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15 May 2021, Volume 42 Issue 9
Basic Research
Preparation and Cytotoxicity of Acrolein-Alanine Adduct
ZOU Zhaojia, ZHENG Jie, HUANG Caihuan, LIU Fu, OU Shiyi
2021, 42(9):  1-6.  doi:10.7506/spkx1002-6630-20200410-141
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Acrolein (ACR) is a food toxin produced during thermal processing and shows high reactivity with amino acids to form adducts. However, the toxicity of the adducts is seldom investigated until now. In this study, ACR was reacted with alanine (Ala) at various molar ratios (2:1, 1:1, 1:2, 1:3 and 1:4) in a water bath at 37 or 50 ℃ for various durations (0.5, 3, 5 and 6 h). The highest yield of adduct was attained with an ACR to Ala ratio of 1:2 at 50 ℃ for 5 h. After separation and purification by reversed-phase silica gel column chromatography, the purity of the adduct reached more than 95%, and it displayed maximum absorption at 220 nm as determined by high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry. Analysis by high-resolution mass spectrometry and nuclear magnetic resonance (NMR) showed that the relative molecular mass of the adduct was 183.082 3, which was a nitrogen-containing six-membered ring compound formed by the Michael addition between one molecule of Ala and two molecules of ACR followed by an aldol condensation. After incubating human normal gastric mucosal cells (GES-1) for 24 and 48 h, it was found that the cytotoxicity of the adduct (with half maximal inhibitory concentration (IC50) of 3.286 and 0.869 mmol/L) was significantly lower than that of its parent toxin, ACR (with IC50 of 0.058 and 0.067 mmol/L). This finding indicates that Ala may act as a potential scavenger of ACR.
The Interaction of Various Factors Leads to Rapid Degradation of Chlorogenic Acid in Roasted Coffee Beans during Processing
LIU Xingyong, CHEN Xinglian, DU Lijuan, LIN Tao, YIN Benlin, YANG Dongshun, SHAO Jinliang, WANG Luxiang
2021, 42(9):  7-14.  doi:10.7506/spkx1002-6630-20200521-259
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In order to study the effect of roasting temperature, duration and pH on the degradation of chlorogenic acid in coffee beans during processing, Arabica green coffee beans were roasted to different degrees. Changes in the pH, mass loss, moisture content, and the contents of 3-O-caffeoylquinic acid (3-O-CQA), 5-O-caffeoylquinic acid (5-O-CQA), 4-O-caffeoylquinic acid (4-O-CQA) and three isochlorogenic acids of samples induced by roasting at different temperatures for different durations were analyzed. The degradation kinetics of 3-O-CQA, 4-O-CQA and 5-O-CQA was modelled and validated using chemical reaction models. The results showed that moisture content and mass loss rate of roasted coffee beans respectively decreased and increased with roasting temperature and duration. The 3-O-CQA content decreased significantly with roasting temperature and time (P < 0.05). Compared with raw coffee beans, the content of 4-O-CQA and 5-O-CQA increased firstly and then decreased with the temperature rises, but decreased significantly with roasting duration (P < 0.05). The contents of 5-O-CQA and 4-O-CQA were significantly negatively correlated with pH and roasting duration (P < 0.05), and 3-O-CQA content was significantly negatively correlated with roasting temperature and duration (P < 0.05) but significantly positively correlated with moisture content (P < 0.05). The interaction of roasting temperature and duration showed a very significant effect on the degradation of chlorogenic acid (P < 0.001). The thermal degradation of chlorogenic acid and its two isomers followed a first-order kinetic model. In the chemical reaction models, 3-O-CQA was converted into 5-O-CQA and 4-O-CQA, and the concentrations of all three compounds decreased significantly with increasing pH and temperature (P < 0.05). The interaction between temperature and pH had a significant effect on chlorogenic acid degradation (P < 0.001). In short, the interaction of roasting temperature, duration and pH can promote the rapid degradation of chlorogenic acid in roasted coffee beans.
Effects of Different Varieties of Peanuts on the Flavor and Quality of Peanut Butter
LIU Yulan, SHU Yao, SUN Guohao, MA Yuxiang, JIANG Yuanrong, CHEN Ning
2021, 42(9):  15-21.  doi:10.7506/spkx1002-6630-20200705-063
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The types and contents of volatile flavor components in peanut butters prepared from seven varieties of peanuts were identified, and their sensory evaluation, particle size, rheological properties, texture and color were measured to analyze the effect of peanut varieties on the flavor and quality of peanut butter. The results showed that the types and contents of volatile components in peanut butters prepared from different peanut varieties were quite different. Heterocyclics were detected at levels of 1.318–9.537 mg/kg in the seven peanut butter samples, including pyrazines (0.611–1.804 mg/kg), furans (0.256–4.300 mg/kg), pyrroles (0.013–4.066 mg/kg), pyridines (0.006–0.896 mg/kg) and other heterocyclic compounds (in lesser amounts); aldehydes (1.988–5.968 mg/kg), ketones (0.655–0.934 mg/kg), alcohols (0.155–1.189 mg/kg), phenols (0–1.570 mg/kg), and olefins (0–0.324 mg/kg) were also detected in these samples. Among them, ‘Silihong’ peanut butter had the highest pyrazine content, the highest sensory evaluation score, and the most recognizable flavor. The peanut butter samples contained 0.66%–0.86% moisture, 48.39%–57.17% crude fat and 21.93%–35.80% crude protein, and had acid values of 0.11–1.21 mg/g and peroxide values of 0.19–6.23 mmol/kg. Among them, ‘Silihong’ peanut butter had the lowest crude fat content and the highest crude protein content, as well as medium acid value and peroxide value. The median particle sizes of the seven peanut butter samples were 7.65–8.34 μm, and the median particle sizes of ‘Silihong’, ‘Yuhua 76’ and ‘Yuhua 65’ peanut butters were all lower than those of the other four varieties. The thixotropic ring area of ‘Silihong’ peanut butter was much larger than that of the other samples. Rheological and texture analysis showed that the spreadability of ‘Silihong’ peanut butter was the best among the samples. On the whole, ‘Silihong’ peanut butter has rich volatile flavor components, together with good sensory, texture and rheological properties, indicating ‘Silihong’ to be a suitable variety for making peanut butter.
Apoptotic Process of Fusarium oxysporum Spores Induced by Air Discharge
LIU Mengdie, JIANG Huiwen, LI Jie, YAN Shoulei, WANG Qingzhang
2021, 42(9):  22-30.  doi:10.7506/spkx1002-6630-20200415-200
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Fusarium oxysporum is the major postharvest spoilage fungus of lotus roots. In this study, air discharge technology was used to treat Fusarium oxysporum isolated from rotten lotus roots. The typical apoptotic characteristics occurring during spore inactivation were used as the cut-in point to investigate the apoptotic process of Fusarium oxysporum with focus on mitochondria under air discharge treatment. The experiment was set up with three treatments, including 6.87 mg/m3 ozone, 5 × 106 ions/cm3 negative ion and their combination; untreated Fusarium oxysporum was used as the control group to detect apoptosis, fluorescence intensity of reactive oxygen species (ROS), mitochondrial membrane potential (Δψm), cytosolic and mitochondrial calcium ion concentrations, and metacaspase activity. Results showed that air discharge treatment increased intracellular ROS level and decreased mitochondrial membrane potential leading to membrane potential depolarization. Cytosolic calcium ion concentration first increased rapidly, then decreased, and finally remained stabled, while the mitochondria Ca2+ increased first sharply and then slowly. Meanwhile, metacaspase was activated in the process of apoptosis. Only apoptosis was observed in the negative ion treatment group, while both apoptosis and necrosis were observed in the other two groups. It can be inferred from the experimental results that air discharge could cause the accumulation of intracellular ROS and an increase in Ca2+ concentration in spores so that the production of mitochondrial ROS could cause the depolarization of mitochondrial membrane potential, thereby leading to the release of cytochrome c from the mitochondria into the cytoplasm, activating metacaspase and eventually inducing apoptosis in spores.
