Table of Content

15 August 2019, Volume 40 Issue 15
Basic Research
Regulatory Effect of Thermal Treatment on the Microstructure of Emulsion Gels and Its Influence on Storage Stability of Different Vitamins Incorporated in Emulsion Gels
LU Yao, QIU Dan, CUI Mengnan, GAO Yanxiang, MAO Like
2019, 40(15):  1-7.  doi:10.7506/spkx1002-6630-20180818-182
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Whey protein isolate (WPI) emulsion gels were prepared through glucono-δ-lactone-induced gelation and were incorporated with both hydrophilic and hydrophobic functional ingredients (sodium isoascorbate and vitamin E). The study focused on the relationship between the microstructure of emulsion gels and the stability of vitamins incorporated in them. The denaturation level of WPI under thermal treatment (85 ℃) was controlled to modulate the microstructure of emulsion gels and the stability of the incorporated vitamins. The findings indicated that the droplet size of emulsions was increased, and the zeta-potential was reduced with the increase in heat treatment time, while the apparent viscosity was not significantly affected. Textural and rheological analyses showed that the hardness and storage modulus of emulsion gels were enhanced with the increase in heat treatment time, but the elasticity was weakened. The prolongation of heat treatment time was beneficial to improve the stability of different vitamins during storage at different temperatures, and there was a synergic effect between the mixed vitamins. It was concluded that the microstructure of emulsion gels could be adjusted by thermal treatment to control the stability of different vitamins incorporated.
Moisture Sorption Isotherms and Thermodynamic Properties of Instant Rice Noodles
WAN Jie, XIA Xue, ZHOU Guohui, LIU Chengmei, DING Yueping
2019, 40(15):  8-14.  doi:10.7506/spkx1002-6630-20180907-079
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In order to provide theoretical guidance for the processing and storage of instant rice noodles, the moisture sorption isotherms at three ambient temperatures (15, 25 and 35 ℃) were determined by gravimetric method. Seven common nonlinear regression models were used to fit the experimental data. By comparison of the determination coefficients, the mean relative deviations and the standard errors of the estimate, the best fitting model was ascertained and its parameters were determined. The thermodynamic properties, namely net isosteric heat of sorption, differential entropy and enthalpyentropy compensation, were determined from the sorption isotherm data. Results indicated that the moisture sorption isotherms belonged to type II behavior. The Peleg and GAB model were suitable for fitting the moisture sorption isotherms. The parameters X0 of the GAB fitted isotherms at 15, 25 and 35 ℃ were 9.23%, 8.34% and 7.65%, respectively. The net isosteric heat of sorption and differential entropy, calculated by using the moisture sorption isotherms decreased as moisture content increased. The enthalpy-entropy compensation theory was applied to the sorption isotherms and the isokinetic temperature for instant rice noodles was calculated by plotting the differential enthalpy versus differential entropy. It was found that the sorption process was enthalpy-controlled and spontaneous. This study provides useful guidance to select proper storage condition for instant rice noodles and further to evaluate the storage periods under different storage conditions.
Sensory Description of Stewed Pork with Brown Sauce by Consumers and Its Regional Differences Based on Internet Big Data
WANG Bo, CAO Zhenxia, LIU Dengyong, SHA Lei
2019, 40(15):  15-22.  doi:10.7506/spkx1002-6630-20180913-131
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In this study, consumer evaluation data on the key sensory attributes of stewed pork with brown sauce from 8 different provincial-level regions were collected by web crawler technology for flavor profiling. A vocabulary of sensory descriptors was established. Multivariate statistical methods such as big data analysis and correlation analysis were used to explore the consumer preferences, the correlation and regional differences of the sensory attributes from the multidimensional perspectives. The results showed that in the past two years, consumers preferred stewed pork with brown sauce which was soft and could be eaten without chewing, was agreeably fatty, and tasted fresh and slightly sweet with a good aroma. There were considerable regional differences in the main sensory attribute, which was determined as agreeably fatty mouthfeel for all 8 regions. Softness and stickiness were the scales for measuring the fatty mouthfeel and were significantly affected by sweetness, pungency and saltiness (P < 0.05). The correlation coefficient between softness and sweetness was 0.707, and those between stickiness and pungency and saltiness were 0.815 and ?0.654, respectively, suggesting that consumers preferred a product with a sweet taste and soft texture or with a pungent and properly salty taste and sticky texture.
Phenolic Contents and Antioxidant Activity of Fruit Peels and Changes in Phenolic Composition during in Vitro Simulated Digestion
XU Hongyu, KUAI Yiyun, ZHAN Zhuangzhuang, DONG Juan’e
2019, 40(15):  23-30.  doi:10.7506/spkx1002-6630-20180806-046
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The peels of 21 different fruit species were screened for their contents of total phenolics and total flavonoids and their antioxidant activity in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline- 6-sulfonic acid (ABTS) cation radical scavenging activity. The selected fruit peels with higher contents of total phenolics and stronger antioxidant activity underwent in vitro simulated gastrointestinal digestion to evaluate the effects of different digestion times on the release of total phenolics and total flavonoids. The bioavailability was investigated by simulated intestinal absorption using a dialysis bag. In addition, the changes in phenolic composition were studied by ultra performance liquid chromatography-diode array detector/electrospray ionization-time of fight-mass spectrometry (UPLC-DAD/ESI-TOF-MS). The results showed that the contents of total phenolics and total flavonoids in pomegranate peel, (58.09 ± 0.46) mg/g and (47.50 ± 0.39 mg/g), respectively, and mangosteen peel (52.09 ± 1.52) mg/g and (36.07 ± 0.46) mg/g respectively were higher than those in the other fruit species. The antioxidant activity of pomegranate peel was stronger than that of mangosteen peel. The release of both total phenolics and total flavonoids from pomegranate peel gradually increased during in vitro simulated gastric digestion, but increased initially and decreased later during in vitro simulated intestinal digestion. The release of total phenolics and total flavonoids during the gastric digestion was significantly lower than during the intestinal digestion. The bioavailability of total phenolics was always higher than that of total flavonoids at each observation time. Five phenolic compounds (α-punicalag, β-punicalag, ellagic acid hexoside, ellagic acid deoxyhexoside, and ellagic acid) were detected from pomegranate peel extract by UPLC-DAD/ESI-TOF-MS. The loss rate of these phenolic compounds was lower during the gastric digestion than during the intestinal digestion, suggesting that phenolic compounds in pomegranate peel maintain a stable structure in acidic environments.
Effect of Hydroxyl Radical Oxidation on Degradation of Myofibrillar Proteins from Coregonus peled
QIN Junwei, LEI Yongdong, QIU Hengheng, GUO Xin, ZHU Xinrong, ZHANG Jian
2019, 40(15):  31-36.  doi:10.7506/spkx1002-6630-20180910-097
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The aim of this study was to explore the effect of hydroxyl radical oxidation on the degradation of myofibrillar proteins in the dorsal muscle of Coregonus peled. Four oxidation systems of 1 mmol/L H2O2 + 0.2 mmol/L FeCl3, 5 mmol/L H2O2 + 0.4 mmol/L FeCl3, 10 mmol/L H2O2 + 0.8 mmol/L FeCl3, and 20 mmol/L H2O2 + 1.0 mmol/L FeCl3 were set up, and the oxidation was carried out at ambient temperature for 0, 15, 30, 60 or 90 min, respectively. The optimal oxidation concentration and time were determined based on protein carbonyl content. Then the oxidized fillets were stored at 4 ℃ and sampled after 0, 1, 7, and 14 days to examine the degree of degradation of myosin heavy chain (MHC), actin, desmin and troponin-T of myofibrillar proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. The results showed that the optimal oxidation conditions were determined as incubation for 60 min in 5 mmol/L H2O2 + 0.4 mmol/L FeCl3. Compared with native MHC, the degradation of oxidized MHC was enhanced. Hydroxyl radical oxidation remarkably accelerated the degradation of MHC (P < 0.05). There was no significant change in the degradation of actin between the oxidized and non-oxidized groups after the same storage time (P > 0.05), suggesting that the natural degradation of actin was dominant during storage. According to the Western blotting analysis, the degradation efficiencies of both desmin and troponin-T in the oxidized group were lower than in the non-oxidized group, implying that hydroxyl radical oxidation inhibits the degradation of desmin and troponin-T. Overall, our results demonstrate that hydroxyl radical oxidation promotes the degradation of myofibrillar proteins of thick filaments, but has little influence on that of thin filaments and inhibits the degradation of cytoskeletal and junctional proteins.
