storage, which reflect the extent of quality deterioration.
Quality Characteristics of Lightly Preserved Cooked Mackerel and Identification of Spoilage Bacteria
ZHANG Yongxing, TANG Fenghua, GUO Quanyou, LI Baoguo
2020, 41(5):  207-213.  doi:10.7506/spkx1002-6630-20190304-035
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This study compared the quality characteristics of lightly preserved cooked mackerel and raw mackerel. Quality changes and safety of cooked mackerel were analyzed during the examination of commercial sterilization. The spoilage bacteria causing swollen bags were identified by Biolog and 16S rDNA gene sequencing. The results showed that the salt content and pH of raw mackerel increased significantly after processing, and the water content, water activity (aw) and total viable count (TVC) decreased significantly. Sensory scores for odor, appearance, elasticity and taste were not significantly different between samples collected at the beginning (A0) and the end (A1; unswollen) of the 10-day period storage (P > 0.05). TVC values were less than 2 (lg(CFU/g)) in A0 and A1 and were in the range of 4 to 6 (lg(CFU/g)) in swollen samples B1, B2, B3 and B4 (on day 2, 3, 6 and 7, respectively), exceeding the safety limit. Bacillus licheniformis, Bacillus subtilis, Bacillus sonorensis and Brevibacterium sp. were isolated from the swollen samples. The pH of A0 and A1 was higher than that of B1, B2, B3 and B4; the pH of A0, A1, B1, B2 and B3 decreased in that order, while that of B4 slightly increased as compared to B3. There was a significant difference in total volatile basic nitrogen (TVB-N) content between the swollen (except B2) and unswollen samples (P < 0.05). The histamine contents of A0 and A1 were both lower than the detection limit (5 mg/100 g). This study provides support for the optimization of lightly cooked mackerel products to control product quality and safety.
Effect of Maize Additives on Storage Stability of Coconut Milk Emulsion
CHEN Jinghao, TU Jinjin, SU Han, CHEN Yingtong, ZENG Shaoxiao, ZHENG Baodong, LU Xu
2020, 41(5):  214-222.  doi:10.7506/spkx1002-6630-20190117-206
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In this paper, changes in the stability and rheological properties of sterilized coconut milk emulsion systems with different maize additives (maize grains, ordinary starch and waxy starch) after 50 days of storage under cold (4 ℃) and hot (40 ℃) conditions were studied. The results showed that the coconut milk emulsions with maize additives had better stability at lower storage temperature. At 4 ℃, the emulsion particles were evenly distributed; the average particle size D[4,3] decreased and the absolute value of ζ potential increased compared with those at 40 ℃. Moreover, in sensory evaluation, the coconut milk emulsion with maize grains scored higher after storage at 4 ℃ than at 40 ℃. The apparent viscocity of the coconut milk emulsion with maize starch was lower after storage at 40 ℃ than at 4 ℃. The number of coliforms and the total number of colonies did not increase after storage in each coconut emulsion system. This study provides a theoretical basis for the development and storage quality improvement of cereal-supplemented coconut milk beverage.
Preparation and Antibacterial and Physical Properties of Antibacterial Membrane Containing Zinc and ε-Polylysine
WANG Hui, WU Min, ZHAO Yujie, GU Xiaolian, ZHANG Xinli, CHANG Chao, WU Jin’e
2020, 41(5):  223-229.  doi:10.7506/spkx1002-6630-20190225-186
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In this paper, an edible antibacterial film incorporated with zinc gluconate (ZG) and ε-polylysine (ε-PL) as antibacterial agents was prepared with sodium alginate aqueous solution (2.5 g/100 mL) containing gum arabic (1 g/100 mL) and glycerol (2 g/100 mL). The effects of the addition of the two antibacterial agents on the color, microstructure, water vapor permeability, mechanical properties and antibacterial activity of the film were investigated, and the efficacy of the film in preserving the quality of raw meat was evaluated. The results showed that after adding ε-PL and ZG, the color of the antibacterial film was yellowish; the water vapor permeability decreased, and the tensile strength, elongation at break and antibacterial activity increased. The antibacterial effect of the film with ε-PL at 2.60 mg/mL and ZG at 0.39 mmol/L on Escherichia coli O157:H7 and Staphylococcus aureus was significant, and it had relatively good physical properties. The thickness, tensile strength, elongation at break and water vapor permeability were (0.097 6 ± 0.000 6) mm, (10.75 ± 0.36) MPa, (29.34 ± 1.03)% and (3 633.75 ± 62.03) g/(m2·d), respectively. After 24 h of storage at 37 ℃, the number of bacteria in meat wrapped with the ε-PL/ZG antibacterial film was much lower than that of the control group, indicating that the ε-PL/ZG antibacterial film had a good bacteriostatic effect. This study provides a theoretical basis for the application of zinc and ε-PL-loaded antibacterial film.