Inhibitory Mechanism of Garlic Disulphides on the Formation of 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) in Deep-Fried Chicken Breast
LUO Xiangxiang, ZHOU Yingqin, HUANG Jingjing, XIE Ningning, YAN Yan, CHEN Xiao’e
2021, 42(9):  31-38.  doi:10.7506/spkx1002-6630-20200927-333
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In order to study the inhibitory effects and mechanisms of diallyl disulfide (DAD) and diphenyl disulfide (DPD) on the formation of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) in deep-fried chicken breast, the influence of DAD and DPD on changes in MeIQx contents, carbonyl values, MeIQx intermediates and precursors in undefatted and defatted chicken breast and MeIQx model system was investigated. The results showed that the content of MeIQx in deep-fried chicken breast meat was significantly higher than in roasted chicken breast (10.9 versus 56.4 ng/g). In the roasted sample, DAD and DPD had no inhibitory effect on MeIQx, while they could inhibit MeIQx in the deep-fried sample by 57.4% and 67.1%, respectively. This was verified in the model system. DAD and DPD could significantly slow down the increase in carbonyl values and the consumption of the precursors. DAD could reduce the formation of formaldehyde, while DPD could significantly inhibit the formation of the three MeIQx intermediates (P < 0.05). It can be speculated that garlic disulfides could inhibit the formation of MeIQx via reducing lipid oxidation and consequently the formation of carbonyl groups, which can catalyze the degradation of the precursor into the intermediates through the Strecker reaction.
Quality and Parboiled Rice Processing Suitability of Rice with Different Storage Times
ZHANG Yurong, ZHOU Xianqing, PENG Chao
2021, 42(9):  39-45.  doi:10.7506/spkx1002-6630-20200422-281
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This study investigated the difference in the quality of parboiled rice processed from rice with different storage times in order to provide a basis for the selection of raw materials for parboiled rice production. Forty samples of Indica rice and 40 samples of Japonica rice with different storage times were selected to process parboiled rice. Then, the cooking characteristics and visual appearance of parboiled rice, and the eating quality and texture parameters of cooked parboiled rice were determined. The quality parameters of parboiled rice were analyzed by descriptive statistical analysis, analysis of variance and principal component analysis. Clustering analysis was used to investigate the suitability to make parboiled rice. The results showed that the water-absorbing rate and volume swelling rate of parboiled rice were increased with increasing storage time of raw rice, and the average water-absorbing rates of parboiled Indica and Japonica rice stored for four years were increased by 49.1% and 35.9%, and the swelling volume rates were increased by 70.6% and 66.6%, respectively, when compared with the counterparts stored for one year. There was no significant change in the pH, iodine blue value or solid content of rice soup. For both rice varieties, the total sensory score of parboiled rice decreased, the color became darker, and the visual appearance deteriorated; the palatability and taste of cooked parboiled rice worsened. The sensory quality of parboiled Indica rice was better than that of parboiled Japonica rice. No significant change was observed in all texture parameters except for an increase in hardness and chewiness for both cooked parboiled rice and a decrease in adhesiveness for cooked Japonica rice. On the basis of sensory quality evaluation, the analysis of texture parameters was introduced to comprehensively evaluate the quality of parboiled rice, and principal component analysis was used to construct a mathematical model for the evaluation of parboiled rice quality. Then, clustering analysis of the comprehensive scores was performed for quality classification, and the number of samples in each storage year was counted, which confirmed that Indica rice was more suitable for parboiled rice processing than Japonica rice, and parboiled Indica rice stored for one or two years had better quality than that with longer storage times.
Food Engineering
Modification of Dietary Fiber from Tartary Buckwheat Bran by Steam Explosion
HE Xiaoqin, LIU Xin, LI Weizhou, ZHAO Jichun, LI Fuhua, MING Jian
2021, 42(9):  46-54.  doi:10.7506/spkx1002-6630-20200820-277
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In order to improve the comprehensive utilization of dietary fiber from tartary buckwheat bran, the effect of steam explosion applied at different pressures for different durations was investigated on improving the physicochemical and functional of tartary buckwheat dietary fiber. The operating conditions were optimized based on soluble dietary fiber content. The monosaccharide composition, physicochemical properties and structural characteristics of the raw and treated dietary fiber were determined. The results showed that the contents of insoluble dietary fiber (IDF), cellulose, hemicellulose, lignin and pectin in tartary buckwheat bran were significantly decreased (P < 0.05), and the contents of soluble dietary fiber (SDF), soluble sugar, reducing sugar and total sugar were significantly increased after steam explosion treatment (P < 0.05). Furthermore, compared with the untreated sample, the content of SDF was increased by 54.11% (12.36 versus 8.02 g/100 g) under optimized conditions (1.2 MPa for 90 s). After the treatment, the monosaccharide composition of tartary buckwheat bran dietary fiber was changed, and the water-holding capacity, oil-holding capacity, swelling power, α-amylase-inhibitory activity, glucose absorption capacity and thermal stability were significantly enhanced. Moreover, more hydroxyl groups were exposed, and a loose multilayer honeycomb-like network structure was observed in the treated SDF. Steam explosion could be useful to increase the SDF content and improve the physicochemical properties of tartary buckwheat bran dietary fiber, which will provide theoretical references for the utilization of SDF from tartary buckwheat bran and the development of dietary supplements.
Effect of Extrusion Treatment on Rheological Properties and in Vitro Digestibility of Pea Starch
QI Mingming, REN Zhishang, ZHANG Guangyao, HE Zhuangzhuang, WANG Chenjie, ZHANG Dongliang, MA Chengye
2021, 42(9):  55-63.  doi:10.7506/spkx1002-6630-20200417-227
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This study investigated the influence of different extrusion conditions including pea starch moisture content (25%, 35%, 40%, 45% and 55%), barrel temperature (50, 60, 70, 80 and 90 ℃) and screw speed (100, 120, 140, 160 and 180 r/min) on the in vitro starch digestibility and rheological properties of pea starch. Hydrolysis degree (HD) was measured using an in vitro digestion model, and rheological properties were determined through steady shear test, frequency sweep test and temperature sweep test. The results showed that after extrusion treatment, HD and the relative content of slowly digestible starch (SDS) increased whereas the relative content of resistant starch (RS) decreased. The maximum relative content of SDS of 34.41% was obtained under the following extrusion conditions: moisture content 25%, barrel temperature 70 ℃ and screw speed 140 r/min. When screw speed increased to 180 r/min with moisture content 40%, barrel temperature 70 ℃, the relative content of RS reached the minimum value of 10.49%. Particle size was positively correlated with SDS relative content and consistency coefficient (K value) (r = 0.60 and r = 0.61, P < 0.05). The extruded pea starch suspension was pseudoplastic. In frequency and temperature sweep tests, storage and loss moduli increased with the degree of starch damage increasing caused by extrusion. The results showed that the extruded pea starch exhibited enhanced structure and elastic gel properties. Therefore, extrusion can affect the in vitro starch digestibility and rheological properties of pea starch, thereby improving food functionality and quality.
Improving the Cooking Quality of Adzuki Beans Based on High-Temperature Air Fluidization
LI Yongfu, JIE Min, HUANG Jinrong, DU Yan, SHI Feng, CHEN Zhengxing
2021, 42(9):  64-69.  doi:10.7506/spkx1002-6630-20200526-311
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The effect of high-temperature air fluidization (for 55 s at 215 ℃ with a feeding rate of 62 kg/h) on improving the cooking quality of adzuki bean was studied by analyzing the grain structure, starch structure, gelatinization characteristics, water absorption, migration and distribution of adzuki bean. The results showed that the dense structure of the grain became loose, the diameter of the capillary pores between adjacent cells in the cotyledons increased, and the structure of some starch granules was damaged in adzuki bean after high-temperature air fluidization treatment. During cooking in near-boiling water at 98 ℃, the gelatinization degree of the untreated adzuki beans at 60 min was similar to that of the treated adzuki beans at 30 min. The gelatinization viscosity and retrogradation tendency of the treated adzuki beans were lower than those of the untreated adzuki beans. After cooking for 60 min, the water absorption rate of the treated adzuki beans was 90.06%, which was 34.84% higher than that of the untreated red adzuki beans, suggesting that the water absorption ability was significantly improved after the treatment. The water migration rate in the treated adzuki bean particles was accelerated significantly and the water distribution was more uniform. Furthermore, the sensory evaluation score of cooked rice with the treated adzuki beans was higher. In conclusion, high-temperature air fluidization improves the cooking quality of adzuki beans by expanding the passage of moisture into the grain and destroying the water absorption barrier to improve the water absorption performance, consequently enable the starch to absorb water more completely and be gelatinized more thoroughly and simultaneously improve the taste of cooked adzuki beans.
