Table of Content

15 February 2020, Volume 41 Issue 3
Basic Research
Effect of Monascus on Texture and Flavor of Camembert-Type Cheese during Ripening Period
WANG Tong, PANG Xiaoyang, LU Jing, MA Changlu, YANG Baoyu, WU Zheng, LIANG Jiaqi, ZHANG Shuwen, Lü Jiaping
2020, 41(3):  1-11.  doi:10.7506/spkx1002-6630-20190104-061
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Two Camembert-type cheeses were manufactured from raw milk with and without (control) Monascus as an adjunct starter, respectively. The effect of Monascus on water content, degree of proteolysis, texture and flavor properties was evaluated during the ripening period of 40 days. The results showed that for both cheeses water content decreased and proteolysis was accelerated gradually with ripening time. The trends of texture parameters during the ripening period were similar between the two cheeses. Hardness and elasticity increased continuously during the first 8 days, and then decreased. Gumminess and chewiness were positively correlated with hardness and their trends were similar to hardness. Adhesiveness continuously rose, while the opposite was true for resilience. Moisture content and the degree of proteolysis increased as a result of the addition of Monascus. In addition, adhesiveness increased, whereas hardness, elasticity, gumminess, chewiness and resilience decreased, indicating that the cheese with Monascus had softer and more uniform texture. As ripening proceeded, the contents of acids, ketones, alcohols and esters showed a similar trend between the two cheeses. The contents of organic acids and alcohols increased continuously during the first 16 days, and then began to decrease; ketones were gradually accumulated; the content of esters increased continuously during the first 24 days, and then remained stable. The addition of Monascus led to a fluctuation in the contents and proportions of various organic acids as well as of alcohols, ketones and esters, synthesized from the precursors. The contents of 2-undecone, 2-tridecanone, phenylethyl alcohol, and butanediol, with a flowery and honey-like aroma, and ethyl hexanoate, ethyl octanoate, and ethyl citrate, with a fruity aroma, were significantly higher in the cheese with Monascus than in the control (P < 0.05), while the contents of nonone, octanone and decanone, with a milky flavor, and the content of 1-octene-3 alcohol, with a typical mushroom-like flavor, were lower in the cheese with Monascus.
Inhibitory Mechanism of Carnosic Acid on Alpha-Amylase
WANG Jing, DIAO Cuiru, WANG Huali, LI Xiang, WANG Mingchun, WANG Hao
2020, 41(3):  12-17.  doi:10.7506/spkx1002-6630-20181211-137
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Inhibiting α-amylase activity could effectively reduce the increase in the postprandial blood glucose level. The purpose of this study was to investigate the inhibitory kinetics and mechanism of carnosic acid on α-amylase. Results showed that carnosic acid exhibited potent inhibitory activity with a half maximal inhibitory concentration (IC50) of 1.12 mg/mL in a reversible and competitive manner. Fluorescence quenching experiments revealed that the fluorescence of α-amylase was statically quenched by binding carnosic acid. Molecular docking results showed that carnosic acid binding to the active site of α-amylase did not result in the formation of any new products but in the formation of a reversible enzyme-inhibitor complex, which triggered allosteric regulation to perturb conformational dynamics of α-amylase, eventually leading to a decrease in the catalytic activity of α-amylase.
Effect of Multi-Enzyme Modification on Branch Structure and Physicochemical Properties of Sweet Potato Starch
XIAO Yu, GUO Li, DENG Yinfeng, WANG Yi, ZHU Chenchen, DU Xianfeng
2020, 41(3):  18-23.  doi:10.7506/spkx1002-6630-20190207-032
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Sweet potato starch was sequentially treated with α-amylase (80 mg), β-amylase (10.6 mg) and different amounts (50, 100, 150, 200, 250 and 300 μL) of transglucosidase. The chain length distribution, branch density, crystal structure and rheological properties of sweet potato starch before and after enzymatic hydrolysis were analyzed by high performance anion-exchange chromatography equipped with pulsed amperometric detection (HPAEC-PAD), proton nuclear magnetic resonance (1H NMR) spectroscopy, X-ray diffraction and rheometry. The results showed that after the enzymatic treatment, the short-chain ratio of sweet potato starch increased significantly (P < 0.05) and the average chain length decreased significantly (P < 0.05), and when 300 μL of transglucosidase was added, the branch density of sweet potato starch was as high as 35%, significantly higher than that of the control sample. The crystal structure was transformed from C type to C + V type after the enzymatic modification. The relative crystallinity of the modified starches was lower than that of the natural starch, which proportionally increased from 10.8% to 14.8% with the amount of transglucosidase added. The solubility and transmittance were significantly higher than those of the control, and they increased with the addition of transglucosidase, reaching the highest value of 66.15% and 73.91%, respectively. The apparent viscosity, storage modulus and loss modulus were significantly lower than those of the control group (P < 0.05), and they all decreased with the addition of transglucosidase. These results provide a theoretical and practical basis for modifying the physicochemical properties of sweet potato starch by a multi-enzymatic method at the level of branch chain structure.
Effect of Heat Shock Protein 27 on Myofibrillar Proteins and Apoptotic Enzymes in Tibetan Sheep Meat during Postmortem Aging
SUN Jinlong, SHI Xixiong, HUANG Feng, HAN Ling, CHEN Cheng, YUE Jianwei
2020, 41(3):  24-29.  doi:10.7506/spkx1002-6630-20181203-038
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In order to study the effects of heat shock protein 27 (Hsp27) on the degradation of myofibrillar proteins and the activity of apoptotic enzymes during the postmortem aging of Tibetan sheep meat, mutton treated with Hsp27 inhibitor KRIBB3 was determined for changes in caspase-3 and -9 activity and the solubility and degradation characteristics of myofibrillar proteins. Besides, the effect of Hsp27 on the degradation of myofibrillar proteins by μ-calcium activase and caspase-3 was explored. The results showed that Hsp27 significantly inhibited the activity of caspase-3 and -9 (P < 0.05), and suppressed myofibril fragmentation and the degradation of myologin and troponin-T. In vitro studies also found that Hsp27 was able to significantly inhibit the degradation of myofibrillar proteins by μ-calcium activase and caspase-3.
Effects of Thermal, Stretching and Melting Treatments on Quality, Intermolecular Force and Microstructure of Mozzarella Cheese
LI Hongjuan, WANG Yi, LIU Yan, YU Hongmei, LI Hongbo, YU Jinghua
2020, 41(3):  30-36.  doi:10.7506/spkx1002-6630-20181205-065
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Mozzarella cheese is one of the most consumed and most popular cheeses with the highest import volume in China. Because it can be melted and strung when heated, Mozzarella cheese is widely used in catering industry. In this paper, the effects of hot-stretching and melting treatments on the quality characteristics of the cheese were studied, and the relationship between the change of cheese quality characteristics and the change of intermolecular interaction was elucidated. The basic composition, texture and functional properties, intermolecular interaction, glass transition temperature (Tg) and microstructure of Mozzarella cheese with different treatments (untreated, blanching, blanching and stretching, hot-stretching, melting, and melting and stretching) were determined. Compared with untreated samples, hot-stretching resulted in fat loss by 30.1% and an increase in moisture content of 15.3% The melting property of hot-stretched cheese decreased by 0.34 cm compared with untreated samples; the length of the strings of melted cheese did not change significantly, but the stringing strength increased significantly after hot-stretching treatment. After hot-stretching, the Tg value of the cheese increased by 1 ℃, suggesting that the intermolecular interaction of casein increased, and its mobility decreased. The results of hydrophobic interaction and protein solubility observed by a fluorescent probe showed that there was no significant change in hydrophobic interaction and the intermolecular hydrogen bonding force was reduced. Scanning electron microscopy showed that the three-dimensional network structure of the cheese became more compact after hot-stretching treatment, which was consistent with the change of Tg value and the determination of the solubility of the cheese.
