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15 March 2019, Volume 40 Issue 5
Basic Research
Effect of Berry Size on the Quality of ‘Merlot’ and ‘Cabernet Gernischt’ Grapes
YUE Xiaofeng, TANG Yonghong, JU Yanlun, GUO Shuihuan, ZHAO Yameng, XI Zhumei, ZHANG Zhenwen
2019, 40(5):  1-7.  doi:10.7506/spkx1002-6630-20180201-017
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Berry size is generally considered to be an important quality indicator of grapes. In this study, ‘Merlot’ and ‘Cabernet Gernischt’ grapes were divided into large, medium and small sizes (diameter): > 14 mm (L), 12–14 mm (M), and < 12 mm (S) for ‘Merlot’; > 15 mm (L), 14–15 mm (M), and < 14 mm (S) for ‘Cabernet Gernischt’. The contents of soluble solids, titratable acids, anthocyanin monomer and monomeric phenols in grapes of different berry sizes were determined over two consecutive years. The results showed that the percentage of medium berries was higher for both varieties and both years. In 2014, soluble solids content (SSC) decreased as berry size increased for both varieties, while in 2015 middle berries had a higher level of SSC. For both years, seed/berry ratio and the number of seeds in individual berries decreased with decreasing berry size, and phenolic contents were higher in small and medium berries for ‘Merlot’ and large and medium berries for ‘Cabernet Gernischt’. The highest total monomeric anthocyanin (TMA) content was found in medium berries for ‘Merlot’, while TMA levels in ‘Cabernet Gernischt’ grapes varied greatly with years. For ‘Merlot’ grapes, total monomeric phenol and flavonol contents were higher in medium berries, while for ‘Cabernet Sauvignon’ higher levels were found in large berries. In conclusion, phenolic contents were higher in medium berries for ‘Merlot’, while large berries had higher phenolic contents for ‘Cabernet Gernischt’.
Comparison of Antibacterial Activity and Major Organic Acids in Fermentation Broths of Different Lactobacillus plantarum Strains
LI Shuhong, LIU Chenjian, REN Beibei, LI Qiangkun, LUO Yiyong, YANG En, LI Xiaoran
2019, 40(5):  8-16.  doi:10.7506/spkx1002-6630-20171028-338
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The major organic acids and antipathogenic activity were evaluated in the fermentation broths of 18 Lactobacillus plantarum strains isolated from traditional fermented foods in Yunnan Province. The antibacterial activity was determined by spot-on-lawn assay and agar well diffusion method, and the organic acids were identified and quantified by high performance liquid chromatography. Three L. plantarum strains were chosen for dynamic monitoring of growth curves, pH and antibacterial activity. Results showed that the antibacterial effect varied depending on L. plantarum strains, pathogenic bacteria and carbon sources. The highest antimicrobial activity of L. plantarum YmL-4-5 was observed using Escherichia coli O157:H7 as an indicator strain and glucose as a carbon source. L. plantarum S5 had the strongest antimicrobial activity when Staphylococcus aureus ATCC 6538 as an indicator strain and fructose as a carbon source were used. Our data suggested that the antibacterial activity of the fermentation broth of L. plantarum was ascribed to the low pH of the supernatant and was mainly due to the presence of organic acids in it. The major organic acid was lactic acid (930.9–3 008.7 μg/mL), followed by malic acid and acetic acid. There was a positive correlation between antibacterial activity against E. coli O157:H7 and lactic acid and acetic acid concentrations (r = 0.474 and 0.488, respectively, P < 0.05). This study provides a theoretical basis for the development of new biopreservatives.
Effect and Mechanism of Garlic Essential Oil on Putrescine Accumulation by Lactobacillus delbrueckii Isolated from Smoked Horse Meat Sausages
HUANG Liyuan, MAO Shun, LI Ruiting, WANG Yongqin, YU Honghong, LU Shiling
2019, 40(5):  17-23.  doi:10.7506/spkx1002-6630-20180226-208
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The effect of different concentrations of garlic essential oil on putrescine accumulation by Lactobacillus delbrueckii isolated from smoked horse meat sausages were explored, and the underlying mechanism was elucidated. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to analyze the gene expression of agmatine deiminase in Lactobacillus delbrueckii when cultured in the presence of different concentrations of garlic essential oil. Ultra performance liquid chromatography was used to monitor putrescine produced by the pure culture of Lactobacillus delbrueckii for 48 h. Additionally, the strain was incubated into smoked horse meat sausages with different concentrations of garlic essential oil and cultured for 28 days. Samples were collected during the fermentation period to measure the total number of bacteria, pH, and putrescine accumulation. Results showed that for both culture modes, garlic essential oil could significantly inhibit bacterial growth. It significantly inhibited the decrease in pH in the pure culture, but had little effect on the final pH of smoked horsemeat sausages. Garlic essential oil had little impact on the transcription of the regulatory gene aguR, but significantly inhibited the transcription of the operon aguBDAC (P < 0.01). Increasing garlic essential oil concentration can significantly reduce the generation of putrescine both in pure culture and during the fermentation process of smoked horse meat sausages.
Correlation of Antioxidant Activity with Bioactive Components of Hops
LI Yujing, LIU Yumei
2019, 40(5):  24-30.  doi:10.7506/spkx1002-6630-20171118-232
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Three varieties of SAST hops were extracted with solvents of different polarities including petroleum ether, chloroform, ethyl acetate, n-butanol and water. The contents of α-acids, β-acids, total flavonoids and total polyphenols in these extracts were measured and compared. Their antioxidant activities were evaluated by hydroxyl radical scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and β-carotene-linoleic acid model system assays. The correlation was analyzed between the antioxidant activity and the contents of bioactive ingredients. The results showed that all parts of hops displayed antioxidant activity. α-Acids and β-acids were more abundant in the petroleum ether extracts, which ranged between 444.29-583.81 and 131.83-293.19 mg/g, respectively; however, lower values were detected in the chloroform extracts, and undetectable levels were found in other extracts. The correlation analysis suggested that α-acids and β-acids were the main antioxidant compounds in the petroleum ether and chloroform extracts. The medium and highly polar solvent extracts were rich in total flavonoids and total polyphenols, which were the main antioxidant compounds. For all three varieties, the highest contents of total flavonoids (20.43-24.13 mg/g) and total polyphenols (34.97-40.24 mg/g) were in the ethyl acetate extracts followed by the n-butanol extracts (9.45-11.68 and 12.12-19.14 mg/g).
Changes in Polyphenol Contents and Antioxidant Activity in Hawthorn (Crataegus pinnatifida Bunge) during Simulated Gastrointestinal Digestion
CHEN Ximiao, LI Meiying, XU Qiuli, XIONG Chuxin, SUN Yuanming
2019, 40(5):  31-37.  doi:10.7506/spkx1002-6630-20170930-447
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This study was aimed to investigate the changes in the total polyphenol and flavonoid contents and antioxidant activity of hawthorn during simulated gastrointestinal digestion. The effect of simulated gastrointestinal digestion on 5 main phenolic compounds was also determined using high performance liquid chromatography (HPLC). The results showed that hawthorn polyphenols were stable to gastric digestion; the contents of total polyphenols and flavonoids and antioxidant activity showed no significant changes during gastric digestion (P > 0.05). However, hawthorn polyphenols were easily degraded during intestinal digestion and the contents of total polyphenols and flavonoids and antioxidant activity decreased by 16.26%, 7.46% and 10.25% after 0.5 h, respectively. Furthermore, HPLC results indicated that 5 phenolic compounds revealed no remarkable changes during gastric digestion (P > 0.05), whereas the changes during intestinal digestion were not consistent. During intestinal digestion, hypericin and isoquercitrin did not change noticeably (P > 0.05), while epicatechin was completely degraded after 0.5 h. Moreover, the contents of chlorogenic acid and procyanidin B2 decreased by 40.78% and 28.99% after 0.5 h (P < 0.05).
Sucrose Laurate Exerts Antibacterial Activity against Staphylococcus aureus by Destroying the Cell Membrane
NING Yawei, YANG Kun, HE Jianzhuo, ZHANG Yan, LI Qiang, WANG Zhixin, JIA Yingmin
2019, 40(5):  38-44.  doi:10.7506/spkx1002-6630-20180301-006
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The antibacterial activity of sucrose laurate against Staphylococcus aureus was determined, and the mechanism of cell membrane damage by sucrose laurate was investigated. The minimum inhibitory concentration (MIC) against S. aureus was determined by the two-fold dilution method, and the time-killing curve was assayed by the plate counting method. We studied the effect of sucrose laurate on the membrane potential of S. aureus was studied by fluorescence spectroscopy using DiSC3(5) as the probe, the effect on the membrane permeability by fluorescence microscopy and flow cytometry, the effect on the leakage of macromolecular substances by ultraviolet spectrophotometry, the effect on the leakage of intracellular potassium ions using the fluorescent probe PBFI, and the effect on the ultrastructure by transmission electron microscopy. The results showed that the MIC of sucrose laurate against S. aureus was 0.312 5 mg/mL. Compared with the control group, the fluorescence intensity of S. aureus with the probe DiSC3(5) increased in a concentration-dependent manner after treatment with sucrose laurate; The percentage of S. aureus stained with PI was 84.7% after the treatment of sucrose laurate at MIC for 30 min. The absorbance at 260 nm gradually increased with increasing treatment time at each concentration of sucrose laurate, but the increment was small. Sucrose laurate caused leakage of intracellular potassium ions and this effect was positively correlated with its concentration. After treatment with sucrose laurate at MIC for 1 h, the surface of bacterial cells became rough with blurred edges. Accordingly we concluded that sucrose laurate could dissipate cell membrane potential and destroy membrane permeability, leading to slight leakage of intracellular substances and consequently exerting antibacterial activity. This investigation can provide a theoretical basis for the development of versatile antibacterial products with glycolipids.