Inhibitory Mechanism of Isoliquiritigenin against α-Glucosidase
HAN Fenxia, FAN Xinjing, GENG Sheng, LOU Wenjuan, LIANG Guizhao, LIU Benguo
2019, 40(15):  37-42.  doi:10.7506/spkx1002-6630-20180830-337
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Developing food-derived α-glucosidase inhibitors is one of the most important research topics in the area of functional food because α-glucosidase is closely related to postprandial glucose levels in diabetic patients. It has been reported that an extract of liquorice has α-glucosidase-inhibitory activity, which may be partly attributed to the presence of isoliquiritigenin as one of the major bioactive components in liquorice. Given this background, the α-glucosidase-inhibitory mechanism of isoliquiritigenin was investigated by using enzyme inhibition measurement, fluorescence quenching and molecular docking in the present study. It was found that isoliquiritigenin inhibited α-glucosidase in a mixed competitive and noncompetitive mode, and its performance was superior to that of acarbose. The fluorescence quenching analysis showed that under the action of hydrophobic forces, isoliquiritigenin and α-glucosidase could combine with each other to form a complex with one binding site. The molecular docking results coincided with the experimental results. Isoliquiritigenin, located in the hydrophobic pocket of α-glucosidase, formed hydrogen bonds with Asp202 and Arg400, and interacted with the many surrounding hydrophobic residues by hydrophobic forces, thereby maintaining the structure of the complex. These obtained results are helpful to develop novel food-derived α-glucosidase inhibitors and promote the application of isoliquiritigenin in the fields of functional food and medicine.
Adsorption Characteristics of Nisin by Magnetic Iron Oxide Nanoparticles Coated with Polydopamine (IONPs@pDA)
JIANG Feihong, SONG Zihan, NIU Chen, ZHANG Yuxiang, WEI Jianping, YUE Tianli
2019, 40(15):  43-49.  doi:10.7506/spkx1002-6630-20190115-169
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This experiment aimed to systematically investigate the adsorption characteristics of iron oxide nanoparticles coated with polydopamine (IONPs@pDA) toward nisin for the purpose of providing theoretical evidence and data support for the preparation of novel antibacterial nisin-IONPs@pDA composites. The amount of nisin adsorbed by IONPs@pDA was determined as a function of temperature and time. The adsorption kinetics and isotherms were also studied. The results obtained demonstrated that the adsorption behavior obeyed the Lagergren pseudo-second-order kinetic model and the Freundlich isothermal adsorption model, indicating the occurrence of a multilayer chemisorption process. The adsorption process was endothermic and the adsorption of nisin increased with the increase of temperature. Finally, IONPs@pDA were demonstrated to be a potential magnetic material for nisin adsorption.
Changes in Antioxidant Activity of Soybean Protein Hydrolysates from Enzyme-Assisted Aqueous Extraction of Oil under Simulated Gastrointestinal Digestion
TONG Xiaohong, WANG Huan, LIU Baohua, ZHANG Qiaozhi, LI Hong, TIAN Ran, ZHAO Jinhan, QI Baokun, LI Yang, JIANG Lianzhou
2019, 40(15):  50-56.  doi:10.7506/spkx1002-6630-20180824-272
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During the enzyme-assisted aqueous extraction of oil from extruded soybean, soybean protein hydrolysates (SPHs) with strong antioxidant capacity are produced by enzymatic hydrolysis (alcalase and flavourzyme). Thus, it is necessary to study the effect of simulated gastrointestinal (GI) digestion on antioxidant properties of SPHs. In this study, the alcalase and flavourzyme hydrolysates were subjected to simulated GI digestion. The degree of hydrolysis (DH) during digestion, amino acid composition, and molecular mass distribution were determined. Antioxidant properties were evaluated by oxidative radical absorption capacity (ORAC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and 2,2’-azinobis- (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) cation radical scavenging assays. The results showed that the alcalase hydrolysate had higher antioxidant activity compared with the flavourzyme hydrolysate, while the opposite was observed when we compared their digests. The antioxidant activity of the digest of the flavourzyme hydrolysate was determined to be 69.15 μmol/mg, 27.29% and 56.21% in the ORAC, DPPH and ABTS cation radical scavenging assays, respectively, and it had a higher peptide content of 75.86%. Moreover, the peptides had higher levels of amino acids with antioxidant activity and fractions with a molecular mass of less than 1 kDa were the most dominant, accounting for 17.35% of the total peptides.
Adsorption Efficiency of Attapulgite Towards Patulin in Pear Juice
ZHANG Shan, ZHANG Rui, XUE Huali, MA Yayun, BI Yang, ZONG Yuanyuan
2019, 40(15):  57-63.  doi:10.7506/spkx1002-6630-20180910-101
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In order to effectively remove patulin from pear juice, the adsorption of attapulgite towards patulin in pear juice was studied. The adsorption isotherms were determined at different temperatures and the thermodynamics and kinetics of the adsorption process were analyzed. Besides, the changes in nutritional quality of pear juice before and after adsorption were examined. The results showed that increasing temperature in the range of 30–50 ℃ was conducive to the adsorption of patulin. The adsorption isotherms accorded with Freundlich equation (R2 > 0.99). The adsorption was a spontaneous endothermic process and the adsorbed patulin was not easily desorbed. At the same time, the adsorption kinetics conformed with the pseudo first-order kinetics model. Nutritional analysis showed that the contents of total acids, reducing sugar, soluble solids and total phenols as well as viscosity in pear juice decreased significantly (P < 0.05), while light transmittance and color values decreased at a slow rate during the adsorption process. The maximum and minimum rate of change in total acidity (46.96%) and light transmittance (2.64%), respectively were observed of the tested parameters when the adsorption was performed at 40 ℃ for 24 h at an initial patulin concentration of 3 μg/mL with the addition of 4.15 g/L of attapulgite. According to the static adsorption curves, the maximum adsorption efficiency of 70.57% was obtained after 24 h of adsorption at 40 ℃ with 4.15 g/L of attapulgite. Under these conditions, attapulalgite could reduce the content of patulin to the maximum extent.
Effect of Raw Milk Somatic Cell Count on Protein Hydrolysis and Flavor and Texture Quality of Hard Cheese
MU Shuo, LIU Xinyu, LUO Jie, REN Fazheng, LI Bo, WANG Na, ZHANG Yongxiang, GE Keshan
2019, 40(15):  64-70.  doi:10.7506/spkx1002-6630-20180821-224
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Proteolysis is an important way of flavor generation during cheese ripening. Manual milking is always applied to free-range dairy cows and small-scale dairy farms, which now still accounts for a large proportion of the total in China, and it results in retention of somatic cells (SCs) in raw milk, affecting cheese ripening and flavor. However, the effect of somatic cells on volatile flavor compounds in cheese through proteolysis has not yet been elucidated clearly. In the present study, three skim milks containing different somatic cell counts were used for cheese manufacture after being analyzed for somatic cell composition, and the changes in protease activity and proteolysis level during 90 days of ripening, as well as the volatile flavor compounds and texture of the ripened cheeses were measured. It was shown that cheese with higher somatic cell count (SCC) had higher levels of both protease activity and proteolysis of αs2-casein and that the SCC in raw milk had different influences on the volatile flavor compounds and texture of cheese. Increasing SCC in an appropriate range (10 × 104 to 30 × 104 cells/mL) was favorable for the formation of cheese flavor. The amount of 3-hydroxy-2-butanone, responsible for the characteristic flavor of cheese, in the medium SCC group was the highest (34.57%), which was 1.2 and 1.6 times higher than that of the low (28.64%) and high (20.72%) SCC groups, respectively. Excessive somatic cells (more than 86 × 104 cells/mL) in raw milk caused excessive hydrolysis and off-flavor generation during cheese ripening. More octanal, furfural, octyl ketone, and hexanal as unfavorable cheese flavor were detected in the highest SCC group.
Prediction Model for Beef Physiological Maturity Based on Improved Grid Search Combined with Support Vector Machine (IGS-SVM)
JI Fangfang, WU Mingqing, ZHAO Yang, CHEN Kunjie
2019, 40(15):  71-77.  doi:10.7506/spkx1002-6630-20180910-093
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Physiological maturity is an important indicator to determine the quality grade of beef. This paper proposes a method to predict the physiological maturity of beef by using a support vector machine (SVM) model with parameters optimized by an improved grid search (IGS) algorithm. A total of 100 beef samples at different slaughter ages of 18, 36, 54 and 72 months (25 for each age) were collected. Using machine vision, the microscopic images of the samples were collected. After image processing, the characteristic parameters of muscle fibers from beef with different physiological maturity were extracted, and the correlation between the physiological maturity of beef and the characteristic parameters of muscle fibers was analyzed by statistical methods. Using the characteristic parameters of muscle fibers as the input, a training set of 76 samples was used to establish a SVM prediction model for beef physiological maturity. An improved grid search algorithm was proposed to optimize the constraint parameter C and the kernel function parameter g of the SVM model. Furthermore, using the leave-one-out cross validation method, the optimal parameter combination (C, g) was obtained and substituted into the classifier to obtain an optimized prediction model for beef physiological maturity. The applicability and estimation performance of the prediction model were tested with independent samples from 24 test sets. The results showed that the accuracy of the prediction model was up to 91.67%. Compared with the traditional grid search algorithm, the IGS algorithm could reduce the model training time by 1 755.41 s. There was a significant correlation between beef muscle fiber characteristics and slaughter age. According to the characteristic parameters of beef muscle fiber, the physiological maturity of beef could be determined automatically using machine vision technology.