Kinetic Analysis of Sol-Gel Transition of Gelatin/Modified Starch Blends Based on Dynamic Rheology
ZOU Xiurong, ZHU Jianhua, LIU Ribin, SHAN Bin
2020, 41(3):  37-46.  doi:10.7506/spkx1002-6630-20181031-365
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To explore the mechanism of the sol-gel transition of gelatin (GL)/modified starch (MS) blends in glucose syrup (GS) cosolute system, the evolving trend of viscoelastic modulus (G’ and G”) and the transition kinetics were investigated by dynamic rheology. Based on the first and second order derivatives of G’ versus t curves, there existed four characteristic temperatures for sol-gel (Tig, Tg, Tcg and Tmg) and gel-sol (Tis, Tcs, Ts and Tms) transition either separately, correspondingly dividing the phase transition process into five stages. During the phase transition process, the existing state of gelatin molecules was determined by these characteristic temperatures. With the increase of GS concentration (0%–60%, m/m), the initial sol-gel phase transition temperature (Tig) and gel point temperature (Tg) were increased, and the gel strength of GL/MS blend was decreased significantly. However, there was a downward trend in the sol point temperature (Ts). The activation energy (Ea) value of the phase transition process in the high temperature zone were decreased firstly and then increased with the increase of GS concentration, while the Ea value in the low temperature zone was not changed significantly. These results could provide a theoretical basis for the process optimization and quality control of GL/MS blend gel products.
Drying Modeling and Comprehensive Quality Analysis of Rosa roxburghii Tratt Fruit
CHEN Siqi, GU Yuanting, WANG Linlan, XIAO Shiyun, DU Bofeng, DING Zhuhong
2020, 41(3):  47-54.  doi:10.7506/spkx1002-6630-20190503-009
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This study aimed to scientifically and reasonably select a practical drying technology for Rosa roxburghii Tratt fruit that allows minimum quality changes and nutritional losses during the drying process. Hot air drying and far-infrared drying were comparatively applied to fresh and frozen fruit, and the drying processes were modeled. Meanwhile, the technique for order preference by similarity to an ideal solution (TOPSIS) and electronic nose technology were applied respectively to evaluate the comprehensive quality and flavor characteristics of the dried products in order to determine the optimal drying conditions. The results showed that page model had the highest fitting degree for hot air and far-infrared drying of fresh fruit and far-infrared drying of frozen fruit, whereas the Diffusion approximation model revealed the best fitting degree for hot air drying of frozen fruit. The models could describe and predict the drying processes. When frozen fruit were dried by far-infrared drying at 50 ℃, the rehydration rate was 7.41, the browning degree was 0.103, 29.39% of VC, 39.54% of total phenols, 13.58% of reducing sugar and 11.09% of total flavonoids were lost, and the Ci value was 0.958, which was the closest to the ideal solution; similarly, the flavor of the dried product was the closest to fresh fruit, indicating that the drying method and drying conditions provided the best comprehensive quality of dried Rosa roxburghii Tratt fruit.
Correlation Analysis between Energy Metabolism and Processing Quality of Channel Catfish with Different Prechilling Durations
ZHANG Wei, SHI Liu, XIONG Guangquan, WU Wenjin, LI Xin, QIAO Yu, DING Anzi, LIAO Li, WANG Lan
2020, 41(3):  55-61.  doi:10.7506/spkx1002-6630-20190128-362
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In order to study the correlation between energy metabolism and processing quality of channel catfish with different prechilling durations, changes in energy reserves (including glycogen, lactic acid, adenosine-5’-triphosphate (ATP), and ATP-related compounds), metabolic enzyme activities (hexokinase (HK), pyruvate kinase (PK), lactate dehydrogenase (LDH), creatine kinase (CK)), and quality indicators (pH value, cooking loss rate, expressible moisture rate, texture characteristics, K value, and color) were evaluated during prechilling for 48 h at 4 ℃ after slaughter. The results showed that the contents of glycogen and lactic acid decreased continuously with increasing prechilling time up to 24 h, and then began to accumulate; the contents of adenosine-5’-diphosphate (ADP), adenosine-5’-monophosphate (AMP) and inosine-5’-monophosphate (IMP) decreased gradually, the content of hypoxanthine (Hx) and inosine (HxR) increased gradually, and ATP was almost undetectable; HK activity continued to decline, PK activity rose to the maximum after 8 h prechilling and then decreased, LDH and CK activity showed a volatile decline; pH and shear force gradually decreased; expressible moisture rate, cooking loss and whiteness remained stable within 24 h, and increased significantly after 48 h (P < 0.05), indicating that water-holding capacity decreased; K value continued to rise and remained within the high freshness range below 20% within 24 h. Correlation analysis showed that there was a significant positive correlation between glycogen and lactic acid contents (P < 0.05); K value was significantly negatively correlated with HK (P < 0.05), but significantly positively correlated with whiteness (P < 0.01); LDH was significantly positively correlated with CK and shear force, but significantly negatively correlated with whiteness (P < 0.05). Expressible moisture rate was significantly positively correlated with cooking loss rate (P < 0.05). Postmortem channel catfish within 24 h of prechilling is more conducive to quality control during processing.
Drying Characteristics and Modelling of Penaeus vannamei during Superheated Steam Drying
YUN Dongling, GENG Wenguang, DU Rui, SUN Rongfeng, WANG Shouquan, ZHAO Gaiju
2020, 41(3):  62-67.  doi:10.7506/spkx1002-6630-20181229-346
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The purpose of this study was to investigate the drying characteristics of Penaeus vannamei in superheated steam. The drying experiments were carried out in the temperature range of 130–160 ℃. Non-linear fitting analysis of the experimental data was carried out using six common drying models to determine and validate the optimal drying model. Further, Effective moisture diffusion coefficients at different temperatures were calculated, and the relationship between effective moisture diffusion coefficient and temperature was established according to the Arrhenius equation. The results showed that the superheated steam drying of Penaeus vannamei was a falling rate drying process, and the drying temperature had a significant effect on the drying process. The higher drying temperature could result in a greater drying rate. Under certain experimental conditions, the experimental data were best fitted to the Logarithmic model. The drying model could accurately estimate the water loss rate of Penaeus vannamei during the drying process at different temperatures of superheated steam. As the superheated steam temperature increased, the effective diffusion coefficient increased from 3.186 08 × 10-9 to 7.289 72 × 10-9 m2/s, with an activation energy of 39.631 kJ/mol. Furthermore, the color of dried product was better at lower drying temperatures, but excessively higher temperatures had a negative effect on it. Considering both the drying rate and the dried product quality, the superheated steam temperature should not exceed 150 ℃.
Synergistic Antibacterial Effect and Mechanism of Helveticin-M Combined with Chlorogenic Acid on Escherichia coli and Salmonella enteritidis
WANG Hongyi, LIU Fang, SUN Zhilan, SU Mengmeng, ZHU Yongzhi, WANG Daoying, XU Weimin, PENG Jing
2020, 41(3):  68-74.  doi:10.7506/spkx1002-6630-20190228-229
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The objective of this study was to explore the synergistic antimicrobial effect of Helveticin-M combined with chlorogenic acid against Escherichia coli and Salmonella enteritidis by examining growth curves and cell viability. Furthermore, the morphology, structure and membrane permeability of the indicator bacteria were characterized by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and extracellular ATP analysis. The results showed that the synergistic effect of Helveticin-M combined with chlorogenic acid was markedly increased when compared with either antibacterial agent alone (P < 0.05). The structure of the bacterial cells subjected to the combined treatment was damaged seriously under SEM and CLSM examination, indicating increased permeability of the cytoplasmic membrane. There was a significant difference in extracellular ATP concentration between the combined treatment and either treatment alone (P < 0.05). In conclusion, the combination of Helveticin-M and chlorogenic acid exerted a notable synergistic antimicrobial effect by increasing membrane permeability and thereby leading to the leakage of intracellular components. This study provides a basis for expanding the industrial application of Helveticin-M and chlorogenic acid.