Mechanism for the Inhibitory Effect of 1-Deoxynojirimycin on α-Glucosidase
GUO Shiyin, LI Lin, ZHOU Hong, TANG Zhonghai, SU Xiaojun, LI Qingming
2019, 40(5):  45-50.  doi:10.7506/spkx1002-6630-20180808-081
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The inhibitory effect of 1-deoxynojirimycin (DNJ) extracted from mulberry leaves on α-glycosidase was investigated by ultraviolet, fluorescence and circular dichroism (CD) spectroscopy. As a result, the half maximum inhibitory concentration (IC50) of DNJ α-glucosidase was 0.297 μg/mL. The type of inhibition was competitive. DNJ interacted with α-glucosidase through electrostatic attraction generating ground-state complexes and resulting in endogenous fluorescence quenching of α-glucosidase. The formation process of DNJ-α-glucosidase complexes was an entropy-driven endothermic reaction. The interaction was mainly driven by electrostatic attraction forces. At different temperatures (273, 298 and 310 K), fluorescence quenching constants (Ksv) were 1.48 × 104, 1.29 × 104, and 1.12 × 104 L/mol, respectively. DNJ resulted in a conformational change of α-glucosidase and rearrangement of the secondary structure inducing closing of the enzyme active pocket and consequently inhibiting substrate binding to the active center. These findings may explain the mechanism by which DNJ inhibited α-glucosidase activity and thus reduced blood glucose levels.
Effect of Tricholoma matsutake Powder on Rheological Properties of Dough and Quality Characteristics of Biscuits
TAO Hongling, WANG Dan, MA Ning, ZHAO Liyan, FANG Donglu, HU Qiuhui
2019, 40(5):  51-56.  doi:10.7506/spkx1002-6630-20180818-185
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In order to study the effect of Tricholoma matsutake powder on rheological properties of dough and quality characteristics of biscuits, the thermal mechanical properties, starch gelatinization characteristics and rheological properties of doughs with different amounts of T. matsutake powder added were analyzed and the physical properties, sensory evaluation and nutrient quality of biscuits made from the doughs were measured. The results showed that dough stability time, maximum viscosity index, peak viscosity, trough viscosity and final viscosity were reduced significantly with the addition of T. matsutake powder, while the degree of protein weakening was increased and the structure of gluten was destroyed. As the proportion of T. matsutake powder increased, tan δ increased firstly and then decreased, which indicated the opposite trend for dough elasticity. The hardness and sensory score of biscuits increased firstly and then decreased. The flavor and taste of biscuits were more acceptable with the addition of 6% T. matsutake powder, and the contents of protein, dietary fiber and essential amino acids were increased by 58.08%, 191.24% and 32.77%, respectively compared to the control without the addition of T. matsutake powder. Moreover, the amino acid profile was in accordance with the Food and Agriculture Organization/World Health Orgnaization standard, and the nutritional value was higher.
Antibacterial Activity and Structural Characterization of Peach Kernel Peptide-Ferrous Chelate
YANG Yurong, LI Anping, ZHONG Zhengchang, YU Zhoufeng
2019, 40(5):  57-62.  doi:10.7506/spkx1002-6630-20180201-006
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The antibacterial activity of chelates formed by ferrous ions with peach kernel peptides with different molecular masses or peptides from other plant sources and chelates of ferrous, zinc, calcium or magnesium with peach kernel peptide were compared. Then, the structures of all chelates were characterized by Fourier transform infrared (FTIR) spectroscopy. Results indicated that the antibacterial activity of low-molecular-mass peach kernel peptide-ferrous chelate (PKP3, < 5 000 Da) was stronger than that of high-molecular-mass peptide-ferrous chelate (> 10 000 Da). Peach kernel peptide chelates with ferrous and zinc both had strong antibacterial activity. There were significant differences (P < 0.05) in the antibacterial activity of the ferrous-chelating peptides from peach kernel, soybean, corn and wheat. Among them, peach kernel peptide-ferrous and wheat peptide-ferrous chelates had the strongest antibacterial activity, with minimum inhibitory concentrations (MICs) of 5.0 mg/mL for Escherichia coli, and MICs of 2.5 and 5.0 mg/mL for Staphylococcus aureus, respectively. FTIR spectra illustrated that –COO-, N–H and C═O in each of the four peptides were involved in the chelation reaction with ferrous ions to form ferrous-chelating peptides.
Rapid Microwave-Assisted Preparation of Carbon Quantum Dots and Its Application for Investigating Pro-oxidative Activity of Epigallocatechin-3-gallate
WU Chunlian, PU Hongbin, QU Jiahuan, SUN Da-wen, WEI Qingyi
2019, 40(5):  63-69.  doi:10.7506/spkx1002-6630-20180211-124
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Aqueous carbon quantum dots were prepared rapidly by high-throughput microwave digestion/extraction workstation, and their pH dependence and stability behavior were studied. The fluorescence quenching of carbon quantum dots by reactive oxygen species produced by epigallocatechin-3-gallate (EGCG) in the presence of Cu2+ and the pro-oxidative dose-effect of EGCG with Cu2+ were investigated. Experimental results indicated that the carbon quantum dots had pH dependence and good stability behavior. The relative quantum yield was 73.67%. When the concentration ratio between Cu2+ and EGCG was 2:1, the fluorescence quenching of carbon quantum dots was serious, and EGCG had strong pro-oxidative activity. This study provides a theoretical basis for the application of EGCG as a functional substance.
Quality Comparison of 10 Japanese Loquat (Eriobotrya japonica Lindl.) Cultivars Introduced in Ankang, Shannxi, China
LI Yantang, HUO Yuhang, MENG Yaoyao, LU Zhoumin
2019, 40(5):  70-76.  doi:10.7506/spkx1002-6630-20180206-083
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A comparative analysis of fruit quality was carried out among 10 Japanese loquat cultivars introduced in Ankang, Shaanxi, China and a method for the quality evaluation of these cultivars was established in order to provide a basis for the classification of various varieties and the selection of suitable varieties for the development of local loquat industry. The physical, nutritional and functional properties of loquats were determined. Principal component analysis (PCA) and cluster analysis (CA) were used to evaluate the quality of loquats. The results showed that the introduced cultivars exhibited significant differences in all fruit quality attributes investigated, and their quality was overall better than that of the local cultivar Maihouhuang. In PCA analysis, four principal parameters, flavor, antioxidant capacity, processing method and total phenol content, were extracted, which contributed cumulatively to 85.666% of the total variation. According to the comprehensive evaluation function developed based on PCA, the top 3 varieties were ‘ADVANCE’, ‘Jinyun’ and ‘CHAMPAGNE’ respectively. CA divided these 10 cultivars into 5 categories. The first category had health beneficial value; the second one was suitable for processing fruit juice and vinegar beverages; the third one could be directly eaten. The combination of PCA and CA could allow comprehensive quality evaluation of loquat fruit, which can provide a basis for loquat breeding and effective utilization.
Food Engineering
Effect of High Intensity Ultrasound on Structural and Rheological Properties of Myosin from Silver Carp
XIE Yaru, LIU Qing, XIONG Shanbai, YOU Juan, LIU Ru
2019, 40(5):  77-84.  doi:10.7506/spkx1002-6630-20180205-064
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Myosin from silver carp was sonicated with varying powers (100, 150, 200 and 250 W) for 3, 6, 9 or 12 min. The changes in the chain conformation, secondary structure and rheological properties of myosin were evaluated by UV absorption spectroscopy, circular dichroism spectroscopy and a rheometer. It showed that the low-temperature self-assembly of myosin was depressed by high intensity ultrasound (HIU) treatment, resulting in decreased zero shear viscosity and increased fluidity. HIU treatment induced the conversion of myosin α-helix to relatively loose β-sheet and random coil, resulting in the exposure of active groups buried inside the molecules. This structural change was beneficial for forming intermolecular interactions during heating and reducing the gelation temperature. Furthermore, ultrasonic treatment under appropriate conditions (100 or 150 W for 12 min) could improve the gel-forming capacity of myosin, but it could lead to a decrease in the gel-forming capacity at too high powers (200 or 250 W for 12 min). Selecting the appropriate ultrasonic treatment is of great importance for improving gelation properties of surimi.
