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Table of Content

15 December 2019, Volume 40 Issue 23
Basic Research
Influence of Partial Sodium Chloride Replacement with Potassium Chloride on the Mass Transfer Kinetics of Duck Thigh Meat during Salting with Vacuum Tumbling
KUANG Wei, AN Liang, XU Jun, WANG Haibin, ZHOU Xiaorong, CHEN Jiwang, XU Wei, LIAO E, CHEN Gongming, REN Guangcai
2019, 40(23):  1-7.  doi:10.7506/spkx1002-6630-20190318-213
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Duck thigh meat was salted with sodium chloride (≥ 99.1%) alone or in combination with potassium chloride (30% KCl + 70% NaCl, namely sodium replacement). Changes in the mass, water content and salt content of duck thigh meat were analyzed during its salting with vacuum tumbling. The kinetic data of mass transfer were obtained. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was carried out to study the influence of tumbling salting with different salts on the protein profile of duck thigh meat. The results showed that changes in meat mass (ΔMt0), water content (ΔMtw) and salt content (ΔMts) had a good correlation with the square root of curing time (t0.5) for the two groups. ΔMt0, ΔMtw and ΔMts increased rapidly with curing time up to 4 h. The effective diffusion coefficient De of full-sodium and reduced-sodium cured meat was 4.432 × 10-8 and 4.462 × 10-8 m2/s, respectively. There was a slight difference between them. The gel electrophoresis maps showed that myofibrillar proteins were constantly degraded during the salting process irrespective of whether sodium chloride was replaced by potassium chloride. In conclusion, the rate of mass transfer can remain unchanged regardless of the replacement of sodium chloride by potassium chloride.
Multiple Spectroscopy Analysis and Calculation of the Interaction between Vitamin D3 and Soy Protein Isolate
CHEN Shuang, WANG Xiaodan, LI Rui, SUN Hongrui, WANG Xibo, JIANG Lianzhou
2019, 40(23):  8-13.  doi:10.7506/spkx1002-6630-20181112-122
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The interaction between vitamin D3 (VD3) and soy protein isolate (SPI) was studied by multiple spectroscopies (?uorescence, synchronous fluorescence, ultraviolet-visible (UV-Vis), and Fourier infrared spectroscopy). The fluorescence spectroscopy results showed that the intrinsic fluorescence of SPI was statically quenched by VD3. The binding constants (KA) at different temperatures were 1.245 × 104 (293 K), 1.250 × 104 (293 K) and 3.531 × 104 (306 K) L/mol, and the numbers of binding sites (n) were 0.973 3, 0.992 4 and 1.094 2, respectively. The binding distance (r) was 2.92, and the binding promoted fluorescence quenching of the protein through non-radiative energy transfer. According to analysis of the thermodynamic data, the reaction of VD3 with SPI was a spontaneous endothermic process, and the interaction was dominated by electrostatic interaction and hydrophobic interaction. The synchronous fluorescence and UV-Vis spectra illustrated that the addition of VD3 changed the conformation of SPI, and the microenvironment of aromatic amino acid residues changed from hydrophobic to hydrophilic status. Fourier transform infrared spectroscopy revealed that VD3 could indude secondary structure changes in SPI.
Effects of Different Drying Methods on Maillard Reaction Products and Their Oxidation Resistant Ability in Oil-Tea Camellia Seed Oil
YANG Nan, LUO Fan, FEI Xueqian, ZHONG Haiyan
2019, 40(23):  14-18.  doi:10.7506/spkx1002-6630-20181031-378
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The effects of hot air drying, infrared radiation and microwave radiation on the antioxidant activity of Maillard reaction products (MRPs) in oil-tea camellia seed oil (camellia oil) were investigated. The changes in the oxidation stability of camellia oil were investigated by measuring the contents of pyruvic aldehyde, glyoxal and 3-deoxyglucosone. The results showed that the production of pyruvic aldehyde and 3-deoxyglucosone increased with heating time, and the contents of pyruvic aldehyde and 3-deoxyglucosone in the camellia oils from the three drying methods under the highest intensity (150 ℃/120 min for infrared radiation and hot air, high power/20 min for microwave radiation) were in the decreasing order of infrared radiation > microwave radiation > hot air. The contents of glyoxal in the three camellia oils were approximately 7.0 μg/g. The MRPs extracted from the camellia oils showed antioxidant activity and were detected to contain pyruvic aldehyde and 3-deoxyosucide. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of the MRPs obtained by the three drying methods followed the decreasing order: infrared radiation > microwave radiation > hot air. The results provide a theoretical basis for exploring the antioxidant mechanism of MRPs in camellia oil and for optimizing the processing of the oil.
Effects of Fifteen Flavonoids on the Contents of Heterocyclic Amines in Roast Chicken Breast
ZHAO Lei, ZHANG Huimin, LI Yubin, HAO Shuai, CHEN Yanlin, XU Jie, WANG Chengtao
2019, 40(23):  19-25.  doi:10.7506/spkx1002-6630-20181105-045
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The effects of 15 flavonoids on the contents of five heterocyclic amines in roast chicken breast were investigated in this study. The sample was extracted with NaOH, followed by liquid-liquid extraction with ethyl acetate, and then the upper phase was purified by solid-phase extraction with a Oasis MCX cartridge. The content of heterocyclic amine was analyzed by ultraperformance liquid chromatography-tandem mass spectrometry. Principal component analysis (PCA) was used to study the differences in the effects of various flavonoids on the formation of heterocyclic amines in roast chicken breast. The results showed that among the 15 flavonoids, genistein, epigallocatechin gallate (EGCG) and luteolin exhibited good inhibitory effects on the formation of Harman and Norharman, with inhibition percentages over 20%. EGCG, naringenin, luteolin and genistein had good inhibitory effects on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, with inhibition percentages over 45%. Genistein, naringenin and luteolin showed good inhibitory effects on the formation of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, with inhibition percentages over 45%. The PCA results demonstrated that EGCG, luteolin and genistein were classified into the same group, exhibiting strong inhibitory effects on the formation of five heterocyclic amines. Based on the chemical structures of these flavonoids, it was speculated that the 5- and 7-hydroxyl groups on the A ring and the 4’-hydroxyl group on the B ring of the flavonoid nucleus play important roles in inhibiting the formation of heterocyclic amines in roast chicken breast. However, the presence of 3-hydroxyl group on the C ring may reduce the inhibitory effects of flavonoids on heterocyclic amine formation. In summary, flavonoids have inhibitory effects on the formation of heterocyclic amines. EGCG, luteolin and genistein have the strongest inhibitory effect. These findings provide a theoretical basis for the processing of safe meat products at high temperature.
Inhibition of Protocatechuic Aldehyde on Virulence Factors of Cronobacter sakazakii
LI Haozhou, HAO Xusheng, GUO Jialu, GUO Du, ZHENG Xiaoying, WANG Shuo, YANG Zhuokai, SHI Chao
2019, 40(23):  26-33.  doi:10.7506/spkx1002-6630-20181213-156
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The aim of this study was to evaluate the inhibitory effect of protocatechuic aldehyde (PA), a plant-derived compound, on the swimming motility, biofilm formation, adhesion and invasion to Caco-2 cells of Cronobacter sakazakii and to determine its effect on the transcription of nine virulence genes in C. sakazakii. The results indicated that the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of PA against six C. sakazakii strains were 2 mg/mL, and the sub-inhibitory concentrations against C. sakazakii ATCC29544 were 1/200, 1/100 and 1/50 MIC. PA at SICs inhibited the swimming motility on soft agar plates and biofilm formation of ATCC29544. PA substantially reduced its adhesion and invasion to Caco-2 cells, and repressed the expression of nine virulence genes in this strain. These findings suggest that PA can inhibit the virulence factors of C. sakazakii, and it has the potential to be developed as an alternative or supplemental agent to prevent and control infections caused by C. sakazakii.
Effect of Heat Moisture Treatment Combined with Sodium Alginate on Physicochemical Properties of Normal Corn Starch
WANG Yusheng, MEI Xuanwei, CHEN Haihua, CHEN Jiangang
2019, 40(23):  34-43.  doi:10.7506/spkx1002-6630-20181204-058
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The effects of heat moisture treatment (HMT) combined with sodium alginate (AG) on pasting properties, thermal properties, crystalline structures, and gel properties of normal corn starch (NCS) were investigated. NCS was subjected to HMT alone or in combination with AG (HMT-AG) under the following conditions: moisture content of 15%?35%, temperature of 80?120 ℃, and time of 1?15 h. The results showed that HMT-AG increased the pasting temperature of NCS, but significantly decreased its breakdown value, setback value, and gelatinization enthalpy (P < 0.05). Either treatment did not change the crystalline pattern of NCS. At moisture content above 25% (P < 0.05), HMT obviously decreased the relative crystallinity (RC) of NCS (P < 0.05) whereas the opposite was observe with HMT-AG. Under the conditions of moisture content of 25%, temperature of 120 ℃, and time of 6 h, HMT-AG resulted in more significant decreases in the viscosity, gelatinization onset temperature, and gel hardness of NCS compared to HMT alone (P < 0.05).