Effect of Electron Beam Irradiation on Quality and Resistance System of Kiwifruit
HUANG Tianzi, LIANG Jin, WANG Dan, ZHANG Lu, LI Ruijuan, YANG Shuxia, LUO Anwei
2021, 42(9):  70-76.  doi:10.7506/spkx1002-6630-20200505-031
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To provide a theoretical basis for developing an electron beam irradiation technique for the preservation of kiwifruit, this study investigated the effect of electron beam irradiation on the storage quality and gray mold of kiwifruit. Freshly harvested ‘Hayward’ kiwifruit were artificially infected with Botrytis cinerea, treated with high-energy electron beam irradiation, and then stored at 0–1 ℃ and relative humidity of 90%–95%. Samples were taken every 15 days to determine fruit physicochemical index and resistance-related enzyme activities. The results showed that compared with the untreated control, electron beam irradiation treatment effectively reduced the fruit mass loss, maintained the soluble solid content, and inhibited the decrease in titratable acid content. The peak value of flavonoids in the 0.4 kGy irradiation group increased by 25.52% in comparison with the control group. Electron beam irradiation increased the peak values of peroxidase (POD), phenylalanine ammonia-lyase (PAL) and β-1,3 glucanase (GLU) activity as compared with the control group, at 0.8 and 1.2 kGy doses advancing the first appearance of peak of β-1,3 glucanase activity by 30 days and elevating the content of malondialdehyde (MDA). This indicates that electron beam irradiation triggers slight lipid peroxidation in the cell membrane. Electron beam irradiation at 0.4 kGy dose caused only marginal changes in the fruit quality but induced strong fruit resistance. Accordingly, an appropriate dose of electron beam irradiation can be used as an effective means to improve the preservation of kiwifruit and inhibit the decay loss.
Nutrition & Hygiene
Gastroprotective Effect of Amorpha fruticosa L. Honey against Ethanol-Induced Acute Gastric Ulcer in Mice
ZHU Min, JIN Lin, ZHAO Hao’an, WANG Qian, ZHANG Jinjin, YANG Erlin, CAO Wei
2021, 42(9):  77-84.  doi:10.7506/spkx1002-6630-20200616-207
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To estimate the gastroprotective effect of Amorpha fruticosa L. honey (AFH) against ethanol-induced acute gastric ulcer, mice pretreated with AFH via oral gavage for 10 days were administered with 65% ethanol to induce acute gastric ulcer injury. The effect of AFH on the gastric pathological morphology and ulcer index of mice was analyzed, and its effect on gastric antioxidant and anti-inflammatory capacity in mice with acute alcoholic gastric ulcer was explored by the determination of biochemical indexes of oxidative stress and inflammatory cytokines. The results revealed that AFH protected the integrity of gastric mucosa, and alleviated the decrease in superoxide dismutase activity and glutathione content as well as the accumulation of malondialdehyde caused by ethanol consumption significantly (P < 0.05). Compared with the model control group, the AFH-treated mice showed significantly higher contents of prostaglandin E2 and NO (P < 0.05), but significantly lower content of tumor necrosis factor α in the gastric tissue (P < 0.05). The results of polymerase chain reaction and immunohistochemical analysis revealed that AFH significantly down-regulated the gene and protein expression of ulcer-related pro-inflammatory cytokines (P < 0.05). Taken together, AFH has a potential gastroprotective effect on ethanol-induced gastric ulcer by protecting the gastric mucosa from ethanol-induced damage and regulating oxidative stress and the expression of inflammatory cytokines.
Preventive Effect of Forsythin from Forsythia suspensa Leaves on Obesity Induced by High-Fat Diet in Rats
WANG Jing, HUANG Qingchen, GAO Minyue, ZHU Xiaopan, CHEN Zitong, WANG Shaokang, SUN Guiju
2021, 42(9):  85-90.  doi:10.7506/spkx1002-6630-20201216-198
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Objective: To study the preventive effect of forsythin extract from Forsythia suspensa leaves on obesity induced by high-fat diet in rats. Methods: A total of 48 SD rats were divided into six groups of blank control, model control, low-, medium- and high-dose forsythin extract treatment (made in our laboratory, containing 13.3% forsythin) and forsythin standard (98% purity) treatment. The rats in the low-, medium- and high-dose forsythin extract groups were orally administered with forsythin extract at doses of 0.2, 0.4 and 1.2 g/(kg mb·d), containing 26.6, 53.2, and 159.6 mg/(kg mb·d) of forsythin, respectively. Forsythin standard was administered at a dose of 54.3 mg/(kg mb·d), similar to the middle-dose forsythin extract. The rats in the blank control group were provided with a basal diet whereas those in the other groups were given a high-fat diet. The administration lasted for 6 weeks. Then, food intake, body mass, obesity index (Lee’s index), fat index, and the serum levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), total bile acid (TBA), leptin (LP) and free fatty acids (FFA) were measured and pathological sections of adipose tissue were examined. Results: The serum levels of TC, LDL-C, TBA, LP, and FFA in the model control group were significantly higher than those in the blank control group (P < 0.05). Pathological examination showed that compared with the blank control group, the number of fat cells in the model control group was reduced, and the adipocytes were full of fat and enlarged with significantly larger equivalent diameter, perimeter and area than those in the blank control group (P < 0.05), besides, fat mass and its coefficient, Lee’s index and body mass were significantly higher than those in the control group, indicating successful obesity induction in rats. In addition, compared with the model control group, the forsythin extract especially at the high dose lowered serum TC, LDL-C, LP and FFA in obese rats, and improved the pathological status of adipose tissue, reducing the number and size of adipocytes, but was ineffective at the low dose. The area of adipocytes in the low-dose forsythin extract group was reduced in contrast to the model control group (P < 0.05), the perimeter and area of adipocytes in the middle-dose group were both decreased (P < 0.05), and the equivalent diameter, perimeter and area in the high-dose group were all decreased. The forsythin extract especially at the high dose lowered the visceral fat mass and coefficient, Lee’s index, and body mass of obese rats, and the middle-dose forsythin extract was as effective as forsythin standard. Conclusion: The forsythin extract can prevent obesity induced by high-fat diet in rats through the forsythin contained in it.
Procyanidin B2-Induced Apoptosis in MCF-7 Cells and Its Mechanism
XUE Hongkun, TAN Jiaqi, LI Qian, TANG Jintian
2021, 42(9):  91-99.  doi:10.7506/spkx1002-6630-20200317-263
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The aim of this study was to investigate the anti-tumor effect of procyanidin B2 (PCB2) on human breast cancer MCF-7 cells and the underlying mechanism. The methyl thiazolyl tetrazolium method was used to measure the effect of PCB2 at different concentrations and treatment times on the survival rate of MCF-7 cells. The changes in Ca2+ concentrations in cells and the apoptotic morphology after Hoechst 33342 staining were observed by confocal laser microscopy. The effects of PCB2 on the apoptosis rate, cell cycle, reactive oxygen species (ROS) level and mitochondrial membrane potential of MCF-7 cells were detected by a flow cytometer. Western blot was employed to determine the effect of PCB2 on the expression levels of apoptosis-related proteins in MCF-7 cells. The results indicated that PCB2 could significantly reduce the survival rate of MCF-7 cells in a dose-dependent manner when the concentration of PCB2 was in the range of 10–80 μmol/L. The IC50 for the survival rate of MCF-7 cells at 24, 48 and 72 h were 114.82, 57.15 and 55.64 μmol/L, respectively. PCB2 could remarkably increase the apoptosis rate, ROS level and nuclear fluorescence intensity of MCF-7 cells, destroy the Ca2+ balance, dramatically decrease the mitochondrial membrane potential, and block the cell cycle in the G0/G1 phase to induce apoptosis. PCB2 could up-regulate the relative expression levels of Bax, cytochrome c, caspase-12 and caspase-3 proteins, and down-regulate the relative expression level of Bcl-2. In conclusion, PCB2 has antitumor effect, and the underlying mechanism is related to the activation of apoptosis pathway mediated by mitochondria and endoplasmic reticulum, cell cycle arrest and an increase of intracellular ROS levels.
Effects of Three Kinds of Coarse Cereals on Gut Microbiota of Rats Explored by Illumina NovaSeq Sequencing Technology
WANG Yong, SONG Ge, PANG Shaojie, QI Wentao
2021, 42(9):  100-106.  doi:10.7506/spkx1002-6630-20200716-226
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To investigate the effect of dietary supplementation with oats, tartary buckwheat and foxtail millet on the intestinal histology, microbiota and short-chain fatty acids (SCFAs) in normal rats, 48 male SD rats were randomly and equally divided into four groups: control (fed a standard maintenance diet), oat (fed the maintenance diet containing 22% oats), tartary buckwheat (fed the maintenance diet containing 22% tartary buckwheat) and foxtail millet groups (fed the diet containing 22% foxtail millet). Body mass was recorded weekly. After 12 weeks of feeding, the rats were sacrificed to collect liver tissue, colon tissue and colonic contents. Histopathological characteristics of liver and colon tissues were observed. The intestinal microbiota was analyzed by Illumina NovaSeq high-throughput sequencing technology. SCFAs in colonic contents were determined by liquid chromatography-mass spectrometry. Results indicated that administration of oats increased gut microbiota diversity and showed higher relative abundance of Lactobacillus and Akkermansia than the control group. Tartary buckwheat and foxtail millet increased the relative abundance of Firmicutes, but decreased the abundance of Verrucomicrobia and Bacteroidetes in the gut of normal rats. Oats, tartary buckwheat and foxtail millet decreased the relative abundance of Bacteroides. Oats and foxtail millet could significantly increase the concentrations of acetic acid and total SCFAs (P < 0.05), and foxtail millet could significantly increase the concentrations of propionic acid and isobutyric acid in colonic contents (P < 0.05). In conclusion, oat supplementation has regulatory effects on the gut microbiota in rats, and tartary buckwheat and foxtail millet have similar effects on it. This study provides a scientific basis for the development of cereal-based functional foods.
