Table of Content

15 October 2020, Volume 41 Issue 19
Basic Research
Peptides Derived from Bovine Myoglobin: Factors Affecting Their Stability during Thermal Processing and Application in Meat Authenticity Identification
LI Yingying, KANG Chaodi, ZHANG Yingying, ZHAO Wentao, LI Jiapeng, LI Huichen, WANG Shouwei
2020, 41(19):  1-8.  doi:10.7506/spkx1002-6630-20200327-405
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The screening and identification of specific peptides is the key to species identification using mass spectrometry because of the difference in the peptide composition between different species. In this study, the stability of the peptides derived from the enzymatic hydrolysis of bovine myoglobin was explored during thermal processing. Factors with a great influence on the stability of the peptides were selected from the processing methods and the chemical factors involved in these methods. The identification rate of myoglobin and the response values to its peptides were comparatively studied at different levels of each factor, and the tolerance of each peptide was analyzed to each factor. The results showed that heating modes, additives, auxiliary materials, and metal ions affected the stability of the peptides. Among these factors, three heating modes (boiling, frying, and high pressure processing), and the addition of sodium chloride or Mg2+ had a greater impact on the stability of the peptides, while heating temperature, heating time, additives, capsaicin, K+, and Ca2+ had less impact on it. Peptide 2# derived from bovine myoglobin and peptide 13# derived from myosin-2 showed high response values and the strongest stability during thermal processing. In addition, peptide 13# has more significant advantages for authenticity identification of meat products. The mechanism for controlling the stability of peptides derived from bovine myoglobin during thermal processing will provide a theoretical basis for selecting stable target peptides for meat authenticity identification.
Effect of Thyme Essential Oil Microcapsules on Mechanism of Histamine Production by Morganella morganii and Proteus bacillus
YU Honghong, WU Mingying, WANG Qingling, DONG Juan, LU Shiling
2020, 41(19):  9-16.  doi:10.7506/spkx1002-6630-20190923-268
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This study explored the effects of thyme essential oil microcapsules on the growth, gene expression and histamine accumulation of Morganella morganii ND and Proteus bacillus R3. High-performance liquid chromatography was used to detect the accumulation of histamine during 48 h culture of the tested strains, and reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to evaluate the expression of histidine decarboxylase (HDC) pathway-related genes under the influence of thyme essential oil microcapsules. The results showed that thyme essential oil microcapsules had strong antibacterial activity against the test bacteria. The minimal inhibitory concentration (MIC) was 1.56 and 0.78 mg/mL for M. morganii and P. bacillus, respectively. Thyme essential oil microcapsules could reduce histamine accumulation by inhibiting the expression of histidine decarboxylase (hdcA) and histidine/histamine antiporter (hdcP) genes in the HDC cluster. The accumulation of histamine could be reduced by 61.08% and 55.89% in M. morganii and P. bacillus by thyme essential oil microcapsules at MIC concentration.
Risk Pre-warning of Hazardous Materials in Cereal Supply Chain Based on Deep Belief Network-Multiclass Fuzzy Support Vector Machine (DBN-MFSVM)
WANG Xiaoyi, LI Liusheng, KONG Jianlei, JIN Xuebo, SU Tingli, BAI Yuting
2020, 41(19):  17-24.  doi:10.7506/spkx1002-6630-20190916-205
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In recent years, food supply chain security problems have occurred frequently. In order to reduce the threat of foodborne risks, risk early warning is becoming a powerful guarantee to strengthen the food safety system. However, in the face of multi-source heterogeneous unstructured data on foods, the existing risk warning method is limited by its low early warning accuracy and high labor cost. Based on analysis of a large number of data from food sample survey and related information from 26 provinces in China, this paper establishes a risk classification and early warning model using deep belief network-multiclass fuzzy support vector machine (DBN-MFSVM). First, the numerous data from grain supply chain sample survey are embedded, coded and normalized to obtain structured food data, which are then input into the DBN model to extract high-dimensional features, and self-adaptively mine the risk change and intrinsic correlation probability among the risk factors in the supply chain. Finally, the high-dimensional features are input into the optimized MFSVM for training to realize the risk classification and early warning of the main hazards in the supply chain. The comparative experimental results show that the DBN-MFSVM model has better robustness and generalizability for grain sample survey data. Its accuracy rate is 98.44%, and the running time is 85 s. It can quickly identify the risk level and priority of hazardous materials in the food supply chain, and thereby provide a scientific basis for the regulatory authorities to develop targeted sampling strategies, establish priority regulatory areas and allocate risk monitoring resources.
Correlation of Physical Properties of Granular Green Tea with Its Appearance Quality
GUO Li, YU Fanglin, ZHAO Feng, ZHANG Yue, ZHU Yin, DAI Weidong, DONG Chunwang, LIN Zhi
2020, 41(19):  25-30.  doi:10.7506/spkx1002-6630-20190930-367
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Granular shape is a preferable appearance for green tea manufactured by a machine. Uncovering the correlation between the physical characteristics of granular green tea and its appearance quality factors is great significance for the mechanical processing and quality control of green tea. Therefore, in this study, 8 kinds of granular green tea and 1 type of curly green tea were chosen for sensory evaluation, and representative samples were selected for analysis of their color and shape features by computer vision technology, and their physical properties such as bulk density, hundred-grain mass, elasticity and plasticity by graduated cylinder and texture analyzer, respectively. The correlation of the physical parameters with the appearance quality factors were explored by multiple stepwise regression analysis (MSRA). The results showed that ‘Gouqing’ tea had a good appearance quality and uniformity, and its appearance quality score was above 85. Accordingly, it could be considered as a typical representative of granular green tea. As the maturity of the raw material increased, the color parameters red channel value, green channel value, blue channel value, lightness value and saturation value decreased, while Hue value increased, and the color changed from yellow green to dark green. The circular degree and shape index of ‘Gouqing’ tea increased whereas the bulk density decreased. Furthermore, the hundred-grain mass increased up to 33.1 g. Meanwhile, the plasticity was weakened, and thus its ratio to elasticity increased up to 1.5. However, there were different correlations of each physical property with the appearance quality of granular green tea. The results of MSRA showed that the effects of blue channel value, hue value, elasticity, plasticity and circularity on the appearance quality of granular green tea were more obvious than those of the other factors. Hue value and elasticity had negative effects on the shape and color. Blue channel value and circular degree were associated with the uniformity. Therefore, scrutinizing the appearance quality factors of granular green tea and evaluating the dominant factors responsible for individual quality attributes will be helpful to reveal the contribution of each physical property to the appearance quality of granular green tea.
Antibacterial Mechanism of Antimicrobial Peptide Brevilaterin Combined with Citric Acid against Escherichia coli
NING Yawei, SU Dan, FU Yunan, LIU Yangliu, WANG Zhixin, JIA Yingmin
2020, 41(19):  31-37.  doi:10.7506/spkx1002-6630-20191008-026
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The synergistic antibacterial effect and underlying mechanism of the antibacterial peptide brevilaterin combined with citric acid were studied against the food-borne pathogen Escherichia coli, with the aim to provide a theoretical basis for the application of this antibacterial peptide and citric acid in the control of E. coli. The effects of brevilaterin and citric acid on the membrane potential of E. coli were investigated by using DiSC3(5) fluorescence probe. The results showed that brevilaterin and citric acid could separately and synergistically dissipate the transmembrane potential of E. coli. Both of them could destroy membrane integrity as determined by propidium iodide/SYTO 9 probe marking combined with flow cytometry. Transmission electron microscopy (TEM) demonstrated that combination of brevilaterin with citric acid synergistically destroyed the ultrastructure of E. coli cells, specifically leading to cell deformation, plasmolysis and the leakage of cell contents. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that brevilaterin and citric acid had no significant effect on protein synthesis in E. coli. Agarose gel electrophoresis showed that brevilaterin and citric acid could separately and synergistically degrade the DNA of E. coli. Therefore, brevilaterin and citric acid can synergistically inhibit the growth of E. coli by disrupting the integrity of cell membrane and degrading bacterial DNA.