Establishment of Activity Assays for α-Glucosidase and Dipeptidyl Peptidase IV Using Porcine Small Intestine Mucosal Extracts
JIA Chengli, Naveed HUSSAIN, DONG Jie, WANG Fen, LI Hantong, ZHANG Shuwen, LU Jing, PANG Xiaoyang, LIU Lu, Lü Jiaping
2019, 40(23):  44-51.  doi:10.7506/spkx1002-6630-20180615-294
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Alpha-glucosidase and dipeptidyl peptidase IV (DPP-4) are two important target enzymes useful in the treatment of type II diabetes. Currently, commercially available enzymes are mainly obtained from microorganisms, making it difficult to screen for inhibitors of the enzymes. Both enzymes are widespread in mammalian small intestines. In this study, fresh porcine small intestinal mucosal secretions and epithelial cells were collected for comparative measurement of α-glucosidase and DPP-4 activities in mucosal extracts from three different intestinal segments. The extracts were used as reaction system of α-glucosidase and DPP-4 and their percentage inhibition by acarbose and diprotin A (IPI) respectively was evaluated. The median inhibition concentration (IC50) against commercial and porcine ileum-derived α-glucosidase was 1.102 4 and 0.244 7 mg/mL for acarbose, and 19.119 7 and 41.268 4 μg/mL for IPI, respectively. The specific activities of α-glucosidase and DPP-4 in porcine ileum mucosal extract were 0.084 1 and 0.053 4 U/mg, which were higher than those in the two other mucosal extracts. Therefore, porcine ileum mucosal extract can be used as an alternative to commercial α-glucosidase and DPP-4 for screening for enzyme inhibitors.
Effect of Thermal Aggregation on Digestion Behavior and Antioxidant Capacity of Digestion Products of β-Lactoglobulin
LIN Zhantuo, GAO Zhiming, DU Xunan, CHEN Gaiting, HU Meng, FANG Yapeng, TANG Hu
2019, 40(23):  52-59.  doi:10.7506/spkx1002-6630-20190117-213
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The structures of protein aggregates can affect their digestion behavior and the physicochemical properties of their digestion products. In this study, β-lactoglobulin (BLG) nanoparticle aggregates (BLGN), BLG worm-like aggregates (BLGW) and BLG fibril aggregates (BLGF) were prepared by heating BLG under various conditions of pH, temperature and heating time, and their digestion behavior and the antioxidant activity of their digestion products were analyzed. Results showed that the hydrolysis degree of BLGN, BLGW, BLGF and BLG in simulated gastric fluid were (11.86 ± 0.24)%, (10.55 ± 0.22)%, (9.08 ± 0.21)% and (3.46 ± 0.16)%, respectively. Thermally induced aggregation of BLG could lead to a decrease in its scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radicals but an increase in reducing power, especially for BLGF.
Effect of in Vitro Digestion Hydrolysate of Bovine Lactoferrin Subjected to Different Pasteurization Treatments on Proliferation of IEC-6 Cells
XI Enze, ZHAO Xiao, CUI Dongying, SHENG Xue, LI Menghan, XU Xiaoxi
2019, 40(23):  60-65.  doi:10.7506/spkx1002-6630-20181017-179
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After being subjected to different pasteurization treatments (63 ℃/30 min, 72 ℃/15 s and 85 ℃/15 s), bovine lactoferrin was digested in vitro in a simulated infant gastrointestinal environment. The resulting hydrolysates were separately used to challenge rat intestinal crypt epithelial cells (IEC-6) to evaluate their immunological activity. The results showed that all the three lactoferrin hydrolysates could promote small intestinal cell proliferation in a dose-dependent manner. Flow cytometry results demonstrated that these hydrolysates increased the percentage of IEC-6 cells in the G2/M and S phase and reduced cell apoptosis. The results of reverse transcription real-time quantitative PCR (RT-qPCR) indicated that the lactoferrin hydrolysates elevated the expression levels of cyclin B1, CDK1 and cyclin E1 and reduced the expression level of p21. Taken together, we found that that pasteurization could completely inactivate the active group of bovine lactoferrin. The two pasteurization treatments, 72 ℃/15 s and 85 ℃/15 s, especially the latter, could ensure food safety while maintaining the immunological activity of lactoferrin to the utmost extent. The best concentration to promote intestinal immunity was 0.1 mg/mL for all the lactoferrin hydrolysates.
Functional Components and in Vitro Antioxidant Activity of Chrysanthemum Flower (Chrysanthemum morifolium Ramat) from Chuzhou
JIA Yumeng, CHEN Qinqin, BI Jinfeng, Lü Ying, QIAO Yening, ZHANG Baiqing
2019, 40(23):  66-72.  doi:10.7506/spkx1002-6630-20181004-010
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The antioxidant composition and activity of chrysanthemum flowers from Chuzhou, Anhui were determined for its further exploitation and utilization. The contents of phenolics, carotenoids and polysaccharides in the extracts of chrysanthemum flowers were measured and their antioxidant activities were investigated in this study. The total phenolic and total flavonoid contents in chrysanthemum flowers from Chuzhou were 53.67 and 70.32 mg/g, which were higher than those in Dayang chrysanthemum flowers, while the contents of polysaccharides and carotenoids were relatively lower. Among the three extracts, the phenolic extract was presented the strongest antioxidant activity with scavenging capacity of 208.79 mmol/g against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and of 160.23 mmol/g against 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical as well as ferric reducing antioxidant power (FRAP) value of 238.35 mmol/g. By high performance liquid chromatography (HPLC), six phenolic acids such as catechin, caffeic acid, chlorogenic acid, ferulic acid, hyperin and quercetin were identified as well as two carotenoids such as lutein and β-caroteonid. The content of chlorogenic acid was the highest (813.21 mg/g) of these phenolic compounds, followed by hyperin (408.17 mg/g). Lutein was the most abundant carotenoid (78.6 mg/g). Chlorogenic acid made the greatest contribution to the ferric reducing power, while hyperin made the greatest contribution to the DPPH and ABTS cation radical scavenging activities when not considering synergism. Lutein in carotenoids contributes most to the of DPPH free radical scavenging activity.
Antibacterial Activity and Mechanism of Durancin GL against Listeria monocytogenes
WU Xueyou, ZHU Yue, CHEN Zhengxing, JU Xingrong
2019, 40(23):  73-78.  doi:10.7506/spkx1002-6630-20190408-101
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Listeria monocytogenes is widely distributed in meat, poultry, eggs, dairy products and vegetables, which has strong adaptability and can grow and multiple at 4 ℃, and it is one of the main foodborne pathogens. Durancin GL is a new bacteriocin produced by enterococci, which has a targeted inhibitory activity against L. monocytogenes. The antimicrobial activity of durancin GL against L. monocytogenes was determined by minimal inhibitory concentration (MIC) and bacteriostatic kinetics. The underlying mechanism was investigated by the measurement of intracellular material leakage and cell survival as well as morphological examination. The MIC value was determined to be (2.5 ± 0.4) mg/L. Durancin GL exerted its inhibitory activity by leading to cytoplasmic leakage, increased extracellular conductivity, and finally cell death.
Comparison of Lactose-Free and Plain Yoghurt Fermented at Different Temperatures
JIA Lingyun, HU Zhihe, XUE Lu, LU Dingqiang, ZHAO Xufei, CHENG Kaili, YANG Xiangli
2019, 40(23):  79-90.  doi:10.7506/spkx1002-6630-20190515-167
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The objective of this work was to systematically compare lactose-free yoghurt and plain yoghurt for differences in acidity, viscosity, total viable count (TVC), color, taste, and odor. The yogurts were prepared at 37 or 42 ℃. The trends of acidity, viscosity and TVC during the fermentation and storage period were detected. An electronic nose, an electronic tongue and an electronic eye were used for testing the odor, taste and color, respectively. The results showed that the acidity and viscosity of lactose-free yogurt increased faster than those of plain yogurt during the fermentation period. At the end of fermentation at 37 or 42 ℃, the quantity of lactic acid bacteria in lactose-free yogurt was 3.50 and 2.30 times as high as that in plain yogurt, respectively. The dominant color of yogurt fermented at 37 ℃ was number 4094 compared to number 4095 for yogurt fermented at 42 ℃. After storage for 21 days, the main color number ratio significantly changed (P < 0.05). Comparison between lactose-free yogurt and plain yogurt fermented at 37 ℃ after storage for 1 day showed a significant difference in umami, sweetness, and bitterness (P < 0.05); and in sourness, sweetness, saltiness, umami, and bitterness after storage for 21 days (P < 0.05). Comparison between the yogurts fermented at 42 ℃ after storage for 1 day exhibited a significant difference in sourness, sweetness, saltiness and bitterness (P < 0.05); and in sourness, sweetness, saltiness, umami and bitterness after storage for 21 days (P < 0.05). Furthermore, there was a significant difference between the yogurts fermented at 37 ℃ in the contents of odor components like 2,3-butanedione, 3-hydroxy-2-butanone, ethyl alcohol, and 2-butanone (P < 0.05). A significant difference was found between the yogurts fermented at 42 ℃ in the contents of ethyl alcohol and 2-butanone (P < 0.05). The four yogurts significantly differed in odor (P < 0.05). Therefore, samples of each yogurt fermented at different temperatures were significantly different from each other, and so were lactose-free yogurt and plain yogurt fermented at the same temperature.