Effect of Particle Size and Interaction on Hardness of Gel Particle Clusters
CHEN Wei, WANG Xinmiao, Enrico Karsten HADDE, ZHU Min, ZANG Yongchun, JI Dahuai, CHEN Jianshe
2020, 41(3):  75-79.  doi:10.7506/spkx1002-6630-20190122-280
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Texture is a sensory response to the physical and structural properties of foods, directly affecting the eating process and sensory pleasure. Food gels are often used after being broken into clusters as swallowing aids for dysphagia patients due to their desirable soft solid texture. In this work, a commercial food gel was broken into particle clusters to investigate the relationship of the hardness of the particle clusters with the gel strength, particle size and the interactions between gel particles. It was found that the hardness of gel clusters decreased steeply and linearly with the decrease in particle size. However, it kept increasing with the increased gel strength interactions between gel particles. This study provides useful experimental evidence and theoretical support for the development and quality control of gel-based foods, especially for those used as an adjuvant for treating dysphagia.
Determination and Partial Correlation Analysis of Nutrient Components and Texture Characteristics of Sufu
ZHUANG Yang, CHEN Lu, TIAN Cheng, MO Kaiju, WANG Xingping
2020, 41(3):  80-85.  doi:10.7506/spkx1002-6630-20190802-028
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The nutritional components and texture of five kinds of famous sufu in Enshi were determined and the relationship between them was analyzed by partial correlation analysis. The result demonstrated that the moisture contents of the sufu samples were around 60%, and the contents of total protein, water-soluble protein, amino acid nitrogen, total acid, salt, fat and total volatile basic nitrogen ranged from 11.26% to 15.66%, 3.94% to 7.24%, 0.56% to 1.95%, 0.32% to 0.78%, 7.90% to 10.82%, 5.88% to 14.46% and, 0.12% to 0.34%, respectively. In addition, the hardness, adhesiveness, springiness, cohesiveness, gumminess ranged from 82.64 to 439.04 g, 9.39 to 167.70 g·s, 0.27 to 0.86, 0.09 to 0.38, and 16.76 to 130.82 g respectively. The partial correlation analysis revealed that the nutritional components prominently influenced the texture. Hardness were significantly positively correlated with the content of total protein, amino acid nitrogen and the ratio of water-soluble protein to total protein content (P < 0.01), but negatively correlated with the content of water-soluble protein and the ratio of amino acid nitrogen to total nitrogen content (AAN/CN) (P < 0.05); gumminess were significantly positively correlated with AAN/CN (P < 0.01), but negatively correlated with the content of amino acid nitrogen and total acid (P < 0.01). In general, the form and content of protein may be an important intrinsic factor affecting the texture of sufu.
Food Engineering
Effect of Drying Processes on Structural and Quality Properties of Fish Oil Microcapsules
JIANG Lianzhou, WANG Zhaoyun, GU Linazi·Maimaitinu, JU Huanhuan, GUO Zengwang, QI Yuman, LI Yang, QI Baokun, ZUO Feng, FAN Zhijun, WANG Zhongjiang
2020, 41(3):  86-92.  doi:10.7506/spkx1002-6630-20181228-344
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The effects of different drying processes on the structural and physicochemical properties of fish oil microcapsules were analyzed. The microcapsules were prepared by preparing a nanoemulsion an ultrasonic technique using deep-sea fish oil, susceptible to oxidation, heat-sensitive and photosensitive, as the core material and soy protein isolate (SPI) and phosphatidylcholine as the wall material, and drying it using spray drying, vacuum freeze drying or microwave drying. The results showed that spray dried microcapsules were spherical particles with a compact structure, no oil droplet aggregation, small particle size, good solubility and high stability against oxidation and heat, as well as good entrapment efficiency (95.54%). Both vacuum freeze-dried and microwave dried microcapsules were irregular in shape with a porous surface, having high surface oil contents and entrapment efficiencies of 86.70% and 74.28%, respectively, and exhibiting a certain degree of oil droplet aggregation, larger particle size and poor solubility. The release rates of free fatty acids from the microcapsules prepared by spray drying, vacuum freeze-drying and microwave drying were 20.03%, 25.98% and 75.91% in simulated gastric juice, and 78.73%, 71.78% and 22.91% in simulated intestinal juice, respectively. The in vitro digestion experiments showed that release rate of free fatty acids from spray dried microcapsules was relatively low in simulated gastric juice, but higher in simulated intestinal juice. Therefore, the performance of spray dried microcapsules is better than that of microcapsules prepared by the other two drying processes. This study provides a theoretical basis for developing an evaluation system for the application of various drying processes in the preparation of microcapsule products.
Intermolecular Interaction Mechanism for Improvement in Solubility of Soy Protein Isolate by Swirling Cavitation
REN Xian’e, LI Chunzhi, YANG Feng, HUANG Yongchun, YAN Liujuan
2020, 41(3):  93-98.  doi:10.7506/spkx1002-6630-20190306-078
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In order to understand the mechanism for solubility improvement of soy protein isolate (SPI) by swirling cavitation treatment, changes in ionic bond, hydrogen bond, hydrophobic interaction, disulfide bond, and non-disulfide covalent bond contents of SPI after the treatment were evaluated and their relationship with the improvement in solubility of SPI was investigated. The results obtained were as follows: 1) the content of ionic bonds was increased with the increase in pressure and time; 2) the contents of hydrogen bonds and hydrophobic interaction were decreased with the increase in treatment time at 0.6 MPa, but they increased first and then decreased at 0.2 and 0.4 MPa; 3) the content of disulfide bonds was decreased with the increase in treatment pressure and time; 4) the content of non-disulfide covalent bonds did not change significantly at 0.2 MPa relative to the untreated group (P > 0.05), but was decreased at 0.4 and 0.6 MPa. Furthermore, the correlation analysis indicated that the solubility of SPI was correlated significantly positively with the content of ionic bonds (r = 0.754) (P < 0.01) and significantly negatively with the hydrophobic interaction and contents of disulfide bonds(r = ?0.714 and ?0.839, respectively) (P < 0.01). These results suggested that the improvement in solubility of SPI during swirling cavitation treatment was correlated with the formation of ionic bonds and the destruction of hydrophobic interaction and disulfide bonds.
Effect of Jet Cavitation on Soy Protein Isolate-Phosphatidylcholine Emulsion Properties
TIAN Tian, JIANG Zhongyang, WANG Zhongjiang, LI Yang, LI Liang
2020, 41(3):  99-105.  doi:10.7506/spkx1002-6630-20190106-079
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This study was undertaken in order to investigate the effect of jet cavitation on physicochemical and functional properties of a soy protein isolate (SPI)-phosphatidylcholine (PC) stabilized emulsion. The conformational changes of the composite system were characterized by fluorescence spectroscopy, and the creaming index, particle size, microstructure, surface hydrophobicity and emulsifying activity and emulsion stability were analyzed. The results showed that jet cavitation significantly improved physicochemical and emulsifying properties of the composite emulsion. The emulsifying activity index (EAI) and emulsion stability index (ESI) of the composite emulsion treated at 0.2 MPa for 10 min were 82.7% and 10.43-fold higher than those of the single SPI stabilized emulsion, respectively. The average particle size of the composite emulsion system became smaller and surface hydrophobicity became higher after jet cavitation as examined by dynamic light scattering and optical microscopy. The lowest average particle size and the highest surface hydrophobicity were obtained with the 0.2 MPa/10 min treatment. Thus, we concluded that jet cavitation could cause the exposure of hydrophobic groups in the interior of the protein, increasing the interaction between the protein and PC. Fluorescence spectroscopy indicated that cavitation force had a quenching effect on the fluorescence intensity of SPI.