Drying Characteristics and Quality of Potato Slices Subjected to Ultrasound-Assisted Cold Air Drying
TIAN Fujin, LIU Yunhong, HUANG Junyan, CAO Xianhao, XUE Sicheng, LEI Yuqing
2019, 40(5):  85-94.  doi:10.7506/spkx1002-6630-20171120-241
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In order to investigate the enhancing effect of ultrasonic treatment on cold air drying of potato slices, an ultrasonic-assisted heat pump cold air dryer was applied to explore the influence of ultrasonic power and drying temperature on the drying process and the microstructure and several major nutritional components of dried potato slices. The results showed that the drying time was reduced significantly by increasing either ultrasonic power or drying temperature and that drying enhancement was more remarkable at a lower drying temperature than at a higher temperature. The drying rate initially remained constant and then declined during the ultrasonic-assisted drying process, indicating transformation from surface diffusion control to internal diffusion control. The application of ultrasonic treatment could enlarge the size and number of micro-channels on the material surface, being beneficial for moisture transfer. The Weibull distribution function could fit the drying process with high precision. The estimated value of moisture diffusion coefficient increased with increasing drying temperature and ultrasonic power, whereas the value of scale parameter α, characterizing the drying time, decreased with the increase in ultrasonic power. Both ultrasonic power and cold air temperature had significant effects on the contents of total phenols, total flavonoids and vitamin C in dried potato products (P < 0.05). It is clear that the application of ultrasonic treatment to cold air drying of potato slices can increase the contents of major nutritional components. The analytic hierarchy process was applied to obtain the optimal parameters as follows: drying temperature 10 ℃ and ultrasonic power 48 W, and the contents of total phenols, total flavonoids and vitamin C in dried potato slices prepared under these conditions were 296, 52 and 96 mg/100 g, respectively. Therefore, the application of ultrasonic treatment to the cold air drying process of potato slices can remarkably shorten the drying time and improve the product quality.
Effects of Different Drying Methods on Turnip Chips as Evaluated Based on Grey Relational Analysis
GAO Qi, LI Jiaheng, HAN Haoting, LIU Ziheng, ZHANG Jiahui, LIU Chunju, LIU Chunquan, XUE Youlin
2019, 40(5):  95-101.  doi:10.7506/spkx1002-6630-20171115-197
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In order to find the best drying method for production of turnip chips, the effects of four different drying methods of freeze drying (FD), hot air drying (AD), infrared drying (ID), and explosion puffing drying (EPD) on the physical properties, nutrient composition and microstructure of turnip chips were compared. The nutritional components were determined by chemical analysis, the physical properties were evaluated by a colorimeter and a texture analyzer, and the microstructure was observed by scanning electron microscopy (SEM). Also sensory evaluation was carried out. Furthermore, a comprehensive evaluation was performed using grey correlation analysis based on the coefficient of variation. The results showed that the physical properties and nutrient contents of turnip chips were significantly changed after each drying process. FD and EPD preserved more nutrients. SEM showed that FD chips had a porous honeycomb-like structure; EPD chips also exhibited a more compact honeycomb-like structure and tasted crispy. The comprehensive evaluation revealed that the drying methods were in the following decreasing order: FD > EPD > ID > AD. However, the cost of an FD device and the drying process was higher and the drying period was longer. Taken together, EPD was selected as the optimum processing method for turnip chips.
Correlation between Enzymatic Browning Inhibition by UV-C Treatment and Reactive Oxygen Species Metabolism of Fresh-Cut Apples
ZHOU Qi, CHEN Chen, ZHOU Fuhui, HU Wenzhong, ZHAO Lei, XU Yuanyuan
2019, 40(5):  102-109.  doi:10.7506/spkx1002-6630-20171102-023
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The inhibitory effect of ultraviolet-C (UV-C) treatment on enzymatic browning of fresh-cut apples was investigated and correlated with the metabolism of reactive oxygen species (ROS). Variations in ROS levels, antioxidant enzyme activities, the content of the antioxidant VC and non-enzymatic antioxidant properties were evaluated during the storage of UV-C-treated apples. The results showed that UV-C treatment significantly inhibited surface browning of fresh-cut apples during storage, accompanied by lowering the production rate of superoxide anion radical, and H2O2 and malondialdehyde (MDA) contents. Furthermore, UV-C treatment enhanced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), increased VC content, slowed down the decrease in non-enzymatic antioxidant properties such as scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals and ferric reducing antioxidant power (FRAP) in fresh-cut apples during storage. Pearson correlation analysis and principal component analysis revealed that browning index (BI) was significantly positively correlated with ROS and MDA levels (P < 0.05) and negatively with enzymatic and nonenzymatic antioxidant activities (P < 0.05, P < 0.01). UV-C treatment improved ROS metabolism of fresh-cut apples as compared to the control. Collectively, these findings suggest that UV-C treatment could enhance ROS metabolism in freshcut apples, thereby alleviating lipid peroxidation and inhibiting surface browning.
Effect of Hot Air Drying on Properties of Semi-Dry Milled Rice Flour
TONG Litao, GENG Donghui, ZHOU Xianrong, WANG Lili, LIU Liya, ZHOU Sumei
2019, 40(5):  110-115.  doi:10.7506/spkx1002-6630-20180104-049
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Objective: To investigate the effect of hot air drying on properties of semi-dry milled rice flour. Methods: Rice was hot air dried at 45 ℃ for 240 min, at 75 ℃ for 45 min or at 105 ℃ for 15 min and then used to prepare semidry-milled rice flour. The moisture absorption rate was determined and apparent cracks on the rice surface were examined. The whiteness and gel properties of semi-dry milled rice flours were analyzed, and the textural properties, tensile properties and breaking rate of fresh rice noodles made from the rice flours were determined. Results: Hot air treatments at 75 ℃ for 45 min and at 105 ℃ for 15 min could shorten the soaking time to reach maximum moisture content in semi-dry milled flour to 11 min. Surface cracks were observed in all three groups under stereomicroscopy. The whiteness and gel properties of semi-dry milled rice flour with hot air treatment at 45 ℃ for 240 min and at 75 ℃ for 45 min were not significant different from those of wet milled rice flour while the second hot air treatment resulted in a decrease in the gel hardness of semi-dry milled rice flour. There was no remarkable difference in the breaking rate of fresh rice noodles between semi-dry milling with hot air treatment at 75 ℃ for 45 min and wet milling (P > 0.05). Conclusion: Hot air treatment at 45 ℃ for 240 min and at 75 ℃ for 45 min can greatly shorten the soaking time to reach maximum moisture content in semi-dry milled flour and improve its properties. The quality of fresh rice noodles made from semi-dry milled flour with hot air treatment at 75 ℃ for 45 min is comparable to that of wet milled rice flour. This study provides a theoretical basis for overcoming the bottleneck problems of rice semi-dry milling such as long soaking time, high risks of microbial infection and difficulties in achieving continuous production.
Variation in Water Content during Vacuum Microwave Drying of Flavored Yam Chips Process Analyzed by Low-Field Nuclear Magnetic Resonance Imaging
LI Dingjin, DUAN Zhenhua, LIU Yan, DUAN Qiuxia, YE Shoulin, ZHU Xianghao, YANG Yuxia
2019, 40(5):  116-123.  doi:10.7506/spkx1002-6630-20171123-289
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In order to gain an understanding of variations in moisture content, distribution and states during the vacuum microwave drying of flavored yam chips, inverted spectra of transverse relaxation time T2 of flavored yam chips dried at different microwave powers were measured using low-field nuclear magnetic resonance (LF-NMR). The results showed that the higher microwave power, the shorter the time it took to remove free water and immobilized water; a greater effect was noted on free water. But excessively high microwave power caused coking of the materials. A linear relationship was seen between the moisture content of flavored yam chips and the total peak area of NMR, which could predict the drying time. NMR images showed that the moisture increased or decreased from the exterior to the interior during the drying process. At the end of drying, the remaining moisture was mainly present in the inner layer of flavored yam chips. Changes in moisture content had a significant effect on the quality of flavored yam chips after drying. LF-NMR imaging can provide visual information of moisture changes during the drying process of flavored yam chips, and this study can provide a basis for designing and optimizing a vacuum microwave drying process for flavored yam chips and for improving the product quality.
