Table of Content

15 January 2019, Volume 40 Issue 1
Basic Research
Self-Assembly Kinetics and Physicochemical Properties of Silver Carp Myosin under Conditions with Different Concentrations and Low Temperature
GAO Xia, CAO Liwei, XIONG Shanbai, HU Yang, YOU Juan, LIU Ru
2019, 40(1):  1-8.  doi:10.7506/spkx1002-6630-20180614-273
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In the present study, the self-assembly kinetics and physicochemical properties of silver carp myosin were investigated at low temperature (4 ℃) through particle size distribution, confocal laser scanning microscopy (CLSM) images and turbidity. Myosin could be assembled at 4 ℃. The turbidity and particle size increased with prolonging assembly time and increasing myosin concentration. Myosin self-assembling could be divided into three stages: nucleating, assembly, and balance. For the samples at low concentrations (0.1-0.3 mg/mL), myosin assembly tended to the balance at 12 h. It took more time for myosin under the condition with the concentration higher than 0.5 mg/mL to reach the assembly balance. In addition, the particle size of myosin assembles fit the model lgZ/270.0=(0.0182ρ+0.00679)t/2.303 very well. Increasing myosin concentration could promote protein interaction, thus leading to the increase in the assembling rate and particle size. The assemblies could be observed by CLSM under the condition with the concentration higher than 0.5 mg/mL. The critical concentration of myosin was 0.5 mg/mL for rapid self-assembly.
Membrane Lipid Peroxidation during Browning of Lily Bulbs
KAN Juan, WAN Bing, XIE Wangjing, CHEN Cuicui, LIU Jun, JIN Changhai
2019, 40(1):  9-15.  doi:10.7506/spkx1002-6630-20170922-316
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The objective of this study was to relate membrane lipid peroxidation and browning in lily bulbs (Lilium lancifolium Thunb.) grown in Yixing, Jiangsu during postharvest cold storage. It was demonstrated that browning degree, cell membrane permeability, superoxide anion radicals production rate, hydrogen peroxide (H2O2) and malondialdehyde contents increased in all bulb parts with storage time. The rate of increase in these parameters was always higher in the middle layer than in the outer and inner layers of bulbs. The activities of exogenous peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and lipoxygenase (LOX) increased initially and decreased thereafter. The middle layer of bulbs showed higher SOD and CAT activities but lower POD and LOX activity than that of the two other layers. Cell viability in lily bulbs gradually decreased with storage time, and it was higher in the middle layer than in the two others. Browning was closely related to membrane lipid peroxidation in lily bulbs. The rate of browning was different among different bulb parts, in the decreasing order of inner > outer > middle layers. The results from this study can provide an experimental basis for understanding the mechanism of lily browning.
Effect of Protein Oxidation during Storage on Cooking and Eating Quality of ‘Jinyou 207’Indica Rice and ‘Jijing 88’ Japonica Rice
WU Xiaojuan, WU Wei
2019, 40(1):  16-22.  doi:10.7506/spkx1002-6630-20170929-423
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In order to investigate the effect of protein oxidation during storage on the cooking and eating quality of rice, newly harvested ‘Jinyou 207’ indicia rice and ‘Jijing 88’ japonica rice were stored under accelerated deterioration conditions (37 ℃ and 85% relative humidity). The results indicated that the degree of protein oxidation was increased with increasing storage time of rice. The peak viscosity, final viscosity and setback of rice flour and cooked rice hardness were significantly correlated positively with the protein carbonyl content in rice and negatively with the total sulphydryl content and free sulphydryl content (P < 0.01). Cooked rice chewiness, springiness, appearance, smell, palatability, taste and cold cooked rice texture were negatively correlated with the protein carbonyl content of rice (P < 0.01), and positively correlated with the total sulphydryl content and free sulphydryl content (P < 0.01). The disulfide content of rice protein was significantly positively correlated with rice flour minimum viscosity and cooked rice hardness and negatively correlated with the cohesiveness, resilience and adhesiveness of cooked rice (P < 0.01). In conclusion, our data demonstrated that during accelerated storage, the degree of retrogradation of rice starch increased with increasing degree of protein oxidation, and the texture properties and sensory quality of cooked rice decreased obviously.
Water Diffusion Characteristics and Microwave Vacuum Freeze-Drying Modelling of Chinese Yam (Dioscorea opposite) Tubers
DUAN Liuliu, DUAN Xu, REN Guangyue
2019, 40(1):  23-30.  doi:10.7506/spkx1002-6630-20180610-129
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This study was undertaken in order to explore the water diffusion characteristics of Chinese yam tubers during microwave vacuum freeze-drying. Low field nuclear magnetic resonance (LF-NMR) was used to analyze water distribution change during the drying process. In addition, changes in water effective diffusion coefficient, water content and drying rate were measured. The results showed that moisture migration from high degree of freedom to low degree of freedom occurred during the drying process. Water effective diffusion coefficient increased from 1.129 × 10-9 to 5.439 × 10-9 m2/s as the microwave power increased from 1.5 to 4.4 W. Similarly, moisture diffusion coefficient, water migration rate and the amount of unbound water converted to bound water increased with increasing microwave power. The Page and Newton models were fitted to the experimental data. Our comparative evaluation showed that the Page model could better describe the drying process with excellent goodness of fit and R2 of greater than 0.99. This study can provide a theoretical basis for real-time monitoring of moisture in the drying process of Chinese yam tubers.
Effects of Different Feeding Systems on Intramuscular Fat Deposition Pathway AMPK-ACC-CPT1 and Meat Quality in Sunit Lamb
YUAN Qian, WANG Yu, SU Lin, LUO Yulong, SU Rina, ZHAO Lihua, JIN Ye
2019, 40(1):  31-36.  doi:10.7506/spkx1002-6630-20171107-076
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In the present study, we assessed the effects of two different feeding systems on the activities and mRNA expression levels of enzymes involved in the AMP-activated protein kinase-acetyl-CoA carboxylase-carnitine palmitoyltransferase (AMPK-ACC-CPT1) pathway, fat content and meat quality in the Biceps femoris muscle of 12-month-old Sunit lambs. The enzyme activities were determined by enzyme-linked immunosorbent assay and gene expression was measured by real-time fluorescence quantitative polymerase chain reaction (PCR). The results showed that AMPK concentration and activity, AMPK mRNA expression, CPT1 concentration, brightness (L* value), yellowness (b* value) and shear force in the biceps femoris muscle of grazed lambs were significantly higher than those in stall-fed lambs (P < 0.05), while the opposite was observed for ACC activity, ACC mRNA expression and intramuscular fat content (P < 0.05). Accordingly we concluded that grazing can activate the AMPK-ACC-CPT1 pathway to reduce intramuscular fat deposition, increase L* and b* values and decrease tenderness, consequently affecting lamb meat quality.
Development of a Laser Propagation-Based Method for Measurement of Fiber Orientation in Extruded Dried Meat
HE Congying, DENG Li, WANG Lei, PENG Jing
2019, 40(1):  37-43.  doi:10.7506/spkx1002-6630-20170829-334
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Extruded dried meat is an updated product for traditional meat jerky. Fiber orientation is an important indicator of the quality of extruded dried meat. In this study, we developed a nondestructive photon propagation-based method to quantify fiber orientation in extruded dried meat. Laser transmission reflection images of samples were recorded using a digital camera for quantitative analysis using self-compiled computer program with Matlab software. The effects of image acquisition parameters such as exposure time and light incident angle, and sample parameters including orientation direction and barrel temperature on the degree of fiber orientation were investigated. The results showed the optimal exposure time and light incident angle that provided an ideal B value for the degree of fiber orientation were determined as 1/400 s and 45°, respectively. Barrel temperature affected the degree of fiber orientation, and the established method could be used to identify fiber orientation in extruded meat.
Antibacterial Activity and Mechanism of (-)-β-Pinene against Salmonella
HE Jingru, LIU Xue, CHEN Wenxue, CHEN Weijun, CHEN Haiming
2019, 40(1):  44-49.  doi:10.7506/spkx1002-6630-20170725-471
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This research aimed to study the antibacterial mechanism of (-)-β-pinene on Salmonella for the purpose of providing a theoretical basis for the potential application of (-)-β-pinene as a natural food preservative. The minimum inhibitory concentration (MIC) was determined using the broth dilution method. The morphology and structure of Salmonella cells exposed to (-)-β-pinene were characterized by scanning electron microscope (SEM) and conductivity measurement. The activity of two key enzymes succinic acid dehydrogenase (SDH) and α-ketoglutarate dehydrogenase (α-KGDH) were measured to analyze the influence of (-)-β-pinene on the tricarboxylic acid cycle. Also, the effect of the change in ATP content on energy metabolism in Salmonella was investigated. The results showed that (-)-β-pinene had an MIC of 20 mL/L for Salmonella, and damaged cell morphology and structure, thus leading to increased conductivity of the bacterial suspension, as well as increased SDH and α-KGDH activity and decreased ATP level in the bacterial cells.