Acid Tolerance in Salmonella Induced by Levulinic Acid
TIAN Muyu, ZHANG Yimin, DONG Pengcheng, MAO Yanwei, LIANG Rongrong, ZHU Lixian, LUO Xin
2019, 40(23):  91-96.  doi:10.7506/spkx1002-6630-20181221-251
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The effects of levulinic acid, L-lactic acid, acetic acid and hydrochloric acid at pH 6.0 and 5.4 on the acid tolerance response of Salmonella typhimurium and S. Derby were investigated. The results showed that the bacteriostatic effects of the four acids were in the following decreasing order: levulinic acid > acetic acid > L-lactic acid > hydrochloric acid. Significantly higher acid tolerance response was induced in Salmonella at pH 5.4 than at pH 6.0 (P < 0.05). The acid tolerance induced by levulinic acid was weaker when compared with the two other organic acids and significantly varied with pH (P < 0.05). The intracellular pH of Salmonella treated with the organic acids was significantly different from that of the control group, and the intracellular pH of S. typhimurium treated with levulinic acid at pH 6.0 was significantly higher than that of S. Derby receiving the same treatment (P < 0.05). The results showed that acidic conditions at pH 6.0 and 5.4 could induce acid tolerance in Salmonella, and the change of intracellular pH was closely related to the acid tolerance response.
Oxidation Characteristics and in Vitro Simulated Digestibility of Myofibrillar Proteins in Dry-Cured Hams from Different Regions
ZHAN Guang, YUE Yi, WANG Ying, SUN Yangying, PAN Daodong, DANG Yali, HE Jun, CAO Jinxuan
2019, 40(23):  97-103.  doi:10.7506/spkx1002-6630-20181005-021
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Myofibrillar proteins from Bama ham, Jinhua ham, Xuanwei ham and Parma ham as typical representatives of dry-cured hams were compared for surface hydrophobicity, sulfhydryl and disulfide bond contents, ultrastructure, particle size and in vitro digestibility. The results showed that the surface hydrophobicity of myofibrillar proteins in Jinhua ham was significantly higher than that of the other hams (P < 0.05). Ultrastructure analysis showed that myofibrillar proteins in Jinhua ham had the lowest degree of cross-linking or aggregation along with a more stretched conformation, while myofibrillar proteins in Parma ham had the largest degree of aggregation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that myofibrillar proteins in Jinhua ham were significantly degraded during in vitro digestion, resulting in a decrease in the particle size. The highest proteolysis rate of myofibrillar proteins was observed in Jinhua ham, while the lowest proteolysis rate was presented in Parma ham after pepsin, trypsin and α-chymotrypsin incubation among the four hams (P < 0.05). This study indicated that the exposure of hydrophobic groups and protein unfolding could provide more recognition sites for digestive enzymes, accelerating the hydrolysis of myofibrillar proteins in Jinhua ham. It demonstrated that the degree of oxidation of myofibrillar proteins significantly affected their digestibility.
Food Engineering
Effect of Konjac Gum on 3D Printing Properties of Blueberry Gel System
WANG Hao, TAN Chang, CHEN Jing, XU Jiaxin, LI Dongnan, MENG Xianjun
2019, 40(23):  104-110.  doi:10.7506/spkx1002-6630-20190423-300
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In this study, the effects of konjac gum on 3D printing characteristics of blueberry pulp gel system were investigated by texture analysis, rheological tests, scanning electron microscopy, Fourier transform infrared spectroscopy. The results showed that konjac gum had significant effects on the 3D printing efficiency, texture properties, rheological properties and microstructure of blueberry gel system. Good 3D printing efficiency was achieved for the gel system consisting of 22.5 g of blueberry pulp (volume of 20 mL, total solid content of 11.89%), 4 g of pectin, 2 g of konjac gum and 1 g of sugar, and the printed sample was highly similar to the original design. This study provides a technical basis for developing food products with 3D printing technology and solutions for food digital design and nutrition control.
Effect of Ultrasonic Treatment on Functional Properties of Soy Protein Isolate-Whey Protein Isolate Mixture
CUI Qiang, WANG Lin, ZHOU Guowei, DONG Yangyang, WANG Xibo, JIANG Lianzhou
2019, 40(23):  111-116.  doi:10.7506/spkx1002-6630-20181101-005
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The effect of ultrasonic treatment at different powers on emulsifying and gelation properties and structural state of soy protein isolate (SPI)-whey protein isolate (WPI) mixture was investigated. Physicochemical properties such as emulsifying activity, emulsion stability, gel strength, water-holding capacity were studied and structural properties were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet (UV) spectroscopy, and scanning electron microscopy. The results showed that the maximum emulsification and emulsifying activities of SPI-WPI mixture of 76.46 m2/g and 22.83 min, respectively were obtained with 300 W ultrasonic treatment. A slight red shift in the UV-Vis absorption spectrum was observed after this treatment, indicating exposure of internal groups outside of protein molecules and protein structure changes. The gel strength and water-holding capacity of SPI-WPI mixture reached maximum values of 1 000.93 g and 87.11% at 300 W, respectively. This was consistent with the results of scanning electron microscopy, which showed that the protein gel had a dense and regular three-dimensional network structure. This study demonstrated that ultrasonic treatment was effective in improving the functional properties of SPI-WPI mixture.
Efficiency and Kinetic Analysis of Microbial Inactivation in Soft Packaged Litchi Processed by High Hydrostatic Pressure Combined with Lemon Juice as a Hurdle Technology
WANG Yucui, ZHANG Fan, FENG Yi, WU Dequan, XIANG Hong
2019, 40(23):  117-122.  doi:10.7506/spkx1002-6630-20181109-090
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Objective: The aim of this study was to explore the inactivation effect of high hydrostatic pressure (HHP) processing combined with lemon juice as a hurdle technology on naturally occurring microorganisms in soft packaged litchi and to do kinetic analysis. Methods: The numbers of aerobic bacteria, mold, yeast and Escherichia coli were measured by plate counting and the degree of swelling of packages was examined after synergistic treatment with different pressures (180, 380 and 500 MPa) and lemon juice concentrations (0%, 50% and 100%) for 5, 10 or 15 min, respectively. The Weibull model was used for kinetic analysis. Results: Microbial inactivation was improved with an increase in pressure level and processing time. In addition, the combined treatment more effectively inhibited the growth of the microorganisms than HHP alone. The inactivation effect of HHP at 380 MPa combined with 100% lemon juice on total aerobic bacteria was comparable to that of single HHP at 500 MPa. Both mold and yeast were more sensitive to high pressure processing and lemon juice with low acidity and could be completely inactivated by the above two treatment for 5 min. E. coli was undetected in the control group or the single HHP group. The packages subjected to the combined treatment with each lemon juice concentration or single HHP treatment for 15 min did no swell after storage at 37 ℃ for 7 days. The correlation coefficients (R2) of the survival curves for all treatment groups were more than 0.900, indicating that the Weibull model was suitable for the kinetic analysis of microbial inactivation. The scale factor b of the model increased with the increase of pressure and synergistic treatment with lemon juice, while the shape factor n decrease with the increase of pressure but slightly increased with synergistic treatment with lemon juice at the same pressure. Conclusion: The synergism of lemon juice combined with HHP can achieve high sterilization efficiency at lower pressures, which is beneficial to preserve the quality of soft-packed litchi fruits and prolong the storage period.