Phase Behavior, Microstructure Transformation and Free Radical Scavenging Activity of Lavender Essential Oil Microemulsion Systems
SONG Xiaoqiu, WANG Liping, SUN Yue, LI Shuaitao, ZHANG Qian, YE Lin, YANG Xiaobo, WANG Yifei
2019, 40(15):  78-83.  doi:10.7506/spkx1002-6630-20180613-203
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Recently, plant essential oil is increasingly applied as a bioactive component in the food industry. Lavender essential oil has multiple bioactivities such as sedative, hypnotic and antioxidant effects. However, poor hydrophobic properties limit its application in food products. In the present study, lavender essential oil microemulsion systems were constructed to evaluate their phase behavior and to investigate the influence of microstructure transformation on their free radical scavenging activity. According to the ternary phase diagram, dipropylene glycol acted as a co-surfactant to expand the single-phase area of microemulsions to 71.4%. Based on the results of dye diffusion and conductivity measurement, the dispersion phase was gradually inverted from a W/O stage (0%–30% water content) to a bicontinuous stage (40%–50% water content), and finally an O/W stage (60%–90% water content) along the dilution line. The viscosity peaked at the bicontinuous stage. This study found that the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity was increased with the increase of water content. In addition, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity was reduced at the W/O and bicontinuous stages, followed by an increase at the O/W stage, peaking at a 70% water content. In conclusion, the systems can effectively improve the solubility of lavender essential oil, and there is a close association of their physical characteristics and antioxidant effect with microstructure transition.
Isolation, Purification and Structural Identification of Heparinoids from Fish Swim Bladder
ZHOU Siyi, ZHONG Saiyi, SU Weiming, DU Zhenxing, CHEN Jianping, HONG Pengzhi, ZHANG Chaohua
2019, 40(15):  84-91.  doi:10.7506/spkx1002-6630-20180728-351
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In the present study, heparin-like compounds were isolated from fish swim bladder by enzymatic hydrolysis, and they were purified and fractionated into four fractions (F1–F4) by anion exchange resin adsorption followed by sodium chloride gradient elution and alcohol precipitation. Each fraction was identified by cellulose acetate electrophoresis. Furthermore, the structural characteristics of F4 were determined, and the homogeneity and molecular mass were analyzed by UV spectroscopy and high performance gel chromatography. Its monosaccharide composition was analyzed by high performance liquid chromatography (HPLC) after pre-column derivatization, functional group structure by Fourier transform infrared (FTIR) spectroscopy, disaccharide composition by enzymatic cleavage and tandem mass spectrometry (MS/MS), and primary structure by nuclear magnetic resonance. The results showed that the yield of F4, with a purity of up to (85.79 ± 0.63)% was (2.21 ± 0.03) mg/g of dried fish swim bladder. Its molecular mass was about 84 000 u. Monosaccharide analysis revealed that F4 was composed of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) with a small amount of aldoluronic acid and galactose. Its electrophoretic shift was similar to that of chondroitin sulfate and it had the characteristic absorption peaks of carboxyl, acetyl amino and sulfate groups (axial stretching). Finally, F4 was identified as chondroitin sulfate-A composed of repeated disaccharide units of [→4GlcUA β1→3GalNAc(4S)β1→].
Effect of High-Temperature Heat Treatment on Digestibility of Soybean Protein
WANG Yahui, XING Jiyun, XU Jingting, GUO Shuntang
2019, 40(15):  92-99.  doi:10.7506/spkx1002-6630-20180911-108
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To investigate the effect of protein denaturation caused by high-temperature heat treatment during the sterilization process on the nutrient digestibility of soybean protein, we simulated in vitro the infant digestion of soybean protein. Results showed that high-temperature heat treated (> 120 ℃, 20 min) soybean protein could generate more enzymatic hydrolysates with low molecular mass compared to that treated at 100 ℃. Meanwhile, the high temperature treatment could induce a significant loss in amino acids, especially cysteine (approximately 48%), destroying the ideal amino acid pattern and decreasing the nutritional value of soybean protein.
Effect of Prebiotics Addition on Gelation Process and Microstructure of Yogurt
WANG Yanan, HAN Yumei, HE Jun
2019, 40(15):  100-105.  doi:10.7506/spkx1002-6630-20180723-277
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This work studied the effects of three different prebiotics inulin, fructooligosaccharide and galactooligosaccharide on the gelation process and microstructure of yogurt. Yogurt without prebiotic was used as a blank control. An optical microrheometer, a Turbiscan stability analyzer and a scanning electron microscope were used to detect the rheological parameters, stability and microstructure of the yogurts with prebiotics during fermentation and storage, respectively. The results showed that in contrast to the other prebiotics, inulin incorporation to yogurt formed a more uniform and loose microstructure. The solid-liquid balance of the yogurt containing fructooligosaccharides was less than 0.5, indicating that fructooligosaccharides were more conducive to enhancing the solid nature of yogurt, while the yogurt containing galactooligosaccharide had better microscopic stability. Therefore, the three prebiotics had different effects on the gelation process and microstructure of yogurt. Still, further studies are needed to ascertain the synergistic effect of these prebiotics on the overall quality of yogurt.
Effect of Extruded Purple Sweet Potato Flour on the Pasting and Thermomechanical Properties of Wheat Dough
LIU Xingli, ZHAO Shuangli, JIN Yanjun, ZHANG Hua
2019, 40(15):  106-111.  doi:10.7506/spkx1002-6630-20180910-104
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Extrusion cooking is a high-temperature and short-time food processing technology, which can change the characteristics of purple sweet potato flour, thus improving the quality of composite dough with wheat and purple sweet potato flours. Therefore, the effects of adding extruded purple sweet potato flour (EPSP) versus non-extruded purple sweet potato flour (NEPSP) on water distribution, gelatinization and thermomechanical properties of wheat dough were investigated in this study. Results revealed that compared with NEPSP, EPSP significantly reduced the transverse relaxation time T21 (P < 0.05), indicating that EPSP could promote tight binding of water to starch or gluten. Moreover, compared with wheat flour, addition of purple sweet potato flour especially EPSP substantially decreased the peak viscosity, trough viscosity, final viscosity, setback value and breakdown value of dough (P < 0.05). The thermomechanical properties demonstrated that EPSP increased the water absorption, enzymatic hydrolysis rate and cooking stability (P < 0.05), and decreased development time, setback value and peak torque (P < 0.05). These results indicated that EPSP addition could not only increase the yield of dough, but also delay the aging of dough and extend the shelf life of the final product. This study provides a theoretical basis for the application of EPSP in wheat products.
Effect of Chitosan Soaking on the Growth and Contents of Major Bioactive Substances of Soybean Sprouts
Lü Xiamin, YANG Rui, JIANG Yu, HUANG Jianying, DONG Lijuan
2019, 40(15):  112-117.  doi:10.7506/spkx1002-6630-20180906-056
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In order to explore the influence of chitosan soaking on the growth and the contents of major bioactive substances of soybean sprouts, soybean was soaked in chitosan solutions at concentrations of 0.2, 0.4 and 0.8 g/100 mL and then cultured until sprouts came out. Hypocotyl length and fresh mass were measured, and the contents of bioactive substances were determined by spectrophotometry and liquid chromatography. The results showed that chitosan treatment could increase the hypocotyl length and fresh mass and simultaneously affect the contents of major bioactive substances of soybean sprouts. After being soaked with 0.8 g/100 mL chitosan and cultured for 5 days, the hypocotyl length and fresh mass of soybean sprouts significantly increased (P < 0.05); the total flavonoid content reached the highest level (0.64 mg/g), and the phytic acid content was at the lowest level (1.56 mg/g). Meanwhile, the contents of total ascorbic acid and total phenols were at the appropriate level. This study provides a theoretical basis for the application of chitosan soaking to produce low-cost functional foods.
Effect of Mechanical Damage on Organizational Structure of Postharvest Navel Orange Rind
DENG Lili, CUI Wenjing, YAO Shixiang, ZENG Kaifang
2019, 40(15):  118-126.  doi:10.7506/spkx1002-6630-20180827-281
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Mechanical damage is the main reason for the occurrence of oleocellosis in citrus fruit because it can cause the rupture of rind oil glands and the consequent symptoms of oleocellosis. Nevertheless, mechanical damage also favors the development of other rind disorders. More complicated physiological disorder symptoms appear in the orange rind after mechanical damage, which cannot be simply attributed to the development of oleocellosis. To better elucidate the initiation and progression of mechanical damage-induced orange rind disorders, the ultrastructural changes occurring in ‘Fengjie’ navel oranges during these processes were investigated by transmission electron microscopy and scanning electron microscopy. The contents of pectin, cellulose and lignin, the rate of generation of superoxide anion radicals and lipoxygenase activity were also measured. Results indicated that after mechanical damage, the integrity of the cell membrane was lost and the cells of oil glands in the flavedo underwent an apparent degradation, resulting in the rupture of oil glands, and consequently the release of orange oil and the degradation of both the flavedo and albedo. During the early stage of storage after mechanical damage, the activity of lipoxygenase and the generation rate of superoxide anion increased steeply, and the content of protopectin reduced sharply. The contents of water-soluble pectin significantly increased from Day 7 to 11 relative to the control (P < 0.05). On the whole, the results from this study can provide some insights into the cause of the ultrastructural changes occurring in navel orange rind after mechanical damage.