Rheological Properties of Hyaluronan Thickened Enteral Nutritional Preparations for Dysphagia Management
WEI Yuanyuan, ZHANG Hongbin, MA Aiqin, GAO Shan
2019, 40(1):  50-55.  doi:10.7506/spkx1002-6630-20171226-334
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The viscosity of gum-thickened foods, non-Newtonian fluids with pertinent high viscosity, is critical for managing dysphagia. The thickening effect of the polysaccharide hyaluronan on enteral nutritional suspensions containing pea protean and soybean oil were investigated by rheological measurements such as flow properties, viscoelasticity and viscosity as a function of shear rate and shearing time. The experimental results indicated that the unthickened sample was a Newtonian fluid with a very low viscosity (only ca. 0.010 Pa·s) which could not meet the requirement of safe swallowing. Hyaluronan had an excellent thickening ability, the initial viscosity of the thickened suspension was up to 8 Pa·s at a hyaluronan concentration of 0.5%, and the thickened suspension showed adjustable viscosity and viscoelasticity and shear thinning behavior, demonstrating the promising application of hyaluronan in dysphagia diet management.
Quality Comparison of Dosidicus gigas Sausages with Heat- and Organic Acid-Induced Protein Gelation
MI Geng, YAN Hongwei, LI Yujin, LI Jianrong
2019, 40(1):  56-61.  doi:10.7506/spkx1002-6630-20171227-338
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Normally cephalopod surimi produced by the conventional process has a weak gel-forming ability. Acid-induced protein gelation is an ideal alternative to heat-induced protein gelation. In this paper, four organic acid salts, sodium citrate, sodium succinate, sodium lactate and sodium acetate were used instead of sodium chloride to dissolve salt-soluble proteins from Dosidicus gigas surimi. The quality of sausages resulting from heat- and organic acid-induced gelation of the saltsoluble proteins was evaluated and compared. The results showed that organic acid-induced sausages had significantly higher values of breaking strength, water-holding capacity, hardness, resilience and chewiness than the heat-induced (P < 0.05). Noticeably, the whiteness of acid-induced sausages exceeded that of heat-induced sausages from some freshwater and marine fishes and Dosidicus gigas. Furthermore, no significant differences in the breaking distance, springiness or cohesiveness of the acid- and heat-induced sausages were found (P > 0.05). The sausages made with sodium succinate by each gelation method had the best sensory quality, and the sausages made with sodium lactate were the worst.
Effect of Processing Conditions on Quality and Protein Secondary Structure in Southern Tofu
ZHAO Lei, ZHU Jie, SU Enyi, YANG Haowen, HU Zhuoyan, LI Lin
2019, 40(1):  62-69.  doi:10.7506/spkx1002-6630-20180607-096
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The effect of processing conditions on the quality of southern tofu prepared from soybeans by the traditional process was investigated. Changes in protein secondary structure were studied by Fourier infrared spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A coagulant dosage of 1.2%, a coagulation time of 20 min and a pressure of 3.0 g/cm2 were found to be the optimal conditions to obtain higher tofu yield and water-holding capacity (WHC) and better hardness and chewiness as well as a whiter color, which presented the tenderness characteristics of southern tofu. The predominant secondary structure of the untreated soybean protein was identified as β-sheet (46.36%), followed by β-turn (18.48%) and random coil (15.45%). After soaking and pulping, the β-sheet content decreased while the β-turn content increased, indicating that the protein conformation was transformed from a dense state to a loose state. However, after subsequent mixing with coagulant, coagulation and pressing, the β-sheet content continuously increased, while the content of random coil structure decreased, which indicates that the protein structure was stable. Little changes were found in soybean protein subunits during tofu processing. Only the protein bands of tofu jelly and southern tofu showed a lighter color. The protein structure of the finished tofu contained 7S and 11S subunits, which illustrates that soybean protein was well retained during tofu processing.
Comparison and Comprehensive Evaluation of Fruit Quality of Different Blueberry (Vaccinium spp.) Varieties
LIU Binghua, SUN Rui, WANG Kaifang, SHU Xiuge, SUN Lei
2019, 40(1):  70-76.  doi:10.7506/spkx1002-6630-20170829-338
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In the present study, the fruit quality of 22 blueberry varieties introduced in Shandong province was analyzed and comprehensively evaluated. The results showed that nine quality indicators were greatly different among different blueberry varieties. The coefficients of variation (CVs) for single fruit mass, specific gravity, hardness, soluble solid content, valid acidity value (pH), anthocyanin content and vitamin C content were greater than 10.00%, indicating significant differences between varieties. Meanwhile, the CVs for fruit shape index and peel brightness index (L* value) were less than 10.00%, suggesting that they were more stable indicators. Five quality indicators including fruit shape index, hardness, L* value, soluble solids content and pH were screened out by using correlation analysis and principal component analysis (PCA) as the core indicators to comprehensively evaluate the fruit quality of different blueberry varieties. The analytical hierarchy process was applied for weight analysis of the core indexes, and a mathematic model was established to calculate the comprehensive evaluation index and evaluate the fruit quality and processing suitability of each blueberry cultivar. Moreover, according to the main quality indexes of blueberry, cluster analysis (CA) was carried out by using the Pearson correlation method. Consistent results were obtained using PCA and CA, indicating that both can be used to analyze blueberry fruit quality index and comprehensively evaluate the fruit quality and processing suitability of different blueberry varieties.
Quality Characteristics, and Antibacterial and Antioxidant Activity of Prunus mume Fruits
LIU Yuxia, YANG Jiaxin, XU Xinglong, LI Qingwei
2019, 40(1):  77-84.  doi:10.7506/spkx1002-6630-20171228-359
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This study was designed to reveal the difference in fruit quality, antibacterial and antioxidant activity of different cultivars of Prunus mume. The cold-resistant cultivars were screened for their fruit quality in order to provide the basis for the breeding of both ornamental and edible cultivars and the utilization of Prunus mume fruits. The quality characteristics (appearance and eating quality), and antibacterial and antioxidant activities of 8 cultivars were evaluated. The phenolic compounds were separated and detected by high performance liquid chromatography-mass spectrometry (HPLC-MS), and the correlations between fruit quality traits and antibacterial and antioxidant activities were analyzed. The results showed significant differences in fruit quality traits of different cultivars of Prunus mume. ‘Dan Fenghou’, ‘Fenye Fenghou’, ‘Wuzangye’ and ‘Fei Lve’ had better fruit quality than other cultivars. The contents of total phenolics and total flavonoids were the highest in ‘Fenghou’, ‘Wuzangye’ and ‘Fei Lve’ and five phenolic compounds were isolated from the three cultivars, including catechin, rosmarinic acid eriodictyol, syringic acid and rutin. The antibacterial activity and antioxidant activity were correlated with the contents of total phenolics and total flavonoids. Therefore, ‘Wuzangye’ and ‘Fei Lve’ were selected as better cold-resistant cultivars for both ornamental and food purposes and could have potential applications as natural sources of antioxidants or functional food ingredients.
Quantitative Exposure Assessment of Listeria monocytogenes in Raw Pork under Three Transportation Modes
LIU Yangtai, SUN Wanxia, LIU Baolin, DONG Qingli
2019, 40(1):  85-91.  doi:10.7506/spkx1002-6630-20170630-454
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The exposure of Listeria monocytogenes in raw pork under three different simplified transportation modes was quantitatively assessed according to the initial contamination levels and environmental settings. The prevalence of L. monocytogenes after non-cold chain, partial cold chain and whole cold chain transportation was 42.12%, 12.07% and 6.50%, respectively, and the probability of exceeding the risk threshold was 21.05%, 1.61% and 0%, respectively. The initial contamination was found to be crucial to the final contamination with correlation coefficient over 0.70 for all chains. Hence, chilled pork was advantageous over fresh pork in avoiding foodborne diseases, especially for that transported in the whole cold chain. Microbial source control and environmental settings were vital for the raw pork supply chains.