Effects of Ten Plant Essential Oils and Antimicrobial Mechanism of Cinnamon Essential Oil against Staphylococcus saprophyticus
LAN Weiqing, LIU Jiali, WENG Zhongming, CHEN Mengling, XIE Jing
2020, 41(19):  38-44.  doi:10.7506/spkx1002-6630-20190826-282
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In order to study their antimicrobial effects, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 10 plant essential oils against Staphylococcus saprophyticus were determined by the bacteriostatic circle and broth dilution methods. The most effective one was selected to further investigate its antimicrobial mechanism. The results showed that cinnamon essential oil had the best bacteriostatic effect on Staphylococcus saprophyticus. The diameter of the inhibition zone was (24.10 ± 2.55) mm, and both MIC and MBC were 1 mg/mL. After being treated with cinnamon essential oil at MIC and 2 MIC, the growth of Staphylococcus saprophyticus was completely inhibited at 5 h. Cinnamon essential oil could destroy the cell membrane integrity of Staphylococcus saprophyticus, leading to an increase in the activity of extracellular alkaline phosphatase (AKP) and the leakage of intracellular protein, and affect the integrity and metabolism system of the cell wall and cell membrane, and this effect was positively related to its concentration. After being treated with cinnamon essential oil, the cell surface of Staphylococcus saprophyticus became obviously shrunk and no longer dense, and bacterial dissolution and cohesion appeared. Moreover, some bacterial cells were disrupted, leading to the leakage of intracellular contents, causing the outer membrane to fall off, and finally leading to bacterial death. In conclusion, cinnamon essential oil has a significant effect on Staphylococcus saprophyticus. It exerts its bacteriostatic effect by destroying the cell wall and cell membrane, and inhibiting the formation of biofilm.
Mechanism for Texture Softening of Canned Yellow Peaches Based on Modification of Pectin Characteristics
YU Xiaoyan, LÜ Jian, BI Jinfeng, WANG Fengzhao, LI Xuan, WU Xinye
2020, 41(19):  45-52.  doi:10.7506/spkx1002-6630-20190904-052
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This paper aimed to explore the changes and formation mechanism of the texture quality of canned yellow peaches. Water soluble pectin (WSP), chelator-soluble pectin (CSP) and carbonate-soluble pectin (NSP) were extracted from canned yellow peaches made from the ‘Goldbaby 5’ cultivar. The pattern of changes in the contents of these pectin components and their characteristics such as degree of methoxylation (DM), degree of acetylation (DAc), molecular mass and chemical functional groups was investigated during the processing of canned yellow peaches, and changes in the activity of polygalacturonase (PG) and pectin methyl-esterase (PME) were also examined. Results demonstrated that precooking and subsequent sterilization could alter the texture quality of canned yellow peaches, leading to an increase in the contents of WSP and CSP but no significant difference in the content of NSP (P > 0.05) compared with fresh yellow peaches. The DM of WSP and CSP decreased, the DAc of WSP significantly decreased (P < 0.05), and the molecular mass of CSP increased after precooking and then decreased after subsequent sterilization. Additionally, infrared spectral analysis was consistent with DM measurement. PME was totally inactivated after sequential precooking and sterilization, while PG activity remained at a high level. The correlation analysis showed that the enzyme activities and the pectin components were differently correlated with the texture quality. It was clear that the changes in the enzyme activities and pectin structure characteristics during processing were the main factor affecting the mechanism for the texture formation of canned yellow peaches. These results provide a theoretical basis for the development of high-quality canned yellow peach with prolonged shelf life in the future.
Observation on Cell Structure of Walnut Kernels and Its Changes during Oxidation during Storage and Raman Spectroscopy Analysis
LAN Wenyan, CAO Jiacheng, QI Lin, JI Yangyang, HE Aimin, DUAN Yuquan, RONG Ruifen
2020, 41(19):  53-61.  doi:10.7506/spkx1002-6630-20191015-143
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Objective: To explore the characteristics of the cell structure of walnut kernels and its changes during oxidation for the purpose of obtaining an in-depth understanding of the oxidation mechanism of walnut kernels. Methods: Optical and transmission electron microscopy were used to observe the cell structure of walnut kernels, and its changes during ambient storage and accelerated storage at 60 ℃ were comparatively analyzed as well as changes in peroxide value and the Raman spectral intensity of unsaturated double bonds. Moreover, the correlation of change in the cell structure with peroxide value and the Raman spectral intensity was evaluated. Results: The basic structure of walnut kernels consisted of endotesta, cortical layer and storage cell tissues. The storage cells were filled with protein and oil bodies. As the degree of oxidation increased, the surface of the protein bodies changed from smooth to rough, the oil body membrane gradually shrank until collapse, and the protein bodies became non-uniform in diameter with a tendency of migration and aggregation to one side of the cells. The gap between the cell wall and the oil body membrane increased, the cell wall shrank and became non-uniform in thickness with the mesohyl layer blurring. Conclusion: Changes in protein and oil body membrane structure have a good correlation with the peroxide value and Raman spectral intensity. Raman spectrum analysis can accurately reflect the oxidation characteristics of walnut oil at normal temperature.
Quality Analysis and Evaluation of Early and Medium Ripening Native Apples in Northern Xinjiang, China
Yiliminuer, HE Miao, LU Biao, Yibadaiti · MUHEDANER, LUO Qinghong
2020, 41(19):  62-67.  doi:10.7506/spkx1002-6630-20191006-005
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In order to meet the demand of the fruit market in Northern Xinjiang for early ripening apple varieties, 27 samples of early and medium ripening apples from three regions in Northern Xinjiang were comparatively and comprehensively evaluated for their appearance and nutritional quality. The results showed that there were significant differences in vertical and transverse diameters, individual fruit mass and hardness among different varieties (P < 0.05). Among all samples tested, the highest content of calcium was found in the ‘Atunuke’ cultivar from Tekesi County (337.70 mg/kg), the highest content of zinc in the ‘Bingtangguo’ cultivar from Tekesi County (6.3 mg/kg), the highest content of soluble sugar in the ‘Wangshanhong’ cultivar from Yining County (7.38 g/100 g), the highest content of malic acid in both the ‘Gezidan’ cultivar from Tacheng County and the ‘Maixirefu’ cultivar from Tekesi County (8.58 g/kg), the highest content of sugar acid in the ‘Xialimeng’ cultivar from Tekesi County (42.46), and the highest content of VC in the ‘Tachenghong 1’ cultivar from Tacheng County (59.59 mg/100 g). Reasonable satisfaction degree analysis showed that ‘Tachenghong 1’, ‘Gezidan’, ‘Erbatai’ and ‘Baitian’ were suitable to be planted in Tacheng city, ‘Xialimeng’, ‘Qiuyouguozi’, ‘Maixirefu’ and ‘Youguozi’ were suitable to be planted in Tekesi county, and ‘Sitagan’ and ‘Wangshanhong’ were suitable to be planted in Yining county. However, from the results of fruit grading according to the quality attributes, the comprehensive economic traits of the apple cultivars tested were at a low level on the whole, indicating the necessity of enhancing the management level of high-yield cultivation of the selected cultivars to improve the comprehensive economic traits of fruits.
Inhibitory Effect of Eugenol on Alternaria sp. Isolated from Blueberry
GE Da’e, WEI Zhaohui, Tursunay · TURGUN, PAN Yue, WANG Fan, TAO Ningping, ZHOU Jianzhong, LIU Xiaoli
2020, 41(19):  68-73.  doi:10.7506/spkx1002-6630-20190909-112
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The antifungal effect and mechanism of eugenol against Alternaria sp. isolated from naturally decayed blueberries was investigated. The effects of different concentrations of eugenol on the mycelia growth and spore germination of Alternaria sp. were determined. The morphology and structure of Alternaria sp. were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Propidium iodide staining was used to observe the effect of eugenol on the cell membrane of Alternaria sp. mycelia and changes in the enzyme activity related to the cell wall of Alternaria sp. were measured. The results showed that eugenol at a concentration of 0.3 mg/mL could completely inhibit the mycelial growth and spore germination of Alternaria sp.. Compared with the control group, the spores and mycelia of Alternaria sp. treated with 0.3 mg/mL eugenol were severely deformed, a lot of wrinkles appearing on the surface, intracellular constituents being lost, and no organelles remaining intact. After staining, red fluorescence appeared. The concentration of extracellular soluble protein and conductivity were 1.18 and 8.02 times as high as those of the control group, and the activities of chitinase and β-1,3-glucanase increased by 3.37 times and 50%, respectively. To sum up, eugenol exerts its antibacterial effect by destroying the cell wall and changing cell membrane permeability, and thus inhibiting the growth and metabolism of Alternaria sp..
Preparation and Properties of Enzymatic Glycosylation Products of Casein with Soluble Soybean Polysaccharide
LIU Yuqi, QIN Xiaoli, KAN Jianquan, ZHONG Jinfeng
2020, 41(19):  74-82.  doi:10.7506/spkx1002-6630-20191006-006
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The present work investigated the impact of mass ratio of casein to soluble soybean polysaccharide and transglutaminase concentration on the physicochemical and structural properties functionalities of conjugates formed between casein and soluble soybean polysaccharide, through the determination of various physicochemical indicators, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, Fourier transform infrared spectroscopy (FTIR) analysis, endogenous fluorescence spectroscopy (EFS) analysis and scanning electron microscope (SEM) observation. When the mass ratio of casein to soluble soybean polysaccharide was 1:1 and the transglutaminase concentration was 5 U/g, a high degree of glycosylation was obtained as evidenced by a browning index of 0.542, intermediate content of 0.907, and grafting degree of 19.9%. The physicochemical properties of the cross-linked product were improved compared with those of casein, the solubility increasing from 47.2% to 67.0%, the emulsifying activity from 116 to 123 m2/g, and the emulsion stability from 16.9 to 37.6 min. The results of SDS-PAGE and FTIRS indicated that soluble soybean polysaccharide was successfully grafted to casein. EFS analysis showed the degree of cross-linking and protein structural changes after cross-linking. The results of SEM suggested that the cross-linked product exhibited a non-homogeneous and loose porous network microstructure. Additionally, when applied to prepare oil-in-water emulsions, the cross-linked product imparted higher surface charge and stronger steric hindrance to emulsion droplets than casein, thereby stabilizing the emulsion droplets against environmental stresses. The results from this study are of reference significance for improving the emulsifying properties of casein, enhancing the physical stability of oil-in-water emulsions stabilized with casein-soluble soybean polysaccharide complex, and applying casein and sugars.