Effect of Ultra-Pasteurization on Microstructure and Aggregation Properties of Casein from Bovine Milk
ZHANG Anqi, WANG Yuying, LI Rui, ZHOU Guowei, WANG Lin, WANG Xibo
2020, 41(3):  106-110.  doi:10.7506/spkx1002-6630-20190103-029
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The effect of ultra-pasteurization (121 ℃/5 s) on the microstructure and aggregation properties of casein in milk was investigated in comparison with non-thermally treated milk and two commonly used pasteurization treatments (65 ℃/30 min, and 72 ℃/15 s). The results showed that the particle size of casein increased significantly after ultra-pasteurization. Under transmission electron microscopy and scanning electron microscopy it was observed that ultra-pasteurization could destroy the casein micelle structure and result in large-scale cross-linking and coagulation, but the coagulation could result in a more uniform state of casein micelles. Differential scanning calorimetry (DSC) analysis showed that the samples treated with ultra-pasteurization had a slightly higher denaturation temperature than the casein micelles without heat treatment. The thermal stability of casein was increased after the second pasteurization treatment when compared with the other treatments, and the denaturation temperature was 99 ℃.
Nutrition & Hygiene
Effect of Dietary Methionine Restriction on Islet Function Injury in Obese Mice Induced by High-Fat Diet
LUO Tingyu, YANG Yuhui, XU Yuncong, GAO Qiuli, SHI Yonghui, WU Guoqing, LE Guowei
2020, 41(3):  111-119.  doi:10.7506/spkx1002-6630-20181101-010
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Purpose: To evaluate the protective effect of dietary methionine restriction (MR) on the pancreas of obese mice induced by high-fat diet. Methods: Totally 210 male C57BL/6J mice were divided into a control group (CON: 0.86% methionine + 4% fat; n = 30) and a high-fat diet group (HF: 0.86% methionine + 20% fat; n = 180). Obesity was successfully induced in 120 of the HF diet fed mice, and the obese mice were further randomly divided into an HF group, an HF + MR group (0.17% methionine + 20% fat), a control diet group (C*: 0.86% methionine + 4% fat) and a C* + MR group ( 0.17% methionine + 4% fat). A subset of animals in each of the four groups were euthanized at 8, 16 and 24 weeks. Glucose tolerance was determined at 24 weeks. Fasting blood glucose and plasma insulin levels, hydrogen sulfide (H2S) levels and redox indicators in plasma and pancreas were investigated. Quantitative real-time polymerase chain reaction (PCR) was used to determine the expression of genes related to insulin secretion and endoplasmic reticulum stress. Results: MR significantly reduced body mass and increased feed and energy intakes in mice (P < 0.05); decreased fasting blood glucose and plasma insulin levels, glucose tolerance and insulin resistance index (P < 0.05); increased H2S levels in plasma and pancreas and improved redox status (P < 0.05); up-regulated the mRNA expression of cystathionine-caseo-lyase (CSE), cystathie-base-synthase (CBS), v-maf musculoaponeurotic fibrosarcoma oncogene homologue (MafA), pancreatic duodenal homeobox-1 (Pdx-1) and B-cell lymphoma 2 (Bcl-2), and down-regulated the mRNA expression of Bcl-2 associated protein X (Bax), X-box binding protein-1 (Xbp-1), C/EBP homologous protein (CHOP), and inositol requiring enzyme 1α (IRE1α) (P < 0.05). Interestingly, the HF + MR and C* + MR groups showed similar trends in all the above indicators. Conclusion: MR can protect the pancreas and promote insulin secretion by improving endoplasmic reticulum stress and redox status in pancreatic tissue of obese mice.
Protective Effect of Flaxseed Oil on Diabetic Nephropathy Induced by Streptozocin in Rats
NIU Jiahui, FU Mengqi, ZHOU Qian, WANG Yaxu, WU Mengying, ZHAO Wen, WANG Jie
2020, 41(3):  120-126.  doi:10.7506/spkx1002-6630-20181219-227
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Objective: To explore the protective effect of flaxseed oil in comparison with fish oil on streptozotocin (STZ)-induced diabetic nephropathy (DN) in rats. Methods: An animal model of DN was established by a single intraperitoneal injection of STZ in rats. The experimental rats were divided into one negative control group, one model group, three flaxseed oil groups (0.3, 0.6, and 0.9 mL/100 g mb), and one fish oil group (0.6 mL/100 g mb). Glucose metabolism indexes including fasting blood glucose, glucose tolerance and glycosylated serum protein (GSP), renal function indexes including urine volume, urine protein, creatinine and urea nitrogen, as well as cytokines and oxidative stress status were determined in all the animals. Histological changes of pancreas and kidney tissues were observed. Results: Compared with the model group, flaxseed oil and fish oil could significantly reduce fasting blood glucose level, improve glucose tolerance and GSP, decrease urine volume and urine protein, improve renal function and reduce inflammatory reactions. Both of them could enhance antioxidant capacity and significantly increase the expression of glucose transporter-4, insulin, pyruvate kinase and hexokinase in liver (P < 0.05 or P < 0.01). Moreover, histopathological observation showed that flaxseed oil could alleviate pancreas and kidney injury in DN rats. Conclusion: Both flaxseed oil and fish oil have a protective effect on STZ-induced DN. The underlying mechanism may be related to the regulation of glucose metabolism, and the anti-inflammatory and antioxidant capacity. Comparatively, fish oil is more effective in regulating carbohydrate metabolism, while flaxseed oil has a better protective effect on the kidney.
Effect of Phytosterol Esters on Selected Serum Metabolites of Rats with Non-alcoholic Fatty Liver Disease (NAFLD)
OUYANG Pengling, GUAN Qi, QU Dan, DING Xinwen, YANG Li, SONG Lihua
2020, 41(3):  127-137.  doi:10.7506/spkx1002-6630-20181016-164
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Based on our previous studies, the effect of phytosterol esters (PSE) on selected serum small-molecule metabolites of rats with non-alcoholic fatty liver disease (NAFLD) was investigated in the present study. Further, we explored the molecular mechanism underlying the preventive effect of PSE on NAFLD. Rats were fed with a high-fat diet to establish a NAFLD animal model, and PSE fortified milk at low (0.05 g/100 g mb·d) and high (0.10 g/100 g mb·d) doses were respectively given to rats in the PSE intervention groups by intragastric administration at the same time. Serum small-molecule metabolites of NAFLD rats were detected using ultra performance liquid chromatography-quadrupole-tandem time-of-flight mass spectrometry (UPLC-Q-TOF-MS). In addition, Progenesis QI v2.3 software, UNIFI data analysis platform and Metabo Analyst were used to analyze differential serum metabolites and the metabolic pathways involving the identified differential metabolites. Our results showed that 27 metabolites were identified, including diglyceride (14:0/22:2(13Z,16Z)/0:0, 15:0/18:3 (6Z,9Z,12Z)/0:0, 16:0/20:3(8Z,11Z,14Z)/0:0, 18:1(11Z)/18:1(11Z)/0:0), glucosylceramide (d18:2/20:0), lactosylceramide (d18:1/18:1(9Z)), heneicosanedioic acid, lysophospholipid (Lyso PC) (15:0, 16:1(9Z), 20:3(5Z,8Z,11Z), 20:3(8Z,11Z,14Z), 18:1(9Z), 18:2(9Z,12Z)), phosphatidic acid(22:4(7Z,10Z,13Z,16Z)/0:0), phosphatidylcholine(16:0/20:3(5Z,8Z,11Z), 16:0/P-18:0, 18:1(11Z)/20:1(11Z), 17:1(10Z)/0:0, 20:3(8Z,11Z,14Z)/18:0, O-18:0/0:0), phosphatidylethanolamine (16:0/0:0, 18:3(6Z,9Z,12Z)/22:6(4Z,7Z,10Z,13Z,16Z,19Z), 20:3(8Z,11Z,14Z)/0:0, 18:4(6Z,9Z,12Z,15Z)/18:0), phosphatidylinositol(20:0/22:2 (13Z,16Z)) and sphingomyelin (d16:1/25:0, d18:1/24:0). The preventive effect of PSE was exerted on NAFLD probably through correcting high-fat diet-induced disturbance of the glycerophospholipid and lipid metabolism pathways.