Food Engineering
Effects of Ultra-high Pressure Processing and Sodium Tripolyphosphate Contents on Water-Holding Capacity of Myosin Gel and Its Heat-Induced Gelation Process
QIAN Chang, XUE Siwen, XU Xinglian, ZHOU Guanghong
2019, 40(1):  92-101.  doi:10.7506/spkx1002-6630-20171222-281
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To investigate the effect of ultra-high pressure (UHP) processing and sodium tripolyphosphate (STPP) contents on the water-holding capacity (WHC) of myosin gel and the heat-induced gelation process, rabbit Psoas major myosin dialyzed against different STPP concentrations (0%, 0.15%, 0.30% or 0.45%) were subjected to UHP treatments (25 ℃, 9 min) at different pressure levels (100, 200 and 300 MPa) before programmed heating (1 ℃/min) to form gels. Unpressurized myosin containing 0.30% STPP was set as the control. The WHC was measured to filter the parameters that had significant effects on gel properties. The protein solubility and ATPase activity and changes in the secondary structure content, surface hydrophobicity, reactive sulfhydryl group content, and rheological properties as well as the gel microstructure during heating were measured. The results indicated that the solubility of myosin containing 0.15% STPP decreased, while its ATPase activity increased significantly (P < 0.05) after pressure treatments below 200 MPa, which indicates that 0.15% STPP could counteract pressure-induced changes in functional properties of myosin. The denaturation and agglomeration process were hindered as well. The counteractive effect was diminished with the increase in STPP content up to 0.30%. The protein underwent sufficient unfolding as well as rapid exposure of buried residues during gelling, which resulted in an elastic, compact and ordered gel network structure and a significant increase in WHC (P < 0.05). The ATPase of myosin was inactivated under 300 MPa, and its solubility decreased as well. The extent of protein denaturation was reduced and intermolecular cross-linking was weakened. As a result, the WHC decreased significantly (P < 0.05). STPP appears to affect the structure and physiochemical properties of myosin, leading to alteration in its denaturation rate and cross-linking pattern during heating and consequently change in WHC eventually.
Effect of Ultrasonic-Assisted Dough Resting on the Quality of Noodles
LUO Denglin, YANG Yuanyuan, WU Ruoyan, XU Baocheng, NIE Ying, LI Peiyan, LIU Jianxue
2019, 40(1):  102-107.  doi:10.7506/spkx1002-6630-20171019-193
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Dough resting has an important effect on the quality of noodles. In this paper, power ultrasonic treatment was introduced to dough resting to improve the quality of noodles. The quality of noodles was analyzed using texture analyzer by comprehensive weighted score method with respect to four variables: ultrasonic power density, sonication time, dough thickness and resting temperature. The results showed that ultrasonic treatment at a power density of 25.55 W/L significantly increased the springiness by 15.9% and reduced the hardness by 7.8%, in addition to improving the cooking properties of noodles in comparison to the untreated control. The highest overall weighted score was obtained under the following conditions: ultrasonic power density 25.55 W/L, sonication time 30 min, dough thickness 6 mm and resting temperature 30 ℃. The surface of starch granules became more porous and apparent peeling was observed under scanning electron microscopy when ultrasonic power density was higher than 25.55 W/L. Overall, ultrasonic-assisted dough resting was a feasible approach to improve the textural properties and cooking characteristics of noodles
Combined Effect of Enzymatic Pretreatment and Extrusion on Quality Properties of Brown Rice Flour
ZHAO Zhihao, LIU Lei, ZHANG Mingwei, ZHANG Ruifen, XIAO Juan, WEI Zhencheng, MA Yongxuan
2019, 40(1):  108-116.  doi:10.7506/spkx1002-6630-20171210-121
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To investigate the combined effect of enzymatic pretreatment and extrusion on the quality characteristics of brown rice flour, extruded brown rice flours with and without enzymatic pretreatment (control) from ordinary, red and black brown rice were examined for water solubility index, water absorption index, agglomeration rate, dispersion time, paste viscosity, color, gelatinization degree, sensory evaluation score, starch, reducing sugar and protein contents, and in vitro starch and protein digestibility. The results showed that compared with direct extrusion, enzymatic pretreatment combined with extrusion increased the water solubility index of ordinary, red and black brown rice flours by 3.04, 2.35 and 2.71 times, decreased the water absorption index by 67.87%, 60.96% and 62.17%, elevated the agglomeration rate by 6.44, 7.27 and 4.07 times, and reduced the dispersion time by 66.61%, 61.79% and 64.30%, respectively. Moreover the combined treatment decreased the viscosity of brown rice paste and weakened the shear-thinning behavior and the viscosity curves were more flat with it. The combined treatment reduced the starch content of ordinary, red and black brown rice flours by 29.22%, 28.71% and 26.70%, and the gelatinization degree by 19.53%, 8.94% and 13.13%; and increased the soluble protein content by 2.50, 3.87 and 3.27 times, respectively. All of these changes were statistically significant (P < 0.05). The color difference (ΔE) values of extruded ordinary, red and black brown rice flours with enzymatic pretreatment were 3.01, 4.66 and 3.28, respectively The combined treatment augmented slightly lightness value, reduced the percentage of rapidly digestible starch, increased the percentage of slowly digestible and resistant starch, enhanced the in vitro digestion rate and digestibility of protein, and resulted in significantly higher sensory evaluation scores (P < 0.05). The above data demonstrated that combined enzymatic pretreatment and extrusion improved the dispersibility of brown rice flour, reduced the paste viscosity, and increased sensory evaluation scores and protein digestibility in vitro. In conclusion, enzymatic pretreatment combined with extrusion can be viewed as a new approach for the processing and utilization of brown rice and has potential for application in cereal processing.
Structure Characterization and in Vitro Digestibility of Microencapsulated Decapterus maruadsi Fish Oil
YANG Xiaobin, ZHOU Aimei, WANG Shuang, HUANG Weichao, WANG Jin
2019, 40(1):  117-122.  doi:10.7506/spkx1002-6630-20171205-066
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Decapterus maruadsi fish oil is rich in unsaturated fatty acids, but it is easily oxidized, causing loss of nutritional value. Microcapsulation has emerged as one of the best strategies to prevent fish oil oxidation. In the present study, scanning electron microscopy, laser scanning confocal microscopy (LSCM), Fourier transform infrared spectroscopy (FTIR) with second derivative fitting, and pH-stat method were used to investigate the morphological structure, the interaction during the formation process and the simulated digestion characteristics in vitro of microencapsulated Decapterus maruadsi fish oil prepared by spray drying using gum arabic, gelatin and trehalose as wall materials. The results showed that the fish oil microcapsules were spherical granules with smooth and compact surfaces. Under LSCM, the fish oil microcapsules presented a mononuclear cavity structure with gelatin evenly distributed on the wall and the fish oil wrapped inside the wall. The FTIR of microcapsules revealed the characteristic absorption peaks of the wall and core materials, which confirmed the formation of an embedded structure. The α-helix content of the secondary structure of gelatin decreased after spray drying, demonstrating the occurrence of protein-protein hydrogen bonding, which enhanced the structure stability of the microcapsule structure. In vitro simulated digestion experiments showed that during the digestive process free fatty acids were released fast initially and then slowly; the accumulative release amount was 72.62% at 120 min. LSCM revealed that during digestion, the core material was migrated to the wall surface and released gradually. The above results provide theoretical data for the development, application and evaluation of microcapsule products.
Effect of Ultrasonic Pretreatment on Acid-Induced Gel Properties of Soybean Protein Isolate Glycoconjugates
ZHAO Chengbin, XU Xiuying, LIU Jingsheng, ZHANG Hao, WU Yuzhu, CAO Yong, WU Fei
2019, 40(1):  123-129.  doi:10.7506/spkx1002-6630-20171210-119
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The glycosylation reaction of soybean protein isolate (SPI) with glucose and maltose in a phosphate buffered saline was allowed to take place after ultrasonic pretreatment. The aim was to investigate the effect of ultrasonic pretreatment on acid-induced gel properties of SPI/sugar conjugates. Fourier transform infrared spectroscopy (FTIR) analysis indicated the formation of covalent conjugates between sugars and SPI. The largest degree of grafting for SPI/sugar conjugates was found upon ultrasonic pretreatment of the reaction system for 20 min. The surface hydrophobicity (H0) and average particle size (D43) of SPI were reduced by glycosylation with glucose and maltose. SPI/sugar conjugates with ultrasonic pretreatment had higher H0 and lower D43. The glycosylation reaction could weaken the network structure of acid-induced SPI gel due to the reduction of hydrophobic interaction, leading to a decrease of gel strength and water-holding capacity. However, ultrasonic pretreatment could reduce or abrogate the weakening effect of glycation on acid-induced SPI gel, and even improve gel properties.
Improved Separation Efficiency of Polyunsaturated Fatty Acids from Simulated Flaxseed Oil by Ultra-high Pressure-Assisted Urea Adduction Method
ZHU Kaili, CHEN Jingchao, FAN Qingping, HUI Ailing
2019, 40(1):  130-136.  doi:10.7506/spkx1002-6630-20171225-315
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An ultra-high pressure-assisted urea adduction method was adopted to enrich thepoly unsaturated fatty acids (PUFA) linoleic acid and linolenic acid from linseed oil, and the content and yield of PUFA in the filtrate were investigated with respect to operating parameters. The content of PUFA in linseed oil was 96.05% when treated under the following conditions: mass ratio of urea to fatty acid mixed 3:2, ratio of urea-fatty acid mixed to 95% (V/V) ethanol 5:14, and cooling of urea inclusion mixture at 20 ℃ for 30 min followed by exposure to 300 MPa for 20 min, which was similar to that (97.41%) achieved by the traditional freezing method (?18 ℃, 18 h). Moreover, the yield of PUFA in the filtrate was increased by 41.39% when compared with that obtained by the traditional method. Subsequently, we investigated the thermodynamic properties and crystal morphology of urea inclusion complexes (UIC) under different stress conditions using a differential scanning calorimeter (DSC) and a scanning electron microscope (SEM). The results exhibited that UIC were more prone to form a hexagonal crystal structure with regular morphology and that the crystals formed were distributed more densely with increasing pressure up to 300 MPa. Accordingly, ultra-high pressure-assisted urea adduction could improve the separation efficiency of PUFA, because the crystal structure of UIC was more regular and stable under pressurized conditions.