Effects of Tree-Hanging Time and Calcium Treatment on Storage Quality of Cherry Fruit
ZHANG Congcong, LIU Jingke, JI Ru, LU Xinyue, YAN Jiawei, AI Jiayin, GE Mingjia, HE Ling
2020, 41(5):  230-236.  doi:10.7506/spkx1002-6630-20190225-163
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In this experiment, ‘Pioneer’ cherry fruit at veraison were sprayed with 20 g/L CaCl2, harvested at different tree-hanging times (harvest maturities) and then stored at (0 ± 1) ℃ and (90 ± 5)% relative humidity. Fruit quality changes were measured after the 50-day storage period. Our aim was to understand the effects of different harvest maturities and calcium treatment on the quality of cherry fruit. The results showed that fruit mass loss and decay rate as well as the decrease in soluble solid content (SSC) and the increase in polyphenol oxidase (PPO) were lowest in 80% maturity fruit among all groups with and without calcium treatment, and this group exhibited the highest ascorbic acid content and L* value and higher total phenolic content. For each maturity, compared with the control, calcium treatment was beneficial to reduce fruit mass loss and decay rate, inhibit the decrease in SSC, fruit hardness and ascorbic acid content and the increase in PPO activity, and elevate peroxidase (POD) activity and the contents of total phenols and the mineral elements Mg, K, Na and Fe. Harvest at 80% maturity and calcium treatment at veraison were beneficial for quality preservation of cherry fruit during storage. This study provides a basis for preserving the postharvest freshness and quality of sweet cherry fruit after harvest.
Reviews
Global Trends in Nutrigenomic Research: A Bibliometric Analysis
XU Zhiyong, MA Aimin
2020, 41(5):  237-245.  doi:10.7506/spkx1002-6630-20190716-213
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In order to provide a reference for relevant researchers and administrative decision makers, a bibliometric analysis of the papers published in Science Citation Index Expanded (SCI-E) database over the last 20 years was carried out to examine the current status and trends in global nutrigenomic research. The results showed that achievements in global nutrigenomic research present a fluctuating growth trend and are still in the “climbing” stage with tremendous and broad prospects for development. The United States as well as research institutions in the country has absolute advantages in the field of nutrigenomic research, but China has not yet entered into the list of major countries and institutions in the world. Nutrition and dietetics are the most important direction in nutrigenomics. Multidisciplinary and cross-disciplinary cooperative research is becoming mainstream. Research hotspots are shifting towards diet and health, from disease treatment to disease prevention (keeping healthy). Nutrigenomic applications, clinical medicine, emerging cross-disciplinary subjects, epigenome damage and mediterranean diet are frontiers of nutrigenomic research. As the most populous country in the world, China should attach more importance to the further development of nutrigenomics so as to meet people’s health demands and seize the commanding heights in the field of biomedicine and health.
Recent Progress in Interface Engineering of Emulsion Colloidal Particles
ZHENG Hongxia, CHEN Hongqiang, GAO Yanxiang, MAO Like
2020, 41(5):  246-255.  doi:10.7506/spkx1002-6630-20190313-162
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An emulsion is a functional factor delivery system which stabilizes the dispersed phase in the form of oil in water (O/W) or water in oil (W/O). Oil-water interfacial microstructure design of emulsions can simultaneously improve the physical stability of the emulsions and the chemical stability of the encapsulated functional factors in the dispersed phase. In this article, four promising colloidal particle interface engineering designs (composite interface engineering, multi-layer interface engineering, particle interface engineering, and integrated interface engineering) and their applications in emulsions are reviewed, with the aim of providing a basis for obtaining structured emulsions with specific physicochemical properties and functions by changing the interfacial composition and structures of the colloidal particles in the future.
Recent Advances in γ-Kokumi Peptide and Its Synthetase γ-Glutamyl Transpeptidase
WU Yuanming, WU Lunjie, WANG Li, LIN Lu, LIU Yi, SUN Weifeng, DING Wenwu
2020, 41(5):  256-265.  doi:10.7506/spkx1002-6630-20190127-352
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Kokumi is one of the sixth basic taste candidates, whose addition to food can enhance the thickness, mouthfulness, continuity and harmony of taste. As a result, kokumi-related flavor products have a great potential to be developed and marketed. γ-Glutamyl peptides with kokumi flavor are an important class of kokumi substances, also called γ-kokumi peptides, composed of γ-glutamyl and amino acid/polypeptide, which could be synthesized by γ-glutamyl transpeptidase (GGT). In this paper, the structural characteristics and food sources of γ-kokumi peptides and the methods used for their taste evaluation and preparation, as well as the structural characteristics, catalytic mechanism and application for the synthesis of γ-kokumi peptides of GGT are reviewed, which will provide a basis for the development of γ-kokumi peptide-related flavor products and their enzymatic synthesis with GGT.