Interventional Effect of Taurine in Mouse Models of Depression
YUAN Jing, YAN Chenjing, ZHOU Qian, NIU Jiahui, WU Mengying, WANG Yaxu, WANG Jie, ZHAO Wen
2020, 41(3):  138-143.  doi:10.7506/spkx1002-6630-20181219-226
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Objective: To study the effect of taurine on depression-related behaviors and biochemical indexes in mouse models of depression. Methods: Two mouse models of behavioral despair or acute depression induced by reserpine, respectively were used for this study. The model mice were randomly divided into 6 groups: negative control, model control, fluoxetine control, and three taurine dose groups (0.5, 1 and 2 g/kg mb), with 10 animals in each group. The effect of taurine on the despair time of mice was investigated by tail suspension, and forced swimming and open field tests, and its effect on depression-related behaviors such as ptosis, rectal temperature and escape rate as well as depression-related biochemical indicators including (adreno-corticotropic hormone) ATCH, brain derived neurotrophic factor (BDNF) and cortisol (COR) in serum and 5-hydroxytryptamine (5-HT), norepinephrine (NE), dopamine (DA), monoamine oxidase (MAO) and corticotropin-releasing factor (CRF) in brain tissue was evaluated in the mouse model of acute depression. Results: Taurine significantly shortened the suspension time of the behavioral despair model mice (P < 0.01) and forced swimming time (P < 0.01). In the open field test, taurine significantly increased the level and number of vertical movements (P < 0.01), but resulted in no significant difference in ptosis rate (P > 0.05). Meanwhile, taurine significantly increased the levels of 5-HT, DA and NE in brain tissue of depressed mice (P < 0.05), decreased MAO activity (P < 0.01), augmented BDNF content (P > 0.05), inhibited excessive secretion of CRF, ACTH and COR (P < 0.01), and improved other relevant biochemical indicators. Conclusion: Taurine may be an effective interventional strategy for reserpine-induced acute depression by improving hormone secretion in model animals.
Inhibitory Effect of Tilapia Head Phospholipid on RANKL-Induced RAW264.7 Cell Differentiation and Mechanism of Osteoclast Apoptosis Induced by It
MA Ting, XIA Guanghua, LI Chuan, SHEN Xuanri
2020, 41(3):  144-150.  doi:10.7506/spkx1002-6630-20181212-148
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This study was performed to investigate the effect of tilapia head phospholipid (TH-PL) on biological functions in osteoclasts. Total lipids from tilapia head were extracted with organic solvents and separated by silica gel column chromatography to obtain TH-PL. Its properties and structure were partially analyzed by thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FTIR) and gas chromatography. In addition, an osteoclast model was established by inducing the differentiation of RAW264.7 macrophages in vitro with receptor activator for nuclear factor-κB ligand (RANKL). The effect of TH-PL on the differentiation of RAW264.7 macrophages into osteoclasts was explored by tartrate resistant acid phosphatase (TRAP) staining. Fluorescent staining, Western blotting and flow cytometry were used to detect osteoclast apoptosis. The results showed that TH-PL accounted for 1.52% of the dry mass of tilapia heads. TLC and FTIR determined that the as-prepared sample was phospholipid and rich in unsaturated fatty acids, accounting for 38% of the total fatty acids. TRAP staining experiments confirmed that TH-PL at doses of 50 and 100 μg/mL significantly inhibited the differentiation of RAW264.7 macrophages into osteoclasts. Furthermore, TH-PL promoted osteoclast apoptosis by reducing mitochondrial transmembrane potential and increasing the expression of caspase-3 in cells. In conclusion, in vitro cell experiments demonstrated that TH-PL could significantly inhibit osteoclast differentiation and promote osteoclast apoptosis.
Packaging & Storage
Release Behavior of Incorporated Hop Extract from Gelatin-Chitosan Antibacterial Film
CHEN Ting, ZHAO Jiuyang, LIU Yumei
2020, 41(3):  151-158.  doi:10.7506/spkx1002-6630-20190213-057
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The release behavior of hop extract in a food stimulant from gelatin-chitosan film, in which hop extract was incorporated as an antibacterial agent was investigated. The effects of different ambient temperatures on the release behavior of hop extract, α-acid and β-acid into 10%, 50% and 95% ethanol solutions were evaluated. The results showed that the release of the antibacterial agent gradually increased with time and temperature, until equilibrium was reached. In different food simulants, the higher the water content, the smaller the release amount of the antibacterial agent. Under the same conditions, the release rate of hop extract was the slowest, and the equilibrium release amount was minimal. The release data were fitted with the Peleg model with correlation coefficient (R2) higher than 0.98, indicating that the model was reliable in predicting the release behavior of hop extract, α-acid and β-acid.
Changes in Lipids of Wheat Flour Samples with Different Processing Degrees during Storage
CHEN Congcong, WANG Xinwei, ZHAO Renyong
2020, 41(3):  159-164.  doi:10.7506/spkx1002-6630-20190225-162
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In this study, five wheat flour samples with different processing degrees were selected and stored at 40℃ and relative humidity of 70% for 6 months. The effect of processing degree on the storage stability of wheat flour was investigated through analyses of changes in their lipids (glyceride contents and fatty acid compositions) and physicochemical properties related to lipids (fatty acid values, peroxide values, and malondialdehyde contents) during storage. The contents of triglycerides and diglycerides in wheat flour samples decreased while the contents of monoglycerides and fatty acids increased with storage time, indicating that the lipids were hydrolyzed. After 6 months of storage, the increase in fatty acid value of sample 5 was 16.22 times higher when compared with sample 1. The lower the processing degree, the higher the degree of hydrolysis of the lipids. Both peroxide values and malondialdehyde contents showed an upward trend with storage time, indicating that oxidation of the lipids occurred accompanied by their hydrolysis. After 6 months of storage, the increase in peroxide value and malondialdehyde content of sample 5 was 4.81 and 7.44 folds when compared with sample 1, respectively. The lower the processing degree was, the greater the increase in peroxide value and malondialdehyde content was, and the faster oxidative rancidity occurred. The wheat flour samples with different processing degrees had similar fatty acid compositions, and both saturated and unsaturated fatty acid compositions of crude lipids extracted from the wheat flour samples did not obviously change with storage time.
Multivariate Analysis of the Effect of Calcium Lactate on the Quality of Baby Ginger Rhizome during Low-Temperature Storage
FU Yunyun, JIANG Cheng, ZHANG Jing, WANG Penglin, JIANG Linjun, LIAO Li, KONG Yan, YAN Xiaoqian, CHEN Anjun
2020, 41(3):  165-170.  doi:10.7506/spkx1002-6630-20190113-148
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In this study, the effects of treatment with different concentrations of calcium lactate on the quality of baby ginger rhizome were studied by multivariate analysis. The One-way analysis of variance (ANOVA) showed that calcium lactate treatment could significantly inhibit decay incidence and the decrease in color difference (ΔE* value) and hardness. It effectively delayed the decrease in total phenol, gingerol and 6-gingerol contents. Principal component analysis and the comprehensive evaluation model showed that calcium lactate treatment delayed the decline of fruit quality during storage. The correlation analysis indicated that total phenol content was significantly positively correlated with 6-gingerol content (r = 0.946, P < 0.01), and hardness was positively correlated with brittleness (r = 0.846, P < 0.05) and negatively correlated with polyphenol oxidase activity (r = -0.883, P < 0.05). Path analysis showed that ΔE* value, hardness, total phenol content and peroxidase activity had a greater direct effect on decay incidence with path coefficients of 1.347, 0.345, ?0.482 and 0.396, respectively. All other indicators had an indirect effect through these four indicators.