Nutrition & Hygiene
Effect of Ganoderma atrum Polysaccharide on Intestinal Mucosal Morphology and Immunity in Immunosuppressed Mice
ZHAO Mingming, YU Qiang, WANG Hui, XIANG Quandan, NIE Shaoping, XIE Mingyong
2019, 40(1):  137-142.  doi:10.7506/spkx1002-6630-20170704-051
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Objective: To study the effect of Ganoderma atrum polysaccharide (GAP) on intestinal mucosal morphology and immunity in immunosuppressed mice. Methods: A mouse model of immunosuppression was established by intraperitoneal injection of cyclophosphamide for 3 consecutive days. The mice were randomly divided into 6 groups: normal control, model, low-, medium- and high-dose (25, 50 and 100 mg/(kg·d)) GAP, and positive groups. Body mass was recorded and the status of the mice was observed every day. The mice were sacrificed after administration for 7 days. The mucosal morphology of the jejunum was observed by optical microscopy after hematoxylin-eosin (HE) staining. The enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). Reverse transcription-quantitative polymerase chain reaction (RTqPCR) was used to analyze the relative mRNA expression of T-bet and GATA-3. Results: Compared with the model group, administration of GAP at all three doses increased body mass, improved intestinal mucosal morphology, augmented the levels of IL-6, IL-10, TNF-α and IFN-γ, elevated the relative mRNA expression levels of T-bet and GATA-3, and shifted the Th1/Th2 balance to Th1. Conclusion: GAP can improve intestinal mucosal morphology and regulate intestinal mucosal immunity in immunosuppressed mice.
Isolation, Purification and in Vitro Antioxidant and in Vivo Antifatigue Activity of a Peptide Derived from Pine Nut Kernels (Pinus koraiensis Sieb. et Zucc.)
ZHENG Yuanyuan, JING Jing, WANG Zhenyu, PENG Fangshuai
2019, 40(1):  143-148.  doi:10.7506/spkx1002-6630-20171213-158
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An antioxidant peptide named PDII was purified by sequential ultrafiltration and SP Sephadex C-25 and Sephadex G-25 chromatography from the protein hydrolysate prepared by sequential enzymatic hydrolysis of pine nut kernels (Pinus koraiensis Sieb. et Zucc.) with pepsin and trypsin. The molecular mass distribution of PDII was determined and its in vitro antioxidant and in vivo antifatigue effect were evaluated. The results showed that the molecular mass of PDII was distributed in the range of 500–1 100 Da, and that it had a strong antioxidant effect. PDII at all investigated doses could maintain normal blood glucose level, increase glycogen storage capacity and decrease serum urea nitrogen and malondialdehyde and blood lactate acid; there results were statistically significant compared with the blank group (P < 0.01), indicating that PDII had both antioxidant activity in vitro and anti-fatigue effect in vivo.
Effect of Konjac Oligosaccharide on Lipid Metabolism in Mice Fed High-Fat Diet
ZHOU Zhongkai, ZHAO Yali, YANG Xingyue
2019, 40(1):  149-154.  doi:10.7506/spkx1002-6630-20170627-388
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In this study, 3% konjac oligosaccharide was added to a high-fat diet to investigate the effect of konjac oligosaccharide on body mass, liver index, lipids and high-fat diet induced oxidative stress in mice. Reverse transcription-polymerase chain reaction (RT-PCR) was adopted to measure gene expression levels to explore the underlying mechanism. Male Kunming mice were randomly divided into normal diet, high-fat diet and oligosaccharide intervention groups. The results showed that the dietary addition of konjac oligosaccharide significantly reduced body mass and liver mass, improved blood lipid profile, and inhibited the generation of malondialdehyde in mice, which may be related to its ability to improve antioxidant capacity in the body. In addition, konjac oligosaccharide could significantly up-regulate the mRNA expression of carnitine palmityl transferase (CPT), thereby accelerating lipid decomposition and metabolism. It could also significantly up-regulate the mRNA expression of low density lipoprotein receptor (LDL-R) and reduce plasma low density lipoprotein cholesterol level. In summary, these results demonstrated that konjac oligosaccharide can effectively reduce the health risks caused by obesity.
Antioxidant and Anti-fatigue Activity of Marine Trash Fish-Derived Oligopeptide
DING Shuhui, QI Manting, QI Bin, ZHANG Jing
2019, 40(1):  155-161.  doi:10.7506/spkx1002-6630-20170922-328
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Objective: To investigate the in vitro antioxidant activity and anti-fatigue activity of oligopeptide derived from defatted fish meal from marine trash fish (mainly anchovy). Methods: The in vitro antioxidant activity was evaluated using four chemical model systems and DNA oxidative damage model system and the anti-fatigue activity was assessed by measuring physiological and biochemical indexes of mice. Results: The oligopeptide scavenged 1,1-diphenyl-2- picrylhydrazyl (IC50 = (4.76 ± 0.57) mg/mL), hydroxyl (IC50 = (5.09 ± 0.27) mg/mL) and superoxide anion radicals (IC50 = (5.91 ± 0.23) mg/mL) and had reducing power (IC50 = (1.31 ± 0.12) mg/mL). Compared with the control group, the oligopeptide at all dosages could significantly increase exhaustive swimming time, decrease the levels of lactic acid and blood urea nitrogen, and increase liver glycogen content and the activities of endogenous cellular antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in mice after exhaustive swimming exercise. Conclusion: The oligopeptide derived from marine trash fish has antioxidant capacity and can increase endurance capacity and facilitate recovery from physical exhaustion.
Water Soluble Flavonoids from Coreopsis tinctoria Flowers Improve Learning and Memory Ability in D-Galactose-Induced Aging Mice
TIAN Yong, ZHOU Du, ZOU Shuangyi, SUN Xingyu, ZHI Qi, LI Fuxiang, MING Jian
2019, 40(1):  162-168.  doi:10.7506/spkx1002-6630-20180724-291
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Our aim in this study was to investigate the effects and mechanisms of water soluble flavonoids from Coreopsis tinctoria flowers (CTWF) on learning and memory ability in D-galactose-induced aging mice. Specific pathogen-free (SPF) Kunming mice were randomly divided into control, aging model, VE (50 mg/(kg·d)), and CTWF low- and high-dose groups (150 and 600 mg/(kg·d)). The mice in the control group were injected subcutaneously with normal saline while the mice in the other groups were successively injected with D-galactose (300 g/(kg·d)) for 42 days. At 1 hour after injection, the drug treatment groups were intragastrically administrated with VE and different dosage of CTWF while the mice from the control and model groups were administrated with an equal volume of normal saline. Learning and memory abilities were detected by Morris water maze test, and acetylcholinesterase (AchE), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities, and acetylcholine (Ach) and malondialdehyde (MDA) contents in brain tissues were measured. Results showed that CTWF significantly improved the learning and memory abilities of aging mice (P < 0.05), elevated SOD and GSH-Px activities and Ach content (P < 0.05), and reduced AchE activity and MDA content (P < 0.05). In conclusion, CTWF has a significant effect on improving D-galactose-induced learning and memory disorders in mice, and its mechanism may be related to enhanced cholinergic system function and reduced free radical-induced damage in brain tissues of mice.
Toxicity of Chitosan on Loach and Mechanism behind Its Acute Lethal Effect on Loach
WANG Zehao, GU Shuang, WANG Xiangyang, PAN Yan, WANG Huangming, CHEN Yanlong
2019, 40(1):  169-176.  doi:10.7506/spkx1002-6630-20170703-029
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It is well known that chitosan has no toxicity to animals. Surprisingly, however, chitosan has an acute lethal effect on loach (Misgurnus anguillicaudatus). The underlying mechanism deserves to be explored. In this study, we evaluated the effect of different types and concentrations of chitosan on the death of loach, and this study also observed symptoms during the dying process and measured half lethal concentration (LC50), respiration rate, cell membrane permeability and erythrocyte cell nucleus abnormality. Results showed that all types of chitosan caused loach to rapidly die. Higher chitosan concentration or higher temperature accelerated the dying process. The LC50 of chitosan for loach was determined as 16 mg/L. In the presence of chitosan, large quantities of mucilage fell off the surface of loach skin, thus making the water appear turbid. Moreover, chitosan destroyed the structure of loach skin, affected gill respiration, stimulated loach to rapidly swim at the early stage of the experiment, and significantly increase respiration rate, resulting in a dissolved oxygen concentration below the safe limit. After using up all the glycogen, loach could not come up to the water surface and have to respire through intestine at the later stage of the experiment. Chitosan also led to exudation of large amounts of chlorine, sodium, potassium ion and ammonium from loach and destroyed cell functions. In conclusion, chitosan exerts its lethal effect on loach mainly by destroying therespiratory system. Since chitosan normally does not enter the human respiratory system, it can be used safely as a food additive.