Effect of Ultrasonic Treatment on the Structure and Antigenicity of Bovine Caseins
XUE Haiyan, CAO Ge, HE Baoyuan, FAN Jiaojiao, XUE Lihuan
2019, 40(23):  123-129.  doi:10.7506/spkx1002-6630-20181101-013
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In this study, changes in the structure and antigenicity of the milk allergenic proteins α-casein (α-CN) and β-casein (β-CN) after ultrasonic treatment were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism (CD) spectroscopy, fluorescence spectroscopy and enzyme-linked immunosorbent assay (ELISA). The results showed that with the increase of ultrasonic power, the molecular mass of α-CN did not change significantly, β-CN aggregated at 600 W; the carbonyl contents of the two caseins increased, and the free sulfhydryl contents decreased first and then rose after reaching a minimum value at 500 W, while the trend was opposite to that of hydrophobicity. The proportion of α-helical secondary structure was reduced after sonication, and the proportion of random coil initially increased with ultrasonic power up to 500 W and then decreased; this trend was opposite to that of β-sheet content, indicating that ultrasonic treatment could destroy the structure of casein. As the ultrasonic power increased, the antigenicity first increased, reaching a maximum level at 500 W, and then decreased. The hydrophobicity of caseins was positively correlated with changes in random coil content, but negatively correlated with changes in β-sheet content. Sonication could affect protein structure conformation while altering the antigenicity of caseins, which was associated with changes in hydrophobicity and random coil content.
High-Efficiency Separation of Goat Milk Casein and Other Components Using Ceramic Membrane Technology
JIANG Zhumao, YANG Baoyu, LU Jing, PANG Xiaoyang, WU Zheng, YUE Yuanchun, WANG Tong, Eman Saad RAGAB, ZHANG Shuwen, Lü Jiaping
2019, 40(23):  130-136.  doi:10.7506/spkx1002-6630-20181224-282
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The objective of this study was to quantify the capacity of a ceramic microfiltration (MF) membrane with a pore size of 0.05 μm to remove whey proteins, lactose, ash, calcium and phosphorus from skim goat milk. Skim goat milk was concentrated three times by microfiltration at 50 ℃, and then the resultant fraction was diluted to the original volume followed by three-fold concentration under the same condition as for skim goat milk. The same treatment was conducted on the fraction obtained from the second microfiltration. During the whole process, the cumulative removal percentages of whey proteins, lactose, ash, calcium and phosphorus calculated from three filtrates were 96.17%, 86.42%, 73.39%, 34.9% and 55%, respectively. After the second filtration, the pure water flux of the membrane was reduced by 55.57%, and the membrane flux was restored to 99.21% of the initial level after cleaning the membrane with 2% NaOH and 1% nitric acid solution. Ceramic membrane with 0.05 μm pore size was effective for the separation of casein and other components.Therefore, this technology is suitable for processing casein micelle powder, whey protein powder, lactose and other milk-based products from fresh milk without cheese whey.
Nutrition & Hygiene
Effect of Peptide Derived from Naked Oat Globulin on Antioxidant Capacity in D-Galactose-Induced Aging Mice
FU Yuan, ZHANG Meili, GAO Shaohui, ZHANG Yu
2019, 40(23):  137-141.  doi:10.7506/spkx1002-6630-20190113-151
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To investigate the influence of peptide derived from naked oat globulin (PNOG) on antioxidant capacity in aging mice, a subacute aging mouse model was established by neck back subcutaneous injection of D-galactose (120 mg/(kg mb·d)) once daily for 6 consecutive weeks. Healthy male mice were randomly divided into 6 groups: normal control group, aging model group, low-, medium- and high-dose PNOG groups (200, 600, 1 000 mg/(kg mb·d)) and vitamin C (VC, positive control) group (100 mg/(kg mb·d)). After 6 weeks, body mass, liver index and brain index were examined and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were measured in the serum of mice. The activities of GSH-Px and monoamine oxidase B (MAO-B) and malondialdehyde (MDA) content were measured in liver and brain tissues. The results showed that body mass in the aging model group increased more slowly, and liver and brain indexes decreased; the activities of SOD, GSH-Px and CAT in serum significantly declined (P < 0.05), and so did GSH-Px activity in liver and brain tissues (P < 0.05), but MAO-B activity and MDA content significantly increased as compared to the normal control group (P < 0.01). For the aging mice treated with PNOG at medium and high doses, body mass increased fast, and liver and brain indexes became greater. The activities of SOD and GSH-Px in serum as well as GSH-Px activity in liver and brain tissues significantly increased, and MAO-B activity and MDA content significantly declined (P < 0.01) as compared to aging model mice. These data indicated that PNOG could effectively remove free radicals, and significantly increase antioxidant capacity in D-gal-induced aging mice in a dose-dependent manner.
Protective Effect of Luteolin and Folic Acid on Aflatoxin B1-Induced Cytotoxicity in Esophageal Epithelial Cells and Their Effect on MTHFR Hypermethylation
FU Lingmeng, WU Yi, WANG Jing, WEI Jie, WANG Shaokang, SUN Guiju
2019, 40(23):  142-150.  doi:10.7506/spkx1002-6630-20190610-097
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Objective: To investigate the protective effect of luteolin (LUT) and folic acid (FA) on aflatoxin B1 (AFB1)-induced injury of human normal esophageal epithelial cells (HEECs) as well as on the methylation of the MTHFR gene. Methods: HEECs were exposed to different concentrations (0, 13, 25, 50, 100 and 200 μmol/L) of AFB1 for 24, 48 or 72 h, and cell viability was assessed by cell counting kit-8 (CCK-8) assay. Subsequently, HEECs were randomly divided into several groups including negative control, AFB1 poisoning, LUT intervention (160 μmol/L), FA intervention (20 and 200 μmol/L) and joint intervention (160 μmol/L LUT + 20 μmol/L FA, and 160 μmol/L LUT + 200 μmol/L FA). After 24 h of treatment, cell viability was assessed by CCK-8 assay, cell cycle and apoptosis were analyzed by flow cytometry, the protein expression of MTHFR was detected by Western blot, and the methylation of the MTHFR gene promoter was detected by the MassARRAY method. Results: Cell proliferation was inhibited after being exposed to each AFB1 concentration. Compared with AFB1 poisoning group, cell cycle arrest and inhibitory and apoptotic rates were significantly reduced and the up-regulation of MTHFR protein expression was decreased in LUT and joint intervention groups (P < 0.05). Moreover, LUT and/or FA interventions reduced the hypermethylation level of the MTHFR gene promoter (P < 0.05). Conclusion: AFB1 has toxic effects on HEECs as indicated by the inhibition of proliferation, cell cycle arrest, the promotion of apoptosis, and the up-regulation of MTHFR protein expression. LUT ameliorates these injuries and protects against the toxic effects of AFB1. Moreover, AFB1 can increase the methylation level of the MTHFR gene promoter, resulting in epigenetic changes. LUT and/or FA intervention can reduce the methylation level and reverse the epigenetic changes.
Effect of Curcumin on Helicobacter pylori and GES-1 Cells Injured by It
REN Jiaoyan, GOU Na, GAO Li, YANG Yiting, LI Liang, YUAN Erdong
2019, 40(23):  151-156.  doi:10.7506/spkx1002-6630-20181021-225
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The inhibition of curcumin on Helicobacter pylori (Hp) and its effect on GES-1 cell injury induced by Hp were investigated. The bacteriostatic tests showed that curcumin significantly inhibited Hp proliferation with a minimum inhibitory concentration (MIC) of 200 μmol/L. Moreover, curcumin showed an obvious inhibitory effect on the urease activity of Hp with a half maximal inhibitory concentration (IC50 ) of 1.735 mmol/L as determined using jack bean urease model based on Berthelot reaction. The effect of curcumin on normal and Hp-infected GES-l cells was studied by using the MTT method. Curcumin could inhibit human gastric epithelial GES-1 cells in a dose- and time-dependent manner except for treatment for 12 h at a concentration of 68 μmol/L. After treatment with curcumin at 68 μmol/L for 12 h, the morphology of the cell injury model, infected with Hp for 24 h, was slightly restored, and the survival rate slightly increased (P > 0.05). But the survival rate significantly decreased after treatment with curcumin at 136 or 680 μmol/L. Thus, the inhibition of curcumin on the viability and urease activity of Hp is not sufficient to help repair Hp-induced damage in GES-1 cells.
Hepatoprotective Effect of Pleurotus ostreatus Polysaccharides on Carbon Tetrachloride-Induced Liver Injury in Male Kunming Mice
ZHANG Yang, ZHU Caiping, LIN Yangnan, CAO Yulin, ZHANG Yifan, FANG Hao
2019, 40(23):  157-162.  doi:10.7506/spkx1002-6630-20181016-151
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In this experiment, the hepatoprotective effect of Pleurotus ostreatus polysaccharide (POP), prepared by hot water extraction, on CCl4-induced liver injury in mice was studied. Totally 48 male Kunming mice were randomly divided into 6 groups including blank control, model, positive control, and low-, medium- and high-dose POP (POP-L, POP-M and POP-H) groups. All treatments were administered orally for 28 consecutive days. On the 22nd and 23rd day, liver injury in all mice except those in the blank control group was induced by intraperitoneal injection of CCl4. On the 29th day, body mass was measured and all mice were sacrificed to harvest blood and liver tissue. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), and the concentrations of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) in serum were measured by commercial kits and then the liver index was calculated. Liver tissue homogenate was prepared to measure the content of malondialdehyde (MDA), total antioxidant capacity (T-AOC) and the activities of total superoxide dismutase (T-SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) using commercial kits. The results showed that compared with the model group, POP treatment at each dose attenuated body mass loss and the swelling degree of liver, decreased significantly serum ALT, AST and ALP activities (P < 0.01) as well as TC, TG and LDL-C concentrations (P < 0.05, P < 0.01), and increased significantly HDL-C concentration (P < 0.05, P < 0.01). Moreover, it significantly decreased MDA level and increased T-SOD, T-AOC, CAT and GSH-Px in liver homogenate (P < 0.05, P < 0.01). In conclusion, POP has significant protective effects against CCl4-induced liver injury in male Kunming mice.