Nutrition & Hygiene
Mechanism of Improvement of Bone Mineral Density in Ovariectomy-Induced Osteoporotic Mice by Sea Cucumber Saponin
WANG Xiaohong, LI Yuanyuan, DAI Yufeng, WANG Jingfeng, LI Zhaojie, XUE Changhu
2019, 40(5):  124-129.  doi:10.7506/spkx1002-6630-20171020-226
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Objective: To investigate the effect and underlying mechanism of sea cucumber saponin (SCS) on bone mineral density in bilaterally ovariectomized mice. Methods: Female C57BL/6J mice were ovariectomized to establish an osteoporotic animal model. After 4 weeks, the mice were randomly divided into four groups: sham operation (normal saline), model (normal saline), low-dose SCS (7.5 mg/kg mb) and high-dose SCS (15.0 mg/kg mb) groups. After administration for 90 days, the urinary concentrations of Ca and P, bone mineral density (BMD) and mineral apposition rate (MAR) were determined to evaluate the effect of SCS on bone minerals. Furthermore, the relative mRNA expression of biochemical parameters of bone formation (ALP, OCN, Col1a, BMP2) and key genes involved in the Wnt/β-catenin pathway were detected to elucidate the underlying molecular mechanism. Results: SCS significantly inhibited the urinary levels of Ca and P (P < 0.05), and decreased the loss of bone mineral. Dual energy X-ray scanning and fluorescence double labeling results showed that SCS significantly increased BMD and bone mineralization in ovariectomized mice (P < 0.05). Quantitative real-time polymerase chain reaction (qPCR) showed that SCS could decrease the relative mRNA expression of ALP, OCN, Col1a and BMP2 by down-regulating the relative mRNA expression of Wnt10b, LRP5, GSK-3β, β-catenin, Runx2 and OSX, the key genes involved in the Wnt/β-catenin pathway (P < 0.05). Conclusion: SCS can improve osteoporosis by inhibiting the loss of bone mineral, increasing BMD and bone mineralization, inhibiting the activation of the Wnt/β-catenin pathway and consequently limiting the compensatory increase in bone formation.
Effects of Egg White-Derived Bioactive Peptide on Antioxidative Enzyme Activities and IL-8 Secretion in HEK293 Cells under Oxidative Stress Induced by Hydrogen Peroxide
ZHANG Yan, HU Rong, ZHENG Jian, MA Zhongsu, YANG Taifen, LIU Jingbo
2019, 40(5):  130-136.  doi:10.7506/spkx1002-6630-20171103-035
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In recent years, antioxidant peptides with high safety and potent antioxidant capacity have become a hot research field. The aim of this study was to investigate the effects of egg white-derived bioactive peptides WNWAD (Trp-Asn-Trp- Ala-Asp), WNW (Trp-Asn-Trp), WAD (Trp-Ala-Asp) and WN (Trp-Asn) on the survival rate, reactive oxygen species (ROS) content, antioxidative enzyme activities and interleukin-8 (IL-8) level in HEK293 cells under oxidative stress induced by H2O2. MTS assay results showed that all four peptides significantly dose-dependently inhibited H2O2-induced cellular oxidative stress in HEK-293 cells and increased the survival rate increased from (48.0 ± 2.4)% to (99.7 ± 1.8)%, (69.4 ± 3.2)%, (78.9 ± 5.1)%, and (72.1 ± 3.6)% at 1.0 μmol/L concentration, respectively. These changes were statistically significant (P < 0.01). 2’,7’-Dichlorofluorescin diacetate (DCFH-DA) fluorescent probe assay proved that all these peptides inhibited oxidative stress by reducing intracellular ROS accumulation in HEK293 cells. They dose-dependently increased the activity of total superoxide dismutase (T-SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in HEK293 cells. In addition, the results of enzyme-linked immune sorbent assay (ELISA) showed that WNWAD and WN up-regulated IL-8 secretion (P < 0.05). All the above results showed that the egg white-derived peptides play a positive role in protecting HEK293 cells against H2O2-induced oxidative stress and improving antioxidant capacity in HEK293 cells.
Preventive and Therapeutic Effect of Total Flavonoid Extract from Vine Tea on Mice with Prediabetes
CHEN Xuan, CHEN Xu, WANG Shaoyun
2019, 40(5):  137-142.  doi:10.7506/spkx1002-6630-20181224-262
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In order to explore the feasibility of preventing, delaying or curing prediabetes by drinking vine tea, a mouse model of prediabetes was established by feeding a high-sugar and high-fat diet and injection of streptozocin (STZ). Then the model mice were divided into model group, low-dose (200 mg/kg mb) and high-dose (500 mg/kg mb) groups orally administered with total flavonoid extract from vine tea, acarbose control group and acarbotane-flavonoid extract group. Parameters of interest were detected. The results showed that fasting blood glucose, glucose tolerance, glycosylated serum protein (GSP) and insulin secretion levels in the high-dose treatment group were significantly lower than those in the model group (P < 0.05). In addition, there was a statistical difference in inflammatory factors (interleukin 4, tumor necrosis factor-α and C reactive protein), plasma lipid indices (free fatty acids, triglyceride, low density lipoprotein cholesterol, total cholesterol and high density lipoprotein cholesterol) and cecal short chain fatty acid levels (acetic acid, propionic acid, and butyric acid) between the model and treatment groups (P < 0.05). A certain dose of total flavonoid extract from vine tea could delay or prevent the development of diabetes in mice by exerting anti-inflammatory activity and regulating glycolipid metabolism and the intestinal microflora.
Ethyl Ester Type Fish Oil Attenuates Posttraumatic Osteoarthritis in Mice
WANG Kai, ZHU Yujie, LI Yuanyuan, DAI Yufeng, WANG Yuming, WANG Jingfeng
2019, 40(5):  143-148.  doi:10.7506/spkx1002-6630-20171114-166
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Objective: To investigate the improving effect of ethyl ester type fish oil (FO) on cartilage degeneration in mice with posttraumatic osteoarthritis. Methods: Nine-week-old male C57BL/6J mice were used to establish an animal model of osteoporosis induced by surgical destabilization of the medial meniscus (DMM). At 7 weeks after the operation, these mice were randomly divided into four groups: sham control group, osteoporosis model, positive control, low-dose FO, and high-dose FO groups. All the animals were orally administered once daily for 60 days. After the administration period, cartilage was harvested for HE staining, toluidine blue staining and quantitative real-time polymerase chain reaction (qPCR) analysis. Results: HE and toluidine blue staining indicated that FO could significantly improve the structure of cartilage and maintain its homeostasis. qPCR results revealed that FO remarkably increased the mRNA expression of Acan and Col2α1, thereby maintaining normal chondrogenic phenotype. Meanwhile, FO significantly decreased the mRNA expression of Col10α1, Runx2, Bcl-2, Bax and caspase-3, thus inhibiting chondrocyte hypertrophy and apoptosis. Mechanistically, FO could activate autophagy through up-regulating the mRNA expression of autophagy-related genes such as LC-3B and ATG5 and suppressing the mRNA expression of mTOR. Conclusion: FO can inhibit cartilage degeneration through activating chondrocyte autophagy in mice with osteoarthritis.
Metabonomic Study of the Intervention Effect of Tartary Buckwheat Protein on Hyperlipidemic Mice
ZHOU Xiaoli, ZHANG Huan, ZHOU Yiming, LIU Taiyi, YAN Beibei, XIAO Ying
2019, 40(5):  149-155.  doi:10.7506/spkx1002-6630-20171030-354
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The present study was carried out to investigate the effect of tartary buckwheat protein (TBP) on metabolic pathways in hyperlipidemic mice and to explore its lipid-lowering mechanism from a metabonomic perspective. A hyperlipidemic mouse model was established by feeding mice a high-fat diet. Plasma metabolic fingerprinting was performed for normal, hyperlipidemic and TBP-treated mice using ultra-high performance liquid chromatography coupled with electrospray ionization tandem ion trap time-of-flight mass spectrometry (UPLC/ESI-IT-TOF/MS). The potential biomarkers for the intervention effect of TBP on hyperlipidemic mice and the related metabolic pathways were determined by partial least squares-discriminant analysis (PLS-DA) based on the metabolic network database. The results showed the presence of linoleic acid, cytidine diphosphate glycerol, phosphatidyl ethanolamine, galactosylceramide, cerebroside, glucosylceramide, phosphatidylcholine, glucuronide, prostaglandin G2, lysophosphatidic acid, lysophosphatidyl choline and sphingomyelin as 12 potential biomarkers in the plasma of hyperlipidemic mice. Tartary buckwheat protein could regulate 6 metabolic pathways (linoleic acid metabolism, glycerophospholipid metabolism, sphingolipid metabolism and pentose-glucuronic acid ester conversion, tryptophan metabolism and four arachidonic acid metabolism) in which 12 potential biomarkers are involved in hyperlipidemic mice, and restore them to normal, thereby ameliorating metabolic disorders in hyperlipidemic mice.
p-Synephrine Suppresses Hepatic Glucose Production via the AMPK-FoxO1 Signaling Pathway in HepG2 Cells
GUO Lixia, ZHANG Yonghong, YIN Zhongyi, PU Yuhan, ZHENG Xuxu
2019, 40(5):  156-161.  doi:10.7506/spkx1002-6630-20171109-105
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Objective: This study was designed to determine the effect of p-synephrine, the primary protoalkaloid of bitter orange and other citrus species, on hepatic glucose production in HepG2 cells and to elucidate the underlying mechanisms. Methods: The cell viability was detected by MTS assay. Glucose production and the activity of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were measured by colorimetry. The protein expression levels of adenosine 5’-monophosphate (AMP)-activated protein kinase (AMPK), phosphorylated AMPK (p-AMPK), acetyl coenzyme A synthetase (ACC), phosphorylated ACC (p-ACC), forkhead box class O1 (FoxO1) and phosphorylated FoxO1 (p-FoxO1) were analyzed by Western blot. The cells were incubated in the presence of selective AMPK inhibitor Compound C or AMPK siRNA to examine the impact of p-synephrine on glucose production and G6Pase and PEPCK activity. Results: p-Synephrine significantly inhibited hepatic glucose production in a dose-dependent manner. AMPK, ACC and FoxO1 phosphorylation were stimulated by different concentrations of p-synephrine. In addition, both enzyme activities were significantly suppressed (P < 0.01). These effects were partially reversed by Compound C and AMPK siRNA. Conclusion: p-Synephrine suppresses hepatic glucose production via the AMPK-FoxO1 signaling pathway in HepG2 cells.