Construction of Pectin/Sodium Caseinate Composite Delivery System and Controlled Release Mechanism of Incorporated Lycopene from It
WANG Qingyu, WANG Mengyao, HUANG Huimin, JIANG Yun, DONG Huibin, CHEN Lei
2020, 41(19):  83-89.  doi:10.7506/spkx1002-6630-20191021-227
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Polyelectrolyte composite nanoparticles were prepared by the electrostatic interaction between sodium caseinate with positive charges and pectin with negative charges. The effect of mass ratio between sodium caseinate and pectin on the particle size and polydispersity index (PDI) of composite nanoparticles was studied. A pectin/sodium caseinate composite delivery system loaded with lycopene was constructed to explore the effect of lycopene concentration on the encapsulation efficiency and loading rate of lycopene. Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to characterize the ternary composite nanoparticles and analyze its particle size distribution, chemical structure and apparent morphology. In order to determine the release efficiency of incorporated lycopene from the composite nanoparticles, an simulated gastric and intestinal digestion model in vitro was established. The release behavior of lycopene in simulated gastric and intestinal fluids with different pH values was evaluated. The results of TEM and FT-IR showed that pectin and sodium caseinate were not simply physically mixed, but could form a binary compound with stable core-shell structure, which could be used for the encapsulation of lycopene. The results of DSC and TGA showed that lycopene existed inside the powder particles in an amorphous form, thus forming a pectin/sodium caseinate-lycopene complex. The encapsulation rate of lycopene reached 96.93% when the ratio of pectin to sodium caseinate was 20% and the loading rate was 8%. Under these conditions, lycopene had good thermal stability, and it was released in a controlled in simulated gastric fluid and released in a large amount in simulated intestinal fluid.
Correlation Analysis between pH, Major Organic Acids, Calcium and Magnesium Ions of Stratified Bottom-Pit-Mud from Chinese Strong-Flavor Baijiu Pit
ZHANG Huimin, MENG Yajing, WANG Yanli, HU Xinhang, WANG Yinhui, HUANG Yan, ZHOU Qingwu, LI Anjun, WANG Lu, XING Xinhui
2020, 41(19):  90-97.  doi:10.7506/spkx1002-6630-20191020-201
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In this study, pH and the contents of four major organic acids, calcium and magnesium ions in stratified bottom-pit-mud (BPM) from young and old pits used for the production of Chinese strong-flavor Baijiu, as well as the turbidity of their centrifugal supernatant/filtrate were measured, and the correlations between these parameters were analyzed. The physicochemical properties of BPM from old pits showed no horizontal variations, whilst in the vertical direction, the increase in pit depth resulted in a higher pH (5.86–9.22), and lower contents of lactic acid (LA, 2 380.07–19.48 mg/kg), caproic acid (CA, 3 134.59–1 904.76 mg/kg), butyrate acid (BA, 559.10–103.95 mg/kg), acetic acid (AA, 2 737.79–536.48 mg/kg), Ca2+ (292.1–35.0 mg/kg), and Mg2+ (258.7–13.3 mg/kg). For BPM from young pits at the center and quarter positions, the increase in pit depth resulted in an increase in pH (4.24–6.42), and a decrease in LA (38 146.5–6 664.7 mg/kg) and Mg2+ (326.70–183.91 mg/kg), but no difference in Ca2+ (1 448.6 mg/kg); at the corner position, it caused an increase in pH (4.13–7.89), and a decrease in LA (14 461.0–81.1 mg/kg), Ca2+ (878.3–362.8 mg/kg) and Mg2+ (197.1–106.3 mg/kg); for each position, the contents of CA (6 663.69 mg/kg), BA (1 403.47 mg/kg) and AA (1 347.00 mg/kg) showed no significant difference when the pit depth increased. Correlation analysis showed that for both young and old BPM, pH was strongly correlated with LA (?0.686 2 vs ?0.789 3), indicating the importance of LA for the pH of BPM. LA content was strongly correlated with Ca2+ (0.418 6 vs 0.717 6) and Mg2+ (0.731 6 vs 0.738 5), indicating the importance of LA for Ca2+ and Mg2+. Compared with young BPM, stronger correlation of LA content with CA (?0.126 8 vs 0.466 0), BA (?0.092 5 vs 0.537 1) and AA (?0.078 0 vs 0.443 3) was observed in old BPM indicatingg stronger LA catabolism in old BPM. The difference in the turbidity of centrifugal supernatant (48.63 NTU vs 62.16 NTU) and filtrate (14.21 NTU vs 24.12 NTU) between young and old BPM indicated more micro-nano particles present in the old BPM. Therefore, this study illustrates that reducing LA content is beneficial to improve the quality of BPM and that the presence of more micro-nano particles in BPM is beneficial to the metabolism of LA-degrading bacteria.
Food Engineering
Effect of Ultrasonic Treatment on Self-Assembly Behavior and Physicochemical Properties of Collagen from Carassius auratus Skin
JIA Junqiang, SUN Shengyuan, ZHOU Xiaorui, MIAO Nan, ZHU Yujie, WU Qiongying
2020, 41(19):  98-104.  doi:10.7506/spkx1002-6630-20190826-275
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In order to determine the effect of ultrasonic treatment on the fibril formation and physicochemical properties of collagen from Carassius auratus skin, the self-assembly kinetics, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern, fluorescence spectra, circular dichroism spectra, fibrillar morphology and NIH/3T3 cell proliferation ability of the collagens with and without ultrasonic treatment were analyzed and compared. The results showed that the nucleation phase of collagen self-assembly was significantly shortened and the fibril formation rate was increased after ultrasonic treatment at 100–200 W for 1–10 min. When the ultrasonic power was 600 W or the ultrasonic time was longer than 10 min, the collagen subunit was degraded, and its characteristics as type I collagen were weakened. After sonication, the ratio of positive to negative Cotton effect (RPN) of collagen from Carassius auratus skin showed a downward trend, and its fluorescence intensity was increased remarkably, with about 3 nm blue shift being observed in the maximum emission wavelength. In addition, the collagen showed a large number of pores and loose cross-sections and its fibers were uniform in morphology after ultrasonic treatment. The results of cell proliferation test showed that ultrasonic treatment in the power range of 100–200 W for 1–10 min could significantly improve the NIH/3T3 cell proliferation capacity of collagen from Carassius auratus skin (P < 0.05). After ultrasonic treatment at 200 W for 1 min, the NIH/3T3 cell proliferation capacity of the collagen was increased by 10.1%. In conclusion, moderate sonication can promote the self-assembly process of collagen from Carassius auratus skin, and effectively improve its structure and physicochemical properties. This study suggests that ultrasonic treatment is an effective modification method for collagen from Carassius auratus skin.
Effect of Vacuum Treatment Combined with Soybean Protein Isolate-Based Composite Cryoprotectant on the Quality of Quick-Frozen Dumpling Stuffing
ZHANG Yanyan, WANG Wentao, ZHANG Zhongyi, CHAI Ying, LIU Xingli, WANG Hongwei, ZHANG Hua
2020, 41(19):  105-110.  doi:10.7506/spkx1002-6630-20190903-030
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In this paper, the effects of vacuum treatment combined with soybean protein isolate (SPI)-based composite cryoprotectant on the moisture distribution, freezeable water content and microstructure of quick-frozen dumpling stuffing were studied. The results showed that 60 min vacuum treatment combined with the cryoprotectant had the best effect on improving various indicators of meat stuffing during frozen storage. On day 90 of frozen storage, the thawing loss rate and thiobarbituric acid reactive substances (TBARS) value of the combined treatment group decreased by 61.3% and 85.8% compared with those of the control group without any treatment; by only 39.3% and 3.3% compared with those of the single cryoprotectant treatment group, respectively. The combined treatment significantly improved the hardness, elasticity, chewiness and cohesiveness of meat stuffing, and increased the content of weakly bound water of 16.1% and 2.4% compared with the control and single cryoprotectant treatment groups, respectively. The combined treatment reduced the size of ice crystals in frozen meat stuffing, the length of most ice crystals being less than 10 μm in this treatment group, and protected the microstrcuture of meat stuffing from damage during frozen storage. In conclusion, the combined treatment could improve the water-holding capacity and texture of meat stuffing, delay fat oxidation, and protect the microstrcuture of meat stuffing from damage during frozen storage, thereby improving the quality of quick-frozen dumpling stuffing.