Anti-inflammatory Activity in Vitro of Water-Eluted Fraction of Total Flavonoids Extracted from Allium mongolicum Regel
WANG Cuifang, WANG Terigele, DU Hongxi, ZHANG Xiuyuan, DAN Ni, SA Ruli, AO Changjin
2019, 40(23):  163-169.  doi:10.7506/spkx1002-6630-20181004-012
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The water eluate of total flavonoids extracted from Allium mongolicum Regel (wAMF) was evaluated for its inhibitory effect on lipopolysaccharide (LPS)-induced inflammation in mouse peritoneal macrophages. The CCK-8 method was used to examine the effect of the purified flavonoids at different concentrations (0, 50, 100, 200, 400 and 800 μg/mL) on the proliferation of mouse peritoneal macrophages. The following groups were created: blank control, LPS-induced model and wAMF pretreatment at different concentrations. The Griess method and enzyme-linked immunosorbent assay (ELISA) were used to determine the concentrations of NO, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and IL-10 in the macrophage culture supernatants, and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was applied to detect the mRNA expression levels of inducible nitric oxide synthase (iNOS), TNF-α, IL-1β, IL-6, IL-10, myeloid differential protein 88 (MyD88) and nuclear factor κB (NF-κB). The results obtained were as follows: 1) Compared with the control group, wAMF at concentrations of 50–800 μg/mL had no toxicity on macrophages (P > 0.05). 2) Compared with the LPS-induced model, wAMF significantly inhibited the concentrations and mRNA expression of proinflammatory mediators including NO, TNF-α, IL-6 and IL-1β (P < 0.01 or P < 0.001), significantly increased the concentration of the anti-inflammatory factor IL-10 and its mRNA expression (P < 0.001) in a dose-dependent manner, and significantly decreased the mRNA expression of MyD88 and NF-κB (P < 0.01 or P < 0.001). To sum up, wAMF has an anti-inflammatory effect on LPS-stressed mouse peritoneal macrophages, probably by inhibiting the secretion of NO, TNF-α, IL-6 and IL-1β and increasing IL-10 concentration; and the mechanism is possibly associated with the NF-κB signaling pathway.
Effect of Recombinant Ganoderma atrum Immunomodulatory Protein on Macrophage RAW264.7 Differentiation into M1 Type Cells
LIU Ling, LI Qizhang, ZHOU Xuanwei, WANG Yuliang
2019, 40(23):  170-175.  doi:10.7506/spkx1002-6630-20180930-337
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Fungal immunomodulatory proteins (FIPs) have immunomodulatory and anti-tumor effects. Macrophages play an important role in tumor immunotherapy, and M1 type macrophages have strong tumor killing ability and antigen presentation ability. This study aimed to explore the effect and underlying mechanism of FIPs on the in vitro activation of macrophage RAW264.7 cells into M1 type. After being treated with a recombinant Ganoderma atrum immunomodulatory protein (rFIP-gat), the phagocytosis ability of RAW264.7 cells was determined by neutral red uptake assay, and nitric oxide (NO) production by a nitric oxide detection kit. Quantitative real-time polymerase chain reaction (qPCR) was used to determine the relative expression levels of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) genes. The results indicated that rFIP-gat enhanced phagocytosis, promoted the production of nitric oxide, and increased the transcription of iNOS and TNF-α in macrophage RAW264.7 cells in a dose-dependent manner. In conclusion, rFIP-gat may induce the differentiation of macrophage RAW264.7 cells into M1 type.
Apoptosis of Colon Cancer Cells Induced by Flax Meal Polyphenols
ZHANG Lichao, YANG Yufei, LI Hanqing, LA Xiaoqin, LI Zhuoyu,
2019, 40(23):  176-182.  doi:10.7506/spkx1002-6630-20180929-335
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The objective of this study was to explore the anti-tumor activity of the polyphenols extracted from flax meal by ultrasonic-assisted extraction. The content of polyphenols in the extract was determined using the Folin-Ciocalteu assay. The clonogenic survival assay was used to evaluate the inhibitory effect of flax polyphenols on the proliferation of colon cancer and normal FHC cells. Flow cytometry was used to detect the apoptosis of fluorescence-labeled cells. Western blotting was used to detect the expression of apoptosis-related proteins. We also evaluated the regulation of intracellular reactive oxygen species (ROS) production by flax polyphenols. The results showed that flax meal polyphenols had obvious anti-cancer activity and pro-apoptotic activity on DLD1 and HCT-116 cells. Meanwhile, flax meal polyphenols could promote the expression of the pro-apoptotic factors Bak and Bax, inhibit the expression of the anti-apoptotic factors Bcl-2 and Bcl-XL, promote the release of cytochrome c, and elevate the level of ROS in colon cancer cells in a concentration-dependent manner. In summary, flax meal polyphenols can exert anti-tumor effects by increasing ROS level in colon cancer cells and activating mitochondrial apoptotic pathways.
Antagonistic Effects of Breakfast Cereals on Arsenic-Induced Reproductive Toxicity in Male Mice
GAO Junyu, YI Huilan
2019, 40(23):  183-188.  doi:10.7506/spkx1002-6630-20181110-120
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The effects of breakfast cereals on arsenic-induced reproductive toxicity were examined in male Kunming mice. The mice in the model group were administrated with water containing 10 mg/L arsenic from sodium arsenite, while those in the intervention groups were additionally provided with 7.15 or 14.30 g/100 mL of breakfast cereals once every three days for 60 days. All mice had free access to water during the administration period. The antioxidant indexes and histological structure of mouse testicles were examined, and the total number of sperm and the percentage of abnormal sperms were recorded at the end of administration. Our results showed that arsenic intake from drinking water decreased testicular coefficient, sperm quantity, superoxide dismutase (SOD) activity and glutathione (GSH) content in mouse testicles. The contents of H2O2 and malondialdehyde (MDA) in testicular tissue increased significantly in the arsenic exposed group, accompanied with pathological changes as well as a reduction in total sperm number and an elevation in sperm deformity percentage. After intervention with breakfast cereals, the testicular coefficient increased, and so did the SOD activity and GSH content in testis tissue. In addition, lower contents of H2O2 and MDA appeared in the intervention groups; together with the alleviation of testicular damage, the sperm number increased and the sperm malformation ratio decreased. The above results showed the protective effect of cereal breakfast on arsenic-induced reproductive system damage in male mice, suggesting a preventive approach to reduce arsenic toxicity.
Inhibitory Effect and Mechanism of the Ethyl Acetate Fraction of Pleurotus ferulatus Triterpenoids on Proliferation of Esophageal Eca109 Cells
WANG Lei, ZHANG Fuchun, LIU Jun
2019, 40(23):  189-198.  doi:10.7506/spkx1002-6630-20181004-003
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Objective: The study investigated the inhibitory effect of the ethyl acetate fraction of Pleurotus ferulatus triterpenoid (PFTP-E) on the proliferation of human esophageal carcinoma Eca109 cells and the possible underlying mechanism. Methods: Cell proliferation in vitro was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Hoechst 33258 staining was used to observe cell apoptosis. Flow cytometry was used to assess cell proliferation, cycle, apoptosis, mitochondrial membrane potential and intracellular reactive oxygen species (ROS). The effects of PFTP-E on the expression of the apoptosis-related proteins Bcl2, Bax, poly ADP-ribose polymerase (PARP), caspase 3 and caspase 9; the cell cycle-related protein cyclin B1; the endoplasmic reticulum stress-related proteins eukaryotic initiation factor 2α (eIF2α) and CHOP; and mitogen-activated protein kinase (MAPK) signaling pathway-related proteins were detected by Western blot. Results: PFTP-E inhibited the proliferation of Eca109 cells in both a time and dose-dependent manner, blocked the cell cycle in G2/M phase and induced cell apoptosis. Meanwhile, PFTP-E decreased mitochondrial membrane potential and increased intracellular ROS production. In addition, PFTP-E could up-regulate the expression of cytochrome c, Bax, p-eIF2α and CHOP, down-regulate the expression of Bcl2 and cyclin B1, significantly increase cleaved-PARP, cleaved-caspase 3 and cleaved-caspase 9 expression levels, induce endoplasmic reticulum stress and activate the MAPK/JNK signaling pathway. Conclusion: PFTP-E can effectively induce apoptosis, and the underlying anti-tumor mechanism is related to mitochondrial damage, cell cycle block, endoplasmic reticulum stress.