Protective Effect of β-Carotene on Liver Oxidative Damage Induced by Hydrogen Peroxide in Zebrafish
QU Huiming, WANG Ying, ZHAO Bo, LIU Jianlong, LIU Kechun, SHEN Hong, CHU Jie
2019, 40(5):  162-166.  doi:10.7506/spkx1002-6630-20171117-217
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The protective effect of β-carotene on H2O2-induced liver injury in zebrafish was investigated. Liver injury model was induced by H2O2 at the proper concentration, and β-carotene at doses of 5, 10 and 20 μg/mL was used to suppress H2O2-induced damage. After 48 h of incubation, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and superoxide dismutase (SOD) activities and malondialdelyde (MDA) content were measured. Pathological changes in the liver were observed by hematoxylin-eosin (HE) staining. The relative mRNA expression levels of SOD, CAT, GSTP2 and Nrf2 were assessed by real-time quantitative polymerase chain reaction (qPCR). The results showed that H2O2 elevated the levels of ALT, AST and MDA and reduced the level of SOD. Compared with the model group, β-carotene decreased the levels of ALT, AST, and MDA and improved the activity of SOD. Moreover, β-carotene significantly ameliorated hepatic pathological changes and upregulated the relative mRNA expression levels of SOD, CAT, GSTP2 and Nrf2. Finally we conclude that β-carotene has a protective effect on liver injury induced by H2O2 in zebrafish.
Longitudinal Study of Protein Content and Amino Acid Composition of Breast Milk at Different Lactation Stages from Southern and Northern Urban Chinese Mothers
PANG Jinzhu, LIU Zhengdong, JIA Ni, LI Jufang, PEI Chenhong, MI Lijuan, LI Tao, FANG Hongtao, DAI Yaohua
2019, 40(5):  167-174.  doi:10.7506/spkx1002-6630-20180306-060
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Aim: To comparatively study the protein content and amino acid composition of breast milk at different lactation stages (0–12 months) from northern (Beijing) and southern (Shenzhen) urban Chinese mothers. Methods: Totally 30 lactating mothers of full-term infants were enrolled in Beijing and Shenzhen separately, and breast milk samples were collected between day 3 and 5 (colostrum), between day 13 and 15 (transitional milk) , and at 3 and 4 weeks and 2, 3, 4, 6, 9 and 12 months (mature milk) following delivery for the determination of proteins and amino acids. Results: The highest protein content was detected in colostrum among the various milk samples from mothers in both cities and it gradually decreased with increasing lactation length, during the first 3 weeks rapidly and then more slowly but a significant difference being still observed (P < 0.05), reaching a stable level at 3 months with no significant difference being found between the two cities for each lactation stage (P > 0.05). Similarly, amino acid contents significantly decreased with increasing lactation length (P < 0.05); the contents of total amino acids, essential amino acids and non-essential amino acids decreased by approximately 58%. Glutamic acid, leucine and asparaginic acid were the most abundant amino acids in breast milk, whereas methionine and tryptophan were the least abundant. Amino acid composition in breast milk differed between the cities for all lactation stages except colostrum and mature milk at 4 months. The proportion of each amino acid to the total amount remained stable with the prolongation of lactation, and essential and nonessential amino acids accounted for about 42% and 58% of the total amino acids, respectively. However, for all lactation times except colostrum, the proportion of phenylalanine to total amino acids in Beijing breast milk was higher than in Shenzhen breast milk. Conclusion: Human colostrum has the highest contents of proteins and amino acids among all lactation times, which decline with increasing lactation time. The contents of amino acids and the proportions to total amino acids but not the protein content of breast milk vary between cities.
Lactobacillus casei Exopolysaccharide Induces Maturation and IL-6, TGF-β and IL-23 Secretion of Mouse Bone Marrow-Derived Dendritic Cells
REN Qiqi, REN Haowei, YANG Cuicui, LIU Ning
2019, 40(5):  175-182.  doi:10.7506/spkx1002-6630-20171113-152
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This study was undertaken in order to understand the effect of Lactobacillus casei exopolysaccharide (EPS) on the maturation of mouse bone marrow-derived dendritic cells (BMDCs) in vitro, the effect of different doses of EPS on interleukin (IL)-6, transforming growth factor-β (TGF-β) and IL-23 secretion in BMDCs, and the effect of EPS on the antigen-presenting function of BMDCs. L. casei EPS was separated and purified from the fermentation broth, and its purity was determined. The bone marrow cells isolated from BALB/c mice were differentiated into BMDCs, and immature BMDCs were treated with phosphate buffer saline (PBS), EPS and lipopolysaccharide (LPS), respectively. The phenotypic maturation of BMDCs, MHC II and CD86 were analyzed using a flow cytometer, the production of cytokines was analyzed by enzyme-linked immunosorbent assay (ELISA), and the proliferation rate of splenic lymphocytes was analyzed by cell counting kit-8 (CCK-8) assay in a mixed culture system with BMDCs and mouse splenic lymphocytes. The results showed that the purity of EPS was 95%. The EPS up-regulated the expression of MHC II and CD86 on the surface of BMDCs. Meanwhile, the EPS significantly promoted the production of IL-6, TGF-β and IL-23 (P < 0.05) but not so effectively as LPS. The EPS also obviously promoted BMDCs-stimulated proliferation of allogenic lymphocytes. In conclusion, L. casei EPS can promote the maturation of BMDCs in vitro, induce BMDCs to secrete cytokines associated with the differentiation and proliferation of Th17 cells, and enhance the antigen-presenting function of BMDCs.
Effect of Goji Berries (Lycium barbarum) on Lifespan and Spawning of Caenorhabditis elegans and Its Antioxidant Capacity
Lü Zhenyu, MENG Jiao, SUN Chuanxin, CHEN Chang
2019, 40(5):  183-188.  doi:10.7506/spkx1002-6630-20171016-119
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Objective: To evaluate the effect of Goji berries (Lycium barbarum) on the lifespan and spawning of Caenorhabditis elegans, and to explore its antioxidant capacity. Methods: The ferric reducing/antioxidant power (FRAP) method was used to assess and compare the antioxidant capacity of Goji berries from three different areas of Ningxia, Qinghai and Gansu provinces. The effect of Goji berries on the level of reactive oxygen species (ROS) in nematodes was detected using the fluorescent dye 2’,7’-dichlorofluorescein diacetate, and the effect on the expression of antioxidant enzymes in nematodes was evaluated by real-time quantitative polymerase chain reaction. In addition, in order to determine the effect of Goji berries on the lifespan and spawning, L4 stage nematodes were placed on NGM plates and incubated with and without added Goji berries. The scavenging capacity of Goji berries against H2O2 in the cytoplasm was detected using two transgenic nematodes: Pmyo3::HyPer and roGFP2::Orp1. The fluorescent dye MitoSox Red was used to measure the scavenging capacity against superoxide anion radical in the mitochondria. Results: Goji berries from all three areas had strong antioxidant activity in vitro with no significant difference being found between them. Goji berries could reduce the level of ROS and increase the levels of antioxidant enzymes in nematodes. However, Goji berries had no significant effect on the lifespan or spawning ability. Goji berries could scavenge mitochondrial superoxide anion radicals but not cytoplasmic H2O2. Conclusion: Goji berries can exert antioxidant capacity in vitro and in vivo, and its antioxidant effect in vivo is achieved by reducing the level of mitochondrial superoxide anion radicals. In addition, Goji berries do not dramatically affect the lifespan or the total number of eggs laid in nematodes.
Effect of Hawthorn Proanthocyanidins on Proliferation and Apoptosis of Human Hepatocellular Carcinoma SMMC-7721 Cells
SUN Siming, XU Hongwei, GUO Kaiyuan, GUO Mengran, CUI Shengnan, CUI Tong, TAN Jianxin
2019, 40(5):  189-196.  doi:10.7506/spkx1002-6630-20180228-250
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Objective: To investigate the effect of hawthorn proanthocyanidins extract, epicatechin and proanthocyanidin B2 on the proliferation and apoptosis of human hepatocellular carcinoma SMMC-7721 cells. Methods: SMMC-7721 cells were cultured in vitro. The effect of different concentrations of hawthorn proanthocyanidins on cell proliferation and apoptosis was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide assay and 4’,6-diamidino-2-phenylindole (DAPI) staining, respectively. The expression of apoptosis-related proteins was detected by Western blotting. The activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and Na+K+-ATPase and malondialdehyde (MDA) level in cells from each group were determined. Results: Hawthorn proanthocyanidins extract, epicatechin and proanthocyanidin B2 all significantly inhibited the proliferation of SMMC-7721 cells in a time-dependent and concentrationdependent manner (P < 0.05) and induced cell apoptosis. Compared with the control group, hawthorn proanthocyanidins extract, epicatechin and proanthocyanidin B2 decreased the activity of SOD, CAT, GSH-Px and Na+K+-ATPase and increased the level of MDA in SMMC-7721 cells. The expression of apoptosis-related proteins casepase-8, caspase-3, Bcl-2-associated X protein and the fragment of poly (ADP-ribose) polymerase were increased, while the expression of Bcl-2 was decreased. Conclusion: Hawthorn proanthocyanidins can inhibit the proliferation of SMMC-7721 cells and induce apoptosis through regulating antioxidant activity and apoptosis-related proteins.