Food Engineering
Changes in Structure and Physicochemical Properties of Myofibrillar Proteins Subjected to Different Cycles of High Pressure Homogenization Treatment
LI Yufeng, XUE Siwen, CHEN Xing, LI Ming, XU Xinglian
2019, 40(15):  127-134.  doi:10.7506/spkx1002-6630-20180911-111
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In order to elucidate the effect of high pressure homogenization (HPH) cycles on the structure and physicochemical properties of chicken myofibrillar proteins (MPs) in aqueous solutions, HPH treatment was applied to homogenize MP aqueous solutions at a pressure of 103 MPa for 1–6 cycles. The results showed that the solubility of MPs was improved significantly by HPH treatment (P < 0.05). As the number of of HPH treatment cycles increased, the particle size of MPs in aqueous solutions decreased initially and then increased; the apparent viscosity declined and the flowability rose; both the surface hydrophobicity and reactive sulfhydryl group content increased, followed by a decrease. Circular dichroism showed that different HPH cycles had distinct effects on the secondary structures of MPs. Excessive HPH cycles could lead to the aggregation of MPs in aqueous solutions, thereby affecting its solubility and stability. The solubility and stability of MPs remained quite good after 4 cycles of HPH treatment. Therefore, the aqueous solubility of MPs can be controlled by selecting the appropriate cycles of HPH treatment, which will provide a new idea for its application in food processing.
Effect of Hydrodynamic Cavitation in Single-Hole Orifice Plate on Physicochemical Properties of Soybean Globulin
WANG Fang, YANG Feng, REN Xian’e, HUANG Yongchun, HUANG Chengdu, LIU Chunyou, ZHANG Kunming, YAN Liujuan
2019, 40(15):  135-141.  doi:10.7506/spkx1002-6630-20180821-228
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In this study, soybean globulin was treated with hydrodynamic cavitation in a single-hole orifice plate. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern, particle size, zeta potential, intrinsic fluorescence spectrum, surface hydrophobicity, and sulfhydryl content of soybean globulin were determined to evaluate the impact of hydrodynamic cavitation on physicochemical properties of soybean globulin. After treatment for 30 min, no change in the molecular mass was observed by SDS-PAGE. On the other hand, the average particle size was decreased from (335.67 ± 3.43) to (234.73 ± 4.32) nm. The zeta potential was increased from (24.47 ± 0.51) to (31.30 ± 2.74) mV. The fluorescence emission maximum showed a red shift, and surface hydrophobicity was increased from (1 970.67 ± 35.00) to (2 373.67 ± 75.57). The exposed sulfhydryl content was decreased from (5.11 ± 0.35) to (3.76 ± 0.16) μmol/g, and the total sulfhydryl content was decreased from (7.31 ± 0.27) to (5.35 ± 0.28) μmol/g. Therefore, hydrodynamic cavitation in single-hole orifice plate altered the spatial structure of soybean and consequently its physicochemical properties. This study provides a theoretical basis for the application of hydrodynamic cavitation in the modification of protein.
Thermal Transition Temperatures of Spray-Dried Whole Egg Determined by Differential Scanning Calorimetry
ZHAO Jinhong, BAI Jie, ZHANG Qing, ZHANG Xiaofei, LI Yumei, YUAN Nuo, LIU Songnan, GUO Hong
2019, 40(15):  142-147.  doi:10.7506/spkx1002-6630-20181014-115
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In order to provide the stability conditions of drying and freezing for whole egg, thermal transition temperatures of spray-dried whole egg powder containing unfreezable water and samples containing freezable water were determined by differential scanning calorimetry (DSC). The adsorption isotherm of whole egg was also established. Spray-dried whole egg powder containing unfrozen water showed two endothermic peaks, which corresponded to the denaturation of ovotransferrin and ovalbumin, respectively. The denaturation temperatures (Td) of ovotransferrin and ovalbumin decreased with the increase of water content. The relationship between freezing point (TF) and water content was modeled using the Clausius-Clapeyron equation. The content of unfreezable water was estimated as 0.18 g/g sample wet basis from the extrapolated enthalpy of ice melting (△Hm), and the corresponding end point of freezing (Tm’) was calculated as ?14.6 ℃ using the Clausius-Clapeyron equation. Only when water content was 0.22 g/g wet basis, was the glass transition temperature detected as ?46.3 ℃. In addition, the water adsorption isotherm of spray-dried whole egg powder was determined at 25 ℃ and the data were fitted to the GAB model. The absorption isotherm was classified as a type II isotherm. The content of monolayer water was found to be 0.043 g/g sample dry basis as the stability criterion based on water activity. These results provide a theoretical rationale for the optimal drying and freezing conditions of whole egg.
Effect of Ultrasonic Treatment on Properties and Bioactivity of Polysaccharides from Blackcurrant Fruit
XU Yaqin, DU Mingyang, YANG Lu, LIU Yusong, WEI Hong, ZHENG Binhao, GUO Yingying, YANG Yu
2019, 40(15):  148-153.  doi:10.7506/spkx1002-6630-20180916-157
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Polysaccharides from blackcurrant fruit (BFPs) were prepared by enzymatic treatment with a mixture of papain and pectinase. Two degraded polysaccharides (UM-15 and UM-30) were obtained by ultrasonic treatment of BFPs at a power of 700 W for 15 and 30 min, respectively. The physiochemical properties showed that the viscosity-average molecular mass and dynamic viscosity of the degraded polysaccharides were reduced compared to BFPs. However, their reducing sugar and uronic acid contents were increased, with UM-30 being higher than UM-15. Structural characterization by Fourier transform infrared spectroscopy, Congo red and iodine-potassium iodide tests showed that the natural and degraded polysaccharides exhibited similar characteristic absorption peaks, and they had no triple helix structure and possessed a complex chain structure. Antioxidant assays indicated that the degraded polysaccharides exhibited higher scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radical and nitrite ion and stronger lipid peroxidation-inhibitory activity than those of BFP, and the antioxidant activity of UM-30 was greater than UM-15. Within the experimental concentration range, the highest scavenging rates of DPPH, superoxide anion radical and nitrite ion by UM-30 were (90.18 ± 0.66)%, (71.43 ± 0.25)%, and (84.46 ± 1.43)%, respectively, and the maximum inhibition rate of lipid peroxidation was (65.83 ± 0.67)%. Thus, ultrasonic irradiation is an efficient and green method to improve the physicochemical properties and bioactivity of polysaccharides.
Nutrition & Hygiene
Screening and Functionality Evaluation of Lactobacillus Able to Regulate Intestinal Motility and Flora
SHEN Xudan, JI Mengxin, ZHAI Qixiao, ZHAO Jianxin, ZHANG Hao, TIAN Fengwei, CHEN Wei
2019, 40(15):  154-161.  doi:10.7506/spkx1002-6630-20180817-175
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Constipation is a common gastrointestinal disease frequently accompanied by abnormal intestinal motility and flora composition. The in vitro physiological characteristics of 45 strains of Lactobacillus were tested in the current study. Out of these, three strains were screened for in vivo functionality evaluation. Meanwhile, we evaluated the regulatory effect of Lactobacillus on intestinal motility and flora. The results indicated that survival rates of the selected strains, Lactobacillus casei LC9, Lactobacillus fermentum LF37 and Lactobacillus rhamnosus LR45, were all higher than 10% when exposed to acid and bile salt. All three strains were able to utilize oligofructose, xylo-oligosaccharide and galacto-oligosaccharide and the production of short chain fatty acids by each strain exceeded 1.2 mmol/L. Furthermore, a series of improved bowel functions were observed in the probiotic group, as manifested by the increased intestinal propulsion rate, the reduced first black stool defecation time, the augmented water content in feces, and the enhanced intestinal motility. The selected Lactobacillus could increase the relative abundance of beneficial bacteria in the mouse fecal flora and improve the structure of the fecal flora. The above results indicate that the three screened strains can regulate intestinal functions in mice, indicating their application potential.