Nutritional Composition, Gamma-Aminobutyric Acid Content and Anti-fatigue Activity of Germinated Brown Rice Bran
WANG Jiayi, PAN Shuxuan, XIA Chen, DENG Haiyun, Lü Xiaohua, CHEN Jian
2019, 40(1):  177-182.  doi:10.7506/spkx1002-6630-20170711-165
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Objective: To determine the contents of nutrients and heavy metals in germinated brown rice bran (GBRB) and establish a high performance liquid chromatography (HPLC) method to detect gamma-aminobutyric acid (GABA) in GBRB, as well as to evaluate the anti-fatigue activity of GBRB. Methods: The content of GABA was determined by HPLC with pre-column o-phthalaldehyde derivatization. Fifty male SD rats were randomly divided into five groups: control, high-fat diet and low-dose (10%), medium-dose (20%), high-dose (30%) GBRB groups. After feeding for 83 days, the rats were forced to swim until exhausted, and the weight-loaded swimming time was recorded. Results: The crude fiber and ash contents in GBRB were nearly 29% of those in ungerminated brown rice bran, although both had similar contents of crude protein, total amino acids and individual amino acids (except for cystine). In addition, the contents of all investigated inorganic elements were lower in GBRB, and the contents of all heavy metals were below the safe limits set in the national standard (GB 2762?2012). Our HPLC method presented good linearity over the concentration range of 68.7–275.0 μg/mL with correlation coefficient (R2) of 0.999 9. The GABA content in GBRB was determined to be 53 mg/100 g. The average recovery of this method was 99.61%. Compared with the control group, high-dose GBRB significantly prolonged the exhaustive swimming time (P < 0.05). Conclusion: The contents of nutrients in brown rice bran change and the GABA content increases after germination. High-dose consumption of GBRB helps prolong the exhaustive swimming time of rats, indicating the anti-fatigue activity of GBRB.
Antioxidant and Antiobesity Effects of Melanoidins from Yunnan Grown Arabica
WANG Yao, WANG Xiaona, ZHANG Xuehui, YIN Jianzhong, PAN Hongmei, WU Zhishuang, FENG Yuemei, WU Shaoxiong, WANG Songmei
2019, 40(1):  183-189.  doi:10.7506/spkx1002-6630-20170917-242
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Objective: To study the antioxidant and antiobesity effects of melanoidin from Yunnan grown arabica. Methods: Total melanoidins from medium roasted arabica were extracted by hot water extraction method, and then were fractionated into three fractions: > 100 kDa (M1), 10-100 kDa (M2) and < 10 kDa (M3) by ultrafiltration. The antioxidant capacity of four samples was determined by hydroxyl radical scavenging, 1,1-diphenyl-2-picrylhydrazyl radical scavenging and total reducing power assays. The effects of the total melanoidins at different concentrations on body mass, body fat content, blood lipid levels, body fat ratio, adipose tissue morphology and liver tissue morphology in a rat model of high-fat dietinduced obesity were determined. Results: All melanoidin samples had antioxidant activity varying with molecular mass at identical concentrations. The total melanoidins at all doses reduced body mass and body fat content in the obese rats. Histological examination showed that the liver tissue structure in the melanoidin treated rats at medium and high doses remained intact, accompanied by homogeneous hepatocytes and cytoplasm as well as clear nuclei. In addition to being intact and orderly arranged, the hepatocytes of the high-dose treated rats were smaller than those of the model group. Conclusion: The total melanoidins and three fractions from Yunnan grown arabica all had strong antioxidant capacity. The total melanoidins had an antiobesity effect by inhibiting body mass gain and reducing fat accumulation in the liver and consequently protecting the liver.
Hepatoprotective Effect of Oligomeric Procyanidins from Rhodiola rosea L. in Atherosclerotic Rats
HAN Xue, ZHOU Qian, NIU Jiahui, WU Mengying, WANG Yaxu, YUAN Jing, ZHAO Wen
2019, 40(1):  190-195.  doi:10.7506/spkx1002-6630-20170719-376
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Objective: To study the hepatoprotective effect and underlying mechanism of oligomeric procyanidins from Rhodiola rosea L. (OPCRR) in rats with atherosclerosis (AS). Methods: A rat model of AS was established by orally administering vitamin D3 and a high-fat emulsion simultaneously. The animals were divided into negative control, AS model, positive control (curcumin at 50 mg/kg mb), and low-, medium- and high-dose OPCRR (60, 120 and 240 mg/kg mb) groups. After administration for 8 consecutive weeks, we determined the changes in liver histology, lipids, oxidative stress and inflammatory cytokines in order to evaluate the effectiveness of OPCRR in alleviating AS. Results: Compared with the AS model group, OPCRR significantly reduced the serum levels of total cholesterol (TC), triglyceride (TG), and low density lipoprotein cholesterol (LDL-c), and significantly increased serum high density lipoprotein cholesterol (HDL-c) level (P < 0.05). Meanwhile, OPCRR significantly reduced AS index, and it improved the morphology of liver cells, protected the structure of hepatic lobules, significantly reduced the number of inflammatory foci and cell degeneration in the liver, and attenuated liver cell damage. Hepatic TC, TG, LDL-c and very low density lipoprotein cholesterol levels dropped significantly, and HDL-c significantly increased in the OPCRR-treated rats compared with the model control group (P < 0.05); malondialdehyde level in the liver significantly reduced, and the activities of superoxide dismutase and glutathione peroxidase increased significantly (P < 0.05). At the same time, the levels of hepatic inflammatory cytokines (interleukin (IL)-1b, IL-6, IL-10, tumor necrosis factor-α, monocyte chemoattractant protein-1 and intercellular cell adhesion molecule-1) significantly decreased (P < 0.05). Conclusion: OPCRR can protect the liver of AS rats by regulating lipid metabolism, oxidative stress and inflammation in the liver, and its effect is better than that of curcumin.
Association between Dietary Habits and Salivary Microbial Diversity in College Students
ZHANG Guoqing, HUANG Ziqi, WANG Mingyue, KONG Junhao, LI Yudong, CHEN Jianshe
2019, 40(1):  196-201.  doi:10.7506/spkx1002-6630-20170926-390
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Objective: To study the salivary bacterial diversity of college students with different dietary habits through high throughput sequencing analysis of 16S rRNA gene. Methods: A total of 36 subjects were selected for a questionnaire survey including 19 students with a preference for meat having a meat-dominated diet (group A), and 17 students with a preference for vegetables having a vegetable-dominated diet (group B). Saliva samples were collected to extract DNA, followed by polymerase chain reaction (PCR) amplification and high-throughput sequencing of bacterial 16S rRNA V3–V4 region using the Illumina platform. The bacterial community structure and diversity were analyzed using the QIIME software. Results: A total of 990 286 high-quality reads were obtained and clustered into 212 operational taxonomic units (OTUs) for further analysis. A total of 16 bacterial phyla and 143 genera were detected. The diversity analysis of salivary microbiota showed that at the phylum level, SR1, Fusobacteria, Candidatus and Saccharibacteria were significantly decreased in group A as compared to group B; at the genus level, the relative abundance of the dominant genera Peptostreptococcus, Parvimonas, Eubacterium, Saccharibacteria_genera_incertae_sedis, SR1_genera_incertae_sedis, Catonella, Mogibacterium, and Solobacterium in group A were significantly lower than in group B, while the opposite was observed for the genus Corynebacterium (P<0.05). Conclusion: Human saliva has a complex microbial community structure. Dietary habits in college students (meat eaters and vegetarians) may have a significant influence on the structure of the oral microbial community.
Risk Assessment of Pesticide Residues via Dietary Intake of Tomatoes from Qiandongnan, Guizhou
HE Jie, LIU Wenfeng, HU Chengcheng, WANG Wei, YANG Mei, WANG Jian
2019, 40(1):  202-208.  doi:10.7506/spkx1002-6630-20171222-278
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The aim of this study was to ascertain the health risk of pesticide residues through the consumption of tomatoes from Qiandongnan, Guizhou and the level of consumer protection of the existing maximum residue limits (MRLs). The risk assessment of pesticide residues in children and the general population was carried out based on the national estimated daily intake and national estimated short-term intake, and the level of consumer protection was assessed based on the theoretical maximum daily intake and theoretical maximum short-term intake. Besides, the matrix ranking was employed to rank the risk of pesticides in tomatoes. The results showed that a total of 26 pesticides in all tomatoes were detected with a detection rate of 2%–20%; of these, 4 exceeded their MRLs, which was found in 2%–4% of the samples. The chronic dietary intake risks of all pesticides except for fipronil (459% and 214%) expressed as percentage relative to the acceptable daily intake were 0.008 40%–23.7% and 0.003 92%–11.0% for children and the general population, respectively, and the acute dietary intake risks expressed as percentage to the acute reference dose were 0.015 6%–56.0% and 0.006 85%–24.6%, respectively, for children and adults. The levels of consumer protection against chronic and acute dietary intake risks were 0.304–60.9 and 0.462–153 for children, and 0.652–130 and 1.05–349 for the general population, respectively. Fipronil was a highly hazardous pesticide that may cause unacceptable chronic dietary intake risk for all consumers. In addition, both chronic and acute risk levels were within an acceptable limit. The level of consumer protection of the MRLs was unacceptable against chronic dietary intake risk of profenofos and chlorothaloni for all consumers and against acute dietary intake risk of iprodione for children. Therefore, more attention should be paid to the pesticides with high risk profenofos, chlorothalonil, iprodione and fipronil in tomatoes from Qiandongnan, Guizhou.