Protective Effect of Betulinic Acid on Liver Injury Induced by T-2 Toxin in Mice
YANG Chenglin, HUANG Chao, LIU Juan, HUANG Weimei, YUAN Zhihang, YI Jin’e, LIANG Zeng’enni, WU Jing
2021, 42(9):  107-114.  doi:10.7506/spkx1002-6630-20200228-317
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Objective: To explore the protective effect of betulinic acid (BA) on liver injury induced by T-2 toxin in mice and its underlying molecular mechanism. Methods: Totally 60 adult male Kunming mice were randomly divided into six groups: blank control, 4 mg/kg mb T-2 toxin, 0.25 mg/kg mb BA + T-2, 0.5 mg/kg mb BA + T-2, 1 mg/kg mb BA + T-2 and 100 mg/kg mb vitamin E (VE) + T-2. After 14 days of continuous administration of betulinic acid, T-2 toxin was intraperitoneally injected into all groups except the blank control group to induce liver injury. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) and total protein (TP) concentration in serum were measured. Histopathological changes in the liver were observed by hematoxylin-eosin staining. Total antioxidant capacity (T-AOC), the activities of catalase (CAT) and superoxide dismutase (SOD), and the contents of glutathione (GSH) and malondialdehyde (MDA) in liver tissues were determined. Apoptosis of hepatocytes was detected by TUNEL staining. The protein expression of Bax, Bcl-2, caspase-3, Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) in liver tissues was evaluated by Western blot. Results: BA pretreatment attenuated the increase in the activities of ALT, AST and ALP and the decrease in TP concentration in serum caused by T-2 toxin. Also, it increased T-AOC, CAT and SOD activity and GSH content, decreased MDA content and the number of apoptotic cells, up-regulated the expression of Bcl-2 protein, and down-regulated the expression of Bax, caspase-3, JAK2, and STAT3 proteins. Conclusion: BA inhibits hepatocyte apoptosis through the JAK2/STAT3 pathway due to its antioxidant capacity, thereby alleviating T-2-induced liver injury in mice.
Effect of the Essential Oil from the Ripe Fruit Pericarp of Zanthoxylum bungeanum Maxim. on Glucose Metabolism in Diabetic Mice Induced by Streptozotocin
LU Mintao, REN Tingyuan, YANG Jian, LU Longfa, QIN Likang
2021, 42(9):  115-122.  doi:10.7506/spkx1002-6630-20200424-321
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Objective: To explore the effect of the essential oil from the ripe fruit percicarp of Zanthoxylum bungeanum Maxim. on glucose metabolism in type I diabetic mice and its possible mechanism. Methods: Totally 50 healthy male Kunming mice were randomly divided into five groups of 10 animals each, including blank control, diabetic model, high-dose (15 mg/(kg mb·d)), middle-dose (9 mg/(kg mb·d)) and low-dose (3 mg/(kg mb·d)) essential oil. Type I diabetes was induced by streptozotocin (STZ). The animals in the blank control and diabetic model groups were orallytreated with the same dose of soybean oil. After 28 days of administration, the levels of insulin, glycosylated serum protein (GSP), glycosylated hemoglobin (GHb), muscle glycogen and liver glycogen were determined. The relative mRNA expression of the phosphoinositide 3-kinase (PI3K), protein kinase B (PKB) and glucose transporter 2 (GLUT2) genes in liver and of the GLUT4 gene in skeletal muscle were determined by quantitative real-time polymerase chain reaction (qRT-PCR ). The protein expression of PI3K (p110), PKB and p-PKB (Ser473) in liver was evaluated by Western blot. Fasting blood glucose and body mass were measured weekly during the experiment, and glucose tolerance was measured on the 28th day of administration. Results: Compared with the model group, food intake, water intake, fasting blood glucose, GHb concentration and GSP concentration in the essential oil treatment groupswere decreased at most by 38.91%, 35.93%, 28.60%, 30.76% and 37.29%, respectively. The levels of insulin, liver glycogen and muscle glycogen were increased at most by 22.56%, 23.61% and 149.75%, respectively. The relative mRNA expression of PI3K, PKB, GLUT2 and GLUT4 was up-regulated (P < 0.05) at most by 87.5%, 53.4%, 77.05% and 133.3%, respectively. Furthermore, the protein expression of PI3K (p110) was up-regulated by 3.20, 2.51 and 1.67 times, and the protein expression of p-PKB (Ser473) was up-regulated by 7.64, 6.12 and 2.73 times in the high-, medium- and low-dose groups, respectively. Conclusion: The essential oil has a hypoglycemic effect in type 1 diabetic mice possibly by activating the PI3K/PKB pathway to translocate GLUT2/4, and promote glucose absorption and utilization by cells.
Extraction of Flavonoids from Durian Seeds and Its Antioxidant and Anti-aging Effects in Caenorhabditis elegans
WANG Feng, XIAO Chuxiang, LIU Shuzhen, WANG Fengwu
2021, 42(9):  123-129.  doi:10.7506/spkx1002-6630-20200409-127
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Objective: To optimize the extraction of flavonoids from durian seeds and to evaluate the antioxidant and anti-aging effects of the extract in Caenorhabditis elegans for the purpose of providing a theoretical basis for screening for bioactive substances with antioxidant and anti-aging properties. Methods: The optimization was performed by combined use of one-factor-a-time method and L9 (34) orthogonal array design. To evaluate the in vitro antioxidant capacity, the scavenging effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radicals were determined by spectrophotometry, the phenanthroline-Fe2+ oxidation method and the pyrogallol autoxidation method, respectively. The effects of the flavonoid extract on the lifespan, mobility, reproductive capacity, paralysis relief and antioxidant enzymes activities of C. elegans as a model organism were determined. The results showed that the optimal extraction conditions were 40% ethanol concentration, 1:220 solid-to-solvent ratio, 400 W ultrasonic power, and 70 min ultrasonic duration. Experiments conducted under these conditions gave an average extraction rate of flavonoids of (9.25 ± 0.05)%. The flavonoid extract could scavenge DPPH (92.6%), hydroxyl (79.4%) and superoxide anion radicals (27.0%) effectively. It could prolong the lifespan of C. elegans, improve the mobility, significantly reduce the paralysis rate (P < 0.05), relieve amyloid β-protein (Aβ) toxicity on it, significantly increase the superoxide dismutase (SOD) activity (P < 0.05) and reduce the malondialdehyde (MDA) content (P < 0.01) without damaging the reproductive capacity. Conclusion: The flavonoid extract from durian seeds has antioxidant capacity in vivo and in vitro, and is able to alleviate oxidative stress and aging-induced diseases.
Coenzyme Q10 Attenuates Platelet Thromboxane A2 Generation through Regulating the Protein Kinase A/Cytosolic Phospholipase A2 Signaling Pathway
YA Fuli, ZHANG Chunmei, CHEN Binlin, GU Shiyan, JIA Xiao’e
2021, 42(9):  130-136.  doi:10.7506/spkx1002-6630-20200608-108
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Objective: Thromboxane A2 (TxA2) derived from platelets can facilitate atherosclerosis and thrombosis. Previous studies have demonstrated that coenzyme Q10 (CoQ10) attenuates platelet activation, aggregation and thrombus formation. Our present study aimed to investigate the effect of CoQ10 on TxA2 generation and to clarify the underlying mechanisms. Methods: Gel-filtered platelets prepared from heathy adults were incubated with different concentrations of CoQ10 (0, 1, 10 and 100 μmol/L) for 50 min. After agonist activation, the level of TxB2 secreted from platelets was determined by enzyme-linked immunosorbent assay. The phosphorylation of cytosolic phospholipase A2 (cPLA2) was measured by Western blot. Results: CoQ10 significantly inhibited platelet TxA2 generation induced by several agonists, including thrombin, collagen and convulxin. Western blot showed that CoQ10 significantly down-regulated thrombin- and collagen-induced cPLA2 phosphorylation. Moreover, pyrrophenone, a cPLA2 specific inhibitor, showed no any additive effects on TxA2 generation when combined with CoQ10. Furthermore, the inhibitory effect of CoQ10 on agonist-induced platelet cPLA2 phosphorylation and TxA2 generation was almost completely reversed by protein kinase A (PKA) inhibitor H89. Conclusion: CoQ10 can attenuate agonist-induced platelet TxA2 generation, and the mechanism is mainly through regulating the PKA/cPLA2 signaling pathway.