Effect of Different High Barrier Packaging Materials on Physicochemical Properties and Microbial Community Diversity of Roast Duck
MU Gang, LUO Xin, LIANG Rongrong, DONG Pengcheng, MAO Yanwei, ZHU Lixian, ZHANG Yimin, YANG Xiaoyin
2020, 41(3):  171-177.  doi:10.7506/spkx1002-6630-20190109-105
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In this present study, the effects of three types of high barrier packaging materials, including silicon oxide plating (SOP), poly(vinyl alcohol) (PVA), and polyvinylidene chloride (PVDC), on the quality of roast duck were compared. Polyethylene/nylon packaging was used as a control. All samples were vacuum packaged and stored for up to 21 days at 4 ℃. The total volatile basic nitrogen (TVB-N) content, color and microbial counts were determined during the storage period, and the microbial community diversity was analyzed using high-throughput sequencing technology. The results showed that in addition to inhibiting microbial growth, SOP could effectively inhibit the production of TVB-N and the minimum value occurred on day 21 of storage, lower than 20 mg/kg. Both storage time and packaging materials had significant effects on the microbial community structure in roast duck. Lactobacillus and Weissella were the dominant bacteria in SOP packaged samples. Lactobacillus, Weissella, Pseudomonas, Myroides, and Carnobacterium were the dominant bacteria in PVA packaged samples. Lactobacillus, Weissella, Thermophilus and Vibrio were the dominant strains in PVDC packaged samples. Comparative analysis showed that SOP was effective against Pseudomonas, Myroides and Thermophilus, thereby maintaining the quality and prolonging the shelf life of roast duck. Taken together, high barrier vacuum packing materials with silicon oxide coating can effectively maintain the quality of roast duck by inhibiting the growth of microorganisms.
Effect of Methyl Jasmonate Treatment Combined with Low Temperature Conditioning on the Quality and Physiology of Postharvest Hot Pepper
LIU Yao, ZHENG Qiuli, ZUO Jinhua, GAO Lipu, LIU Jing, SHI Junyan, LI Miao, WANG Qing
2020, 41(3):  178-184.  doi:10.7506/spkx1002-6630-20181224-267
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The effect of methyl jasmonate (MeJA) combined with low temperature conditioning (LTC) on physiological and biochemical parameters in hot pepper during postharvest storage was investigated. In this experiment, “Jinyinda” peppers were soaked in 5 μmol/L MeJA solution for 10 min, and then taken out and dried before being stored at 10 ℃ for 2 days and then transferred to storage at 4 ℃, and they served as a combined treatment group. In the LTC treatment group, water instead of MeJA solution was used. The chilling injury index, chlorophyll and vitamin C and malondialdehyde (MDA) content, the activities and gene expression of antioxidant enzymes were measured during storage. The results showed that MeJA + LTC treatment could effectively inhibit chilling injury, delay the decrease in chlorophyll and VC content, suppress the increase in MDA content and maintain cell integrity. MeJA + LTC treatment maintained the activities and gene expression of peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) in pepper fruit. These results indicated that MeJA combined with LTC could reduce the chilling injury, maintain the storage quality and prolonged the shelf life of hot peppers. Therefore, MeJA combined with LTC should be recommended for improving the storage quality and antioxidant capacity of hot peppers.
Effect of 1-Methylcyclopropene Treatment on Firmness Change of Postharvest Plum Fruit and Underlying Mechanism
CHEN Ou, WU Xueying, DENG Lili, ZENG Kaifang
2020, 41(3):  185-191.  doi:10.7506/spkx1002-6630-20190128-235
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In order to investigate the firmness change of plum fruit after 1-methylcyclopropene (1-MCP) treatment, three native plum cultivars in Chongqing (‘Mai’, ‘Qingcui’ and ‘Waizui’) were treated with 1-MCP at 5 μL/L for 6 h at room temperature, and then stored at 0 ℃. Changes in firmness, substances and enzyme activities related to firmness and other fruit quality attributes during storage were measured. Results showed that 5 μL/L 1-MCP treatment could effectively inhibit the reduction in protopectin and the formation of water-soluble pectin, repress the activity of pectin methylesterase and polygalacturonase, and slow the increase in a* and the decrease in soluble solids content (SSC), titratable acidity (TA), vitamin C content and fruit firmness. These results preliminarily revealed the underlying mechanism by which 1-MCP treatment could delay the decline of firmness, which will provide a theoretical basis for hardness and quality maintenance in postharvest plum fruit.

Effects of Different Storage Temperatures on Lactic Acid Metabolism Flux in Postmortem Pork
ZHANG Chengyun, HE Xingxing, PANG Guangchang, ZHANG Dequan, ZHANG Chunhui, GUAN Wenqiang
2020, 41(3):  192-197.  doi:10.7506/spkx1002-6630-20190708-099
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We aimed to investigate the effect of different storage temperatures on lactic acid metabolism flux in postmortem pork loin in this study. Pork samples were stored at 4 or ?1 ℃ and evaluated for the rate of change in glucose, lactic acid and NADH contents at different time points (0.5, 2, 6, 12, 24, 72, 120 and 168 h). Besides, the pattern of rigor mortis and the lactic acid metabolic pathway were analyzed in order to a central metabolic network model to determine lactic acid metabolism flux. The results showed that lactic acid metabolism flux varied with storage temperature and time. The flux of glucose entering the pentose phosphate pathway at ?1 ℃ was significantly higher than at 4 ℃, while lactic acid metabolism flux between 0.5 and 12 h at ?1 ℃ was significantly lower than at 4 ℃. The rate of decline in lactic acid flux between 24 and 168 h at ?1 ℃ was lower than at 4 ℃. This indicated that the lower the temperature was, the slower the catabolic rate was. Storage at ?1 ℃ could delay the accumulation of lactic acid and the rate of glycolysis, which was beneficial to the preservation of fresh meat. This study provides a theoretical basis for fresh meat preservation from the perspective of metabolism.
Quality Changes and Predictive Modeling of Shelf Life of Matcha Stored at Different Temperatures
LIU Zhengquan, ZHANG Hui, WANG Huifang, XIAO Zhipeng, CHENG Shuhua, ZHANG Zhengzhu
2020, 41(3):  198-204.  doi:10.7506/spkx1002-6630-20190117-199
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The quality changes of matcha during storage under four temperature conditions (?18, 4, 25 and 37 ℃) were analyzed, and a predictive model for the shelf life of matcha was constructed. The results showed that the contents of chlorophyll, tea polyphenols and ascorbic acid, greenness and sensory?evaluation showed a downward trend at each storage temperature, while the opposite trend was observed for moisture content. Person correlation analysis showed that moisture and chlorophyll contents had the highest correlation with sensory evaluation. Based on the Arrhenius equation, the shelf life prediction model was established. The activation energy (Ea) was 10 269.77 and 7 140.86 kJ/mol for moisture and chlorophyll contents, respectively, and the pre-exponential factor (k0) was 0.659 4 and 0.026 2, respectively. The theoretical shelf life was consistent with the actual shelf life, and the shelf life of matcha could be predicted based on moisture and chlorophyll contents.
Inhibitory Effect of Prohexadione-Calcium Combined with Calcium Nitrate on Bitter Pit of Fuji Apple
PENG Yong, WANG Junxiao, MA Yurong, LIU Pei, WANG Qingguo
2020, 41(3):  205-211.  doi:10.7506/spkx1002-6630-20190124-308
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In order to control the occurrence of bitter pit in postharvest apple, Fuji apples were treated under water pressure with prohexadione-calcium, calcium nitrate and their combination. Changes in bitter pit incidence, total calcium and calcium species contents and antioxidant enzyme activities were investigated, and the mechanism underlying the control of bitter pit by prohexadione-calcium combined with calcium nitrate was discussed. The results showed that prohexadione-calcium alone could not alleviate the occurrence of bitter pit in Fuji apple, while the incidence of bitter pit in apples treated with calcium nitrate alone and in combination with prohexadione-calcium after storage for 40 days was decreased by 15.62% and 50.00%, respectively, when compared with the control. Furthermore, the combined treatment significantly increased the content of total calcium and water-soluble calcium in apple skin, and decreased the content of non-physiological active calcium such as calcium phosphate and calcium oxalate at the later stage of storage. In addition, the combined treatment significantly improved 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging activity and superoxide dismutase activity, and inhibited the increase in malondialdehyde (MDA) content in apple skin, thus protecting against oxidative injury caused by calcium stress.