Effect of Superfine Grinding on Physicochemical Properties and Functional Properties of Four Kinds of Coarse Cereals
WANG Bo, YAO Yijun, LI Zhifang, WANG Lifeng
2020, 41(19):  111-117.  doi:10.7506/spkx1002-6630-20190912-150
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In this paper, four kinds of common coarse cereals in China (adlay, red bean, hulless barley, and buckwheat) were superfinely ground using a jet mill, and evaluated for their physicochemical properties (particle size distribution, solubility, microscopic morphology) and functional properties (cation exchange capacity, glucose absorption capacity, anti-pancreatic lipase activity, oil-holding capacity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity). The results showed that superfine grinding had significant effects on the physicochemical properties and functional properties of the four kinds of coarse cereal flours. Superfine buckwheat flour had the highest solubility, up to 52.4% at 90 ℃, and showed the most significant morphological changes under scanning electron microscope (SEM). Moreover, the glucose absorption capacity (GAC) of superfine buckwheat flour was 0.256 mmol/g under the condition of 100 mmol/L glucose concentration, which increased by 30.0% compared with that of coarse buckwheat four. The DPPH radical scavenging capacity of superfine buckwheat flour was 94.1%, which was higher than that of coarse buckwheat flour and showed the most significant change among the four kinds of coarse cereals. In terms of anti-pancreatic lipase activity and oil holding capacity, superfine grinding had the greatest influence on hulless barley flour, resulting in an increase in the two parameters of 18.5% and 26.3% compared with coarse grinding, respectively. Therefore, superfine grinding had significant effects on the physicochemical properties and functional properties of coarse cereal flours, and the properties of buckwheat and hulless barley flours varied most significantly after superfine grinding.
Effect of Multi-Stage Far-Infrared Radiation-Assisted Heat Pump Drying on the Quality Characteristics of Longan
PENG Jian, WANG Weijie, TANG Daobang, WEN Jing, LI Lu, YANG Wanyuan, WU Jijun, YU Yuanshan
2020, 41(19):  118-123.  doi:10.7506/spkx1002-6630-20191020-210
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The influence of multi-stage far-infrared radiation-assisted heat pump drying versus heat pump drying on the textural characteristics, microstructure, browning degree, color, soluble sugar content, free amino acid contents and 5-hydroxymethylfurfural (5-HMF) content of longan was evaluated. The results indicated that the combined drying method could reduce the hardness, improve the springiness and chewiness (P < 0.05) and enhance the porosity of dried longan when compared with heat pump drying. The color change after drying mainly originated from the decrease of L* (turning darker) and the increase of a* (turning yellow), while far-infrared radiation at 60 ℃ coupled with heat pump drying could inhibit the browning effectively. Furthermore, the contents of soluble sugar, free amino acids and 5-HMF could affect the color of dried longan. Notably, when the far-infrared radiation temperature was 100 ℃, the contents of soluble sugar and free amino acids decreased, while the content of 5-HMF increased significantly (P < 0.05). The present study confirmed that multi-stage far-infrared radiation-assisted heat pump drying could improve the quality of dried longan, and the Maillard reaction was the major cause of the color change during the drying process.
Effect of Atmospheric Pressure Plasma Jet on Structural and Rheological Properties of Chicken Myofibrillar Protein
LI Ke, LI Yan, KANG Chaodi, XIANG Qisen, ZHAO Dianbo, BAI Yanhong
2020, 41(19):  124-131.  doi:10.7506/spkx1002-6630-20190916-202
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To evaluate the effect of atmospheric pressure plasma jet (APPJ) on the structure and rheological properties of chicken myofibrillar proteins (MP), MP samples were treated by APPJ for different durations (0, 10, 20, 30 and 40 s) and then measured for their pH, turbidity, particle size, solubility, protein composition, structural and rheological properties. The results showed that as APPJ treatment time prolonged, the pH and solubility of MP were gradually decreased, and the turbidity and particle size were significantly increased (P < 0.05). APPJ treatment increased the storage modulus (G’) and loss modulus (G’’) at each elevated temperature and angular frequency. Reduced and non-reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the composition and molecular mass of MP were not changed. In addition, the total content of disordered secondary structures (β-turn and random coil) in MP were increased, while the total content of ordered secondary structures (α-helix and β-sheet) were reduced. The tertiary and quaternary structures of MP were also changed by APPJ. The surface hydrophobicity was increased, and the content of free sulfhydryl groups was increased firstly and then decreased. In summary, APPJ can modify the physicochemical properties and structure of chicken MP, and improve the rheological properties, thereby affecting MP function and muscle quality.
Effect of Different Drying Methods on Chemical Composition, Antioxidant and Antibacterial Activities of Essential Oils from Buds of Magnolia wufengensis
CHENG Jiali, MA Jiang, XIAO Aihua, ZHU Zhonglong, SANG Ziyang, MA Lüyi
2020, 41(19):  132-139.  doi:10.7506/spkx1002-6630-20190905-074
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In order to investigate the effect of drying methods for flower buds on the extraction, antioxidant and antibacterial activities of essential oil from Magnolia wufengensis, essential oils from the flower buds of Magnolia wufengensis ‘Jiaohong 1’ dried by freeze drying, shade drying, sun drying or oven drying at 55 ℃ were obtained by supercritical CO2 fluid extraction and analyzed for chemical composition by using gas chromatography-mass spectrometry (GC-MS) combined with retention index (RI). Furthermore, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging and reducing power assays were used to evaluate the antioxidant activity of the essential oils. Disk diffusion method was used to measure the antibacterial activity. The results indicated that the highest essential oil yield was obtained from the freeze-dried sample, up to (2.736 ± 0.138)%, and in total 49 compounds were identified in the essential oils from the four dried samples, among which, 26 compounds were found to be present in the essential oil from the freeze-dried sample, the most abundant being γ-sitosterol and 4H-xanthalongia; and 20, 20 and 30 compounds in the essential oils from the sun-dried, oven-dried and shade-dried samples, respectively, the most abundant being γ-sitosterol and hydrocarbon. The antioxidant activity of the four essential oils was in the decreasing order of freeze drying > shade drying > sun drying > oven drying, all of which had broad-spectrum antibacterial activity. In general, freeze drying is the best pretreatment method for extracting essential oils from the buds of M. wufengensis.
Effect of Steam Explosion on Physicochemical Characteristics of Bovine Bone
Zhang Shuqing, Liu Shengyong, MA Peng
2020, 41(19):  140-145.  doi:10.7506/spkx1002-6630-20190903-043
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Objective: This study aimed to explore the effect of steam explosion on the physicochemical properties of bovine bones for the purpose of providing a new method for beef bone processing. Methods: Steam explosion was applied to treat bovine bone to investigate the granularity, hardness, and protein, calcium and phosphorus contents of the treated samples as a function of pressure and holding time. Five levels were selected for either processing parameter, and they were combined to form 25 experiments. The treated samples were analyzed by a texture analyzer, Fourier transform infrared spectrometer (FTIR), and a Kjeldahl analyzer. Results: Bone hardness decreased with increasing either pressure or holding time. The amounts of protein and calcium released from bones increased markedly (P < 0.05). In particular, steam explosion under the condition of high pressure or long holding time accelerate the loss of inorganic matters and protein, weakened bone strength, fragmented bones, and enhanced the release of calcium ions. As the pressure or holding time increased, the FTIR spectrum of the treated bovine bones was increasingly similar to that of hydroxyl apatite, and the intensity of C–H bond vibrations decreased indicating that steam explosion causes significant loss of organic components from bovine bones. Conclusion: Steam explosion is useful as a pretreatment approach for the preparation of deeply processed bovine bone products and hydroxyl apatite for high-efficiency utilization of bovine bones.
Effect of High Pressure Homogenization on Soybean Protein Isolate-Soybean Isoflavone Interaction and Functional Properties of Their Complex
WANG Na, WU Changling, CHEN Fanfan, LI Yang, TENG Fei
2020, 41(19):  146-153.  doi:10.7506/spkx1002-6630-20190929-344
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In order to find out the effect of high pressure homogenization on the interaction between soybean protein isolate (SPI) and soybean isoflavone (SI) and the functional properties of their complexes and to determine the best treatment conditions, complexation between 10 mg/mL SPI and 0, 0.2 or 2 mg/mL SI was triggered using different homogenization pressures. The conformational differences among the resulting composites were analyzed by ultraviolet spectroscopy (UVS), fluorescence spectroscopy (FS) and Fourier transform infrared spectroscopy (FTIR). Their hydrodynamic radius and functional properties were characterized by their particle size, zeta potential, solubility and hydrophobicity. The results showed that the fluorescence quenching of SPI by SI was static as evaluated by FTIR. When the pressure was 80 MPa and the SI concentration was 0.2 mg/mL, the particle size distribution was stable, and the absolute value of zeta potential, solubility, and hydrophobicity were remarkably improved (P < 0.05). UVS and FTIR indicated that the microenvironment near tryptophan residues in SPI was more hydrophilic and the secondary structure of SPI was changed.