Effect of Sweet Potato Juice on Life Span and Antioxidant Capacity in Drosophila melanogaster
ZHANG Biying, QIAN Zilin, TANG Ling, ZHANG Jing, JIANG Heti
2019, 40(5):  197-201.  doi:10.7506/spkx1002-6630-20171021-232
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In order to investigate the antioxidant and anti-aging effect of sweet potato juice, Drosophila melanogaster was chosen as an animal model. Male and female Drosophila melanogaster with eclosion and without mating within 8 h were fed on a diet supplemented with low, moderate or high doses (0.10, 0.15, and 0.20 mg/mL) of sweet potato juice. The survival rate of D. melanogaster was investigated, and the activity of superoxide dismutase (SOD), total antioxidant capacity (T-AOC) and malondialdehyde (MDA) content were measured in its homogenate. The results showed that compared with the control group, average life span and maximum life span in all dose groups were significantly increased (P < 0.05 or P < 0.01) in a dose-dependent manner. SOD activity and T-AOC were significantly increased in all dose groups (P < 0.05 or P < 0.01), whereas MDA content was significantly decreased in the middle- and high-dose groups (P < 0.05 or P < 0.01). Compared with the control group, average life span in the high-dose group was extended by 17.93% and 16.00% for female and male flies, the activity of SOD was increased by 50.51% and 58.61%, T-AOC activity was increased by 79.73% and 62.67%, while the content of MDA was decreased by 35.59% and 37.14%, respectively. In conclusion, sweet potato juice can prolong life span and delay aging in D. melanegaster.
Protective Effect of Skipjack Tuna Oil against D-Galactose-Induced Aging in Mice
ZHENG Linbo, BAI Dong, YU Zhou, ZHANG Hailing, XIE Chao
2019, 40(5):  202-206.  doi:10.7506/spkx1002-6630-20171214-174
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The objective of this research was to evaluate the anti-aging effect of skipjack tuna oil (STO) on a mouse model of D-galactose-induced aging. Healthy ICR mice of reproductive age were randomly divided into 6 groups (n = 8): blank control, low-, middle- and high-dose STO, aging model and positive control groups. Mice in the control group were subjected to subcutaneous injection of 0.9% saline every day, while mice in other experimental groups were subjected to subcutaneous injection of 4% D-galactose (1 000 mg/kg mb) and administrated with different concentrations of STO (20, 50 and 100 mg/mL) at a dose of 10 mL/kg mb by gavage. Mice in the positive control group were administrated with commercial fish oil (100 mg/kg mb) and those in the blank control and aging model groups were by gavage administrated with an equal volume of normal saline for 6 weeks. The activity of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD) and catalase (CAT), and the content of malondialdehyde (MDA) in the liver and serum of mice were determined. The pathological changes of liver tissues were observed. Results indicated that the liver and spleen indexes in the high-dose and blank control groups were significantly lower than in the model group (P < 0.05). The serum and hepatic activities of GSH-Px, T-SOD and CAT in the model group were significantly decreased relative to the blank control group (P < 0.05) while the opposite was found for MDA content. STO at all doses increased the levels of GSH-Px, T-SOD and CAT in serum and liver tissue and reduced MDA level. Pathological observation showed that STO could alleviate liver damage during aging, especially at high dose.
Packaging & Storage
Effect of 2,4-Epibrassinolide Treatment on Rhizopus Rot and Energy Metabolism in Postharvest Peach Fruit
ZHANG Zhengmin, YANG Yilin, LI Meilin, WANG Jing, JI Nana, ZHENG Yonghua
2019, 40(5):  207-213.  doi:10.7506/spkx1002-6630-20180828-312
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The effect of 2,4-epibrassionolide (EBR) treatment on Rhizopus rot and energy metabolism in postharvest peach fruit (Prunus persica (L.) Batsch cv Baifeng) was investigated. Peach fruit were treated with EBR solutions of different concentrations (0, 1, 5 and 10 μmol/L) for 10 min, then inoculated with Rhizopus stolonifer, and finally stored at (20 ± 1) ℃ for 60 hours. The results showed that treatment with EBR at 5 μmol/L was the most effective in suppressing the increase in lesion diameter and disease incidence in peach fruit (P < 0.05) and maintaining good quality during storage. Compared with the control group with the inoculation of Rhizopus stolonifer alone, EBR treatment could increase the activity of Ca2+-ATPase, H+-ATPase, succinate dehydrogenase and cytochrome oxidase, delay the decrease in adenosine triphosphate and adenosine diphosphate contents, and inhibit the increase in adenosine monophosphate content, thus maintaining high energy level of peach fruit. Correlation analysis showed that disease incidence and energy level were significantly negatively correlated in the control (r = ?0.939, P < 0.01) and EBR treatment groups (r = ?0.962, P < 0.01). These results suggested that EBR treatment could inhibit Rhizopus rot of postharvest peach fruit, which may be related to maintenance of high energy level.
Effect of Postharvest BTH Treatment on Aroma Monoterpenes and Key Metabolic Enzymes in ‘Yujinxiang’ Melon
WANG Yu, LI Jixin, LI Jingwei, HAO Lanlan, HU Yanyun, WANG Bo, JIANG Yumei
2019, 40(5):  214-221.  doi:10.7506/spkx1002-6630-20180112-156
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The objective of this study was to investigate the effect of postharvest treatment with the plant resistance inducer benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) on the activity of l-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) and aroma-active monoterpenes in muskmelon (Cucumis melo L. cv. Yujinxiang) and to analyze the correlation between DXR activity and the release of aroma-active monoterpenes. Changes in DXR activity, involved in the metabolic pathway of aroma-active monoterpenes and monoterpene composition were monitored during postharvest storage at room temperature. The results showed that a total of nine aroma-active monoterpene components were detected in the samples during the storage period. Eight of these compounds were positively correlated with DXR activity. Upon postharvest BTH treatment, DXR activity and the release of monoterpenes were inhibited accompanied by delayed peak time of DXR activity as well as altered release pattern of aroma-active monoterpenes and correlation with DXR activity. Compared with the CC group (distilled water immersion), DXR activity in the rind and pulp of BTH-treated melon was reduced by 19.48% and 25.49%, respectively. The effect of distilled water immersion on DXR activity and the release of aroma-active monoterpenes was irregular although it increased the peak of DXR activity. From these findings, it is clear that postharvest BTH treatment can inhibit DXR activity, delay the peak time of DXR activity and affect the release of aromaactive monoterpenes and its correlation with DXR activity.
Effect of Cooling Method on FAD and LOX Gene Expression and Core Browning in Postharvest Yali Pears
FAN Xiaolan, LI Yueyuan, ZHANG Yinyin, HAN Yunyun, LI Ling, YAN Shijie, XIAO Lixia
2019, 40(5):  222-227.  doi:10.7506/spkx1002-6630-20180102-017
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In order to explore the effects of rapid and slow cooling on ω-3 fatty acid desaturase (ω-3FAD) and lipoxygenase (LOX) gene expression and core browning in Yali pears, Hebei grown Yali pears (Pyrus bretschneideri Rehd cv. Yali) were chosen to determine the contents of fatty acids and the gene expression and activities of FAD and LOX. The results showed that the core browning index of the fruits subjected to rapid cooling was significantly higher than that of those subjected to slow cooling during storage. Cold resistance occurred in the rapid cooling group, resulting in increased contents of unsaturated fatty acids, up-regulated expression levels of ω-3FAD1 and FAD2, and enhanced activities of LOX. Moreover, low-temperature stress activated the expression of LOX gene, accelerated membrane lipid peroxidation, and reduced fruit quality. Therefore, timely harvested Yali pears should be cooled slowly in order to improve the storage quality.
Application of Multi-functional Integrated Packaging Design in the Preservation of ‘Kyoho’ Table Grapes
YANG Da, LIU Huixian, LI Dongli, XU Wencai, LIAO Ruijuan, SHI Jiazi, FU Yabo, WANG Jigang
2019, 40(5):  228-233.  doi:10.7506/spkx1002-6630-20180113-173
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Dual-functional integrated packaging (DFIP) and triple-functional integrated packaging (TFIP) consisting of two and three functional films, respectively were applied to ‘Kyoho’ table grapes, and quality changes were monitored during storage at room temperature (25 ℃). Unpackaged grapes were used as a control. The results showed that through comprehensive evaluation of commercial value, the shelf life of the grapes with DFIP and TFIP was 4 and 8 d, respectively, while the control could be stored for only 2 d. DFIP and TFIP effectively maintained high contents of total soluble solids (TSS) and vitamin C and good berry firmness and reduced water loss compared with the control group. Moreover, sustained release of 1-methylcyclopropene from TFIP delayed stem browning. These results suggested that the multi-functional integrated packaging can extend the shelf life of table grapes.