Packaging & Storage
Effect of β-Aminobutyric Acid Treatment on Redox Status and Induction of Disease Resistance in Postharvest Peach Fruits
CHEN Si, WANG Li, XIA Mingxing, WU Dongzhi, LIAO Yunxia, WANG Kaituo, ZHENG Yonghua
2019, 40(1):  209-215.  doi:10.7506/spkx1002-6630-20171018-174
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The present study was conducted to investigate the pattern of disease resistance induced by 10 mmol/L β-aminobutyric acid (BABA) treatment in postharvest peach (Prunus persica Batsch cv ‘Baifeng’) fruits and to analyze the underlying mechanism with respect to the change in redox status. The results showed that the peach fruits treated with 10 mmol/L BABA alone demonstrated remarkably higher concentrations of the endogenous reductive signaling molecule nitric oxide (NO) and higher expression levels of PpNPR1-like, PpCHI and PpGNS genes after 2 days of storage at 20 ℃ when compared with the control, accompanied by an increase in disease incidence. Meanwhile, the fruits simultaneously treated with BABA and inoculated with the pathogen Rhizopus stolonifer exhibited significantly higher expression levels of PpNPR1-like, PpCHI and PpGNS genes during the first three days of storage than did those receiving either treatment alone (P < 0.05), and maintained high levels throughout the storage period. Moreover, either BABA treatment alone or the combined treatment stimulated the accumulation of NO and simultaneously elevated the activities of glucose 6-phosphatedehydrogenase and 6-phosphogluconate dehydrogenase, which are recognized as key enzymes in the pentose phosphate pathway (PPP), thereby contributing to enhanced production of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH) and lower contents of NADP+ and oxidized glutathione and consequently enhanced redox status. Therefore, 10 mmol/L BABA could confer peach fruits with enhanced resistance to R. stolonifera infection by activating the priming defense, thereby reducing the incidence of soft rot disease. At the same time, BABA treatment could induce the accumulation of the reductive signaling molecule and increase the activities of the key enzymes in PPP and consequently enhance the reduction potential and activate relevant transcription factors, thereby inducing the expression of PR gene.
Effect of 1-Methyleyelopropene and Ethylene on Mitochondrial Proteome Changes in Postharvest Zizania latifolia Analyzed Using iTRAQ Labeling Technique
LUO Haibo, ZHOU Tao, KONG Xiaoxue, TAO Mingxuan, JIANG Li, WANG Libin, WANG Weihua, YU Zhifang
2019, 40(1):  216-225.  doi:10.7506/spkx1002-6630-20180531-447
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In order to explore the molecular mechanism of postharvest senescence of Zizania latifolia, the effect of 1-methyleyelopropene (1-MCP) and ethylene (ET) treatments on mitochondrial proteome changes in postharvest Z. latifolia after storage at 25 ℃ for 0 (control), 3 and 6 days were investigated by using isobaric tags for relative and absolute quantification (iTRAQ) labeling. The results showed that a total of 1 908 proteins were identified with at least two peptides, of which 315 proteins showed an 2.0-fold change in their relative quantitation in the untreated, ET-treated, 1-MCPtreated groups at day 3 and 6 of storage as compared to their counterparts at day 0, with statistically significant differences being observed between results from replicate experiments (P < 0.05). A bioinformatics analysis of these differentially expressed proteins revealed that metabolic pathways, the biosynthesis of secondary metabolites, the biosynthesis and metabolism of amino acids, nucleotide metabolism, and the metabolic pathways of nucleobase-containing small molecules were related to postharvest senescence of Z. latifolia and that the citrate cycle, oxidative phosphorylation (OXPHOS), the pentose phosphate pathway (PPP), C5-branched dibasic acid metabolism and amino acid metabolism may play critical roles in postharvest senescence of Z. latifolia. Based on their biological functions, postharvest senescence of Z. latifolia may be closely associated with accelerated carbohydrate hydrolysis as well as strengthened PPP and weakened glycolysis and OXPHOS, leading to reduced energy supply and aggravated oxidative damage and consequently activating Ca2+/MAPKs, cytochrome c and jasmonate signaling pathways to cause primary metabolic disturbance and an increase in the accumulation of secondary metabolites such as lignin and consequently induce cell apoptosis or necrosis and finally accelerate senescence.
Effect of Exogenous Spermidine Treatment on Lignification and Related Enzyme Activities in Shiitake Mushrooms (Lentinula edodes)
DING Shudong, LI Yanjie, GUO Yuxi
2019, 40(1):  226-232.  doi:10.7506/spkx1002-6630-20180615-313
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In this experiment, shiitake mushrooms was subjected to negative pressure osmosis treatment with different concentrations of spermidine (10, 15 and 20 mg/L), and then were stored at 4 ℃ for 16 days. The changes in hardness, the contents of lignin, chitin, cellulose and total phenolics, and the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) were examined during the storage period. Our results showed that none of the treatments could inhibit the decrease in hardness, although they all resulted in an increase in cellulose content. In addition, 15 mg/L spermidine treatment showed no significant decrease in chitin content during the late stage of storage, and total phenol content in all groups increased first and then decreased during the entire storage period. Both 15 and 20 mg/L spermidine treatments could maintain a low PAL activity from day 4 to 6 of storage. Furthermore, 20 mg/L spermidine inhibited POD activity between the fourth and sixth day and delayed the peak of lignification.
Change of Cuticle Components in Mature Satsuma Mandarin Fruits (Citrus unshiu) during Cold Storage and Their Effects on the Growth of Penicillium digitatum
ZHANG Jing, WANG Rongrong, SHAN Yang, PAN Lang, FU Fuhua, DING Shenghua
2019, 40(1):  233-239.  doi:10.7506/spkx1002-6630-20170928-411
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The cuticle plays multiple important roles in the postharvest physiology of fruits. In this study, we examined the change of cuticle components during the postharvest cold storage of Satsuma mandarin (Citrus unshiu) and we also investigated their effects on the spore germination and mycelial growth of Penicillium digitatum. The results showed that the amounts of cutin and wax, the main components of cuticle, increased firstly and then decreased during cold storage and the amount of cutin changed more significantly. Free fatty acids were the most abundant wax components in the epicuticular wax. The amount of free fatty acids increased from 0.73 to 3.09 μg/cm2 over the first ten days of storage and then it decreased to 0.64 μg/cm2 on the 40th day. The most abundant wax components in the intracuticular wax were terpenoids and their content was fluctuated during the storage process. Cutin was mainly composed of cinnamic acid and hexadecanedioic acid. The content of cinnamic acid decreased gradually and reached the lowest level of 13.90 μg/cm2 on the 40th day, while the content of hexadecanedioic acid increased to 17.90 μg/cm2 on the 10th day and then decreased to 6.60 μg/cm2 on the 40th day. Results of in vitro tests showed that the spore germination could be inhibited by cutin and mycelial growth of Penicillium digitatum could be inhibited by intracuticular wax (P < 0.05). These findings reveal the biochemical basis of the change in the cuticle during storage and the effects of its components on the growth of Penicillium digitatum, which will provide an important basis for improving the storability of Satsuma mandarin.
Effects of Exogenous Calcium and Calmodulin Antagonist Treatments on Chilling Tolerance of Cold-Stored Peach Fruit
LING Chen, XIE Bing, HONG Yujie, WANG Li, JIN Peng, ZHENG Yonghua
2019, 40(1):  240-248.  doi:10.7506/spkx1002-6630-20180521-296
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The effects of calcium (CaCl2) and calmodulin antagonist trifluoperazin (TFP) dipping treatments on chilling tolerance of postharvest peach fruit (Prunus persica Batsch ‘Baifeng’) during cold storage were investigated with distilled water as control. The results showed that CaCl2 treatment could significantly reduce internal browning of peach fruit during cold storage, mitigate chilling injury, decrease relative electric conductivity and malonaldehyde (MDA) content, reduce hydrogen peroxide (H2O2) content and superoxide anion radical (O2 -·) production rate, and the activity of proline dehydrogenase (PDH). In addition, CaCl2 treatment improved the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), Δ1-pyrroline-5-carboxylate synthetase (P5CS), ornithine δ-aminotransferase peroxidase (OAT) and glutathione reductase (GR). High levels of proline, vitamin C and glutathione (GSH) were also observed in peach fruit treated with CaCl2. However, the opposite effect was observed with TFP treatment. These findings suggested that the Ca2+-CaM complex was involved in the regulation of cold tolerance in postharvest peach fruit and that CaCl2 treatment could maintain reactive oxygen metabolism balance, alleviate lipid peroxidation and membrane damage, and increase the accumulation of the osmoregulator proline, thereby reducing chilling injury, maintaining fruit quality and extending the storage life of peach fruits during cold storage.