Nutrition & Hygiene
Influence of Epigallocatechin Gallate on the Regulation Effect of L-Theanine on Serum and Intestinal Free Amino Acids in Mice
PENG Yingqi, YUAN Dongyin, LIN Ling, GONG Zhihua, SUN Hongbo, WANG Heng, WANG Songbai, XIAO Wenjun
2020, 41(19):  154-160.  doi:10.7506/spkx1002-6630-20190829-325
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To explore the influence of epigallocatechin gallate (EGCG) on the regulatory effect of L-theanine on free amino acids in the serum and intestine of mice, 50 Kunming male mice were equally and randomly divided into normal group, L-theanine group, EGCG group, instant green tea group and L-theanine + EGCG group (n = 10). The animals were administered intragastrically with the corresponding drugs or distilled water for 28 days. The results showed that compared with the normal group, the concentration of some non-essential amino acids in the serum and the contents of free amino acids in the duodenum were increased, and the contents of most free amino acids in the jejunum and ileum were decreased in the EGCG group (P < 0.05). Instant green tea increased the concentration of some non-essential amino acids in the serum and most free amino acids in the duodenum and jejunum, and decreased the contents of most free amino acids in the ileum (P < 0.05). The concentration of some essential and non-essential amino acids in the serum and most free amino acids in the ileum were decreased in the L-theanine and L-theanine + EGCG groups, while the contents of most free amino acids in the duodenum and jejunum were increased. The contents of most free amino acids in the small intestine were higher in the L-theanine + EGCG group than in the L-theanine and EGCG groups (P < 0.05). Therefore, combined intervention with L-theanine and EGCG is more beneficial to increase the content of free amino acids and promote intestinal absorption and utilization of amino acids than either alone.
Protective Effect and Mechanism of Prunella vulgaris Honey Extract on Dextran Sulfate Sodium-Induced Injury in Caco-2 Cells
WAN Zhengrui, LI Qiangqiang, WANG Kai, WU Liming
2020, 41(19):  161-169.  doi:10.7506/spkx1002-6630-20190926-321
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Purpose: The aim of this study was to reveal the protective effect and underlying mechanism of Prunella vulgaris honey (PVH) extract on dextran sulfate sodium (DSS)-induced human colon epithelial cell (Caco-2) injury at cellular and molecular levels. Methods: The contents of total polyphenols and flavonoids in PVH and acacia honey (AH) as a control were determined by Folin-phenol reagent method and aluminum nitrate method, respectively. 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, 50% maximum inhibitory concentration (IC50), and ferric ion reducing antioxidant power (FRAP) were used to evaluate in vitro antioxidant activity of the two honeys. Then, the protective effect of PVH on ulcerative colitis in rats was studied using a rat model of DSS-induced ulcerative colitis by real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting and Transwell migration analysis. Results: The contents of total phenolic acid and total flavonoids in PVH were respectively (52.4 ± 0.4) and (7.0 ± 0.3) μg/g. PVH extract at concentrations of 50–100 μg/mL could significantly alleviate the decrease of cell viability caused by 2.5% (V/V) DSS treatment. Based on RT-qPCR analysis, PVH significantly up-regulated the mRNA expression of antioxidant cytokine genes such as NQO-1, Txnrd1 and Nrf2 and tight junction gene such as ZO-1. Based on immunofluorescence analysis, PVH extract could protect the key tight junction protein ZO-1 in Caco-2 cell monolayers against DSS-induced damage. In addition, PVH extract could significantly up-regulate the expression of antioxidant proteins such as NQO-1, Txnrd1 and Nrf2 as evaluated by Western blot assay. Conclusion: PVH has great potential for development and utilization in alleviating DSS-induced damage to the barrier function of intestinal epithelial cells.
1-Deoxynojirimycin Promotes Hepatocyte Mitochondrial Biosynthesis and Mitophagy in Obese Mice
LI Siyuan, NING Junli, DING Xiaowen, HUANG Xianzhi
2020, 41(19):  170-178.  doi:10.7506/spkx1002-6630-20190923-275
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Mitochondria play an important role in regulating lipid metabolism as an important place for energy metabolism. This study investigated the effect of 1-deoxynojirimycin (DNJ) on mitochondrial synthesis and mitophagy in the hepatocytes of obese mice. An obese mouse model was established by feeding Kunming a high-fat diet, and then the obese mice were administered with DNJ at doses of 8.0, 4.0 and 2.0 mg/(kg mb·d) for 45 days. At the end of this period, serum and liver parameters were determined. The results showed that compared with the obese control group, high-dose DNJ could delay body mass gain, mitigate inflammation, significantly increase?serum adiponectin?by 43.19% and 29.58% (P < 0.01) in female and male mice. In addition, it could increase?fibroblast growth factor 21 (FGF21) in female mice by 37.03% (P < 0.01), and improve FGF21 resistance in male mice. Also it could upregulate the mRNA expression of adenosine 5’-monophosphate (AMP)-activated protein kinase (AMPK) α1 as well as the mRNA expression of peroxisome proliferator activated receptor γ coactivator-1α, nuclear respiratory factor 1 and unc-51 like kinase 1, all related to mitochondrial biosynthesis, to increase the corresponding protein levels by 28.27% and 43.99% (P < 0.01), 50.25% and 40.26% (P < 0.01), and 19.24% and 22.76% (P < 0.05) in female and male mice, and increase carnitine palmitoyltransferase1 activity by 58.05% and 49.60% (P < 0.05) in female and male mice, respectively. Conclusion: DNJ can control body mass by reducing inflammation, improving FGF21 and adiponectin levels, upregulating the mRNA expression of AMPKα1 to promote mitochondrial biosynthesis and autophagy and simultaneously activating the fatty acid oxidation rate-limiting enzyme, carnitine palmitoyltransferase 1 to promote fatty acid breakdown.
Effect of Theasaponin on Blood Glucose in Streptozocin-Induced Diabetic Rats
LIU Zhijun, LIN Ling, LEI Zhengyan, ZENG Wenzhi, CHENG Fujian, LIN Quannü, YANG Jiangfan
2020, 41(19):  179-184.  doi:10.7506/spkx1002-6630-20190624-283
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Objective: To investigate the hypoglycemic effect of theasaponin on a type 2 diabetic rat model. Methods: The rat model was established by feeding of a high-fat diet combined with intraperitoneal injection of streptozotocin (STZ). Fasting blood glucose, glucose tolerance, and blood lipids were measured after 40 days of continuous administration of theasaponin. Liver function and other related indicators were observed. Results: Theasaponin could effectively regulate hyperglycemia and dyslipidemia in type 2 diabetic rats, and significantly improve serum total cholestrol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels (P < 0.01). Furthermore, it could significantly decrease the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum (P < 0.01) and repair the morphology of islet and liver tissue in diabetic rats. Conclusion: Theasaponin at a certain dose (50–150 mg/(kg mb·d)) has obvious hypoglycemic effects on the STZ-induced type 2 diabetic rat model.
Protective Effect and Mechanism of Inonotus obliquus Polysaccharide on Blood Lipids and Liver in Hyperlipidemia Rats Induced by High-Fat Diet
CUI Jingai, WANG Siji, LIU Chang, YU Ting, CHEN Xiaoping
2020, 41(19):  185-190.  doi:10.7506/spkx1002-6630-20191015-147
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Objective: To investigate the intervention effect of Inonotus obliquus polysaccharide (IOP) on liver disease in hyperlipidemic rats by measuring serum lipid content, antioxidant defense indices, liver damage and fatty acid synthase activity. Methods: Forty male Sprague-Dawley (SD) rats were randomly divided into normal control, hyperlipidemia model and low-, medium- and high-dose IOP groups. Commercial kits were employed to determine the following blood lipid parameters: total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL); antioxidant indices: superoxide diamutase (SOD), malondialdehyde (MDA) and glutathion peroxide (GSH-Px); liver injury indices: alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and fatty acid synthetase (FAS) and human hydroxymethylglutaryl CoA reductase (HMGCR). Results: Compared with the high-fat group, high-dose (200 mg/kg mb) of Inonotus obliquus polysaccharide has a significant effect on reducing blood lipid levels in rats and protecting liver from damage. And the dose group TC, TG, LDL decreased significantly, HDL increased significantly, MDA content decreased, SOD, GSH-Px activity increased, FAS and HMGCR activity decreased significantly. Conclusion: Polysaccharide from Inonotus obliquus can protect against lipid disorders, liver damage in rats with hyperlipidemia caused by high-fat diet, may be related to its antioxidant effect.