Biological Activity and Structural Characterization of Riboflavin-Binding Peptide
YIN Hongjie, JU Huapeng, ZHONG Limin, SUN Na, LIN Songyi
2021, 42(9):  137-144.  doi:10.7506/spkx1002-6630-2020212-123
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The microscopic features of riboflavin-binding peptide, prepared from the pine nut peptide Ac-QWFCT and riboflavin, were examined by scanning electron microscope, and the immunomodulatory activity was evaluated by measuring cell viability, neutral red phagocytosis rate and NO production. Moreover, the antioxidant activity was evaluated by determining the scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radicals, and Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance were used to determine the interaction between the peptide and riboflavin. The absorption characteristics of riboflavin-binding peptide were studied by the rat everted gut sac method. The results showed that the microstructure of Ac-QWFCT changed from reticular to flocculent after binding with riboflavin. The neutral red phagocytosis rate and NO release rate of riboflavin-binding peptide were higher than those of Ac-QWFCT and riboflavin, reaching the maximum value at a concentration of 25 μg/mL. At 0.1 and 0.2 mg/mL, the DPPH radical and ABTS cation radical scavenging capacities of riboflavin-binding peptide were significantly higher than those of Ac-QWFCT and riboflavin. Tryptophan and phenylalanine residues in the peptide bound to riboflavin through hydrophobic interactions. Binding to the peptide Ac-QWFCT could increase the absorption of riboflavin in the intestine of rats. This study can provide a theoretical basis for the development of new vitamin B2 supplements.
Effect of Taurine-Hydrolyzed Soybean Protein Composite System on Exercise-Induced Fatigue in Rats
BAI Haijun, LI Zhijiang
2021, 42(9):  145-150.  doi:10.7506/spkx1002-6630-20200501-003
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In this study, mixed aqueous solutions of taurine and hydrolyzed soybean protein with different mixing ratios were screened for their antioxidant activity in vitro. A rat model of exercise-induced fatigue was established and administered by gavage with the selected mixtures. To evaluate their in vivo antioxidant activity, the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) and the concentration of malondialdehyde (MDA) in the serum of rats were measured. Their anti-fatigue capacity was judged by the concentrations of serum lactic acid (LA) and blood urea nitrogen (BUN) and exercise endurance time. The results showed that the exercise endurance time of rats with exercise-induced fatigue was significantly shortened compared with normal rats (P < 0.05). The activities of SOD, GSH-Px and CAT were increased and MDA concentration was decreased after administration with the taurine-hydrolyzed soybean protein mixtures. The 1:10 (m/m) mixture had the most significant antioxidant effect in vivo. Correspondingly, it was the most effective in prolonging the exercise endurance time and reducing the concentrations of serum LA and BUN, indicating the best anti-fatigue effect. SOD activity was plotted against exercise endurance time, revealing a positive correlation between the antioxidant capacity of the taurine-hydrolyzed soybean protein mixture and its anti-fatigue effect (R2 = 0.820 5). This research can provide a reference for the development of compound functional anti fatigue products based on hydrolyzed protein and taurine.
Packaging & Storage
Synergistic Effect of Salicylic Acid and Nitric Oxide Treatment on Quality and Antioxidant Activity in Postharvest Mango Fruit
REN Yanfang, XUE Yuhao, TIAN Dan, HE Junyu, ZHANG Liming, WU Qing, LIU Shu
2021, 42(9):  151-159.  doi:10.7506/spkx1002-6630-20200507-065
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In order to investigate the synergistic effect of salicylic acid (SA) and nitric oxide (NO) treatment on the storage quality and antioxidant capacity of mango after harvest, the fruit (Mangifera indica L. cv. ‘Tainong’ ) were pretreated with 2 mmol/L SA, 0.25 mmol/L sodium nitroprusside (SNP, a NO donor) or their combination before storage at room temperature, and the changes in their appearance, flavor, antioxidant contents, total antioxidant capacity, reactive oxygen species (ROS) levels and malondialdehyde (MDA) contents, and antioxidant enzymes activities were analyzed during storage. The results showed that SA and SNP especially when they were combined effectively delayed the yellowing and softening process of mango fruit, decreased the mass loss and disease index, inhibited the decrease in the contents of titratable acid, ascorbic acid and total phenols, improved the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), enhanced total antioxidant capacity, and decreased the rate of superoxide anion production and the accumulation of hydrogen peroxide and MDA, thereby alleviating oxidative stress, when compared with the control group treated with distilled water. Altogether, these findings indicated that SA and SNP had synergistic effects in maintaining the storage quality of mango fruit, which can provide a theoretical basis for improving the storage quality and prolonging the shelf life of mango fruit.
Variations in Physicochemical Properties and Eating Quality of Two Fragrant Rice Varieties during Storage at Different Temperatures
ZHAO Qingyu, GUO Hui, SHEN Qun
2021, 42(9):  160-168.  doi:10.7506/spkx1002-6630-20200408-116
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The quality changes of two fragrant rice varieties of ‘Daohuaxiang 2’ and ‘Jasmine’ during storage at 15 ℃, room temperature (20–25 ℃) and 37 ℃ were analyzed in terms of physicochemical, texture, cooking, and gelatinization characteristics. The results showed that pronounced changes in all quality characteristics were seen at all storage temperature, being more pronounced at higher temperature. During storage, ‘Jasmine’ rice presented greater decreases in water content, protein content, sulfhydryl content, the color parameters L* and a*, and pH, as well as a greater increase in hardness than did ‘Daohuaxiang 2’ rice. The increases in amylose content, b* value, and swelling rate were greater for ‘Daohuaxiang 2’ rice than ‘Jasmine’ rice. The adhesiveness decreased, while the water-absorbing capacity and gelatinization temperature increased for both varieties. While no significant change was observed in the resilience during storage at 15 ℃, a significant increase was found at other storage temperatures (P < 0.05). The elasticity of ‘Daohuaxiang 2’ rice did not significantly change overall, whereas ‘Jasmine’ rice showed a downward trend. The chewiness of ‘Jasmine’ rice was more stable than that of ‘Jasmine’ rice. Taking into account chewiness, peak viscosity, and breakdown, ‘Daohuaxiang 2’ and ‘Jasmine’ rice had the best taste after storage at 37 ℃ for 4 and 6 months, respectively, and the taste value of ‘Jasmine’ rice after storage was higher than that of ‘Daohuaxiang 2’ rice.
Analysis of Bacterial Diversity and Volatile Flavor Compounds of Cooked Cured Ham Stored at Different Temperatures
RAN Miao, HE Laping, ZHU Qiujin
2021, 42(9):  169-176.  doi:10.7506/spkx1002-6630-20200402-016
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In order to reveal the relationship between the bacterial community and volatile flavor compounds of cooked cured ham at different storage temperatures, high-throughput sequencing technology and gas chromatography-mass spectrometry (GC-MS) were used to determine the compositions of bacterial communities and volatile compounds in ham samples at the early and middle stages of storage at 4 ℃, and at the late stage of storage at 4, 10, 15, 20 and 25 ℃. According to their relative odor activity values (ROAV), 19 volatile flavor compounds were identified such as linalool. Orthogonal partial least squares discriminant analysis (OPLS-DA) divided all samples into two distinct groups. Eleven species of bacteria such as Acinetobacter were found to differ between the two groups. The relative abundance of each species was significantly positively correlated with hexanal ROAV (r ≥ 0.776, P < 0.05). The relative abundance of Serratia as the dominant bacterium at the late stage of storage at 4 and 10 ℃ was highly significantly positively correlated with α-pinene ROAV (r = 0.896, P < 0.01). Higher storage temperature resulted in higher relative abundance of Enterobacter and Enterococcus, which were highly significantly positively correlated with indene ROAV (r ≥ 0.952, P < 0.01). This study will provide a reference for the flavor preservation of cooked cured ham during storage.