Recent Studies on Free and Bound Phenolic Compounds in Edible Plants: A Review
XING Chen, WANG Lijuan, WANG Xiaoqin
2020, 41(5):  266-275.  doi:10.7506/spkx1002-6630-20181212-154
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Phenolic compounds have function to prevent chronic diseases related to oxidative stress. Plants are the main source of phenolic compounds for humans, and in-depth exploration of phenolic compounds is of great significance for the development of functional foods. In recent years, increasing studies have demonstrated that phenolic compounds are present in plant matrices in free and bound forms, which affect their in vivo metabolic pathways and biological activities. In this review, the methods used for the separation and extraction of free and bound phenolic compounds, their distribution in plant tissues and organs and in vitro and in vivo activities, and the factors affecting their distribution are summarized, which will provide valuable information for scientific development of functional foods rich in phenolic compounds.
Advances in Research on Pollution Status and Toxicological Effects of Perchlorate in Food Matrices
TIAN Yimei, GONG Zhiyong
2020, 41(5):  276-281.  doi:10.7506/spkx1002-6630-20190221-127
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Perchlorate is a persistent pollutant that is widely found in foods and can competitively inhibit iodine uptake, thereby impairing thyroid function and affecting the growth and development of infants and young children. The body ingests perchlorate in different foods, and so it is of great importance to study the metabolism of perchlorate in the body. In this paper, recent progress in understanding the status of dietary exposure to perchlorate and its toxicity is reviewed.
The European Union’s Experience in Prudential Supervision over Genetically Modified Foods and Its Enlightenment for China
LIU Ting
2020, 41(5):  282-289.  doi:10.7506/spkx1002-6630-20190409-113
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In order to avoid economic losses caused by the accidental admixture of genetically modified (GM) crops and to empower consumers to make fully informed choices, the European Commission has implemented the coexistence guidelines, under which, GM crops, at the top of the food supply chain, will also be regulated. The EU has implemented prudential supervision over GM foods from legal principles to regulatory models and from legislative frameworks to law enforcement entities, which provides a new path for risk management of GM foods. The regulation of GM foods in China and innovations in this field can draw on the EU experience in imposing strict control on the risks of GM foods. At present, GM food regulation in China is still at an exploratory stage, which is in transition from rule by law to rule of law. GM food regulation under the rule of law is in a more flexible manner, and the legal basis for it is more perfect. The regulatory authority’s initiative can be brought into full play under the rule of law. Hence, the principles of GM food regulation in the country should be further specified, and the regulatory framework and model should be improved. Ensuring administration according to law, strict law enforcement and strict punishment on violations are essential to achieve the goal of GM food regulation.
Advances in Research on Toxicity and Mechanism of Action of Microcystins
HE Yan, HUANG Xianzhi, DING Xiaowen
2020, 41(5):  290-298.  doi:10.7506/spkx1002-6630-20190408-078
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In recent years, the excessive reproduction of harmful algae caused by the eutrophication of freshwater and the consequent algal toxin contamination have been widely studied worldwide. Microcystins (MCs), toxic metabolites produced by algae such as Microcystis and Anabaena, are widely distributed, and have stable structure and high toxicity. MCs can enter the human body through drinking water, aquatic products and crops, and have toxic effects on the liver, kidney, reproductive system and nervous system, posing a serious threat to human health. In this paper, the toxicity and mechanism of action of MCs are summarized and analyzed. We believe that this review can provide valuable information for preventing and controlling MCs from causing any harm to human health.
Effects of Light Quality on Aroma Metabolites in Tea: A Review of Recent Literature
YUE Cuinan, WANG Zhihui, SHI Xuping, JIANG Xinfeng, LI Yansheng, YANG Puxiang
2020, 41(5):  299-305.  doi:10.7506/spkx1002-6630-20190217-076
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Tea aroma is one of the important factors affecting tea quality, and is also a biochemical and physiological characteristic of tea trees in response to the environmental in the process of evolution. The regulation of light on plant growth and development has been widely studied, and the influence of light wave on secondary metabolites of tea trees has been a topic of increasing interest. Studies on the regulatory mechanism of different light sources on the formation of volatile aroma compounds during tea processing will contribute to tea quality improvement. In this paper, the pigments that occur in tea trees in response to light signals, and the effect of light on aroma compounds of tea are elaborated. Emphasis is put on the metabolic characteristics of various aroma substances under different light quality conditions, and future prospects for the application of light quality in tea processing are discussed.
A Review of Functional Components and Bioactivities in Loquat (Eriobotrya japonica Lindl.)