Protective Effect and Mechanism of Resveratrol on Cerebral Nerve Cells of Aging Mice
ZHANG Xianyi, SONG Yehao, LI Lu, YIN Shuhua, FU Wangwei, WU Ruiting, PAN Meng, WU Wenying, TANG Xiaofang, LI Wenjuan
2019, 40(15):  162-168.  doi:10.7506/spkx1002-6630-20180728-349
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Objective: To investigate the protective effect and underlying mechanism of resveratrol (RSV) on cerebral nerve cells in aging mice induced by D-galactose (D-gal). Methods: An aging mouse model was established by intraperitoneal injection of D-gal. The changes in body mass and brain index (brain/body mass ratio) were calculated. Apoptotic rate, reactive oxygen species (ROS) level and mitochondrial membrane potential (MMP) in cerebral cortical neurons were measured by flow cytometry. Mitochondrial caspase-9 and caspase-3 activity were measured, and the difference in the expression of mitochondrial and cytoplasmic cytochrome c (Cyt c) was analyzed by Western blotting. Results: There was no significant difference in body mass among all groups within the experimental period (P > 0.05). Brain index decreased significantly in the aging model group (P < 0.05), the number of times the mice crossed the hidden platform declined and the apoptotic rate of neurons significantly increased (P < 0.01) compared with the normal group, indicating that D-gal significantly damaged nerve cells in mice. Brain index in all three RSV treatment groups especially at a dose of 25.00 mg/kg mb was significantly higher than in the model group (P < 0.01), the number of times the mice crossed the hidden platform increased but with no significance (P > 0.05), and the apoptotic rate of nerve cells declined significantly (P < 0.01), leading to the conclusion that RSV has a protective effect on cerebral neural cells of D-gal-induced aging mice. ROS content in nerve cells of the model group increased significantly (P < 0.01), and MMP significantly decreased compared with the normal group (P < 0.01). Moreover, the expression of mitochondrial Cyt c decreased, the expression of cytoplasmic Cyt c increased, and mitochondrial caspase-9 and caspase-3 activity increased significantly in the model group (P < 0.01), indicating that D-gal could lead to mitochondrial damage. Compared with the model group, ROS level in nerve cells significantly decreased in the RSV groups (P < 0.01); MMP significantly increased (P < 0.01); the expression of mitochondrial Cyt c significantly increased, while the expression of cytoplasmic Cyt c significantly decreased (P < 0.05); and the activity of caspase-9 and caspase-3 significantly decreased (P < 0.01), indicating that resveratrol exerts its protective effect on nerve cells of aging mice through the mitochondrial pathways. Conclusion: Resveratrol can protect cerebral nerve cells of aging mice induced by D-gal through the mitochondrial pathways.
Regulation of Intestinal Flora Structure by Pasteurized Fermented Milk with Lactobacillus plantarum YW11
HAO Xiaona, LUO Tianqi, ZHANG Jian, ZHAO Xiao, YU Zhijian, CAO Yongqiang, YANG Zhennai
2019, 40(15):  169-176.  doi:10.7506/spkx1002-6630-20180604-040
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In order to explore the influence of pasteurized fermented milk with probiotic Lactobacillus plantarum YW11 on the human intestinal flora structure, an in vitro simulated human digestion model was established and high-throughput 16S rRNA sequencing was applied to analyze the diversity and composition of the intestinal flora. Results indicated that the pasteurized fermented milk could increase the richness and diversity of intestinal microbial species. At the phylum level, it increased the abundance of Firmicutes and reduced the abundance of Proteobacteria. At the genus level, it increased the abundance of highly enriched bacteria and the abundance of 45.71% of the intestinal flora. In addition, the fermented milk increased the abundance of butyric acid-producing bacteria, such as Lachnospiraceae, Roseburia, Ruminococcus, and the abundance of Lactobacillus and Bifidobacterium. At the same time, the fermented milk also increased the bacteria implicated in relieving inflammatory bowel disease (IBD), such as Bacteroides, Faecalibacterium, Phascolarctobacterium and Collinsella, and reduced those related to the development of IBD, such as Erysipelotrichaceae, Pseudomonas and Escherichia-Shigella, indicating the beneficial effect of the pasteurized fermented milk on the human intestinal flora. Therefore, this fermented milk can function to regulate the human intestinal flora. These experimental results can provide a theoretical basis for the development of probiotic-fermented milk.
Effect of Curcumin Supplementation on Intestinal Antioxidant Function in Weaning Piglets with Intrauterine Growth Retardation
WANG Fei, HE Jintian, SHEN Mingming, ZHANG Hao, NIU Yu, ZHANG Lili, WANG Tian
2019, 40(15):  177-183.  doi:10.7506/spkx1002-6630-20180814-145
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Purpose: To investigate the protective effect of curcumin on intestinal oxidative damage in weaning piglets with intrauterine growth retardation (IUGR). Methods: A total of 16 newborn piglets with normal birth mass (NBM) and 16 newborn piglets with IUGR, half male and half female were selected for this study. After weaning at the age of 26 days, these piglets, fed on a basal diet (diet 1) or the same diet supplemented with 400 mg/kg curcumin (diet 2), were allocated to 4 groups of 8 animals each: NBM + diet 1 (group N), NBM + diet 2 (group NC), IUGR + diet 1 (group I), and IUGR + diet 2 (group IC). Every piglets were fed to 50 d, slaughtered, sampled, and then tested for antioxidant index. Results: Compared with group I, group IC significantly reduced protein carbonyl (PC) and 8-hydroxy-2’-deoxyguanosine contents in jejunum tissue, and malondialdehyde and PC contents in ileum tissue (P < 0.05). Compared with group I, group IC showed a significant increase in total antioxidant capacity (T-AOC), catalase (CAT) activity and glutathione (GSH) content in jejunum tissue (P < 0.05); a significant increase in CAT activity and a significant decrease in H2O2 content in ileum tissue (P < 0.05). Compared with group I, the mRNA expression levels of nuclear factor- erythroid 2-related factor 2 (Nrf2), CAT, superoxide dismutase (SOD), glutathione S-transferase (GST) and NAD(P)H : quinone oxidoreductase l (NQO1) were significantly increased in jejunum tissue of group IC (P < 0.05), and the mRNA expression levels of Nrf2, GST, NQO1 and thioredoxin reductase 1 were significantly increased in ileum tissue (P < 0.05). Conclusion: Dietary addition of curcumin at a dose of 400 mg/kg can alleviate intestinal oxidative stress caused by IUGR and improve intestinal antioxidant status.
Comparison of the Nutritional Value of Shark Meat and Fin
YANG Shaoling, QI Bo, LI Laihao, YANG Xianqing, ZHAO Yongqiang, WANG Jinxu, CEN Jianwei, WEI Ya
2019, 40(15):  184-191.  doi:10.7506/spkx1002-6630-20180815-157
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In order to comprehensively and objectively evaluate the nutritional value of shark meat and fin (including whole fin and fin cartilage), the nutritional composition of shark meat and fin from Carcharhinus falciformis and Prionace glauca was analyzed. The results showed that protein content was high in both shark meat and fin (24.34%–37.03%), and was higher in shark fin than in shark meat for the same species. Crude fat content was very low in shark meat and fin from each species, less than 0.50%. Ash content was surprisingly high (6.18%–7.09%) in whole fin due to its sandy surface, but it was just slightly higher in meat than in fin cartilage (1.23%–1.63% vs. 0.86%–0.90%). Both shark meat and fin contained a wide variety of amino acids and the latter had a higher level of total amino acids (TAA) than the former. Nevertheless, the content of essential amino acids (EAA) was higher in shark meat than in fin (41.94%–42.42% vs. 17.93%–22.61%), and only shark meat met the Food and Agriculture Organization/World Health Organization standard for amino acid profile (EAA/TAA ≥ 40% and EAA/non-essential amino acids (NEAA) ratio ≥ 60%). Therefore, the nutritional value of amino acids in shark meat was higher than shark fin, and shark meat but not fin was a source of high-quality protein. The amino acid score (AAS), chemical sore (CS) and essential amino acid index (EAAI) results showed that the AAS score, CS score and EAAI score of shark meat were approximately twice higher than those of shark fin, indicating that the nutritional value of amino acids in shark meat was significantly higher than that of shark fin. According to AAS and CS evaluation, methionine and cysteine were the first limiting amino acids in shark meat, while leucine (according to AAS score) or methionine + cysteine (according to CS score) was the first limiting amino acid in shark fin. Thirteen fatty acids were detected in shark meat and the contents of saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) decreased in that order. Similarly, 16 fatty acids were detected in shark fin, and the content of various fatty acids followed the decreasing order of SFA > MUFA > PUFA. Both shark meat and fin were rich in oleic acid, docosahexaenoic acid (DHA) and arachidonic acid (ARA), which are unsaturated fatty acids with important physiological activities and met the ideal fatty acid profile (PUFA/SFA ratio > 0.4), but the PUFA/SFA ratio of shark meat was significantly higher than that of shark fin. Both shark meat and fin were rich in collagen, and its level was significantly higher in the latter than in the former (7.61%–11.99% vs. 0.27%–0.41%). Chondroitin sulfate was also found in both shark muscle and fin, and its content was very high in whole fin (2.67 mg/g and 10.87 mg/g for Carcharhinus falciformis and Prionace glauca, respectively), but low in muscle and fin cartilage (< 1.2%).