Chlorogenic Acid Treatment Induced Resistance to Postharvest Gray Mold on Apples
WANG Dajiang, ZHANG Mengyu, YUE Zhengyang, ZHOU Huiling
2021, 42(9):  177-183.  doi:10.7506/spkx1002-6630-20200514-156
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Chlorogenic acid is the most predominant phenolic compound in apple fruit. This study demonstrated chlorogenic acid to be able to inhibit the growth of Botrytis cinerea in vitro when used at a concentration of 300 μg/mL. ‘Fuji’ apples were dipped in chlorogenic acid solution at this concentration for 30 min, wounded and inoculated with Botrytis cinerea after 24 h. Distilled water treatment was used as a control. Relevant metabolic enzyme activities and the contents of total phenols, flavonoids and lignin in the fruit samples were measured. The results showed that 300 μg/mL chlorogenic acid treatment significantly reduced the incidence of gray mold disease on apple fruit and suppressed the expansion of lesion diameter (P < 0.05). This treatment increased the activity of chitinase and β-1,3-glucanase, induced the response of the enzymes involved in the phenolic metabolism pathway as manifested by significantly increased activities of phenylalanine ammonia lyase, cinnamic acid 4-hydroxylase and 4-coumalyl CoA ligase (P < 0.05), and promoted the accumulation of total phenols, flavonoids and lignin, thereby delaying the development of gray mold disease. This study provides theoretical references for the application of chlorogenic acid in the prevention of gray mold disease on apple fruit.
Effects of Storage Time of Raw Beef on Microflora Changes and Protein Degradation in Fermented Beef Sausages
XU Ye, LIU Shiyu, WANG Yilun, NIU Shuhui, YANG Yifang, YU Qinxin, XIAO Zihan, LIU Shuliang, HE Li, CHEN Shujuan, LIU Aiping, YANG Yong
2021, 42(9):  184-191.  doi:10.7506/spkx1002-6630-20200414-183
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Traditional microbial counting methods, high-throughput sequencing, the Kjeldahl method and high performance liquid chromatography (HPLC) were applied to explore the effects of different postmortem storage times of beef (0, 12, 24 and 36 h at 0–4 ℃) on microflora changes and proteolysis during the processing of fermented beef sausages as well as on the correlation between them. The results showed that the total number of bacterial colonies, coliform count, the diversity and richness of bacterial communities and proteolysis indexes increased, while the content of total free amino acids in fermented beef sausages decreased as the storage time of raw beef increased. A significant positive correlation appeared between total volatile basic nitrogen (TVB-N) and total biogenic amine contents during the ripening process (P < 0.01). The average values of total number of bacterial colonies and Shannon?diversity index of fermented sausage prepared from 36 h-chilled beef were 4.03 × 107 CFU/g and 2.89, respectively, which were both higher than those (2.40 × 107 CFU/g and 1.39) of fermented sausage prepared from unchilled fresh beef (P < 0.05 for total number of bacterial colonies). The dominant bacteria in the former were Staphylococcus over the whole processing period, while the dominant bacteria in the latter were Weissella spp. at the early stage and Staphylococcus at the late stage. The average total free amino acid content decreased from 7.09 to 6.44 mg/g, whereas the average total biogenic amine content increased from 92.14 to 117.42 mg/kg (P < 0.05). These results indicated that controlling the storage time of raw beef could effectively reduce the total microbial load and the microbial diversity of fermented sausages, retard the accumulation of biogenic amines and inhibit proteolysis, thereby ensuring the safety of fermented sausages.
Effect of Artificial Ripening on Postharvest Pineapple Fruit Quality and Its Recognition by Spectroscopy
XU Sai, LU Huazhong, LIANG Xin, QIU Guangjun, LIN Wei
2021, 42(9):  192-198.  doi:10.7506/spkx1002-6630-20200513-144
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To explore the effect of artificial ripening on postharvest pineapple fruit quality and develop a fast quality recognition method, the changes in black heart symptoms as well as the contents of total soluble solids (TSS) and titratable acid (TA) in the flesh, heart, and whole fruit of ripened and unripened pineapples during postharvest storage were determined, and the feasibility of applying visible near/infrared (VIS/NIR) spectroscopy to the real-time recognition and prediction of pineapple quality was evaluated. The order of TSS and TA contents in both treated and untreated pineapples was flesh > whole fruit > heart. TSS content was higher in ripened pineapples than in unripended ones at the early stage of postharvest storage; TSS content gradually declined with storage time in the former, while it increased in the latter. TA content was higher in ripened pineapples than in unripended ones at the early stage of storage, showing no obvious changing trend with storage time in the former but a continuous increasing trend in the latter. The order of TSS/TA ratio in the ripened and unripened pineapples was heart > whole fruit > flesh. At day 4 postharvest, TSS/TA ratio was higher in unripened pineapples than in ripened ones, and the difference became smaller with the prolongation of storage time. At day 9, TSS, TA contents and TSS/TA ratio were similar between them. It was feasible to apply VIS/NIR spectroscopy to acquire the features of pineapples, allowing identification whether pineapples were artificially ripened, black heart degree, ripened pineapples at different storage times (at days 4, 5, 6, 7, 8 and 9 postharvest), and unripened pineapples at different storage times (at days 4, 5–7, 8 and 9 postharvest) and prediction of whether black heart would occur at day 6. The results of this study provide a reference for pineapple planting and postharvest management and are of positive significance to the pineapple industry.
Effect of Simulated Circulation Modes at Different Temperatures on Firmness, Sugar and Acid Composition of Peach Fruit
LIU Hui, LÜ Zhenzhen, YANG Wenbo, ZHANG Chunling, LIU Jiechao, JIAO Zhonggao
2021, 42(9):  199-205.  doi:10.7506/spkx1002-6630-20200512-138
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In order to study the effects of three circulation modes of room temperature, cold chain and broken-off cold chain on the quality of peach fruit, the fruit were stored under temperature conditions simulating each circulation mode. Changes in flesh firmness, the contents of cell wall pectin, soluble sugars and titratable acids, and sugar and organic acid composition were analyzed during the simulated circulation process. The results showed that the fruit quality was significantly affected by the circulation temperature. The commodity value was lost within four days in the simulated room temperature environment. The constant low temperature condition (simulated cold chain circulation) could well maintain the fruit quality during storage and shelf life. However, the quality of peach fruit in the simulated broken-off chain circulation condition rapidly decreased after entering the shelf life period due to the increase in temperature at various stages such as packaging and warehouse-in/warehouse-out during storage. The flesh firmness (2.14 g/cm2), sucrose content (46.48 mg/g) and malic acid content (3.13 mg/g) were significantly lower than those in the simulated cold chain circulation group on the 2nd day of shelf life (P < 0.05). The fluctuation of circulation temperature caused by broken-off cold chain during the transportation and storage of peaches should be avoided as much as possible. These results will be helpful for the improvement of the cold chain circulation systems for vegetables and fruits.
Changes in the Quality and Protein Properties of Seasoned Fish during Repeated Freeze-Thaw Cycles
WU Chenyan, YANG Mei, WANG Keli, LIU Xinjie, LIU Sijia, MA Lizhen
2021, 42(9):  206-213.  doi:10.7506/spkx1002-6630-20200419-250
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In order to explore the effects of repeated freeze-thaw cycles on the quality and protein properties of seasoned split fish prepared by ultra-high pressure (UHP) or tumbling (TB) marination, after being quickly frozen at ?35 ℃, the two fish samples were stored at ?18 ℃ for 20 days and then thawed and the freeze-thaw process was repeated five times consecutively. Changes in total bacterial count (TBC), thiobarbituric acid reaction substances (TBARS) value, total volatile basic nitrogen (TVB-N) content and protein oxidation indexes (sulfhydryl group and disulfide bond contents) were determined as well as in protein composition analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The microstructure, functional groups and secondary structure of myofibrillar proteins were evaluated by scanning electron microscopy (SEM), ultraviolet (UV) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The results showed that TBC in both samples remained at low levels, TVB-N content and TBARS value in both samples increased but also remained at low levels with increasing number of freeze-thaw cycles. Moreover, the sulfhydryl group content of myofibrillar proteins decreased significantly (P < 0.05), while the disulfide bond content increased significantly (P < 0.05); the relative contents of α-helix and β-turn decreased, whereas the relative contents of β-sheet and random coil increased. The electrophoretic bands of myosin heavy chain and actin became thinner and lighter. SEM observation revealed that the surface of the samples became wrinkled and rough with cavity after repeated freeze-thaw cycles. The quality change of UHP samples was significantly lower than that of TB samples, indicating that the UHP marination could delay the quality changes of seasoned split fish during repeated freeze-thaw process.