Effect of Lactobacillus acidophilus on Regulating the Production of Immune Factors in HT-29 Cells under Initial Weak Acidic and Alkaline Conditions
ZHANG Qiuyue, WANG Gang, CHEN Kunpeng, PAN Daodong, ZENG Xiaoqun, WU Zhen, GUO Yuxing
2020, 41(19):  191-197.  doi:10.7506/spkx1002-6630-20191110-108
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In order to investigate the immunomodulatory effects of Lactobacillus acidophilus on human intestinal cells, Lactobacillus acidophilus, showing different adhesion characteristics when cultured at pH 5.5 and 7.5, were co-cultured with human colon cancer HT-29 cells, and the changes of immune factors in HT-29 cells were determined. The relative gene expression levels of heat shock protein (Hsp) 70, interleukin (IL)-8, IL-10, nuclear factor κB (NF-κB), Toll-like receptor 4 (TLR-4) and tumor necrosis factor-α (TNF-α) were detected by reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR), and enzyme-linked immunosorbent assay (ELISA) was applied to determine the protein expression levels of IL-8, IL-10 and TNF-α. RT-qPCR results showed that after the co-cultivation of HT-29 cells and Lactobacillus acidophilus at either pH, at the transcriptional level, Hsp70 and TNF-α were significantly up-regulated, while IL-8, NF-κB and TLR-4 were significantly down-regulated when compared with the blank control cells without the presence of Lactobacillus acidophilus (P < 0.01). The gene expression levels of Hsp70, IL-10 and TNF-α were significantly up-regulated in the pH 7.5 group when compared with the pH 5.5 group; meanwhile, NF-κB and TLR-4 were significantly down-regulated (P < 0.05). The ELISA results showed that under both pH conditions, the TNF-α expression level in HT-29 cells was significantly higher than that in the blank control group, while the concentration of pro-inflammatory factor IL-8 was significantly decreased; the anti-inflammatory factor IL-10 in the pH 7.5 group was significantly higher than that in the pH 5.5 group (P < 0.01). In summary, Lactobacillus acidophilus under weak acidic and weak alkaline intestinal conditions can promote the immunity of intestinal cells, and the weak alkaline condition with pH 7.5 is more effective than the weak acidic intestinal environment with pH 5.5, which can significantly enhance the immunoregulatory effect of Lactobacillus acidophilus on the intestinal tract, thereby helping maintain intestinal health.
Mulberry Leaf Alkaloids Improve D-Galactose-Induced Oxidative Damage in the Mouse Kidney
YANG Zhongmin, SHEN Yihong, WANG Zuwen, HUANG Xianzhi, DING Xiaowen
2020, 41(19):  198-203.  doi:10.7506/spkx1002-6630-20190816-179
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Objective: To explore whether mulberry leaf alkaloids can improve oxidative damage in the kidney of mice for the purpose of providing a theoretical basis for the development and utilization of mulberry leaf alkaloids. Methods: A mouse model of renal oxidative damage was induced by D-galactose (D-Gal) and the model mice were administered with different doses of mulberry leaf alkaloids for 4 consecutive weeks. At the end of the 4th week, the levels of protein carbonyl (PCO), advanced oxidation protein products (AOPP), 8-iso-prostaglandin F2α (8-iso-PGF2α), 8-hydroxy-2’-desoxyguanosine (8-OH-dG) and 5-hydroxy-2’-deoxycotosine (5-OH-dC), and the activity of total superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), reduced nicotinamide adenine dinucleotide phosphate oxidase (NOX), and protein kinase C (PKC) in the kidney was measured. Results: Compared with the model control group, high-dose mulberry leaf alkaloids (200 mg/kg mb) could reduce the protein oxidation products PCO and AOPP in the kidney tissues of mice by 37.27% and 42.71%, respectively (P < 0.01), the lipid oxidation product 8-iso-PGF2α by 51.07% (P < 0.01), and the DNA oxidation products 8-OH-dG and 5-OH-dC by 31.66% and 18.91%, respectively (P < 0.01); increase the activity of antioxidant enzymes SOD and GSH-Px by 83.74% and 59.31%, respectively; and decrease NOX and PKC activity by 41.21% and 40.65%, respectively (P < 0.01). Conclusion: Mulberry leaf alkaloids have a good effect on improving D-Gal-induced oxidative damage in the mouse kidney, and the underlying mechanism may be related to increasing the activity of SOD and GSH-Px and inhibiting the activity of NOX and PKC, thereby reducing the overproduction of reactive oxygen species (ROS) in the body.
Extraction of Polysaccharides from Fruiting Bodies of Phellinus igniarius and Its Protective Effect on D-galactose Induced 3T3 Cell Injury
HU Xiaotong, YE Yujie, SHI Guang, ZHAO Nanxi, GU Mingliu, YAN Yuning, ZHOU Jianing, AN Liping
2020, 41(19):  204-211.  doi:10.7506/spkx1002-6630-20190906-078
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This study was aimed to optimize the extraction process for polysaccharide from the fruiting bodies of Phellinus igniarius and to explore the antioxidant activity in vitro of the polysaccharide and its protective effect on D-galactose (D-gal)-induced mouse embryonic fibroblast (3T3) cell injury. The extraction was performed by the traditional method of water extraction followed by alcohol precipitation. The extraction process was optimized by a combination of single factor and orthogonal array design experiments. The crude polysaccharide was purified by agarose gel column chromatography. The effect of the purified polysaccharide on D-gal-induced 3T3 cell injury model was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide-thiazolyl blue tetrazolium bromide (MTT) assay and senescence-associated-β-galactose (SA-β-gal) staining, and its effect on the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and catalase (CAT) activity in the cell culture supernatant was determined. The mRNA expression levels of the genes related to the nuclear?factor?erythroid-2-related factor 2-antioxidant responsive element (Nrf2-ARE) signaling pathway in senescent cells were determined by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the optimal extraction conditions were as follows: extraction temperature 80 ℃, extraction time 3 h, solid-to-solvent ratio 1:40, and four extraction cycles. The average yield of polysaccharide was 6.64%. After purification, the polysaccharide content was 76.28%. The polysaccharide showed antioxidant activity in terms of scavenging rates for 1,1-diphenyl-2-picrylhydrazyl radical (DPPH, 77.14%), superoxide anion radical (31.22%) and hydroxyl radical (56.86%). MTT assay showed that compared with the model group, the cell survival rate was significantly increased by the polysaccharide at a concentration of 100 μg/mL (P < 0.01). The results of SA-β-gal staining also showed that the polysaccharide could significantly increase the survival rate of the model cells (P < 0.05), and protect 3T3 cells from D-gal-induced injury. Compared with the model group, the polysaccharide reduced ROS levels (P < 0.05) in 3T3 extracellular fluid, significantly decreased MDA levels (P < 0.01), and increased CAT activity (P < 0.05). Compared with the model group, the mRNA expression of the three downstream genes in the Nrf2 signaling pathway GCLC, NQO1 and GCLM were significantly increased in the polysaccharide-treated group (P < 0.05). In conclusion, the optimized extraction process is stable and reliable. The polysaccharide from P. igniarius fruiting bodies has antioxidant activity, cell proliferation activity, and protective effect on D-gal-induced 3T3 cell damage. The antioxidant mechanism of the polysaccharide may be mediated by the Nrf2 signaling pathway, associated with enhancing the mRNA expression of GCLC, NQO1 and GCLM.
Packaging & Storage
Differential Proteomic Analysis of the Response of Straw Mushrooms (Volvariella volvacea) to Cold Stress
WU Zhiliang, HUANG Ying, WANG Zejin
2020, 41(19):  212-220.  doi:10.7506/spkx1002-6630-20190829-322
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In order to explore the mechanism of the response of straw mushroom (Volvariella volvacea) to cold stress, the fruit body of straw mushroom was analyzed for differentially expressed proteins after cold stress treatment using isobaric tag for relative and absolute quantitation (iTRAQ) proteomic technology. A total of 2 455 proteins were quantitated including 332 differentially expressed proteins, 64 of which were up-regulated while the remaining 268 were down-regulated. Gene ontology analysis indicated that the differentially expressed proteins were involved in cellular and metabolic processes, and related to molecular functions such as binding and catalytic activity. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis showed that the differentially expressed proteins were associated with 57 specific KEGG pathways. Using clusters of orthologous groups of proteins (COG) analysis, 328 differentially expressed proteins were annotated and classified into 22 COG functions. Moreover, the metabolic processes in which the differentially expressed proteins were involved in response to cold stress were very complicated, which were associated with energy metabolism, hydrolase activity, trehalose metabolism, amino acid metabolism, aminopeptidase activity, mitogen-activated protein kinase signaling pathway, active oxygen metabolism, membrane lipids metabolism, and so on. Quantitative polymerase chain reaction (qPCR) was used to validate the differential expression of glyceraldehyde-3-phosphate dehydrogenase and NADH-quinone oxidoreductase genes. The transcription levels of these genes were consistent with their protein expression levels. These results provide a theoretical basis for further investigating the response mechanism of the straw mushrooms to cold stress.