Effects of Phytosterol Esters on Selected Hepatic Metabolites in Rats with Nonalcoholic Fatty Liver (NAFLD)
OUYANG Pengling, GUAN Qi, QU Dan, DING Xinwen, SONG Lihua
2019, 40(15):  192-202.  doi:10.7506/spkx1002-6630-20180526-372
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To explore the mechanisms of the preventive effect of phytosterol esters (PSE) on nonalcoholic fatty liver disease (NAFLD), we investigated the effects of PSE on selected hepatic small-molecule metabolites in rats with NAFLD. A high-fat diet was used to establish a rat model of NAFLD, and PSE-fortified milk at low (0.05 g/100 g mb) and high (0.10 g/100 g mb) doses were intragastrically administered to the rats of the PSE intervention groups. Hepatic metabolite profiling of NAFLD rats was performed using ultra performance liquid chromatography tandem time-of-fight mass spectrometry (UPLC-Q-TOFMS). Using Progenesis QI v2.3 software, UNIFI data analysis platform and Metabo Analyst (http://www.metaboanalyst. ca/faces/upload/PathUploadView.xhtml), 20 differential metabolites were identified, including phosphatidic acid (PA; 16:0/20:2 (11Z, 14Z), 20:1 (11Z)/0:0); phosphatidylcholine (PC; 16:0/18:1 (11E), 18:1 (6Z)/0:0, 18:1 (9Z)/18:0, 20:3 (8Z, 11Z, 14Z)/0:0, 15:0/18:1 (11Z), 16:0/16:1 (9Z), 16:0/2:0, 17:1 (10Z)/0:0, 19:3 (10Z, 13Z, 16Z)/0:0, 20:4 (5Z, 8Z, 11Z, 14Z)/14:0)); phosphatidylethanolamine (PE; 20:3(8Z, 11Z, 14Z)/22:6(4Z, 7Z, 10Z, 13Z, 16Z, 19Z), 22:6 (4Z, 7Z, 10Z, 13Z, 16Z, 19Z)/17:1 (9Z)); phosphatidylglycerol (PG; 17:2 (9Z, 12Z)/22:6 (4Z, 7Z, 10Z, 13Z, 16Z, 19Z)); sphingomyelin (SM, d18:0/16:0); glycocholic acid; and lysophosphatidylcholine (LysoPC; 18:1(9Z), 20:3 (5Z, 8Z, 11Z)), 20:3 (8Z, 11Z, 14Z)). High-dose PSE effectively regulated high-fat diet-induced glycerophospholipid metabolic pathway disorders. These results indicated that PSE could mitigate the progression of NAFLD by regulating the contents of small-molecule metabolites of phospholipids and bile acids.
Superfine Dietary Fiber from Phyllostachys praecox Shoots Improves Hyperlipidemia in Mice
SU Yu, LI Lu, HUANG Liang, FU Xiaokang
2019, 40(15):  203-210.  doi:10.7506/spkx1002-6630-20180604-037
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In this study, we determined the effect of superfine powders of dietary fiber from Phyllostachys praecox shoots (PPDF) prepared by three different grinding methods on high-fat diet-induced hyperlipidemia in mice. The hyperlipidemic mice were administered by gavage with a suspension of each superfine powder in distilled water at a dose of 2.5 g/(kg·d mb) by gavage (20 mL/kg). The results showed that compared with the normal control group, the body mass of mice in the model group significantly increased (P < 0.05); serum total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), atherosclerosis index (AI), and fat/body mass ratio increased significantly (P < 0.01), whereas high density lipoprotein cholesterol (HDL-C) was significantly lower (P < 0.01); superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in both serum and liver tissue decreased and increased, respectively (P < 0.05); and in the feces, dry and hard, water content decreased, while fecal fat and cholesterol levels increased (P < 0.05). Compared with the model control group, PPDF significantly reduced body mass, serum lipid level and fat/body mass ratio of mice but increased HDL-C (P < 0.01). In addition, PPDF enhanced SOD activity and decreased MDA content in serum and liver tissue (P < 0.05), increased fecal water content, and reduced the levels of fecal fat and cholesterol (P < 0.05). Moreover, at the same dose, the smaller the particle size of PPDF the more obvious its effect on hyperlipidemic mice. In conclusion, this study indicates that PPDF can improve hyperlipidemia.
Dose-dependent Modulation of Intestinal Microbiota and Peristalsis in Mice by Lactobacillus casei LC01
LU Wenwei, HU Wenbing, CAO Wenjin, YANG Zhennan, DING Liwei, YANG Jingmei, CHEN Wei
2019, 40(15):  211-217.  doi:10.7506/spkx1002-6630-20180423-307
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In order to investigate the gut benefits of Lactobacillus casei LC01, the impact of different LC01 doses on the intestinal microbiota and peristalsis in mice was evaluated. Based on MiSeq high-throughput sequencing, the modulatory effects of LC01 on the intestinal microbiota in normal mice and those with intestinal microbiota imbalance caused by penicillin were compared. The propulsion rate of ink was applied to estimate the effect of LC01 on intestinal peristalsis in mice with constipation. Results indicated that administration of LC01 significantly increased the relative abundance of Lactobacillus and Bacteroides, but decreased the abundance of the opportunistic pathogens Prevotella and Helicobacter in the gut of normal mice, evidencing that LC01 markedly regulates the mouse gut microbiota. Furthermore, after two weeks of intervention, the penicillin-treated group showed higher relative abundance of Bacteroides, Clostridum and Lactobacillus than the model group. Moreover, LC01 improved intestinal peristalsis in mice with constipation, and it was more effective at a viable cell count of 60 billion than at 30 billion. These results revealed that LC01 could exert a modulatory effect on the mouse intestinal microbiota and peristalsis, indicating that LC01 may have potential as a probiotic strain for human health.
Packaging & Storage
Effect of Vacuum Skin Packaging on Quality Changes of Sturgeon (Acipenser schrencki) Fillets during Cold Storage
LIU Yi, ZHANG Yuanshan, ZHOU Xing, TIAN Ying, LI Pinglan
2019, 40(15):  218-224.  doi:10.7506/spkx1002-6630-20190227-214
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The purpose of this study was to investigate the quality changes of sturgeon fillets with vacuum skin packaging relative to vacuum packaging and tray packaging during storage at 4 ℃. The chemical indexes such as thiobarbituric acid reactive substance (TBARS) value, total volatile base nitrogen (TVB-N) content, biogenic amine content, the contents of ATP and its related breakdown compounds and K value were determined. Physical indexes such as pH, sensory score, color and texture, as well as total microbial count were measured as well. The results showed that the shelf life of sturgeon fillets with vacuum skin packaging was 9 days at 4 ℃, which was 3 days and 6 days longer compared with vacuum packaging and tray packaging, respectively. Vacuum skin packaging could effectively inhibit the increase in TBARS value, and the contents of TVB-N, biogenic amines and hypoxanthine, K value and yellowness (b*) value and slowed down the decrease in elasticity and hardness as well as the content of inosine monphosphate (IMP) as a umami taste compound. Compared with vacuum packaging and tray packaging, vacuum skin packaging could make the product more appealing in appearance, thereby simulating consumers’ purchase desire. In conclusion, vacuum skin packaging holds promise for applications in aquatic product packaging.
Effect of Cinnamaldehyde Combined with Ultra-High Pressure Treatment on the Quality of Paralichthys olivaceus Fillets during Cold Storage
XU Yongxia, YIN Yiming, ZHAO Honglei, LI Xuepeng, ZHU Wenhui, LI Qiuying, XIE Jing, LI Jianrong
2019, 40(15):  225-230.  doi:10.7506/spkx1002-6630-20180816-170
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The individual and combined effects of cinnamaldehyde and ultra-high pressure (200 MPa for 10 min) on the quality of Paralichthys olivaceus fillets during cold storage at 4 ℃ were investigated in this paper. In order to evaluate the effect on the shelf life, the changes in total bacterial count, water-holding capacity, thiobarbituric acid (TBA) value, total volatile basic nitrogen (TVB-N) content, K value and texture profile analysis were measured periodically for the treatment and the control groups. The results showed that the quality of the treatment groups was preserved significantly better than that of the control group. The combined treatment with cinnamaldehyde and ultra-high pressure provided the best quality preservation by significantly inhibiting the growth of bacteria, delaying the increase of TVB-N content, TBA value and K value and the decrease of water-binding capacity (P < 0.05), and effectively retarding the decrease in texture properties such as hardness, springiness and chewiness during the refrigeration of fillets. This combination extended the shelf life by approximately 8 days compared with the control group and by 4 days compared with either treatment alone.