LIU Lili, LIU Yuyin, WANG Jie, ZHAO Xiaona, LU Zhoumin
2020, 41(5):  306-314.  doi:10.7506/spkx1002-6630-20190128-361
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As a traditional Chinese medicinal and culinary plant, Eriobotrya japonica always plays a significant part in human life. Its fruit taste both sweet and sour and are rich in nutrients. Its leaves have been used as a folk medicine for the treatment of cough and pulmonary heat in China since the Wei, Jin and Northern and Southern dynasties, and today still play an important role in treating cough as Pipa syrup and confection. With the development of scientific research, the types, contents and bioactivities of functional components in loquat leaves, flowers, fruit and seeds have been progressively unraveled. This paper mainly reviews recent studies on the functional components and bioactivities of loquat and the patterns of their changes, in order to provide a theoretical guidance for the application of loquat to develop new medicine and healthcare products.
Recent Progress in the Application of Carbon Nanotubes in Tea Quality and Safety Detection
LIU Tengfei, YANG Daifeng, DONG Minghui, XU Qi, ZHAO Jiaxin
2020, 41(5):  315-322.  doi:10.7506/spkx1002-6630-20190213-053
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Tea is one of the most consumed beverages throughout the world and is favored by people worldwide for its unique aroma as well as medicinal and health promoting properties. Increasing public awareness of nutrition and health has led to growing concerns about the quality and safety of tea. Extensive studies in this field have been carried out worldwide. Due to the multiplicity and complexity of tea matrices, the detection of nutrients and toxicants in tea is faced with numerous difficulties and challenges. Carbon nanotubes possess unique structures and excellent physicochemical properties, which have been widely applied in the detection of tea quality and safety in recent years. Herein, the types and traits of carbon nanotubes are described, and the recent progresses in the application of carbon nanotubes in tea quality and safety detection are also discussed. This review is expected to provide valuable information for future studies in this field.
Recent Progress in Food Delivery Systems for Improving Bioavailability of Phenolic Compounds
CHEN Yulu, SUN Wanqiu, GAO Yanxiang, MAO Like, YUAN Fang
2020, 41(5):  323-330.  doi:10.7506/spkx1002-6630-20190228-225
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Phenolic compounds have aroused particular interest in the food and pharmaceutical fields because they have been demonstrated to be associated with reduced incidences of coronary heart disease, diabetes, cancers, and other chronic diseases. However, extremely low absorption rate of phenolic compounds restricts their bioactivity in vivo. Such low absorption and bioavailability are due to their low water solubility, poor stability, passive diffusion, and active efflux in the gastrointestinal tract.?The best way to remove these limitations is to encapsulate phenolic compounds through food delivery systems, which can effectively improve the stability and bioavailability of active ingredients. This article outlines the functional properties of phenolic compounds and the common methods used for evaluating their bioavailability. Then, we summarize the existing food delivery systems used for improving the bioavailability of phenolic compounds. Finally, problems existing in this field of research are discussed and future research directions are proposed.
Experience and Enlightenments Drawn from Comprehensive Management of Health and Functional Food Market in Japan
WANG Xinxi, DENG Yong
2020, 41(5):  331-337.  doi:10.7506/spkx1002-6630-20190916-194
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Japan is always a model for food safety management in Asian countries, and the field of health and functional foods is no exception. Since Japan had an early start in the field of health functional foods, it has formed a comprehensive governance framework system from governmental governance to industry associations, food production enterprises and consumer governance for the management of the health functional foods market, which provides a good paradigm for the transformation of China’s health food market from traditional mechanical single governmental governance to social governance. Therefore, this paper aims to find a way to improve the overall management level of China’s health food market by examining how Japan uses its government, health and functional food industry associations, food production enterprises, and consumers to conduct comprehensive management of its health food market in a multi-center and multi-dimensional manner.
Science and Technolgy Innovation in the Modern Marine Food Industry: Current Development Status and Policy Suggestions
WANG Wenyue, CHEN Hangjun, LI Dongmei, ZHANG Hui
2020, 41(5):  338-344.  doi:10.7506/spkx1002-6630-20191227-330
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As an important part of China’s marine economy, the marine food industry is now playing a vital role in ensuring Food security and realizing the great goal of constructing a ‘Healthy China’ and ‘Marine Economic Power’. Science and technology innovation is an important engine to drive the healthy development of the marine food industry. In this paper, the current situation and frontier of science and technology innovation in the marine food industry in typical countries are comprehensively and systematically reviewed. We propose the great opportunities for the development of this industry in China, and deeply analyze the bottlenecks restricting science and technology innovation in China’s marine food industry. Furthermore, some policy suggestions are put forward in accordance with the national conditions of China. This review provides valuable information for the transformation and upgrading of China’s marine food industry and enhancing the capability of science and technology innovation.