Correlation Analysis between Electrical Impedance and Quality of Mutton during Controlled Freezing-Point Storage
WANG Zhenggang, ZHAO Lihua, SU Lin, JIN Ye
2019, 40(1):  249-255.  doi:10.7506/spkx1002-6630-20171016-150
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This study investigated the correlation between the electrical impedance and quality characteristics of mutton stored under controlled freezing-point condition ((?1.0 ± 0.6) ℃) for 8–216 h after slaughter. The quality characteristics such as color, drip loss rate, shear force value and pH were measured, as well as the electrical impedance properties, including intracellular resistance (Ri), extracellular resistance (Re), cell membrane capacitance (Cm), relaxation factor (α), and Cole- Cole plots. The results showed that as the storage time increased, Ri and Re initially increased and then decreased until reaching a stable level for both the positive and negative groups. Cm and α gradually decreased, and so did the radius of Cole-Cole plots. Overall, the electrical impedance properties of the negative group were lower than those of the positive group at the same times postmortem. The positive group maintained better water-holding capacity, color difference and tenderness but showed a decrease in pH compared with the negative one. During a certain stage of storage, Ri, Re and Cm were significantly correlated with water loss percentage, a* value, shear force and pH for both groups (P < 0.05). Therefore, the electrical impedance properties can be importance indicators to evaluate mutton quality at a certain stage of controlled freezing-point storage.
Effect of Immersion Freezing on Quality Changes of Snakehead Blocks during Frozen Storage
LIU Shulai, ZHANG Zhenyu, TANG Wenyan, ZHAO Dandan, CHEN Shanping, SUI Chuang, DING Yuting
2019, 40(1):  256-262.  doi:10.7506/spkx1002-6630-20171026-300
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The objective of this study was to investigate the effect of immersion freezing (IF) on ice crystal formation and quality changes in snakehead blocks under different freezing temperatures (?20, ?30 and ?40 ℃) in comparison with air freezing (AF). Quality indices including salt-soluble protein content, pH, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid (TBA) value and water-holding capacity (WHC) were determined in all samples. The results showed that the time needed to pass through the zone of maximum ice crystal formation was 310, 226 and 125 s for IF at ?20, ?30 and ?40 ℃, respectively, and the areas of ice crystals generated were 308.8, 142.4 and 86.5 μm2, respectively. However, AF took a significant longer time (3 412 s) to pass through the zone of maximum ice crystal formation and resulted in a significantly larger area (939.6 μm2) of ice crystals (P < 0.05). In addition, during storage at ?18 ℃, a significantly higher concentration of salt-soluble protein was noted in the IF frozen sample as compared to the AF frozen sample, accompanied by a significant decrease in ice crystal size, pH, TBA value, TVB-N value, drip loss and cooking loss. Moreover, ?40 ℃ IF treatment caused minimal quality changes in snakehead blocks. Collectively, it was suggested that IF could better maintain snakehead quality during frozen storage than AF, and lower freezing temperature could lead to higher freezing rate and formation of smaller ice crystals, thus being more favorable for quality maintenance.
Physicochemical Properties of Goose Skin Collagen/Chitosan Composite Membrane and Its Potential for Food Preservation
RUAN Yifan, ZHU Jingjing, PAN Daodong, SUN Yangying, SHEN Jianliang
2019, 40(1):  263-269.  doi:10.7506/spkx1002-6630-20171028-333
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In order to develop a safe and non-toxic edible composite membrane with antioxidant properties made from natural biomaterials, edible composite membranes were prepared from mixtures of 30 g/L goose skin collagen (GSC) and 30 g/L chitosan (Ch) at volume ratios of 10:0, 8:2, 6:4, 4:6, 2:8, and 0:10, and their physicochemical properties was assessed, as well as their application for duck preservation. The results showed that the composite membrane with a 6:4 GSC to Ch ratio had the highest tensile strength (36.05 MPa) along with good water vapor permeability (WVP), light transmittance and elongation at break. Duck samples coated with this composite membrane showed the lowest thiobarbituric acid (TBA) value (0.35 mg/kg) and total volatile base nitrogen (TVB-N) content (18.04 mg/100 g) values after 12 days of storage. The total number of bacteria in duck samples coated with the composite membrane with a 4:6 GSC to Ch ratio was the lowest, only 4.75 (lg(CFU/g)), and the composite membrane with a 6:4 GSC to Ch ratio showed a higher value of 5.49 (lg(CFU/g)). In summary, the composite membrane with a GSC to Ch ratio of 6:4 has good mechanical properties and good potential in food preservation.
Cell Membrane Injury and Enzyme Activity of Pleurotus geesteranus during Simulated Storage and Transportation with Cool-Storage Agent
WANG Lei, YU Lingfeng, LI Junhao, YAN Jiawei, LUO Zisheng, LI Li
2019, 40(1):  270-277.  doi:10.7506/spkx1002-6630-20180615-304
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The edible mushroom Pleurotus geesteranus is delicious and nutritious and has high commercial value. Nonetheless, the mushroom readily loses its freshness during poastharvest storage and transportation. Simulated storage (at room temperature (24 ± 2) ℃) and transportation (at air temperature of 2–25 ℃) experiments of Pleurotus geesteranus were carried out at different mass ratios between cool-storage agent and Pleurotus geesteranus (1:1, 1:2, 1:4 and 0:1). Results showed that cool-storage agent could effectively preserve the quality of Pleurotus geesteranus, delay mass loss, maintain surface color, cell membrane permeability, and the activities of superoxide dismutase (SOD) and catalase (CAT), protect the integrity of cell membrane and inhibit the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2). On the contrary, the quality of Pleurotus geesteranus deteriorated at a ratio of cool-storage agent/Pleurotus geesteranus was 1:1 in the simulated storage experiment. For an economical perspective, the optimal ratio cool-storage agent/ Pleurotus geesteranus was 1:4. In the simulated transportation experiment, the 1:1 ratio of cool-storage agent/Pleurotus geesteranus was most effective in maintaining appearance, reducing mass loss and inhibiting MDA accumulation, the increase in cell membrane permeability and the reduction in SOD activity. Storage and transportation temperature, time and cost, and the dosage of cool-storage agent all should be synthetically considered in practical application.
Inhibitory Effect of Kojic Acid on Dominant Spoilage Bacteria in Chilled Duck Meat and Its Mechanism
HOU Wenfu, OUYANG Heyi, WU Ji, HAN Qianhui, ZHOU Min, WANG Hongxun
2019, 40(1):  278-285.  doi:10.7506/spkx1002-6630-20180613-226
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The bacteriostatic effects of kojic acid against the dominant spoilage bacteria Pseudomonas sp., Aeromonas sp. and Brochothrix thermosphacta and the pathogenic bacterium Salmonella sp. in chilled duck meat were studied by determining the diameter of inhibition zone, growth curves in LB liquid medium and minimal inhibitory concentration (MIC). The underlying mechanism was explored by analyzing the effect of kojic acid on the cell membrane and intracellular substances. The results showed that kojic acid had good bacteriostatic properties against all four strains. Brochothrix thermosphacta was sensitive to kojic acid treatment with an MIC of 0.5 mg/mL, and its growth in the liquid medium was completely low concentration of kojic acid. The diameter of zone of inhibition of Salmonella, Pseudomonas, and Aeromonas increased significantly with the increase of kojic acid concentration, with an over 2-fold increase being observed for Pseudomonas and Aeromonas. Kojic acid treatment at 2.0 mg/mL could completely inhibit the growth of all above 3 strains in the liquid medium. Kojic acid treatment could increase cell surface hydrophobicity by two to three folds, reduce the selective permeability of the cell membrane, and destroy the structure of the cell membrane, thereby leading to increased levels of extracellular Ca2+, K+ and Mg2+. Kojic acid treatment could also destroy respiratory chain dehydrogenase activity, and result in the leakage of intracellular β-galactosidase and alkaline phosphatase and cell membrane rupture to form pores. Besides, kojic acid treatment caused a significant increase in extracellular protein content, with a simultaneous decrease in intracellular proteins with molecular mass more than 66.4 kDa and less than 20 kDa. Overall, kojic acid inhibited the four strains via the same mechanism, namely, by promoting hydrophobic substance exposure, destroying related enzyme activities and changing cell membrane permeability, as well as disturbing protein metabolism.