Modes of Action of 2,4-Epibrassionolide against Postharvest Gray Mold Decay of Grapes
YANG Yilin, ZHANG Zhengmin, LI Meilin, ZHAO Liyan, JIN Peng, ZHENG Yonghua
2019, 40(15):  231-238.  doi:10.7506/spkx1002-6630-20180821-222
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The inhibitory effect of 2,4-epibrassionolide (EBR) treatment on gray mold disease caused by Botrytis cinerea in postharvest grape berries (Vitis vinifera L. × V. labrusca L. cv. ‘Kyoho’) and the possible mechanisms were investigated. Grapes were pretreated with 5 μmol/L EBR for 12 h, inoculated with B. cinerea, and then stored at 25 ℃ for 60 h. The results showed that EBR treatment effectively inhibited the occurrence of gray mold and the expansion of lesion diameter. Grapes pre-treated with EBR showed stronger and faster response to the challenge of pathogen inoculation compared with either treatment alone, which corresponded to a significant increase in the activities of defense-related enzymes including chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase as well as total phenols content (P < 0.05), the accumulation of H2O2 and higher activities of superoxide dismutase, catalase, ascorbate peroxidase, and significantly increased expression levels of defense-related genes like VvCHI、VvGNS and VvPAL-like (P < 0.05). In vitro experiment showed that EBR treatment could inhibit spore germination but had no influence on germ tube elongation of B. cinerea. These results suggest that EBR treatment can improve resistance against gray mold decay in grapes, which is closely associated with the priming of defense responses.
Mechanism of Action of Methyl Jasmonate against Kiwifruit Soft Rot and Its Effect on Fruit Quality
LI Xiaoqian, LONG Youhua, YIN Xianhui, WU Xiaomao, ZHAO Zhibo, FAN Rong, MO Feixu, JIANG Yanling, HUANG Yaxin, TANG Jingwen
2019, 40(15):  239-248.  doi:10.7506/spkx1002-6630-20180625-467
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In this study, ‘Guichang’ kiwifruits were used to investigate the mechanism of action of methyl jasmonate (MeJA) against kiwifruit soft rot (Botryosphaeria dothidea) and to evaluate the effect of pre-harvest treatment with 0.50 mmol/L MeJA on the control of soft rot and fruit quality. The results showed that the inhibitory effect of MeJA on B. dothidea increased with increasing its concentration in the range of 0–0.80 mmol/L, and so did the relative electrical conductivity and the leakage of proteins and nucleic acids from the fungal mycelia. The mycelia treated with 0.80 mmol/L MeJA showed dissolved cell walls, increased number of mitochondria with irregular shapes and enlarged cell cavity. In addition, the MeJA treatment increased β-1,3-glucanase activity in the cell wall. Field experiments showed that 0.50 mmol/L MeJA treatment performed one month before harvest had a control efficiency of 77.70%. More importantly, this MeJA treatment improved fruit appearance, and it increased the contents of vitamin C and soluble solids, inhibited the decrease in hardness, and delayed the increase in soluble solids and soluble sugar as well as the loss of vitamin C during storage, thereby improving the storage quality of kiwifruits. In conclusion, MeJA inhibits B. dothidea growth by destroying the structural integrity of the cell wall, and can be used for the field control of kiwifruit soft rot and for improving fruit quality and storage stability.
Effect of γ-Aminobutyric Acid on Storage Quality of Eggs
JIANG Guochuan, YAN Xiaohui, TAN Chuanxin, SUN Hongrui, ZHANG Jialin, LIU Xuejun, WANG Liyan
2019, 40(15):  249-254.  doi:10.7506/spkx1002-6630-20180909-089
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In order to improve the storage quality of eggs, this study determined the effect of injection of different concentrations of γ-aminobutyric acid (GABA) into eggs on its freshness after storage at 37 ℃ for 14 days, and it also examined the effect of storage temperature (4, 25 and 37 ℃) on the freshness of eggs in the 100 mg/mL GABA treatment and control groups (saline) and the effect of GABA on the concentrations of ovotransferrin and ovalbumin in eggs stored at 37 ℃ for 14 days. The results showed that the Haugh units (HU) and yolk index of eggs were the highest and the storage quality was the best when GABA concentration was 100 mg/mL. After 14 day of storage at 4, 25 and 37 ℃, the HU value was 86.91, 72.28 and 71.50, respectively, and the yolk index was 0.53, 0.35 and 0.24, respectively, which were higher than that of the control group. After storage at 37 ℃ for 14 days, the concentrations of ovotransferrin and ovalbumin in the 100 μg/mL GABA treatment group were 1.12 times higher and 39% relative to the control group, respectively. Therefore, GABA can be used to improve the storage quality of eggs.
Phenolics in Wines I: A Review of Categories, Structures and Detection Methods
ZHANG Xinke, ZHAO Xu, CHENG Chifang, QI Mengyao, SHI Ying
2019, 40(15):  255-268.  doi:10.7506/spkx1002-6630-20180916-159
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Wine is favored by consumers because of its complex flavor. Phenolic substances are important chemical components of wine affecting its organoleptic properties. In addition, the functional properties of wine are attributed to phenolic compounds. Wine comprises a variety of complex phenolic substances, including flavonoids and non-flavonoids. The former consists of anthocyanin and their derivatives, flavanols and flavonols, while the latter includes hydroxybenzoic acids, hydroxycinnamic acids and stilbenes. This review aims to systematically describe these phenolic substances in wine with respect to their categories, structures and properties. Also, the major analytical methods for detecting these compounds and recent advances in this field are summarized. This review provides valuable academic information for researchers interested in this field, and also provides practical guidance for people engaged in the wine industry.
A Review of Process in Understand Biosynthesis Pathway and Metabolic Regulation of Phenolic Acids in Cereals
MA Yan, WEI Yuan, WANG Mian, SUN Maomao, WANG Pei, GU Zhenxin, YANG Runqiang
2019, 40(15):  269-276.  doi:10.7506/spkx1002-6630-20180918-198
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Phenolic acids are widely found in higher plants. A large number of studies have shown that phenolic acids have strong pharmacological activities such as anti-oxidant, anti-inflammatory, anticancer, and immune-enhancing functions. In recent years, with the development of the whole grain concept, phenolic acids in cereals has become one of the current hotspots in the area of food research. In this article, the composition and distribution, biosynthesis pathway and metabolic regulation of phenolic acids in cereals are reviewed, and future research directions are also discussed.
Application of in Vitro Bioassays in Safety Evaluation of Food Contact Materials: A Review
WANG Wenjuan, CAI Xiaofang, TANG Jie, ZHANG Xirong, FENG Di
2019, 40(15):  277-284.  doi:10.7506/spkx1002-6630-20180822-234
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In vitro bioassays are a series of in vitro short-term toxicity tests utilizing yeasts, bacteria or cells, which allow the evaluation of the hazards of analytes and the exploration of the underlying toxicity mechanisms by effectively focusing on a specific effect in organisms. Owing to providing comprehensive information on the overall actual hazards of migrants (mixtures) from food contact materials, in vitro bioassays have been increasingly applied in the hazard assessment of food contact materials in recent years, especially focusing on three toxicological endpoints including cytotoxicity, genotoxicity and endocrine disruption effect. In this paper, the basic principles of the three kinds of bioassays and the progress made in their applications in the hazard assessment of food contact materials in the past two decades are reviewed. It is expected to provide a theoretical basis for future studies on the biological safety evaluation of food contact materials.
Color Problems in Cooked Beef and Influencing Factors: A Review
LIANG Rongrong, ZHANG Yimin, MAO Yanwei, YANG Xiaoyin, ZHU Lixian, DONG Pengcheng, LUO Xin
2019, 40(15):  285-292.  doi:10.7506/spkx1002-6630-20180731-376
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In recent years, there has been a great increase in the consumption of western beef products including steaks, beef patties, hamburgers and roasted beef by Chinese consumers, especially the burgeoning middle class, and there have been increasing quality and safety requirements for beef product. However, color problems often occur in these beef products during the cooking process. The major color problems during the cooking of beef products are reviewed, including premature browning, persistent pinking and color reversion. The major causes of each color problem, the major factors influencing it and solutions to it are presented. Furthermore, the major factors affecting the color of cooked beef are summarized, and the molecular mechanism for color problems in cooked beef are put forward. This review will provide some useful information for cooked beef color control in China.
A Review of Laser-Induced Breakdown Spectroscopy and Its Application in Food Analysis
WEN Rongxin, HU Yingying, YU Jing, KONG Baohua, CHEN Qian
2019, 40(15):  293-299.  doi:10.7506/spkx1002-6630-20180906-070
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Laser-induced breakdown spectroscopy (LIBS) is a spectroscopic technique for the qualitative and quantitative analysis of elements where the surface of samples is burned by laser to obtain the plasma spectra of the target elements in them. As an efficient reagent-free online testing technology, LIBS has the advantages of environmental friendliness, minimal invasion, low cost and ease of operation. With the gradual maturity of this technology and the development of relevant scientific theories, it has become an emerging analytical tool in the area of food research. The basic principle of LIBS is briefly described in this article, and the latest progress in its application in food research is reviewed. Finally, the potential of LIBS in food analysis is also evaluated. Despite its many advantages, the application of LIBS in food analysis is still in its infancy, and there are still challenges in detection sensitivity, matrix effect elimination and portability.