Antioxidant Activity of Vine Tea (Ampelopsis grossedentata) Extract on Lipid and Protein Oxidation in Vegetarian Meatballs during Refrigerated Storage
ZHANG Xuan, XU Yu, XUE Hai, JIANG Guochuan, YAN Xiaohui, LIU Xuejun
2020, 41(3):  212-217.  doi:10.7506/spkx1002-6630-20190207-024
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Oxidation is one of the most important factors limiting the shelf life of many food products. The objective of this study was to investigate the inhibitory effect of vine tea (Ampelopsis grossedentata) extract (VTE) on lipid and protein oxidation in vegetarian meatballs during refrigerated storage. The physicochemical properties, peroxide value (POV), thiobarbituric acid reactive substances (TBARS) value, and carbonyl and sulfydryl contents of vegetarian meatballs added with VTE at 0.1% and 0.3% were compared with those of the blank and positive (0.01% butylated hydroxy toluene (BHT)) controls. The results showed that VTE could effectively maintain the moisture content, lightness (L*) and elasticity of vegetarian meatballs compared with the blank control group (P < 0.05). In addition, VTE significantly inhibited the increase of POV and TBARS values (P < 0.05) and suppressed the formation of carbonyl compounds in a dose-dependent manner (P < 0.05), and the inhibitory effect was higher than that of BHT, suggesting that VTE could significantly inhibit lipid and protein oxidation of vegetarian meatballs during refrigerated storage. These results provide a theoretical basis for the application of VTE as a natural antioxidant in meat-like products.
Effect of Composite Preservatives on Active Oxygen Metabolism, Cell Membrane Permeability and Browning of Fresh-Cut Mango
YUAN Fang, QIU Shiming, LI Li,
2020, 41(3):  218-223.  doi:10.7506/spkx1002-6630-20190225-151
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In order to investigate the effects of different composite preservative treatments on active oxygen metabolism, cell membrane permeability and browning of fresh-cut mango, fresh-cut ‘Jinhuang’ mango fruit were treated with 1.0 g/100 mL citric acid + 1.0 g/100 mL isoascorbic acid alone or in combination with 0.5 g/100 mL disodium ethylenediaminetetraacetate (EDTA-2Na) or 0.5 g/100 mL calcium chloride in this paper. The results showed that as compared with the control, all three treatments inhibited the increase of membrane permeability, reduced the rate of superoxide anion (O2-·) production, and maintained high activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), inhibited polyphenol oxidase (PPO) activity and reduced the peroxidase (POD) activity at the later stages of storage, thereby reducing browning index and maintaining high ascorbic acid (AsA) content of fresh-cut mango, but they had no significant effect on total phenol or flavonoid contents (P > 0.05). Citric acid + isoascorbic acid combined with EDTA-2Na or calcium chloride was superior to citric acid + isoascorbic acid in inhibiting the increase of cell membrane permeability, maintaining CAT activity, and decreasing the generation rate of O2-·.
Viscosity Characteristics and Physiological Functions of Dietary Fiber: A Review
CAI Songling, LIU Lin, ZHAN Qian, ZHANG Yu, WEN Yadi, LIU Yi, XU Zekun, SUI Zhongquan
2020, 41(3):  224-231.  doi:10.7506/spkx1002-6630-20181202-020
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Dietary fiber, known as the seventh nutrient, is an important raw material of function foods with a wide range of physical and chemical properties and physiological functions. Mucopolysaccharides are a kind of dietary fiber which is viscous in liquids. This article mainly reviews recent studies on dietary fiber viscosity, including the basic concepts, the measurement instruments and methods, and the influencing factors, and it summarizes the physiological functions of dietary fiber (mainly mucopolysaccharides), such as regulating blood glucose response, lowering blood lipids, affecting intestinal enzyme activities and digestibility and laxative effects. These advances can provide a scientific basis and rationale for future in-depth studies on the viscosity characteristics and physiological activity of dietary fiber and for its application in the food industry.
Bactericidal Mechanism of Nano-Titanium Dioxide Photocatalysis Technology and Its Application in Food Packaging: A Literature Review
HU Yingying, LI Qixuan, LIU Haotian, KONG Baohua, CHEN Qian
2020, 41(3):  232-238.  doi:10.7506/spkx1002-6630-20181211-139
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Nano-titanium dioxide photocatalysis (TPC) technology has become a hot research topic as an emerging non-thermal technology. TPC technology has been widely used in non-thermal food processing due to its high antibacterial activity, chemical stability, non-toxicity, environmental friendliness, and low cost. TPC technology can be widely used for the sterilization of foods due to the production of active substances such as singlet oxygen, superoxide anion radicals and hydroxyl radicals during the catalytic process. This paper outlines the principle and bactericidal mechanism of TPC technology, reviews its application in food packaging, discusses possible strategies for improving the photocatalytic efficiency of nano-titanium dioxide, and evaluates the safety of TPC technology. Finally, future research and application directions are proposed. The purpose of this paper is to provide a theoretical basis and technical supports for the application and promotion of TPC technology in food research.
A Literature Review of the Application of Foodomics in Studying Nutritional and Functional Properties of Bioactive Compounds
LI Yuanyuan, MAI Mengqi, HU Xiaosong, ZHANG Yan
2020, 41(3):  239-245.  doi:10.7506/spkx1002-6630-20181130-368
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Foodomics is an advanced omic technology which integrates biostatistics, chemometrics and bioinformatics in food and nutrition research. Foodomics allows systematic studies of the nutritional properties and health benefiting mechanisms of dietary bioactive compounds. The basic concept of foodomics is described in this review. Emphasis is placed on recent progress in the application of transcriptomics, proteomics and metabolomics in evaluating the nutritional and functional properties of bioactive food compounds. Furthermore, this review briefly outlines some biomarkers associated with the nutritional and functional properties of bioactive food compounds, and it discusses future prospects for the application of foodomics in this field. We expect this review to provide a better explanation of the association between dietary nutrition and health.
Recent Progress in Black Tea Quality and Related Biochemical Factors
FAN Jie, WANG Qiushuang, QIN Dandan, FANG Kaixing, ZHU Haiyan, JIANG Xiaohui, CHEN Dong, WU Hualing
2020, 41(3):  246-253.  doi:10.7506/spkx1002-6630-20190217-077
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Black tea, featured with a strong aroma and sweet flavor as well as ‘red infusion and red leaves’, is made from fresh buds, leaves and tender stems through a series of procedures including withering, rolling (kneading and cutting), fermentation and drying. As the international demand for black tea has continued to increase recently, a variety of black tea products with distinctive sensory flavor characteristics have emerged in many regions. In order to gain insights into the characteristics of black tea and the underlying biochemical basis, this paper summarizes recent studies in the chemistry of black tea quality and specifies the chemical factors related to the color, aroma, taste and other key sensory attributes of black tea, including theaflavins, thearubigins, theabrownines, aromatic substances, polyphenols, caffeine and amino acids, with the aim of providing a theoretical basis for the innovation and quality improvement of black tea.
Advance in Self-Assembly and Gelation Properties of Soy Protein
AN Di, HONG Rui, LI Liang
2020, 41(3):  254-259.  doi:10.7506/spkx1002-6630-20181218-212
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Molecular self-assembly is the process through which molecular building blocks spontaneously organize themselves into ordered aggregates by non-covalent interactions. Gels formed by self-assembly of proteins are drawing increasing research interest. The gelation process can denature proteins, causing various functional groups to be exposed outside. The interaction between biologically active components and polypeptide chains imparts excellent biocompatibility and biodegradability to self-assembled hydrogels, allowing a wide range of applications in both the food and pharmaceutical fields. Soy protein is an excellent raw material for self-assembled gels due to its good functional properties. In this paper, the mechanism of the self-assembly of soy protein, the forces involved in the process and the way of formation of self-assembled gels are reviewed, which will provide a theoretical basis for studying soy protein self-assembled gels.