Composite Hygroscopic Pad Containing Chitosan and Nisin for the Preservation of Ground Pork
HE Yezi, XU Dan, ZHANG Chunsen, XU Qiyang
2019, 40(1):  286-291.  doi:10.7506/spkx1002-6630-20171016-135
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Highly hygroscopic pads with antibacterial activity were prepared by freeze-drying using a combination of chitosan, sodium carboxymethyl cellulose and montmorillonite as base material with different amounts of nisin added, and they were applied for the preservation of chilled pork. Grounded fresh pork was placed on each of the pads, which was located at the bottom of a plastic tray, and stored at 4 ℃. Total viable count (TVC), total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value, pH, cooking loss, hardness and color were examined every day. The results revealed that the application of the pads significantly inhibited microbial growth in meat, slowed down the increase in TVB-N content, TBARS value, and pH value, reduced cooking loss, and maintained the hardness and color of meat. The antimicrobial and antioxidant activities of the pads were improved by the combined use of chitosan and nisin, thus leading to better preservation of meat quality. By applying the nisin pad containing 0.5 g of nisin per kilogram of meat, the shelf life of fresh meat was extended to at least 4 days, which was twice longer than that of the control.
Recent Advances in Composition, Nutrition and Preparation of Milk Fat Globule Membrane
ZHANG Xue, YANG Jie, WEI Wei, JIN Qingzhe, WANG Xingguo
2019, 40(1):  292-302.  doi:10.7506/spkx1002-6630-20170829-337
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Human milk fat is dispersed in the form of emulsified fat globules, which are encapsulated by three layers of fat globule membranes. Recent studies have demonstrated that the composition of milk fat globule membrane play a crucial role in the growth and development of infants and young children. In this article, we review the composition and content of milk fat globule membrane, especially phospholipids, the nutritional role of added fat globule membrane in formula milk powder for infants and young children, and the current commercially available products rich in milk fat globule membrane as well as and their preparation methods. This review can provide the scientific basis for narrowing the differences between infant formula and the nutritional requirements of infants and young children.
Recent Progress in Regulation of Dietary Nutrition for Sarcopenia
LIANG Jiling, WANG Cenyi, CHEN Ning, WANG Mei
2019, 40(1):  303-312.  doi:10.7506/spkx1002-6630-20180814-140
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Sarcopenia is the age-related loss of muscle mass and strength. It has gained extensive attention due to its increasing prevalence all over the world. Adverse health consequences of sarcopenia are rising gradually, thereby resulting in the loss of independent living, increasing health costs, and reducing the quality of life. As the population ages, the incidence of skeletal muscle diseases including sarcopenia increased. Numerous mechanisms have been suggested as potential contributors to sarcopenia onset, including aging anorexia, protein imbalance, and oxidative stress. Likewise, no pharmacological remedies are yet available to prevent the onset of age-related muscle wasting. In this scenario, the combination of nutritional and physical interventions appears to be the most effective strategy available for the management of sarcopenia. In this article, the definition and pathogenesis of sarcopenia, current knowledge on the role of dietary nutrition as a countermeasure for sarcopenia, and the mechanisms of action of relevant dietary agents for sarcopenia are summarized and discussed; novel nutritional strategies for the prevention and treatment of sarcopenia are proposed. Finally, the synergistic strategy between rational diet and exercise training is elaborated, in order to provide an optimal choice for the prevention and treatment of sarcopenia.
Progress in Modeling of Foodborne Pathogen Growth at Lag Phase
YUE Siyuan, SU Liang, REN Pengcheng, LIU Yangtai, WANG Xiang, LIU Qing, DONG Qingli
2019, 40(1):  313-318.  doi:10.7506/spkx1002-6630-20171221-258
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Predicting accurately the number and growth of foodborne pathogens based on predictive microbiology is of great significance for reducing food safety risks. The review deals with recent progress in the modeling of foodborne pathogen growth at the lag phase. We present a summary of the commonly used techniques for lag period determination and modelling approaches. After reviewing the previous studies on lag phase modeling, we point out the limitations and we suggest that the lag phase should be redefined based on the microbial growth mechanism. In the future, improved and innovative enumeration techniques and modeling methods will be developed according to the new definition of lag phase. Quantitative analysis and integration into lag phase modeling of the factors influencing the lag phase remain to be conducted.
Recent Advances in Bioactivities and Technologies for Bioavailability Improvement of Citrus Flavonoids
HUANG Rui, SHEN Shuyu, CHEN Honglin, WU Wenyan, CHEN Shiguo, YE Xingqian
2019, 40(1):  319-326.  doi:10.7506/spkx1002-6630-20170904-054
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Citrus flavonoids, with various biological activities such as antioxidant, anti-inflammatory, dyslipidemiaregulating, anticancer and neuroprotective effects, are one of the most important sources of dietary flavonoids. However, the oral bioavailability of most citrus flavonoids is a bit low. In this review, recent advances in the mechanism of the versatile bioactivities of citrus flavonoids and in the development of technologies for enhancing citrus flavonoid bioavailability such as cyclodextrin inclusion, enzymatic treatment, and the use of liposome delivery system and emulsion delivery system are systematically summarized. Furthermore, future research directions and potential applications are presented. We hope that this review will provide useful information for the development of citrus flavonoids-based nutraceuticals and auxiliary drugs.
Recent Progress in Understanding the Relationship between Protein Structure Change and in Vitro Digestibility after Different Treatments
GUO Weibo, ZHAO Yan, XU Mingsheng, YAO Yao, WU Na, DU Huaying, TU Yonggang
2019, 40(1):  327-333.  doi:10.7506/spkx1002-6630-20180612-181
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The complex structural characteristics of proteins determine their unique functional properties, and different protein structures correspond to different digestive properties. Digestibility reflects the extent to which proteins are absorbed and utilized. This article reviews recent progress in understanding the relationship between protein structure changes after different treatments such as heat treatment, ultrasonic-assisted treatment and alkali treatment and in vitro digestibility in order to provide a theoretical guidance for exploring the relationship between protein structure and nutritional value and for the choice of protein processing methods.
Bibliometric Study of Patents on Rapid Food Safety Detection Technologies
2019, 40(1):  334-340.  doi:10.7506/spkx1002-6630-20170819-240
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Rapid food safety detection technologies have currently seen rapid development and wide applications and have become a research priority. However, there is a lacuna of bibliometric studies on rapid food safety detection technologies in the literature. This article presents an analysis of patents on rapid food safety detection technologies based on the Derwent Innovations Index Database and the Derwent Innovation Patent Analysis Platform with the aim of revealing the technology trends, understanding the worldwide patent portfolio of the main original technologies and finding hot topics of frontier research. Also, this article provides insights into the domestic and international situation China faces in implementing technical innovations for rapid food safety detection and existing problems in this area. China is the world’s largest applicant for patents on rapid detection food safety technologies, but the proportion of patent grants in the country still needs to be improved. There is a trend that Chinese inventors prefer to apply for patents in their own country. According to the international patent classification number, the major technical fields in China are focused on the use of optical methods, monoclonal antibody, nucleic acid and genetic engineering for rapid food safety detection. Through the patent map, this article provides a thorough understanding of the technical layout change of rapid food safety detection worldwide and the current hot topics, which will provide useful information for food researchers.
Recent Progress in Biogenic Amines and Bioamine Oxidases in Foods
LI Binbin, XU Ye, NIU Shuhui, ZHANG Nan, LI Wei, SONG Guisen, ZHANG Ruoyao, YANG Yong
2019, 40(1):  341-347.  doi:10.7506/spkx1002-6630-20171205-054
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Biogenic amines are a group of bioactive substances with potential toxicity that are widespread in foods. Bioamine oxidases, a class of enzymes responsible for decomposing biogenic amines into aldehydes, ammonia and hydrogen peroxide, are widely found in animals and plants. These enzymes are very promising for application in eliminating biogenic amines in foods. In this article, we review the contents of biogenic amines in various foods, the classification of bioamine oxidases and related factors, their microbial producers and degradation characteristics.
Legal Issues of Online Food Trading Security
YIN Hongqiang
2019, 40(1):  348-353.  doi:10.7506/spkx1002-6630-20180721-269
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Compared with traditional physical store transactions, online food transactions involve more steps and a wider variety of participants, which integrate the virtuality of online transactions, and cross-temporal, cross-spatial, crossadministrative regional characteristics, resulting in highly complicated legal relationship of online food transactions, unsatisfactory supervision, and frequent violations of consumer rights. Online food transactions have brought new tasks and challenges to government regulation. The author believes that online food transaction security governance can not be independently completed by government regulatory agencies. In order to achieve satisfactory comprehensive management of online food transaction security, it is recommended that government supervision should dominate online food transaction security governance, force the third-party online food trading platform to establish a preface online food transaction information database and gives it some “quasi-regulatory” rights; at the same time, the government regulators should improve the construction of the network credit management mechanism, conducts credit classification supervision over online food operators, and guides industrial associations and consumers to actively participate in online food transaction security governance.