A Review on the Application of Spectral Analysis Techniques in Research on Wild-Grown Bolete Mushrooms
WANG Yuanyuan, LI Jieqing, LI Tao, LIU Honggao, WANG Yuanzhong
2019, 40(15):  300-306.  doi:10.7506/spkx1002-6630-20180830-350
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As wild mushroom species popular all over the world, bolete mushrooms are of great economic importance and can be used for both culinary and medicinal purpose. Controllable quality and safety of bolete mushrooms is the foundation for ensuring consumer health and green and sustainable development of this industry. Developing comprehensive, stable and systematic quality evaluation methods is beneficial for the quality control of bolete mushrooms and is important for the stable development of the market. Thanks to their advantages such as simplicity, rapidity and high practicability, spectral analysis techniques can make up for the defects of traditional sensory evaluation and improve the analytical accuracy. Hence, spectral analysis techniques have been widely applied to evaluate the quality of bolete mushrooms and have provided important technical support for the quality assessment and authentication of bolete mushrooms and for ensuring product quality stability and consistency. This article reviews the current status and progress in the application of spectral analysis techniques in research on wild-grown bolete mushrooms. Future prospects for the application of infrared spectroscopy and ultraviolet spectroscopy as well as multi-spectral information fusion technique to identify the geographical origin, species, storage time of bolete mushrooms. This review is expected to provide evidence for further research and reasonable utilization of bolete mushrooms.
Biofilm Formation Characteristics of Escherichia coli and Control Measures: A Review
WU Lina, DONG Pengcheng, ZHANG Yimin, MAO Yanwei, LIANG Rongrong, ZHU Lixian, LUO Xin
2019, 40(15):  307-313.  doi:10.7506/spkx1002-6630-20180910-100
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Escherichia coli is part of the normal human flora and also an important pathogen that can cause significant morbidity and mortality. E. coli can form a biofilm on both biotic and abiotic surfaces, thereby enhancing its survival in adverse environments, especially against various disinfectants, detergents and antibiotics. In this article, the recent advances in the biofilm formation of E. coli, including its main process, characteristics and molecular regulatory mechanism, the factors influencing it, and control measures against it are reviewed. Some future research directions are proposed as well. This review is aimed to provide a basis for the prevention and control of E. coli biofilm.
Progress in Research on the Efficacies and Mechanisms of Action of Various Non-thermal Sterilization Technologies in Inactivation of Microbial Spores in Foods
BAI Yan, GE Yujun, XIANG Yingchun, LI Yuan, DING Tian, HU Yaqin
2019, 40(15):  314-322.  doi:10.7506/spkx1002-6630-20180908-083
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Traditional thermal sterilization has been demonstrated to cause adverse effects on food quality, resulting in undesired consequences including color changes, odor generation and nutritional loss. The non-thermal sterilization technology is a new processing technology that has been applied in the food industry, which has little influence on the color, aroma, taste and nutritional components of foods by keeping a relatively low temperature during their processing. At the same time, non-thermal sterilization is beneficial to maintain the physiological activity of various functional components in foods to meet the demands of consumers for high-quality foods. Microbial spores have strong resistance to food processing and have great potential for germination and growth in foods. Therefore, inactivation of microbial spores by low-temperature or non-thermal sterilization technology is currently a serious challenge and an important topic in the food industry. The effects and mechanisms of action of various non-thermal sterilization technologies such as high hydrostatic pressure, high-pressure CO2, non-thermal plasma, ultraviolet radiation, and high voltage pulsed electric field individually or in combination with other treatments on spore inactivation are summarized. Focus is given on the application and molecular mechanism of spore inactivation in the food industry. This review is expected to provide solutions for the production of safe foods and reduction of microbial contamination in different kinds of foods.
A Literature Review on the Application of Natural Biomacromolecules and Their Complexes in Food Microgel Delivery System
GAO Yaxin, YU Youqiang, ZHU Qiaosha, HOU Zhanqun, DUAN Shenglin, MOU Dehua
2019, 40(15):  323-329.  doi:10.7506/spkx1002-6630-20180911-107
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Microgels are nano- or micro-scale particles that are internally cross-linked to form a three-dimensional network and can serve as a delivery vehicle for food functional factors. This article provides an overview of two kinds of natural biomacromolecules suitable for making microgels: proteins and polysaccharides. The composition and gelling properties of common proteins and polysaccharides from different sources are described. The latest applications of natural biomacromolecules in food delivery systems are also presented. Finally, we conclude with some remarks on the potential value of natural biomacromolecules in the preparation of food microgels as well as future research hotspots.
Recent Progress in Decontamination Technologies for Beef Carcasses and Chilled Beef
HAN Jina, ZHANG Jia, LUO Xin, ZHU Lixian, LIANG Rongrong, ZHANG Yimin, YANG Zhengang
2019, 40(15):  330-337.  doi:10.7506/spkx1002-6630-20180625-465
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Numerous research efforts have been made to develop decontamination technologies to reduce microbial levels on carcasses and chilled meat in order to extend the shelf life and to increase the safety of meat. Therefore, the recent progress in the development of decontamination technologies for beef carcasses and chilled beef is summarized in this article. Physical decontamination technologies including carcass trimming, water spraying, thermal sterilization, ultraviolet sterilization and cold atmospheric plasma and chemical ones including spraying of organic acid and peroxyacetic acid are covered. At the same time, the advantages and disadvantages of each technology are listed. Overall, water spraying combined with lactic acid spraying is both economical and effective in reducing microbial levels on beef carcasses. This review may provide evidence for meat industries to choose reasonable measures to reduce bacterial contamination.
Progress in the Application of Immunomagnetic Separation in Rapid Detection of Foodborne Pathogens
CAO Xiao, ZHAO Lichao, CHEN Xun, XIE Hui, ZHANG Jingfeng, LIU Zhuokun, WANG Li
2019, 40(15):  338-345.  doi:10.7506/spkx1002-6630-20180702-025
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Establishing a new fast and efficient detection method and strategy for foodborne pathogens is critical to control the outbreak of foodborne diseases. Sample preparation is a crucial step in the quick screening of pathogens. Conventional techniques for the detection of foodborne pathogens usually require pre-enrichment and selective separation for increased concentrations of the target bacteria, which are time-consuming and have low sensitivity. Immunomagnetic separation (IMS) is capable of separating and concentrating the target pathogens from complex food samples in a short period of time, which has been applied to the detection of various foodborne pathogens. This article reviews the application of IMS in the detection of foodborne pathogens. Meanwhile, it mainly focuses on the principle of IMS and the factors influencing the efficiency of IMS, as well as the latest progress in its combined application with other detection technologies in rapid detection of foodborne pathogens. This review aims at providing theoretical support for deeper applications of IMS and the development of rapid food safety detection technologies in China.
A Review of the Application of Low Field Nuclear Magnetic Resonance in Detection and Analysis of Water in Meat and Meat Products
SUN Wenbin, LUO Xin, ZHANG Yimin, ZUO Huixin, NIU Lebao, MAO Yanwei
2019, 40(15):  346-351.  doi:10.7506/spkx1002-6630-20180903-024
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Recently, low field nuclear magnetic resonance (LF-NMR) has been widely used as a burgeoning analytical technique in the detection and analysis of water in meat and meat products. Therefore, a review of the literature in this regard is highly needed. In this article, the principle of LF-NMR is described and the applications of LF-NMR in the analysis of water distribution and mobility during meat production, processing and storage, and quality evaluation, adulteration identification and freshness detection of meat products are reviewed, with the aim of promoting further development and application in meat processing and quality control of LF-NMR.
Towards the Construction of Food Safety Inspector Supervision System in China
LI Bo, LI Xue, LIU Shibu, XIAO Pinghui, SONG Yuande, HOU Tiantian
2019, 40(15):  352-358.  doi:10.7506/spkx1002-6630-20190130-384
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Food safety is a major livelihood issue in China. A food safety supervision system is the most important measure to ensure food safety. However, the lack of professional supervision measures is the biggest obstacle to the improvement of food safety supervision in China. By analyzing and drawing on the useful experience of different countries and regions in the field of professional food safety supervision system, this article proposes some suggestions for the construction of a food safety inspector supervision system in China such as improving the qualification requirements for food safety inspectors, more clearly defining the duties of food safety inspectors, strengthen the training, assessment and management of food safety inspectors in order to enhance the country’s food safety supervision and guarantee capacity.
Two-Component Regulatory System and Its Mechanism of Action in Regulating Bacterial Acid Tolerance Response: A Review
LANG Chenxiao, LUO Xin, ZHU Lixian, ZHANG Yimin, HAN Guangxing, DONG Pengcheng
2019, 40(15):  359-366.  doi:10.7506/spkx1002-6630-20180914-152
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The two-component regulatory system (TCS) is a vital structure for maintaining the survival of bacteria in complex environments. Food processing can induce high osmotic pressure, weak acid and other stressful environments. The two-component system can help bacteria to perceive the external environment and mobilize the internal resistance mechanism in time. However, this process can produce strains that are resistant to acids, osmotic pressure, and high temperature, and even highly virulent strains threatening food safety. This paper summarizes the structural composition, recognition signal and regulatory role of TCS. Based on the acid shock proteins, cell membrane system and amino acid metabolism associated with acid tolerance response (ATR), the activation process of ATR by TCS in response to signal molecules under acidic conditions is also discussed.