Reviews
Progress in the Construction and Application of Fluorescence Sensors for the Detection of Folic Acid
LI Yining, HUANG Kunlun, YAO Zhiyi
2021, 42(9):  214-221.  doi:10.7506/spkx1002-6630-20200407-090
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Folic acid is a water-soluble B vitamin. The rapid and accurate detection of folic acid is of great significance for ensuring the safety and effectiveness of food and medicine and assisting in the clinical diagnosis of diseases. In recent years, folic acid sensors based on fluorescent probes have received more and more attention due to their fast response, high sensitivity and convenience. In this review, the construction and characteristics of fluorescence sensors based on different sensing materials for the detection of folic acid are summarized. Moreover, the application of these sensors in food and drug quality control, clinical detection and evaluation, and cell imaging is reviewed. Finally, future directions and prospects are discussed.
Application of Oral Soft Friction Theory and Experimental Methods in Studying Food Sensory Perception
WANG Qi, ZHU Yang, CHEN Jianshe
2021, 42(9):  222-232.  doi:10.7506/spkx1002-6630-20200327-406
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Food oral processing is a highly complicated process involving mastication, size reduction, saliva secretion, and bolus formation. It is not only a process of food oral manipulation, but also a process of sensory perception. During oral processing, relative surface movements occur between food particles and between food particles and oral surfaces. Therefore, how to accurately describe the physical principle of food oral processing is beyond the scope of traditional rheology, and many sensory properties (smoothness, fattiness, oiliness and aftertaste) cannot be assessed simply by rheological measurements. In recent years, oral soft friction technology has emerged as a feasible approach for linking food oral processing to sensory perception. This article aims to describe the fundamental principle of tribology and the ABC of oral soft friction technology with focuses on the biological basis and measurement methods for oral soft friction theory. The latest advances in the application of oral soft friction technology in food design and sensory evaluation are highlighted.
Progress in Understanding the Inhibitory Mechanism of Plant Extracts on Advanced Glycation End Products
HAN Yu, HU Yingying, HE Jinglei, WANG Hui, CHEN Qian, QIN Ligang
2021, 42(9):  233-240.  doi:10.7506/spkx1002-6630-20200404-050
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Advanced glycation end products (AGEs) encompass a class of substances formed by the reaction of free amino groups in proteins, lipids or nucleic acid with carbonyl groups in reducing sugars. It has been confirmed that these substances are pathogenic and can cause neurodegenerative diseases, inflammatory reactions, cardiovascular and cerebrovascular diseases, diabetes, cancer and other diseases. The purpose of this article is to summarize the origin, formation mechanism and pathogenicity of AGEs, with focus on the current status in research on the inhibitory mechanism of plant extracts on AGEs, which can provide a theoretical basis for controlling the production of AGEs during food processing.
Advances in Research of the Effects and Mechanisms of Protein Oxidation and Post-translational Modification on Meat Quality
HUANG Linlin, ZHANG Yimin, ZHU Lixian, LIANG Rongrong, LUO Xin, CHENG Haijian, MAO Yanwei
2021, 42(9):  241-247.  doi:10.7506/spkx1002-6630-20200330-435
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The postmortem conversion of muscle to meat involves a series of biochemical changes, and their interaction will determine meat quality. Protein oxidation induced by oxidative stress and post-translational modification of proteins have an important effect on the formation of meat quality. However, there are rare reports discussing the underlying mechanisms systematically. This paper describes the relationship between oxidative stress and protein oxidation, and summarizes the effects and mechanisms of protein oxidation and post-translational modification on the formation of meat qualities such as tenderness, water-holding capacity, color and nutritional value; which will theoretically guide meat science research in the future.
Progress in the Biological Functions of Sanshool
NIU Bo, PANG Guangchang, LU Dingqiang
2021, 42(9):  248-253.  doi:10.7506/spkx1002-6630-20200314-221
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Sanshool, the most important numb-taste substance, has a strong affinity to a variety of drug target receptors of great interest (cannabinoid receptor and vanillic acid receptor), and can activate a variety of ion channels and exert a wide range of biological effects in the body. This article summarizes the structure, physicochemical properties, taste mechanism and biological activity of sanshool, focusing on its effects on the sensory and intestinal peristalsis in humans, anti-cancer, analgesic and anti-obesity properties, and auxiliary therapeutic effects on diabetes. Future directions for sanshool research are discussed. We hope that this review will provide a theoretical reference for studies on the structure and functions of sanshool.
Progress in Research on Cassava Starch-Based Film Materials
CHEN Xuehua, XU Xindong, WANG Qing, QI Pengxiang, CHEN Shan
2021, 42(9):  254-263.  doi:10.7506/spkx1002-6630-20200404-049
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Cassava starch has the advantages of good ductility, viscosity and permeability, and is feasible to be used in the production of degradable natural polymer film materials due to its good degradability and film-forming capacity. Most current studies on cassava starch-based film materials are focused on the fields of biodegradable film, antibacterial film, pH indicator film and slow-releasing film. However, cassava starch-based film materials have worse thermal stability and mechanical properties than conventional thermoplastic materials. Hence, modification of cassava starch-based film materials will be the focus of future studies. This paper summarizes the methods commonly used for preparing, strengthening and modifying cassava starch-based film materials and reviews the application of cassava starch-based film materials. Meanwhile, an outlook on future trends is presented.
Progress in Food Delivery Systems Used for Curcumin Encapsulation
REN Shuang, DONG Wenxia, LIU Jinfang, MAO Like, GAO Yanxiang, YUAN Fang
2021, 42(9):  264-274.  doi:10.7506/spkx1002-6630-20200327-402
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Curcumin has various pharmaceutical functions such as antioxidant, anti-tumor, blood lipid-reducing, and Alzheimer’s disease-preventing effects. It can also be utilized as a natural colorant, a food preservative and an antioxidant in various foods and beverages. However, this compound’s poor water solubility, instability, fast metabolic rate, and low bioavailability limit its applications in the food field. The above problems can be solved by using natural biomolecules as wall materials to encapsulate curcumin in delivery systems. This article describes the structural characteristics and properties of curcumin, as well as the main factors and principles that limit its application. Meanwhile, we summarize the existing delivery systems used for improving the bioavailability of curcumin. Finally, some problems existing in this field of research and future research directions are proposed.
Current Status of Mechanochemistry and Its Application Prospects in Wheat Milling
TIAN Xiaoling, WANG Xiaoxi
2021, 42(9):  275-282.  doi:10.7506/spkx1002-6630-20200503-015
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Wheat milling is a process in which wheat grains are made into wheat flour by crushing, grinding, grading, mixing and other operations. According to the existing theory of wheat milling, mechanical force imposed on wheat grains only affects its physical properties such as grain size and damaged starch content during the milling process. However, accumulating studies show that the difference in grain size is not sufficient to explain the difference in flour quality during the milling process. Mechanochemistry is the study of chemical or physicochemical changes that occur in solids due to mechanical forces. These changes include material fragmentation, particle size reduction, crystal structure destruction, chemical bond change, and so forth, which can reduce the energy required for some chemical reactions, making the reactions easier to occur. Mechanochemistry has been applied to material surface modification, physical degradation, and other fields. This paper summarizes the mechanochemical theory and principle model as well as its application in synthesis, degradation and modification. In addition, it illustrates the basic theory of wheat milling, the problems encountered in current practice, and the current status of the application of mechanochemistry in research on starch and protein and other macromolecular components in cereals. Finally, the application prospects of mechanochemical theory in wheat milling are discussed.
Progress in Research on the Mechanism of Enzymatic Browning in Fruits and Vegetables
LI Caiyun, LI Jie, YAN Shoulei, WANG Qingzhang
2021, 42(9):  283-292.  doi:10.7506/spkx1002-6630-20200401-008
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Enzymatic browning has a significant impact on the quality of fruits and vegetables during processing and preservation, and increasing studies have been devoted to the mechanism of enzymatic browning. This article summarizes recent studies on the mechanism of enzymatic browning from the perspectives of polyphenol oxidase (PPO) and its phenolic substrates, including the types and catalytic sites of PPO and the methods used to extract, separate and purify PPO and determine its activity; changes in the types and contents of phenolics and the cause thereof; enzymatic oxidation of phenols, quinone production pathway, secondary metabolism process, oxidation end product characteristics and the mechanism of the inhibition of enzymatic browning by anti-browning agents. We hope that this review will provide a reference for systematic and in-depth studies on the mechanism of enzymatic browning.