Packaging & Storage
Application of Nanosilver Esterified Starch Film in Beef Preservation
YANG Bin, CAO Yinjuan, YU Qunli, HAN Ling, LIN Liang, ZHU Yueming, CAO Hui
2019, 40(23):  199-205.  doi:10.7506/spkx1002-6630-20181220-244
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A nanosilver esterified starch film was prepared, and its performance in preserving beef quality was measured by determining its effect on quality changes in beef during storage. Beef was wrapped with the starch film and stored in a polyethylene bag under vacuum packaging at 4 ℃. The changes in pH, color, water-holding capacity, thiobarbituric acid reactive substances (TBARS) value, total volatile base nitrogen (TVB-N) content, aerobic plate count (APC) and sensory evaluation were detected during storage. The results showed that the sensory score of beef packaged with the starch film was higher than that of the control group, and the pH, color, pressing loss, TVB-N, and APC were significantly lower than those of the control group (P < 0.05). The storage period of nanosilver esterified film-treated beef was up to 24 d, which was 9 d longer than the control group. Therefore, the nanosilver esterified starch film is useful to prolong the shelf life of beef.
Development and Application of an Intelligent Biolayer Packaging Film as a Freshness Indicator for Salmon
ZOU Xiaobo, XUE Jin, HUANG Xiaowei, ZHAI Xiaodong, ZHANG Junjun, ZHANG Zexiang, GAN Ziyu
2019, 40(23):  206-212.  doi:10.7506/spkx1002-6630-20181126-298
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In order to improve the stability of natural anthocyanins as freshness indicators in food packaging, a novel packaging film, consisting of a protective dense outer layer formed from chitosan and polyvinyl alcohol and an inner layer formed from gellan gum and mulberry anthocyanins, was developed by layer-by-layer assembly as an intelligent indicator and applied for monitoring salmon freshness. The bilayer film with a chitosan-to-polyvinyl alcohol ratio of 1:1 (V/V) had the best mechanical properties. The tensile strength and elongation were 40.65 MPa and 54.36%, respectively. The film had the lowest water vapor transmission rate. The scanning electron microscopic image showed that the film has the best structure compatibility imparting the best stability to anthocyanins incorporated. When applying this film to detect salmon freshness, total volatile basic nitrogen (TVB-N) content increased with stored time at 4 ℃, reaching a level greater than 30 mg/100 g on the 4th day. At this time, thiobarbituric acid reactive substances (TBARs) value was 0.921 mg/kg and pH was 6.75. In addition, macroscopic observation showed that the color of the film changed from dark red to lavender, and then bluish brown, indicating that the fish were spoiled. In conclusion, the developed bilayer film improves the oxidative stability of anthocyanins incorporated and hence can be used as an intelligent indicator for salmon freshness.
Effects of Different Freezing Methods on Water State, Tissue Structure and Quality Changes of Trachinotus ovatus
GONG Taoshuo, LAN Weiqing, WANG Meng, XIE Jing
2019, 40(23):  213-219.  doi:10.7506/spkx1002-6630-20181113-149
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This work was undertaken in order to study the effects of different freezing methods on water state, tissue structure and quality changes of Trachinotus ovatus. Four different freezing methods such as plate freezer (PF), spiral freezer (SF), cryogenic freezer (CF) and ordinary freezer (OF) were used to freeze fresh Trachinotus ovatus. The pH, total volatile basis nitrogen (TVB-N) content, texture profile analysis (TPA) parameters, color difference, water retention capacity (water holding capacity (WHC), cooking loss rate and juice loss rate) of the frozen fish samples were measured and they were also evaluated by low-field nuclear magnetic resonance (LF-NMR) and light microscopy. The results showed that SF samples were generally superior to OF samples in all the parameters tested. The pH and TVB-N content of CF and SF samples were lower, and the TPA parameters, color parameters and water retention capacity changed more slowly than those of PF and OF samples. From the results of LF-NMR, it was found that SF had the least effect on water loss. The observation of muscle tissue microstructure showed the presence of narrow intermyofibrillar space that was evenly distributed as well as small ice crystals, indicating that the quality of Trachinotus ovatus could be well maintained. Therefore, the overall performance of SF was better than the other freezing methods.
Effects and Mechanism of Different Pretreatment Techniques on the Quality of Refrigerated Silver Carp Meat
HU Weijie, SHEN Yuntao, MA Liang, DAI Hongjie, GUO Ting, ZHOU Hongyuan, YU Yong, ZHANG Yuhao
2019, 40(23):  220-226.  doi:10.7506/spkx1002-6630-20181119-222
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Different pretreatment techniques were compared for their effectiveness in preserving the quality of silver carp meat. Two techniques that were found to be the most effective among the ones tested were selected for further investigation. Our focus was on exploring the pattern of quality changes in pretreated fish meat during refrigeration storage and the underlying mechanism. The results showed that both control and modified atmosphere packaged fish were spoiled after refrigeration storage for two weeks. Ultra-high pressure (UHP) processing and ClO2 + 100% CO2 modified atmosphere packaging (MAP) were the most effective pretreatments for preserving fish quality. The water-holding capacity and texture characteristics of UHP-treated sample were significantly improved, and the cooking loss rate was significantly reduced (P < 0.05) relative to the untreated control. The quality of ClO2 + 100% CO2 MAP packaged sample was not maintained so well as UHP-treated sample but was maintained better than the control group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis and Raman spectroscopy showed that UHP treatment promoted the formation of new hydrogen bonds in fish meat, making the protein structure more orderly compared with the control group and consequently improving the quality characteristics of fish meat. ClO2 + 100% CO2 MAP could improve the quality of fish meat by inhibiting endogenous enzyme activity and as a result reducing the degradation of fish proteins during storage.
Effect of Exogenous p-Coumaric Acid on Phenylpropanoid Metabolism and Antioxidant Capacity of Postharvest Peach Fruit
LI Yaoyao, CAO Maomao, WANG Xiaolu, SU Jinlong, GAO Hui
2019, 40(23):  227-232.  doi:10.7506/spkx1002-6630-20181130-367
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In order to explore the effect and underlying mechanism of exogenous p-coumaric acid (p-CA) on chilling injury (CI) in postharvest peach fruit, ‘Shahong’ peach fruit were immersed in 0, 0.5 and 1 mmol/L p-CA to investigate the effect of p-CA on CI index and malondialdehyde (MDA) content during subsequent storage at 4 ℃. It turned out that 0.5 mmol/L p-CA was selected as the optimal treatment concentration. In this case, we further studied the effect of p-CA treatment on phenylpropanoid metabolism and antioxidant capacity in postharvest peach fruit. The results showed that p-CA treatment significantly delayed the development of CI and the generation of MDA in peach fruit. p-CA treatment stimulated the activity of shikimate dehydrogenase, phenylalanine ammonia lyase, cinnamate-4-hydroxylase and 4-coumarate coenzyme A ligase, but inhibited polyphenol oxidase and peroxidase activities, which contributed to higher total phenolic content in peach fruit and thus enhanced 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radical scavenging capacity. This study indicated that the alleviating effect of p-CA on CI was associated with its ability to regulate phenylpropanoid metabolism and antioxidant capacity in peach fruit.
Impact of Immersion Freezing on Oyster Quality and Water Migration
LIANG Zuanhao, CHEN Haiqiang, LIANG Fengxue, LUO Hongyue, XIE Yan’an, YU Ming
2019, 40(23):  233-238.  doi:10.7506/spkx1002-6630-20181101-016
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In order to seek an efficient freezing method for oysters, this study evaluated the effect of immersion freezing on the water migration and quality of oysters. The freezing temperature was optimized. On this basis, the effect of immersion freezing on the water status, content and distribution of oysters was analyzed by low-field nuclear magnetic resonance (LF-NMR). The results showed that oysters frozen by immersion freezing at ?35 ℃ maintained good water-holding capacity and elasticity after thawing with no obvious protein degeneration occurring. The freezing speed of immersion freezing at ?35 ℃ as a ultrafast freezing method was 13.03 cm/h, which was higher than that of static freezing at ?18 ℃ and was 5–6 folds higher than that of airflow freezing at ?35 ℃ and ultra-low temperature freezing at ?80 ℃. Moreover, immersion freezing led to the lowest loss of immobilized water, and the magnetic resonance images showed almost no drip loss inside oysters after thawing.