Analysis of Bacterial Community Composition and Its Metabolic Function in Lateolabrax japonicus with Different Ice Treatments by High-Throughput Sequencing
ZHANG Wanjun, LAN Weiqing, DUAN Xianyuan, SUN Xiaohong, XIE Jing
2019, 40(5):  234-241.  doi:10.7506/spkx1002-6630-20180123-314
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Objective: To evaluate variations in the bacterial community composition of Lateolabrax japonicas during storage with different ice treatments and to determine its correlation with quality attributes. Methods: The fish were treated with slurry ice (SI), acidic electrolyzed water ice (AEWI) or crushed ice (CI). Total volatile basic nitrogen (TVB-N) content and K values (freshness index) were measured during ice storage. The structure and metabolic function of the bacterial community were also analyzed by using high-throughput sequencing. Results: SI and AEWI could maintain the quality of fish with the former being more effective in inhibiting the degradation rate of protein and nucleotide. The relative abundance of Bacillus, Lactococcus and Oceanobacillus in the CI and AEWI groups were much higher than in the SI group at the early stage of storage (0–3 d). During the middle to late periods of storage (12–21 d), the relative abundance of Pseudomonas, Shewanella, Moritella, Escherichia and Aliivibrio in the SI group increased rapidly; in the AEWI group, Pseudomonas and Acinetobacter gradually became dominant; the relative abundance of Acinetobacter as the dominant spoilage bacteria was up to 27.77% in the CI group on the 21st day. The results of principal component analysis (PCA) showed that ice storage and storage time had a significant influence on the bacterial community composition of Lateolabrax japonicus. Pseudomonas, Acinetobacter, Psychrobacter and Shewanella were positively correlated with TVB-N contents and K values , which may be the specific spoilage organisms of Lateolabrax japonicas during ice storage. The relative abundance of genes related to amino acid, lipid and carbohydrate metabolism in the AEWI and CI group were greatly higher than in the SI group. This may partially explain why SI could delay spoilage at the level of bacterial metabolism. This study provides a theoretical basis for optimizing the preservation and storage of Lateolabrax japonicas by microbial inhibition.
Effect of 1-(2-Chloropyridin-4-yl)-3-phenylurea Treatment on Degradation Characteristics of Cell Wall Polysaccharides in Lotus Seeds
SUN Fengjie, LUO Shufen, YAN Tingcai, HU Huali, ZHOU Hongsheng, ZHANG Leigang, LI Pengxia
2019, 40(5):  242-249.  doi:10.7506/spkx1002-6630-20180102-008
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In order to investigate the effect of 1-(2-chloropyridin-4-yl)-3-phenylurea (CPPU) treatment on the degradation of cell wall polysaccharides in lotus seeds, lotus pods from the cultivar ‘Taikonglian 36’ were treated with 5 mg/L CPPU. The samples treated with distilled water were used as controls. It was found that CPPU treatment could significantly maintain good phenotype of lotus pods and seeds, as well as crisp and tender taste of the seeds as compared with control. Meanwhile, CPPU treatment increased covalently bound pectin content in lotus seeds and maintained the structural integrity of cellulose polysaccharide chains. In addition, CPPU treatment inhibited the activity of pectin-degrading enzymes such as pectin methylesterase (PME) and polygalacturonase (PG) and the activity of cellulose-degrading enzymes such as cellobiohydrolase 1 (C1), β-1,4-endoglucanase (Cx) and β-glucosidase in lotus seeds, thus degrading the degradation of covalently bound pectin and the accumulation of water-soluble pectin and ion-bound pectin and maintaining cellulose and hemicellulose. CPPU treatment could maintain the integrity of the cell wall and the morphology of cellulose microfibrils in lotus seeds and inhibited plasmolysis. Therefore, CPPU treatment can inhibit the degradation of cell wall polysaccharides, maintain cell integrity in lotus seeds as well as the taste and delay postharvest senescence of lotus pods and seeds. This experiment can provide theoretical and technical support for postharvest preservation of lotus pods and seeds.
Quality Changes and Predictive Modeling of Shelf Life of Sauced Duck Stored at Different Temperatures
ZHANG Jianyou, ZHAO Yuliang, ZHANG Mengyu, DING Yuting, Lü Fei
2019, 40(5):  250-257.  doi:10.7506/spkx1002-6630-20180102-018
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The quality changes of vacuum packaged sauced ducks at different storage temperatures (4, 25 and 37 ℃) were investigated and shelf life predictive models were established. Experimental results demonstrated that total viable count (TVC), total coliform count, mold count, acid value (AV), peroxide value (POV) and thiobarbituric acid reactive substance (TBARS) value continuously increased during storage at all temperatures, while sensory score decreased. Pearson correlation analysis indicated that mold count and TBARS value had the highest correlation with sensory attributes, which was fitted to the zero-order kinetic model. Arrhenius equation was used to develop shelf life predictive models based on mold count and TBARS value. The activation energy (Ea) and pre-exponential factor (k0) were 16.24 kJ/mol and 179 871.86 for mold count, and 26.33 kJ/mol and 1 347.49 for TBARS value, respectively. The predicted shelf life of sauce duck stored at 4, 25 and 37 ℃ agreed with the actual values. Therefore, mold count and TBARS values could be useful to predict the shelf life of sauced duck.
Relationship between Postharvest Physiology, Quality and Electrical Properties of Kiwifruit Treated Preharvest with 1-(2-Chloropyridin-4-yl)-3-phenylurea and Postharvest with Ozone
LI Lin, LUO Anwei, LI Yuanyuan, SU Miao, BAI Junqing, LI Rui, FANG Yimeng, MA Huiling
2019, 40(5):  258-266.  doi:10.7506/spkx1002-6630-20171214-175
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In order to investigate whether postharvest O3 treatment can counteract the negative effect of preharvest 1-(2-chloropyridin-4-yl)-3-phenylurea (CPPU) treatment on kiwifruits based on macroscopic electrical properties, the relationship between postharvest physiology, quality and electrical properties was studied on ‘Qinmei’ kiwifruit treated with 20 mg/L CPPU at 28 days after flowering and then treated with 70 mg/m3 O3 for 2 hours every 15 days during postharvest storage at (0 ± 1) ℃ and relative humidity of 90%–95% . The results showed that CPPU + O3 treatment led to significantly higher catalase (CAT) activity, VC and titratable acid (TA) content and significantly lower respiratory rate, polygalacturonase (PG) and cellulase (Cx) activities than did CPPU treatment alone. Postharvest O3 treatment could weaken the negative effect of CPPU treatment on kiwifruit. The characteristic frequency for CPPU-treated kiwifruit was 0.1 kHz among the selected 24 frequencies, while the characteristic frequency for both control and CPPU + O3 treated kiwifruit was 3 980 kHz, which further indicates that O3 can weaken the negative effect of CPPU treatment on kiwifruit through macroscopic electrical characteristics.
Reviews
Advances in Biosynthesis and Regulation of Fusarium Trichothecenes
ZHANG Wenwei, WANG Yanling, XUE Huali, BI Yang
2019, 40(5):  267-275.  doi:10.7506/spkx1002-6630-20180305-056
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Trichothecenes are a large family of toxic secondary metabolites mainly produced by the Fusarium genus, which threaten human and animal health. In this article, the genes, pathways, enzymes, and regulatory mechanisms for the biosynthesis of thrichothecenes are summarized. The biosynthetic enzymes and direct regulatory proteins of trichothecenes are encoded by at least 3 gene clusters: Tri5, Tri1-Tir16 and Tri101, including Tri5 encoding trichodiene synthase, Tri4, Tri11 and Tri13 encoding cytochrome P450 monooxygenases, Tri6 and Tri10 encoding a regulatory protein, Tri7, Tri3, Tri16 and Tri101 encoding acetyltransferases, Tri8 encoding deacetylase, Tri1 encoding hydroxylase, and Tri12 encoding a trichothecene efflux pump. The biosynthesis of trichothecenes begins with to the cyclization of trans-farnesyl pyrophosphate to form trichodiene, followed by oxygenation, isomerization, cyclation and esterification to eventually form toxins with different structures. The types of toxins mainly determined by metabolic pathways and genetic differences. The biosynthetic pathways are regulated by not only specific transcription factors such as TRI6 and TRI10 but also global regulatory factors such as Pac and VeA related to the external environment. This review aims to provide a theoretical basis for the prevention, control and detoxification of mycotoxins in food and feed.