Progress in Application of Bacteriophages in Control of Meatborne Pathogens
YANG Huixuan, LUO Xin, ZHU Lixian, YANG Xiaoyin, HAN Guangxing, DONG Pengcheng, ZHANG Yimin
2021, 42(9):  293-301.  doi:10.7506/spkx1002-6630-20200428-372
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In recent years, with the increasing variety of meat products and the optimization of processing technologies for meat products, the pollution risk of foodborne pathogens at all steps of meat processing is increasing. How to effectively prevent and control foodborne pathogens is a focus of concern in meat research and the meat industry. As a biological antibacterial substance that can replace traditional bacteriostatic agents, bacteriophage has drawn wide attention from researchers; however, its application in the meat industry has not yet been summarized and evaluated comprehensively. Therefore, the advantages and safety of bacteriophages are reviewed in this article. Also, the current status of the application of bacteriophage in the prevention and control of foodborne pathogens such as Escherichia coli, Salmonella and Listeria monocytogenes in raw meat and meat products under different conditions of temperature, multiplicity of infection, preparation composition, and meat product type is summarized in details. Moreover, future directions for the application of bacteriophage in protecting the safety of meat and its products are presented. In a practical point of view, the information gathered in this article will provide a reference for further application of bacteriophage in the field of meat food safety.
Progress in Research on the Preventive Effect and Mechanism of Tea on Ultraviolet Radiation-Induced Oxidative Stress
TANG Xiangyue, CHEN Ying, YU Penghui, LU Yan, GONG Yushun
2021, 42(9):  302-311.  doi:10.7506/spkx1002-6630-20200405-053
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Excessive ultraviolet radiation can put cells under stress, resulting in excessive accumulation of reactive oxygen species and DNA damage, and consequently disturbing the intracellular homeostasis. Tea is known to have a preventive effect against ultraviolet radiation-induced damage and related diseases. As a major class of function ingredients in tea, tea polyphenols are able to directly absorb ultraviolet radiation and assist metabolic regulation by binding to the specific targets in the body. In this paper, we review recent studies on how tea can prevent ultraviolet radiation-induced damage by maintaining the intracellular homeostasis. The mechanisms of action of tea in repairing ultraviolet radiation-induced damage are also described, including enhancing the repairing of DNA damage, inhibiting the activation of inflammasomes, maintaining the dynamic balance of inflammatory factors, and regulating the repairing mechanism of stress-induced sleep damage. Moreover, future directions for research on the preventive effect of tea on ultraviolet radiation-induced damage are discussed.
Progress in Research on Osmotic Pressure of Breast Milk and Infant Formula Milk and Its Effect on Infant Health
JIA Hongxin, SU Miya, CHEN Wenliang, QI Xiaoyan, JIE Liang
2021, 42(9):  312-318.  doi:10.7506/spkx1002-6630-20200407-079
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Breast milk is the best food for infants. It can not only provide comprehensive nutrients for infants, but also contribute to the healthy growth of infants due to its unique physiological characteristics. The osmolality of breast milk is usually 300 mOsm/kg H2O, which is not affected by race or lactation time. However, the osmolality of formula milk on the market is higher than that of breast milk. Hypertonic feeding has been considered to be related to a high incidence of gastroesophageal reflux (GER) and necrotizing enterocolitis (NEC) in infants (especially preterm infants) due to their immature gastrointestinal and renal systems. It is also considered to be not conducive to the healthy development of infant kidneys. In this paper, we systematically analyzes the clinical data of hyperosmotic feeding and infant GER, NEC and kidney health. The existing data show that hyperosmotic feeding could prolong the retention time of foods in the infant stomach, increase the chance of infant GER, increase the contents of microalbumin and retinol binding proteins as biomarkers for early glomeruli and renal tubule injury respectively, damaging infant kidney health; however, current data do not support a clear correlation between hyperosmotic feeding and NEC in infants. Besides, the article summarizes recent studies on the osmotic pressure of human milk and infant formula and the factors affecting it, presents some strategies for regulating the osmotic pressure of infant formula, and proposes future directions for the development of infant formula.
Progress in the Encapsulation of Natural Phenolic Compounds by Electrospinning
SHI Yuanyue, YANG Yufan, KONG Baohua, WANG Hao
2021, 42(9):  319-327.  doi:10.7506/spkx1002-6630-20200407-092
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Natural phenolic compounds have gained much attention in food, nutraceutical, pharmaceutical and other fields in recent years because of their benefits on human health. However, the application of phenolic compounds is limited due to their poor solubility, stability, and bioavailability. How to protect and deliver these compounds effectively and to maintain their functional properties has become a research hotspot. Electrospinning is a simple and low-cost technique to produce nanofibers, which can serve as nanovehicles for the encapsulation and controlled release of bioactive compounds. It can be used as an effective method to encapsulate phenolic compounds. This review presents an overview of the fundamental principle, types and operating parameters of electrospinning, the polymer matrices commonly used in electrospinning and the advantages of electrospinning, and it summarizes recent studies investigating the application of electrospinning in the encapsulation of phenolic compounds. Finally, future prospects for its application in the food industry are discussed, which will provide theoretical guidance for the application of electrospinning in the food industry.
A Review of Antimicrobial Peptides from Marine Fish and Its Potential Application in Food Safety
CHEN Xuan, CHEN Xu, HAN Jinzhi, WANG Shaoyun
2021, 42(9):  328-335.  doi:10.7506/spkx1002-6630-20200507-077
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The sustainable development of the food industry is hindered by the threat of drug resistance, which is caused by the overuse of antibiotics. Fortunately, marine fish-derived antimicrobial peptides with broad-spectrum activity are considered to be the best new antibiotic substitutes in the future. Therefore, discovering more antimicrobial peptides from marine fish and exploring its application in the field of food safety have become a hot research topic. This paper reviews recent progress in understanding the structure, biological activity and mechanism of action of antimicrobial peptides derived from marine fish, and it discusses future prospects for the application of the antimicrobial peptides in food safety. This paper is expected to provide evidence rationale for the research and utilization of antimicrobial peptides derived from marine fish.
Natural Antibacterial Agents and Their Application in Food Packaging: A Review
GUO Juan, ZHANG Jin, WANG Jiamin, ZHU Quanshan
2021, 42(9):  336-346.  doi:10.7506/spkx1002-6630-20200406-066
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Natural antibacterial agents, compounds essential to maintain the quality of fresh foods so as to protect human health, are non-toxic and widely available and has a significant antibacterial effect. Natural antibacterial agents has become a focus of concern in the food industry and packaging field. The types, sources, mechanisms of action and application of natural antimicrobial agents from plants, animals and microorganisms are described in this article. The major bioactive ingredients, antibacterial characteristics and application in food packaging of three classes of natural antibacterial agents are summarized as well as the laws and regulations that must be observed when using natural antibacterial agents, which will provide a reference for the preparation of packaging systems containing natural antibacterial agents. In addition, the opportunities for and challenges facing the application of natural antibacterial agents in food packaging are discussed.
Progress in Analytical Methods for the Determination of Azodicarbonamide in Wheat Flour and Its Products
TIAN Linshuang, GU Pengcheng, WU Cunbing, XU Ao, DOU Xuemei, SHI Fengzhen, CHEN Fei
2021, 42(9):  347-354.  doi:10.7506/spkx1002-6630-20200507-073
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Azodicarbonamide (ADA) is a common food additive used to whiten wheat flour and strengthen the elasticity of wheat flour dough. ADA is not stable in hydrothermal environment, readily converted into biurea (BIU) and semicarbazide (SEM). SEM is a metabolite of the veterinary drug nitrofurazone, which has strong carcinogenic, teratogenic and mutagenic effects. Direct and indirect methods are currently available for the determination of ADA in wheat flour and its products. ADA can be determined directly or indirectly by determining BIU and SEM. This article reviews the development of the methods for ADA detection in wheat flour and its products, analyzes the problems with the current ADA detection standards in China, and discusses future trends, with the aim of providing a reference for the research and practice of ADA detection.
Isolation, Characterization and Application of Exosome-Like Nanoparticles from Fruits and Vegetables: A Review
YANG Mengnan, LIU Shiqi, ZHANG Jing, RAN Longyi, CHEN Zhongjia, MA Chao
2021, 42(9):  355-361.  doi:10.7506/spkx1002-6630-20200418-240
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The exosome-like nanoparticles (ELNs) in fruits and vegetables are nano-scale extracellular vesicles released by fruit and vegetable cells, with similar structures to the exosomes of mammal cells, and have significantly varying lipid, protein and nucleic acid profiles as well as unique biological functions. In this review, the progress that has been made in studies on the ELNs in dozens of fruits and vegetables since 2013 are summarized with a special focus on the methods used for ELNs extraction and characterization and on the differences in the chemical profiles including lipids, proteins, and nucleic acids of ELNs from different plant sources. Also, the potential health benefits and application as drug carriers of these ELNs are reviewed. This article is expected to provide enlightenments for further investigations on ELNs from fruits and vegetables.