Recent Progress in the Mechanism Underlying Tenderness Deterioration of Beef at Intermediate Ultimate pH
KONG Xiao, LUO Xin, ZHU Lixian, SONG Enliang, ZHANG Wenhua, ZHANG Yimin
2020, 41(3):  260-265.  doi:10.7506/spkx1002-6630-20190124-312
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Tenderness is one of the most important factors to evaluate the eating quality of beef, and it is also an important factor influencing consumers’ willingness to purchase meat. Compared with beef at high ultimate pH (pHu) (pHu > 6.2) and normal pHu (pHu < 5.8), beef at intermediate pHu (5.8 < pHu ≤ 6.2) has poorer tenderness and requires longer ageing time to achieve the desired tenderness. However, the underlying mechanism for tenderness deterioration is not clear yet. Therefore, in this paper, the causes of tenderness deterioration of beef at intermediate pHu are elucidated by comparing the degree of degradation of cytoskeleton proteins and the functions of endogenous enzyme systems (i.e. calpain, cathepsin, caspase and proteosome) among beef with different pHu, and by determining the expression characteristics of small heat shock proteins in beef at intermediate pHu. The information gathered here will provide a theoretical basis for improving the tenderness of beef with intermediate pHu.
The Role of Whey Protein and Whey Protein-Derived Bioactive Peptides in Blood Glucose Regulation: A Review
WU Shangyi, LI Rushu, SHI Jiaxin, LI Lanxin, CAO Xueyan, YANG Mei, TAO Dongbing, YUE Xiqing
2020, 41(3):  266-271.  doi:10.7506/spkx1002-6630-20181024-278
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Whey protein and whey protein-derived bioactive peptides have multiple health benefits, and have become a research hotspot due to their effectiveness in attenuating hyperglycemia. Whey protein and whey protein-derived bioactive peptides can delay the onset of type 2 diabetes mellitus (T2DM). T2DM accounts for more than 90% of all cases of diabetes and is nowadays one of the top ten causes of death worldwide. Lifestyle intervention and medical nutritional therapy are currently the important management strategies for T2DM. Previous studies have shown that whey protein and whey protein-derived bioactive peptides can regulate blood glucose levels by improving insulin resistance, inhibiting α-glucosidase, and promoting incretin secretion. This paper reviews recent progress in understanding the role and mechanism of whey protein and whey protein-derived bioactive peptides in the regulation of blood glucose, and it summarizes recent studies on whey protein-derived dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides, aiming to provide incentives for innovations in the milk industry.
Formation and Control of Polycyclic Aromatic Hydrocarbons in Fried Foods: A Review
ZHANG Lang, DU Hongzhen, TIAN Xinglei, LIU Qian, KONG Baohua
2020, 41(3):  272-280.  doi:10.7506/spkx1002-6630-20181210-111
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Frying is an important cooking method and fried foods are loved by consumers due to their special texture, color and flavor. However, because of the high temperature during the frying process, a large amount of polycyclic aromatic hydrocarbons (PAHs) are generated in fried foods. PAHs have carcinogenic, teratogenic, genetic and immune toxicity, which are extremely harmful to human health. Given this background, this paper reviews the structures, characteristics, sources, formation mechanisms and hazards of PAHs. Emphasis is placed on the factors influencing the formation of PAHs in fried foods and the solutions to this problem.
Implications of the Experience of Hong Kong, China in Edible Agricultural Products Supply Regulation
ZHANG Kaihua, ZANG Mingwu, WANG Shouwei, LI Dan, ZHANG Zheqi, LI Xiaoman
2020, 41(3):  281-287.  doi:10.7506/spkx1002-6630-20190331-397
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The quality and safety of edible agricultural products is the basis of food safety. Mainly relying on imports, edible agricultural products in Hong Kong are distributed through wholesale markets or order direct sales, characterized by taking legal system establishment as the first priority, strong regulatory execution, brand construction via governmental strength, scientific and effective regulation measures, and laying stress on public welfares. This paper presents a comparison of edible agricultural products supply regulation in Hong Kong and the Chinese mainland. On this basis, some suggestions for improving the edible agricultural products supply regulation system in the Mainland, especially megacities, such as improving the legal system concerning edible agricultural products, developing an innovative collaborative supervision system, promoting brand construction of edible agricultural products, and constructing a long-term supervision mechanism are proposed.
Advances in the Application of Proteomics in Non-thermal Sterilization of Foods
QIAN Jingya, ZHANG Mi, SUN Wenjing, DAI Chunhua, HUO Shuhao, MA Haile
2020, 41(3):  288-294.  doi:10.7506/spkx1002-6630-20190120-240
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Proteomic analyses have been performed to study the adaptation and response of microorganisms to various stresses. Non-thermal sterilization technologies have gained significant attention since they have the potential to provide new food products with better nutritional properties than traditional ones. Non-thermal sterilization can cause changes in proteins in microorganisms, which are related to microbial inactivation. This review addresses the application of proteomics in non-thermal sterilization technologies, which is important for understanding the mechanism of non-thermal sterilization from the perspective of molecular biology.
Recent Progress in Research on Food Addiction in Juveniles
QIANG Yueyue, LIN Shaoling, FU Jianwei, ZENG Shaoxiao
2020, 41(3):  295-304.  doi:10.7506/spkx1002-6630-20190128-355
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Obesity in juveniles is a chronic metabolic disease which is influencedthe interactions of many factors including diet and environment. It is alarming that the incidence of obesity in juveniles is increasing yearyear. As one of the main causes of the high prevalence of obesity, food addiction has attracted more and more attention scientists due to the physical and psychological harms to juveniles. Into provide useful information for preventing food addiction in juveniles and ensuring their dietary health, this article summarizes recent progress in the study of food addiction in juveniles with regard to the assessment methods, the mechanism for its development and the preventive and therapeutic measures. Furthermore, Chinese dietary culture, habit and structure can provide useful guidance for preventing food addiction in juveniles and ensuring their dietary health.
Advances in Aptasensors Based on Smart Materials for Rapid Detection of Mycotoxins
WANG Changchang, MA Liang, LIU Wei, GUO Ting, TAN Hongxia, ZHANG Yuhao, ZHOU Hongyuan, CHEN Lu, LI Daoliang
2020, 41(3):  305-313.  doi:10.7506/spkx1002-6630-20190125-330
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Research of aptasensors based on advanced materials such as Au nanoparticles (AuNPs), graphene and graphene nanocomposites, and quantum dots (QDs) for the quick detection of mycotoxins is one of the emerging hotspots and trends in the field of mycotoxin detection in recent years. The superior optical, mechanical and electrical properties of advanced materials combined with aptasensors greatly increase the sensitivity and selectivity of mycotoxin detection. This paper summarizes the aptamer sequences of major mycotoxins reported in the literature in the last decade, and reviews the application of aptasensors based on advanced materials in rapid detection of mycotoxins. The main existing problems are also proposed. We hope that this review could provide the basis and inspiration for the development of mycotoxin detection methods.
Frame Reconstruction of Mobile Traceability Information System for Fresh Foods Based on Blockchain
ZHAO Lei, BI Xinhua, ZHAO Anni
2020, 41(3):  314-321.  doi:10.7506/spkx1002-6630-20181119-217
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The traditional traceability system is facing the problems of credibility, regulation dilemma, scalability and cost payment, which hinder the marketization transformation of the traceability industry. After customer requirement analysis from the perspective of information ecology, this paper proposes a risk compensation scheme for the subject of liability as the core competence of commercialized operation of a traceability information system. By process reengineering, it provides a new framework model. The implementation scheme is as follows: Firstly, the product label is used as the bottom traceability data carrier to generate a product real-time e-resume by tag backup. Secondly, mobile ad-hoc network is adopted to support dynamic real-time access of light load nodes to write the traceability data in time. Thirdly, smart contract is involved in calling traceability data intricately to divide the liability. Finally, the services of risk compensation and big data analysis are provided through the data interface of the blockchain.