Antifungal Activity and Mechanism of ε-Polylysine against Geotrichum citri-aurantii
Xiao Yuan, PAN Zhaoping, Yin Chunxiao,, Su Jin,, hu xiao,, Zhu Xiangrong, Shan Yang, Fu Fuhua
2020, 41(19):  221-229.  doi:10.7506/spkx1002-6630-20190824-258
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Epsilon-polylysine (ε-PL) is a safe and biodegradable natural food preservative without any adverse effects on the environment or human health. The antifungal activity and mechanism of ε-PL on Geotrichum citri-aurantii were investigated in this study. The mycelium growth inhibition rate, spore germination inhibition rate, extracellular relative electric conductivity and absorbance at 260 nm (A260 nm) value of Geotrichum citri-aurantii were determined after being treated with ε-PL. Additionally, laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM) were used to study the effects of ε-PL treatment on the cell membrane integrity and mycelium morphology of Geotrichum citri-aurantii, respectively. The results showed that the minimum inhibitory concentration (MIC) was 400 mg/L, and the half maximal effective concentration (EC50) for inhibiting mycelium growth and spore germination were 128.79 and 214.77 mg/L, respectively. When used at concentrations of 1 600, 3 200 and 6 400 mg/L, ε-PL significantly lowered the incidence of sour rot and lesion diameter in citrus fruit with stab inoculation compared to the control fruit (P < 0.05). After being treated with ε-PL at 1 × MIC and 2 × MIC, extracellular relative electric conductivity, A260 nm and fluorescence intensity were significantly increased relative to the control group (P < 0.05), which indicated increased cell membrane permeability, thereby leading to the leakage of intracellular components such as nucleic acids and causing damage to the integrity of the membrane. Furthermore, ε-PL treatment induced severe distortion and disruption of the mycelia of Geotrichum citri-aurantii. Therefore, ε-PL can destroy the structure of the cell membrane, causing the leaking of intracellular contents and distortion of the mycelia, retarding spore germination, and thus inhibiting the growth and development of Geotrichum citri-aurantii.
Ultrasonic Treatment for Improved Properties of Soybean Protein Nanocomposite Packaging Film and Its Application in Preservation of Cherry Tomatoes
ZHAO Xiaotong, XU Lina, ZHANG Hong, ZHANG Huajiang, XIA Ning, ZHANG Yinglong, SUN Rui, CHEN Xiaoying
2020, 41(19):  230-237.  doi:10.7506/spkx1002-6630-20190903-040
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In this study, soybean protein isolate (SPI), polyvinyl alcohol (PVA) and nanocellulose (NCC) were selected as the main raw materials to prepare nanocomposite films. Based on tensile strength, elongation at break, water vapor permeability, oxygen permeability, carbon dioxide permeability and light transmittance, the optimum preparation conditions were obtained using single factor experiments as follows: SPI concentration 3.0%, ratio of PVA to NCC 1:2, ultrasonic power 40 W, sonication time 20 min, and temperature 60 ℃. The as-prepared composite film had good packaging properties. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM) and contact angle analysis showed that the surface of this film was smoother and its internal reticular structure was denser than that of pure SPI film and the composite film without ultrasonic treatment. The ultrasonic-treated composite film could effectively maintain the hardness, moisture, soluble solids and VC contents of cherry tomatoes during storage, thereby extending its shelf life, indicating that this nanocomposite film, with excellent packaging performance, has potential application prospects in the preservation of fruits and vegetables.
Performance of Covalent Organic Framework and Its Application in Food Safety Detection: A Review
LIU Jingyi, ZHAO Haitian, YAO Lei
2020, 41(19):  238-244.  doi:10.7506/spkx1002-6630-20191012-089
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Covalent organic frameworks (COFs) are an emerging porous organic material. Due to its excellent performance, high specific surface area, structural regularity, low density, functionalizability and high stability, COFs have been widely used in gas storage, catalysis, optoelectronics, separation and drug delivery. This paper mainly reviews the material properties of three major types of COFs: boron-containing COFs, striazine COFs and imine COFs, and their advantages and limitations in practical applications. It also summarizes recent progress in the application of COFs in the analysis of toxic and hazardous substances in foods, with a focus on the typical substances such as antibiotics, biotoxins, and additives, in order to provide a theoretical reference for promoting the application of COFs in new technologies for food safety detection.
Recent Progress in Sonodynamic Technology in the Field of Food Sterilization
QIU Jianqing, LI Shiyang, YE Qianwen, LIN Shaoling, ZENG Shaoxiao, HU Jiamiao
2020, 41(19):  245-252.  doi:10.7506/spkx1002-6630-20191008-018
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In recent years, pathogenic infections related to the consumption of unhygienic foods have frequently occurred. Foodborne pathogens are not only seriously hazardous to human life, but also they hinder the development of food, medical and other related industries. Although the traditional sterilization methods can effectively kill pathogenic bacteria, they are often time-consuming and labor-intensive, especially for the food industry, they can damage the texture and flavor of foods. Besides, the emergence of drug-resistant pathogens due to antibiotics abuse poses a severe challenges to human beings. Continued scientific efforts have been made to explore better sterilization solutions. Sonodynamic sterilization technology is a new type of non-thermal sterilization technology, which has attracted much attention due to the advantages of being fast and safe, strong penetrability and good biological inactivation effect. This article summarizes the mechanism of sonodynamic sterilization technology, and analyzes the influence of sonosensitizer, ultrasonic and other factors on acoustic power sterilization as well as recent progress in this regard, which may provide a theoretical rationale for the application of sonodynamic sterilization technology in the food safety area.
Recent Progress in Research on Bioactive Components and Starch of Lepidium meyenii
LI Xue, SUO Keke, ZHANG Xiaomiao, YI Juanjuan, ZHU Jiaqing, ZHANG Liming, KANG Qiaozhen, HAO Limin, LU Jike
2020, 41(19):  253-262.  doi:10.7506/spkx1002-6630-20200429-382
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Maca (Lepidium meyenii) is a culinary and medicinal herb belonging to the Brassicaceae family. Maca originates in the high plateaus of the Andes of Peru, and now it has been introduced successfully in Yunnan and other places in China. Maca has been approved as a new food resource and contains lots of bioactive compounds, including polysaccharides, alkaloids, glucosinolates, sterols, and flavonoids. These compounds show a variety of biological activities, such as anti-fatigue, antioxidant, immunoregulatory, fertility-promoting, endocrine regulatory and anti-tumor effects. Maca tubers are also rich in nutrients such as protein, starch and amino acids. This paper briefly reviews the current status of studies on the extraction, purification, quantitative analysis and evaluation of bioactive components in Maca and of studies on Maca starch, which is expected to provide reference for further research and utilization of Maca.
Advances in Bacterial Cellulose in the Study of the Structure and Function of Plant Cell Wall
LI Zhaofeng, CAO Xiao, ZHU Jie, CHEN Siqian, LI Lin
2020, 41(19):  263-271.  doi:10.7506/spkx1002-6630-20190929-349
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Plant cell wall is the main source of dietary fiber for humans, which affects the taste of and nutrition absorption from plant-derived food products. The cell wall components are complex, and hence there are certain difficulties in exploring its structure. Bacterial cellulose produced by Komagataeibacter xylinus can form composites with various cell wall polysaccharides that can be used to establish plant cell wall models. The advantages of this model include: 1) high purity, 2) feasible characterization of its macro-mechanical and rheological properties and 3) its self-assembly process is similar to the formation of plant cell wall. The plant cell wall model based on bacterial cellulose has been used to study the structures and interactions of cell wall polysaccharides, and also has been applied to theoretical studies in the field of food science such as investigating dietary fiber digestion characteristics and cell wall adsorption of polyphenols. These studies are of great importance for understanding the process of human digestion, and are also valuable for the development of high-quality plant food products. This paper briefly summarizes the composition and structure of plant cell wall, and provides a detailed review of bacterial cellulose and recent advances in its application in the theoretical research of plant food raw materials.