Effects of Nitric Oxide Fumigation on Cell Wall Metabolism and Black Spot Control of Postharvest Melon
SHI Ling, WU Bin, JING Yuanyuan, LI Yaling, LI Ling, HE Huan, LIAO Haihui, ZHU Xuan
2019, 40(23):  239-245.  doi:10.7506/spkx1002-6630-20181201-006
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In order to investigate the effect of NO fumigation on cell wall metabolism and disease resistance in postharvest melons, “Xizhoumi 25” melons (Cucumis melo L. var. saccharinus cv. Xizhoumi) were fumigated with 60 μL/L nitric oxide gas for 3 h and then kept at room temperature for 12 h. The fumigated fruit were inoculated with Alternaria alternata and stored at room temperature. Disease incidence, hardness, cell membrane permeability, the contents of protopectin, soluble pectin and cellulose, and the activities of polygalacturonase (PG), pectin methyl esterase (PME) and cellulase (Cx) were regularly measured during storage, and changes in the surface structure of melon rinds was observed by scanning electron microscopy (SEM). The results showed that NO fumigation treatment could effectively reduce the lesion diameter, lesion depth and disease incidence of postharvest melons, maintain high fruit hardness and high contents of protopectin and cellulose, suppress the increase in cell membrane permeability and soluble pectin content, and reduce the activities of PG, PME and Cx. In addition, SEM results exhibited that NO treatment could inhibit the growth of mycelium in surface stomata and cracks and maintain the integrity of the stomatal structure of melon fruit. Therefore, exogenous NO fumigation treatment at appropriate concentration can delay the cell wall degradation process and enhance disease resistance in postharvest melons.
Effect of High Temperature Steaming Pretreatment on Quality of Phyllanthus emblica L. Juice and Analysis of Browning Behavior during Storage
XU Juan, ZHANG Wenwen, LI Kai, LI Kun, LIU Lanxiang, MA Jinju, GAN Jin, ZHANG Hong
2019, 40(23):  246-252.  doi:10.7506/spkx1002-6630-20190628-370
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This study aimed to analyze the effect of high temperature steaming pretreatment on chemical components of Phyllanthus emblica L. juice and to elucidate its browning behavior during storage. Juices prepared from the fruit subjected or not to the pretreatment (designated as samples D and W, respectively) were stored for up to 42 days at different temperatures. Changes in the concentrations of vitamin C, total phenols, 5-hydroxymethyl furfural (5-HMF) and reducing sugar along with browning degree (BD) were examined during the storage period, and path analysis was employed to explore the main causes of browning. The results indicated that high-temperature steaming pretreatment could slow the loss of vitamin C, total phenols and total sugar, and reduce the production of 5-HMF and the BD of Phyllanthus emblica L. juice under all tested storage conditions. In addition, low-temperature storage was beneficial for retaining nutrients in the fruit juice. High-temperature steaming pretreatment changed the main causal factors of browning during its storage. For sample W, total phenol concentration had the largest direct impact on BD, and the interaction between total phenol and 5-HMF concentration was the chief determinant of browning at 4 ℃. For sample D, 5-HMF concentration had the largest direct impact on BD, and the interaction between 5-HMF and total phenol concentration was the chief determinant of browning at 4 ℃. At 25 ℃, the browning of Phyllanthus emblica L. juice was mainly dependent on total phenol concentration for both samples. At 37 ℃, total phenol concentration had the largest direct impact on BD and was the chief determinant of browning for sample W, while for sample D, vitamin C had the largest direct impact on BD and the interaction between vitamin C and 5-HMF concentration was the chief determinant of browning.
Effect of Composite Antimicrobial Coating Containing Cinnamaldehyde on Postharvest Preservation of Litchi Fruit
YANG Yajing, HAN Yuzhu, MENG Xing, WANG Yuying, LI Kai, XU Siqi, YANG Yemei
2019, 40(23):  253-261.  doi:10.7506/spkx1002-6630-20181026-316
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The major decay-casuing pathogen isolated from stored litchi fruit was confirmed by Koch’s postulates, examined morphologically and identified by internal transcriptional spacing (ITS) sequence analysis. The formulation of a composite antimicrobial coating containing cinnamaldehyde was optimized and its application in litchi preservation was investigated. Rhizopus nigricans was identified as the major pathogen causing postharvest decay in litchi fruit. The composite antimicrobial coatings markedly inhibited mildew in litchi fruit. The individual components (chitosan, zein and glycerol) significantly attenuated the decrease in soluble solids content and the increase in mass loss percentage and extend the storage period of litchi fruit. Using an orothogonal array design, the optimal combination was obtained as follows: 750 mg/L of cinnamaldehyde, 1.2 g/100 mL of chitosan, 1.6 g/100 mL of zein, and 0.7 g/100 mL of glycerol. The decay index and marketable fruit percentage of litchi fruit treated with the optimized antimicrobial coating were 0.16 and 92.3%, respectively after 8 d of storage at normal temperature. Its peel had a bright color and the sensory quality was good, indicating that the antimicrobial coating had good efficacy in preserving litchi quality.
Effect of Protective Solution Combined with Temporary Culture on Waterless Live Transportation of Lateolabrax maculatus
ZHANG Yuhan, XIE Jing
2019, 40(23):  262-268.  doi:10.7506/spkx1002-6630-20180830-326
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We investigated the waterless live transportation of Lateolabrax maculatus at ecological ice temperature. The effect of temporary culture with vitamin C (VC) and dipping in protective solutions before subsequent transportation on blood biochemical indexes, gill Na+ /K+-ATPase (NKA) activity, serum lysozyme concentration and immunoglobulin M (IgM) level of Chinese sea perch was evaluated. The results showed temporary culture with 30 mg/L VC for 12 h followed by cold acclimation and immersion in protective solution G2 (0.09% lysozyme + 0.3% sorbitol + 0.08% Zingiber officinale juice) for 2–3 s before separate packaging was the most effective at keeping fish alive during subsequent transportation. The combination of temporary culture with 30 mg/L VC and protective solution G2 could maintain the serum concentration of total protein and albumin at levels higher than those observed with the other treatments. In addition, serum lysozyme, IgM and gill NKA activity were maintained. The application of the protective solution could effectively attenuate gill and renal damages, form a protective film on the body surface of fish and facilitate the excretion of metabolic waste, resulting in a 1%–5% reduction in the mortality rate after waterless transportation.
Effects of Short-Wave Ultraviolet (UV-C) Light and 60Co-γ Irradiation on the Storage Quality of Cherry Fruits
TIAN Zhuxi, LONG Mingxiu, LI Yongfu, HE Yangbo, LIANG Qian, SHI Bin
2019, 40(23):  269-276.  doi:10.7506/spkx1002-6630-20181225-297
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In order to investigate the efficacy of different radiation treatments in preserving the quality of ‘Agate Red’ cherries, cherry fruit were treated with different doses of short-wave ultraviolet light (UV-C) irradiation (1.37, 2.05 and 2.74 kJ/m2) or 60Co-γ irradiation (0.75, 1.5 and 2.25 kGy) and then stored under cold conditions. Physiological quality attributes and pericarp ultrastructure were regularly assayed during storage. The results showed that compared to the control group, 1.37 kJ/m2 UV-C irradiation and 0.75 kGy 60Co-γ irradiation significantly delayed the decline of marketable fruit percentage, inhibited the loss of fruit mass, maintained better textural characteristics, promoted anthocyanin synthesis, effectively inhibited the decline of peroxidase (POD) and superoxide dismutase (SOD) activities, but they had little effect on soluble solids content, and even increased malondialdehyde (MDA) content. Due to the positive effects of both irradiation treatments on the core sensory quality indicators such as marketable fruit percentage, hardness, mass loss percentage and anthocyanin content, the adverse changes in MDA content was not enough to affect the commodity quality evaluation of cherry fruit. The results of electron microscopy showed that compared to the control group, the damage of cell membrane, mitochondria, chloroplast and other cell structures could be reduced to a certain extent after the irradiation treatments, thereby significantly delaying senescence in pericarp cells. In addition, each treatment exerted different effects at the early and late stages of storage. For short-term storage for up to 5 days, 1.37 kJ/m2 UV-C irradiation is appropriate, while 0.75 kGy 60Co-γ irradiation is appropriate for long-term storage.
Reviews
Recent Advances in Intermediate Materials of Starch
HAN Wenfang, LIN Qinlu, ZHAO Siming, MEI Dongxu, YANG Qiqi, LI Jiangtao
2019, 40(23):  277-282.  doi:10.7506/spkx1002-6630-20181105-060
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Starch is used as an important ingredient or accessory material in the food industry and its molecular structure restricts the performance of starch-based products. It is generally accepted that starch is comprised mainly of highly branched amylopectin (AP) and predominantly linear amylose (AM). As the understanding of starch structure has been increasingly improved, the current widely accepted theories regarding amylose and amylopectin have become insufficient to solve many practical problems encountered in the study of starch function and structure. It has been demonstrated that there may be a third fraction defined as intermediate material (IM) intermediate between AP and AM in starch. IM is considered one of the major factors affecting starch properties, but its molecular structure is not clear yet, so that the structure and properties of starch is not fully understood. In this paper, we review the recent progress made in understanding the concept of IM as well as its separation, structure and properties, which will provide valuable information for studying the structure of starch and IM.