Progress in Understanding the Regulatory Effect and Mechanism of Fluorescent Light and Light-Emitting Diode Irradiation on Antioxidant Properties of Fruits and Vegetables during Postharvest Storage
MA Yadan, ZHANG Cuicui, LI Linjie, ZHAN Lijuan
2019, 40(5):  276-281.  doi:10.7506/spkx1002-6630-20180131-432
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How to maintain and/or increase antioxidant properties of postharvest fruits and vegetables is a hot topic among researchers. Light irradiation, a new physical preservation method, has significant effects on antioxidant properties of postharvest fruits and vegetables. In this paper, the major light source types and the possible underlying mechanism are reviewed, mainly focusing on the regulatory effect and mechanism of light irradiation on antioxidants (vitamin C, polyphenolic compounds, and carotenoids) and antioxidant capacity in postharvest fruits and vegetables. Finally, we conclude with a discussion of problems existing in the research and application of light irradiation technology in postharvest preservation of fruits and vegetables.
Risk Assessment of Antibiotic-Resistant Bacteria in Foods: A Review
JIANG Zhumao, AI Chunmei, WANG Yeru, DONG Qingli, LIU Donghong, DING Tian
2019, 40(5):  282-288.  doi:10.7506/spkx1002-6630-20181008-054
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In recent years, the misuse and abuse of antibiotics have become a widespread problem. Antibiotic-resistant bacteria and antibiotic-resistant genes in foods are a global concern because diseases caused by them pose a threat to human health. Therefore, it is of significant importance to conduct a comprehensive risk assessment of antibiotic-resistant bacteria from the farm to the table. This paper describes the five steps of hazard identification, release assessment, exposure assessment, dose-response relationship assessment, and risk assessment based on the principles and guidelines for microbiological risk assessment developed by the Codex Alimentarius Commission. We analyze cases of risk assessment of antibiotic-resistant bacteria. Furthermore, we review recent progress in risk assessment of antibiotic-resistant bacteria in foods and prevention and control measures against them, in order to provide a theoretical basis for risk assessment of antibiotic-resistant bacteria in the future.
Progress in Research on Physiological Functions and Mechanisms of Capsinoids
ZANG Yufan, QIN Hong
2019, 40(5):  289-294.  doi:10.7506/spkx1002-6630-20180129-391
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Capsinoids are a class of non-pungent and lowly toxic capsaicin analogs extracted from ‘CH-19 sweet’ pepper and exert various physiological functions, thus having great potential for broad applications. Recently, capsinoids have been studied widely for their benefits in improving lipid and glucose metabolism and promoting anti-tumor, anti-inflammatory and antioxidant functions as well as enhancing endurance exercise capacity. In addition, capsinoids have many other bioactivities including anti-nociceptive, anti-allergic, swallowing reflex-enhancing, dermal insulin-like growth factor-up-regulating and brain region-activating effects. This paper reviews recent studies on capsinoids from physiological and mechanistic viewpoints with the goal of providing a theoretical basis for further studies and applications of these phytochemicals.
Natural Products Alleviate Alzheimer’s Disease through Regulating miRNA and the Autophagy Signal Pathway
CHEN Dandan, CHEN Ning, KOU Xianjuan
2019, 40(5):  295-302.  doi:10.7506/spkx1002-6630-20181013-105
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Alzheimer’s disease (AD), an age-related neurodegenerative disease, can seriously affect the health of the elderly. Since the pathogenesis of AD is very complex, the commonly used drugs in clinical practice against AD can attenuate the symptoms of mild to moderate AD, but cannot prevent, terminate or reverse the progression of AD. Therefore, natural products that can prevent and treat AD have gained great attention, and the majority of studies have confirmed that natural products can improve two major pathological features of AD, senile plaques and neurofibrillary tangles. Recently, accumulating studies have demonstrated that natural products function to prevent and treat AD through regulating miRNA and autophagy, which will be beneficial for establishing novel and effective strategies for the prevention and treatment of AD in the future.
Progress in Egg Yolk Immunoglobulin Metabolism and Toxin Neutralization
QIU Taotao, XU Zhenlin, GAN Qingqing, WANG Lanteng, SHEN Xing, LI Xiangmei, SUN Yuanming, LEI Hongtao
2019, 40(5):  303-308.  doi:10.7506/spkx1002-6630-20180122-300
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Improper food processing or storage is associated with the production of macromolecular protein toxins and small molecular toxins. Nowadays, there is an increasing interest in nutritional supplements that may counteract the detrimental effects of toxic compounds and prevent multiple diseases in humans. Egg yolk immunoglobulin (IgY) as a nutraceutical supplement for therapeutic and prophylactic intervention and against macromolecular protein toxins has been extensively studied. This article reviews recent progress in the factors affecting IgY activity, its metabolism and application for the neutralization of macromolecular protein toxins as well as the underlying mechanism. Meanwhile, we discuss the current status of understanding the detoxifying effect of IgY on small molecular toxins and future prospects for its application in this area. IgY has potential application in food and feed as an oral detoxicant.
Recent Progress in Research and Application of Ganoderma lucidum Triterpenoids
LIU Wei, HU Xiaozhen, ZHU Li, GAN Jianhong, LU Ying, TAO Ningping, WANG Xichang, XU Changhua
2019, 40(5):  309-315.  doi:10.7506/spkx1002-6630-20180201-021
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Ganoderma lucidum is rich in many bioactive ingredients with different pharmacological effects. Triterpenoids are one of the main active ingredients in G. lucidum, which have liver-protecting, antitumor, immunoenhancing, antioxidant, and hypolipidemic effects, among others. The purpose of this review is to summarize published literature concerning the physical and chemical properties, pharmacological activity, optimization of fermentation condition, quality control method and functional foods of G. lucidum triterpenoids in the past five years. Future research and application trends are discussed. We hope that this review will provide a basis for G. lucidum in food production, processing and clinical application.
The Mechanisms of Acid Tolerance Response of Salmonella and Listeria monocytogenes: A Review
TIAN Muyu, ZHANG Yimin, DONG Pengcheng, MAO Yanwei, LIANG Rongrong, ZHU Lixian, LUO Xin
2019, 40(5):  316-322.  doi:10.7506/spkx1002-6630-20180129-406
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Salmonella and Listeria monocytogenes are considered as the major foodborne pathogens in meat products. Both pathogens can develop a strong tolerance response to a weakly acidic environment inducing high toxicity and resistance to acid and osmotic pressure, which poses potential health hazards to consumers. In this article, we mainly review the history of the discovery of the acid tolerance response (ATR) of Salmonella and Listeria monocytogenes, the hazards of ATR and the factors affecting its development. Furthermore, we elucidate the molecular mechanism of ATR based on intracellular pH modulation, stress proteins and cell membrane composition and fluidity.
Recent Progress in Research on Nutrients, Functional Components and Health Benefits of Morchella esculenta
SUN Qiaodi, ZHANG Jiangping, XIE Yangyang, YAN Wenjie
2019, 40(5):  323-328.  doi:10.7506/spkx1002-6630-20180411-135
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Morchella esculenta is a rare wild edible and medicinal fungus with delicious taste. It contains plentiful nutrients such as proteins and vitamins and many functional components including polysaccharides and polyphenols with hepatoprotective, hypolipidemic, immunoenhancing, antitumor, antioxidant, digestion promoting, antifatigue and antimicrobial effects. Morchella esculenta can be used as an ingredient in food flavorings, nutritional supplements and nutraceuticals. This article summarizes the nutrients, functional components and health benefits of Morchella esculenta.
Recent Progress in Hyperspectral Imaging for Nondestructive Evaluation of Fish Quality
WANG Hui, HE Hongju*, LIU Lu, MA Hanjun, LIU Xi, MO Haizhen, LIU Rubiao, PAN Runshu, KANG Zhuangli, ZHU Mingming, ZHAO Shengming, WANG Zhengrong
2019, 40(5):  329-338.  doi:10.7506/spkx1002-6630-20180129-392
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Hyperspectral imaging (HSI) as a non-destructive, fast and accurate green analytical technology has been widely applied in the quality evaluation of aquatic products. This spectral imaging technology can not only acquire the physical and geometrical characteristics such as color, size, shape and texture of samples, but also can provide the chemical and molecular information of internal components such as moisture, fat, protein and other hydrogen-bonding substances. In this article, the latest progress in the application of HSI for the rapid and nondestructive evaluation of fish quality is reviewed in terms of chemical composition, physical properties, microbial contamination and freshness and future prospects are discussed. We expect that versatile online HIS devices will be developed in the near future.
On Online Food Safety Co-regulation
KANG Zhiyong, GUAN Xiaolin, YANG Haoxiong
2019, 40(5):  339-345.  doi:10.7506/spkx1002-6630-20180927-292
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As online shopping has become increasingly popular, safety problems of foods sold online have occurred frequently and the traditional supervision mode has been unable to meet the requirements for online food safety governance. This article analyzes the business models of food e-commerce in China as well as difficulties in online food safety governance and their causes. Furthermore, an online food safety co-regulation system is proposed considering both regulation and supervision, which highlights the importance of quality control of food sources, strict management of the transaction process and whole-process supervision and emphasizes the necessity of multipartite online food safety co-regulation. This system can provide new ideas for online food safety governance.