Recent Advances in Analytical Methods for Polysaccharides from Edible Mushroom
SHAO Shuangyu, SI Xiali, ZHANG Yansong, TU Pengfei, ZHANG Qingying
2020, 41(19):  272-280.  doi:10.7506/spkx1002-6630-20200512-140
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Edible mushroom has a long history of culinary and medicinal use in China, and polysaccharides have complex chemical structures and are recognized as the major functional constituents of edible mushroom. Currently, there are many methods available to analyze polysaccharides, and each has its own distinctive features. Recently, much new progress has been made in research on polysaccharides from edible mushroom using various analytical methods. However, the currently available methods to analyze edible mushroom polysaccharides have scarcely been systematically and comprehensively reviewed in the literature. Through a systematic retrieval from searches of databases such as Web of Science, PubMed, SciFinder Academic, and China National Knowledge Infrastructure (CNKI), we summarize the literature over the past 20 years describing methods for the extraction, isolation, purification, and qualitative and quantitative analysis of edible mushroom polysaccharides, and we present a comparative evaluation of the different methods, aiming to provide reference for in-depth studies on edible mushroom polysaccharides.
Advances in Understanding the Biotransformation of Deoxynivalenol and Its Masked Forms
TANG Yuqian, PAN Yaoyin, LIU Chendi, YANG Jiguo
2020, 41(19):  281-289.  doi:10.7506/spkx1002-6630-20190908-104
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Deoxynivalenol (DON) is one of the most widely distributed and most important trichothecenes in moldy grains. DON is metabolized by plants and microorganisms into various masked mycotoxins, and these transformations are usually incomplete, resulting in complex poisoning symptoms and thereby increasing the safety risk of cereal crops and their by-products. This paper mainly reviews the transformation patterns of DON by various organisms and their effects on the type, distribution and toxicity of its masked forms, which is expect to provide reference for future research on the degradation of DON and its masked forms.
Advances in Foodborne Microbial Biofilm Control Based on Bacteria Quorum Quenching
WANG Feifei, WU Haoyi, LIN Chen, ZHANG Yan, FU Linglin, WANG Yanbo
2020, 41(19):  290-295.  doi:10.7506/spkx1002-6630-20200425-328
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Foodborne pathogens and specific spoilage bacteria exist on the food surface and in food industrial environment in the form of biofilms, representing an important cause of food quality and safety problems. The foodborne microbial quorum sensing (QS) system is thought to play an important role in the development of biofilm formation. In this context, herein the regulatory role of the QS system in foodborne biofilm formation is scrutinized, and the current status of studies on quorum quenching (QQ) in the control of microbial biofilm formation and the mechanism of QQ is elaborated in detail. Moreover, an outlook on key future research directions on the control of foodborne microbial biofilms is given finally. This review aims to enrich the basic theory in the field of food quality and safety, and provide support for improving food quality and ensuring food safety.
A Review of the Development and Application of Graphite Phase Carbon Nitride in Sample Pretreatment Techniques for Food Analysis
MA Shuai, YOU Tianyan, WANG Kun, WANG Meng, PAN Ligang
2020, 41(19):  296-302.  doi:10.7506/spkx1002-6630-20191018-181
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As a new two-dimensional graphene analogue, graphitic carbon nitride (g-C3N4) shows great potential for separation science and sample pretreatment techniques. g-C3N4 has excellent properties such as ultra-high hardness, low density, good biocompatibility, surface modifiability and strong adsorption affinity. The structure and surface physicochemical properties of g-C3N4, related to its absorption behavior, are mainly depended on the preparation and adsorption conditions. The N-rich functional groups and electronic delocalization properties endow g-C3N4 with a complex absorption mechanism involving complexion, hydrogen bonding, redox reaction, π–π conjugation, hydrophobic effect, acid-base reaction and electrostatic interaction. At present, g-C3N4 has been applied in sample pretreatment techniques including solid-phase extraction, magnetic solid-phase extraction, and solid-phase microextraction for food analysis. In order to improve the knowledge of its superior properties and facilitate its applications as a sorbent in sample pretreatment for food analysis, the structure, properties, and adsorption mechanism of g-C3N4 are reviewed in this article.
Recent Advances in New Meat Thawing Technologies and Their Effects on Protein Properties
PENG Zeyu, ZHU Mingming, SUN Hongdong, HE Hongju, WANG Zhengrong, ZHAO Shengming, KANG Zhuangli, MA Hanjun
2020, 41(19):  303-310.  doi:10.7506/spkx1002-6630-20190920-259
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Thawing is an important pretreatment step for frozen meat before its processing. Selecting appropriate thawing method is crucial to ensure the quality of defrosted meat. Since traditional thawing methods have the disadvantages of long time consumption and causing quality deterioration, new efficient thawing technologies have been rapidly developed and applied to maintain meat quality. Quality attributes such as water-holding capacity will inevitably change during thawing, due to the damage to cells caused by ice crystals during freezing, as well as protein oxidation, conformational changes, and changes in aggregation properties. This article briefly summarizes the advantages and disadvantages of new thawing technologies and the latest advances in their applications in the field of meat products. Protein oxidation, and changes in protein conformation and aggregation characteristics are explored to reveal an association between protein oxidation and water-holding capacity in meat products. This review will provide reference for the application of new low-energy-consumption and high-efficiency meat thawing technologies.
Advances in Studies on the Regulation of Polysaccharides on Autophagy in Tumor Cells
XU Hanyu, LI Yuting, JIN Zhouyu, SONG Hui
2020, 41(19):  311-317.  doi:10.7506/spkx1002-6630-20190904-057
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In recent years, polysaccharides have become a research hotspot due to their demonstrated anti-tumor activity. Autophagy is a highly conserved self-degradation process where damaged organelles and macromolecules are degraded by lysosomes for reuse. Autophagy is closely related to the occurrence of various diseases such as tumors and neurodegenerative diseases. Abnormal autophagy occurs in tumor cells, and regulating it can be an important way to treat this class of diseases. Whether polysaccharides can affect tumor autophagy to achieve anti-tumor effect has become the focus of research on the anti-tumor activity of polysaccharides. This article summarizes the recent ten-year research on the regulation of polysaccharides on autophagy in tumor cells in China and abroad, with a focus on the effects of polysaccharides on the autophagy-related signaling pathways and the relationship between polysaccharides and autophagy in tumor cells.
Recent Progress in Understanding the Involvement of miRNA in the Protective Effect of Probiotics on Intestinal Barrier Function
LI Aili, ZHANG Xin, LI Ying, YANG Jiajie, MA Xiangyang, JIA Xindong, DU Peng
2020, 41(19):  318-326.  doi:10.7506/spkx1002-6630-20190911-146
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Previous studies have confirmed that probiotics colonizing the intestine can enhance intestinal barrier function by activating intestinal immunity, inhibiting abnormal apoptosis of intestinal epithelial cells, and regulating tight junction protein, thereby being beneficial to the health of the host. Latest studies demonstrate that as one of the important factors regulating host gene expression, non-protein-encoding small molecule RNA (microRNA or miRNA) is not only a monitor of intestinal barrier homeostasis, but also an important link between intestinal probiotics and the host. This article reviews the recent studies on the role of miRNA in probiotic protection of intestinal barrier function, and analyzes the mechanism of probiotics in promoting intestinal health at the molecular level, aiming to provide new theoretical support for the application of probiotics in the prevention and treatment of intestinal diseases.
Recent Advances in Preparation and Antimicrobial and Antioxidant Activity of Chitosan-Monosaccharides Maillard Reaction Products
QIU Tingting, TAN Xiao, LI Ruonan, ZHOU Lisha, ZHAO Yanyun, CHEN Shunsheng, ZHANG Hongcai
2020, 41(19):  327-333.  doi:10.7506/spkx1002-6630-20190911-138
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Aroma compounds from the Maillard reaction (MR) between protein and monosaccharide during food processing are widely applied in the field of foods. MR can also occur between chitosan and monosaccharide, and the resulting reaction products (melanoidins) have stronger antibacterial and antioxidant activity than chitosan. However, there are few studies worldwide in this regard. Thus, the objective of this article is to review the latest progress in the preparation of Maillard reaction products (MRPs) between chitosan and monosaccharide and their antibacterial and antioxidant activity, which will provide a theoretical basis for wide application the MRPs in the field of food processing and preservation.
A Review of Methods for Freshness Detection of Aquatic Products
MA Congcong, ZHANG Jiukai, LU Zheng, HAN Jianxun, XING Ranran, HAO Jianxiong, CHEN Ying
2020, 41(19):  334-342.  doi:10.7506/spkx1002-6630-20190930-370
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Freshness is one of the most important quality indicators of aquatic products. Accurately judging the freshness of aquatic products is not only an important measure to regulate the aquatic product market, but also a necessary trend to meet the increasing requirements of consumers for food quality and safety. Traditional sensory evaluation, and microbial, physicochemical and electrochemical assays have been widely used to evaluate the freshness of aquatic products. What’s more, in order to meet the requirements for sensitive, rapid and non-destructive detection of aquatic products freshness, some detection methods have been developed by integrating modern spectroscopy with mass spectrometry and/or other emerging technologies, which have the advantages of fast analysis, high repeatability, and accurate quantitation. This paper summarizes and analyses the commonly used methods for freshness detection of aquatic products with a focus on their advantages and disadvantages, and it gives an outlook on future trends in this area.