Recent Progress in Understanding Quality Differences among Beef with Different Ultimate pH and Underlying Mechanism
WANG Jing, LUO Xin, ZHU Lixian, LI Hang, HAO Jiangang, ZHANG Yimin
2019, 40(23):  283-288.  doi:10.7506/spkx1002-6630-20181109-109
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The quality of beef with different ultimate pH is significantly different. Beef with high ultimate pH is dark, firm and dry and easily spoils, while beef with intermediate ultimate pH (5.8–6.2) has poor tenderness. This paper summarizes the differences in the quality and safety of beef with different ultimate pH in terms of tenderness, water-holding and microbiology, as well as the potential mechanisms causing these differences. It aims to provide useful ideas and theoretical guidance for researchers interested in finding ways to improve the quality of beef with different ultimate pH and more broadly to reduce the economic loss of the beef industry.
Recent Advances in Understanding the Effect of High Power Ultrasound on Protein Functional Characteristics and Its Applications in Meat Processing
KANG Dacheng, LIU Yunguo, ZHANG Wangang
2019, 40(23):  289-297.  doi:10.7506/spkx1002-6630-20181105-053
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The ultrasound-assisted processing technology has been widely evaluated in agricultural and food processing. The functional properties of protein can be significantly improved by applying ultrasonic treatments. In the field of meat processing, ultrasonic treatment has been used as an environmental friendly and non-thermal processing technology to improve meat quality, develop new products and prolong the shelf life through modifying the structure and functional properties of myofibrillar protein. Therefore, ultrasonic is advantageous in meat processing. This paper reviews the effect of ultrasonic on the functional properties of protein and its application in meat processing.
Recent Progress in Application of Raman Spectroscopy in Meat Processing and Quality Control
LI Ke, YAN Luhui, ZHAO Yingying, ZHAO Dianbo, BAI Yanhong
2019, 40(23):  298-304.  doi:10.7506/spkx1002-6630-20181130-358
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As a novel spectroscopic technique, Raman spectroscopy has the advantages of convenience, simplicity, fast and non-invasive detection, and high efficiency in the analysis of the structure and physicochemical properties of meat and meat products, and it has soon become one of the most important detection techniques used in the field of meat research. This paper briefly describes the principle of Raman spectroscopy and summarizes its application in meat processing and quality control such as processing quality, eating quality and safety evaluation, as well as the advantages of its combined application with chemometrics in meat research and industrial production of meat products. Meanwhile, future directions for the development directions of Raman spectroscopy in meat research are proposed.
A Review of the Mechanism of Action of Plant Antifreeze Proteins and Their Application in Food
YU Jing, HU Yingying, WEN Rongxin, QIN Ligang, CHEN Qian
2019, 40(23):  305-312.  doi:10.7506/spkx1002-6630-20181109-100
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Antifreeze proteins (AFPs) are a family of proteins with thermal hysteresis activity that bind to ice crystals, inhibit?their growth, reduce the freezing point, and suppress recrystallization. AFPs play a positive role in prolonging the storage period and improving the quality of frozen food products due to their special structures and functions. This article provides a brief review of recent studies on plant AFPs with respect to their mechanism of action in food processing, the currently available methods for their separation and purification, and their applications in food in the future. It is expected to provide a theoretical basis for the application of plant-derived AFPs in frozen food products.
Interaction between Plant Polyphenols and Peanut Allergenic Proteins and Mechanism for Allergenicity Reduction: A Review
ZHANG Chi, LI Chunyi, WANG Qiming, TANG Yuwan, ZHAO Jichun, LI Fuhua, MING Jian
2019, 40(23):  313-318.  doi:10.7506/spkx1002-6630-20190427-358
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Peanut allergy is one of the most important types of food allergy, and peanut allergenic proteins are the major allergens. The currently available methods for solving peanut allergy such as thermal processing, genetic engineering, and enzymatic treatment have disadvantages such as low efficiency, high safety risk, and easy destruction of nutrients. Plant polyphenols are a group of natural active phytochemicals with a wide range of physiological functions, such as anti-oxidation, hypoglycemic and anti-inflammatory activities. The interaction between plant polyphenols and peanut allergenic proteins represents a new way to solve peanut allergy. It has been reported in the literature that plant polyphenols have anti-allergic effects. This paper mainly describes the interaction between plant polyphenols and peanut allergenic proteins and the potential mechanism by which plant polyphenols reduce the allergenicity of peanut proteins. Moreover, future research directions are proposed, in order to provide new ideas for the application of plant polyphenols to solve peanut allergy.
Recent Progress in Techniques for Adulteration Identification of Meat and Meat Products
SHI Zihe, Josef VOGLMEIR, LIU Li
2019, 40(23):  319-326.  doi:10.7506/spkx1002-6630-20181229-354
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Meat is one of the most important parts of the diet due to its high nutritious value and unique flavor. Driven by high profits, the problem of adulteration of meat and meat products occurs frequently in the meat processing industry and market. Therefore, the development of efficient techniques and methods for the identification of adulterated meat and meat products is of great significance for ensuring the rights of consumers. The requirements for adulteration identification techniques vary with the type of product and consumption pattern. This review describes the basic principles and applications of the methods currently available for meat adulteration detection, including proteomics-based immunoassay and mass spectrometry, DNA-based polymerase chain reaction and non-invasive sensor and spectroscopic technologies. Additionally, the disadvantages of these methods and some suggestions on the development of new adulteration identification techniques are proposed. We expect that this review will provide a theoretical basis for adulteration identification of meat and meat products.
A Review of Recent Research on the Effect and Underlying Mechanism of Calcium Salts on Meat Color
ZHANG Mengmeng, LUO Xin, ZHANG Yimin, MAO Yanwei, YANG Xiaoyin, LEI Hongmei, HAN Mingshan, LIANG Rongrong
2019, 40(23):  327-333.  doi:10.7506/spkx1002-6630-20181210-122
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In the meat industry, calcium salts are often used in tenderness improvement, as nutritional fortifiers in meat products, or as a partial substitute for sodium chloride in low-sodium meat products. However, it has been found that calcium salt treatments can readily meat color deterioration. Currently, there are many disagreements on the effect of calcium on meat color, which may be associated with the type and addition amount of calcium salts various environmental factors. In order to clarify the mechanism underlying the effect of calcium on meat color, the relationship between calcium and lipid oxidation and metmyoglobin reducing capacity in meat is considered in this paper. Meanwhile, it reviews recent research on the effect of calcium on the color and color stability of meat and meat products. We hope that this review will provide a basis for reasonable application of calcium in meat production.
Recent Advances in Understanding the in Vivo Distribution and Metabolism of Ergothioneine and Its Roles in Disease Prevention
PAN Hongyu, GUO Liqiong, LIN Junfang
2019, 40(23):  334-340.  doi:10.7506/spkx1002-6630-20181016-158
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Ergothioneine (EGT), a naturally occurring amino acid with strong antioxidant property, is produced by only a few microorganisms, including Actinobacteria, Cyanobacteria, and some fungi like Streptomyces and Mycobacteria. Although EGT cannot be synthesized in animals (including human) and plants, plants can absorb EGT synthesized by microorganisms from the soil through their roots, while animals can absorb and accumulate dietary EGT. EGT is easily absorbed by the human body via the organic cation transporter 1 (OCTN1) and is widely distributed in human cells and tissues. Numerous studies have elucidated the biosynthesis, distribution, chemical properties, and antioxidant activity of EGT. Despite intensive efforts in investigating its antioxidant and cytoprotective capacity in vitro against a variety of oxidative stresses, its physiological roles and potential mechanisms of action in vivo have not been fully determined yet. This review aims to elucidate the unique properties and biosynthesis of EGT as well as its potential as a therapeutic agent in the prevention of diseases.
A Review of Recent Research on Key Aroma Compounds in Tea
WANG Mengqi, ZHU Yin, ZHANG Yue, SHI Jiang, LIN Zhi, Lü Haipeng
2019, 40(23):  341-349.  doi:10.7506/spkx1002-6630-20181015-132
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The aroma is one of the most important determinants of the quality of tea. Studies have shown that tea contains a small amount of key aroma compounds which are of significant interest to researchers because of their important contribution to tea aroma quality. In this paper, the recent progress in research on the key aroma compounds of tea is reviewed by summarizing the existing methods used to analyze and identify these compounds and the key aroma compounds identified from the major tea types (green tea, black tea, oolong tea and dark tea) and reprocessed tea (mainly refers to scented tea). Future research directions are discussed as well. The existing research outcomes enrich the basic chemical theory of tea flavor quality and provide a scientific basis for improving the modern tea processing technology and regulating the quality of tea aroma.