Table of Content

15 September 2019, Volume 40 Issue 17
Basic Research
Antioxidant Activity of Fermented Soy Whey with Kombucha Consortium
TANG Sijie, TU Chuanhai, HU Wenxiu, DONG Mingsheng
2019, 40(17):  1-6.  doi:10.7506/spkx1002-6630-20180705-080
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Soy whey is a major by-product from the soy product industry, which is suitable for the growth of microorganisms due to rich nutrients. Kombucha is a sweet and sour functional beverage made from sweet black tea fermented by a symbiotic?consortium of yeasts and acetic acid bacteria. In this study, we used soy whey as a new fermentation substrate for kombucha consortium to develop a novel functional beverage. The results demonstrated that after fermentation for 6 days, pH decreased to 3.24, which corresponded to an increase in total titration acidity up to 0.121 mol/L, and the content of reducing sugar decreased to 1.37 mg/mL. Total flavonoids from unfermented and fermented soy whey were extracted using 80% methanol and were qualitatively and quantitatively determined by high performance liquid chromatography (HPLC). Their antioxidant capacity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) cation radical scavenging ability, ferric reducing antioxidant power and reducing power. The results showed that the total flavonoids concentration of 6-day fermented soy whey was up to 268.45 mg/L; the soybean isoflavonoids glycoside concentration was reduced to 49.76 mg/mL, and the soybean isoflavonoids aglycone concentration was increased to 150.95 mg/mL compared with the unfermented one. The fermentation could significantly improve the antioxidant activity of soy whey. This study provides a new way of utilizing soy whey resource.
Numerical Simulation and Optimization of Isothermal Drying-Tempering Process for Paddy
WU Zhonghua, WANG Shanshan, DONG Xiaolin, ZHAO Lijuan, ZHANG Zhongjie
2019, 40(17):  7-13.  doi:10.7506/spkx1002-6630-20180926-277
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In this paper, the three-dimensional mathematical model for heat and mass transfer that we previously developed was applied to simulate the isothermal drying-tempering process of paddy. The pattern of moisture distribution inside paddy grains was analyzed and compared with that in the simple drying process. The results showed that compared with the simple drying process at 60 ℃, the tempering operation could reduce the maximum moisture gradient, which was related to the drying stress and cracking, and consequently reduced the drying time. Tempering could also greatly decrease the final moisture gradient of paddy grains by about 50%. Besides, it was found that tempering temperature, drying/tempering ratio, and tempering time were important process parameters. The optimal drying-tempering process was obtained involving three stages: shorter-time tempering, drying and longer-time tempering, which could reduce effectively the maximum and final moisture gradient as well as the whole tempering time and number. The findings obtained in this paper provide theoretical and technical support to the drying-tempering operation practice.
Effect of Rice Bran Rancidity on Structural Characteristics of in Vitro Pepsin Digest of Rice Bran Protein
WU Wei, HE Liyuan, HUANG Huimin, WU Xiaojuan, LIN Qinlu
2019, 40(17):  14-21.  doi:10.7506/spkx1002-6630-20180925-262
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Rice bran protein was prepared from fresh rice bran subjected to stabilization and defatting after storage for different times with a view to investigating the effect of rice bran rancidity on structural characteristics of its in vitro pepsin digest. The results showed that as the extent of rancidity of rice bran increased, the time required for complete pepsin digestion of albumin subunits, glutelin acidic subunits, and globulin subunits firstly advanced, and then delayed, while glutelin base subunits and prolamin subunits became more difficult to digest by pepsin. The results of molecular mass distribution and particle size distribution indicated that oxidative aggregates of rice bran protein were formed as a result of rancidity, thereby inhibiting its in vitro pepsin digestion. In addition, as the extent of rancidity increased, the pepsin digest exhibited an increase followed by a decrease in the red shift in maximum fluorescence emission wavelength, while the surface hydrophobicity gradually decreased. In conclusion, protein oxidation caused by lipid rancidity in rice bran has important effects on the covalent cross-linking state, aggregation behavior and surface hydrophobicity of in vitro pepsin digest of rice bran protein.
Impacts of Lactobacillus plantarum B02012 on Gluten Structure and Immunoreactivity in Sourdough
LIAO Lan, WEN Xiaoyan, CHEN Linping, ZHANG Fengli, LIN Weijie, YANG Yanhong, CHEN Xueqin, ZHANG Lianyue, NI Li
2019, 40(17):  22-29.  doi:10.7506/spkx1002-6630-20180802-006
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Two different sourdoughs, named SLB02012 and SL20998, were prepared respectively with Lactobacillus plantarum B02012 and Lactobacillus alimentarius 20998, having similar acid production rate and acidification performance in this study. Also, sourdoughs SYLB02012 and SYL20998 were made with each of the two strains in combined with yeast, respectively. Traditional yeast-fermented sourdough (SY) and non-fermented sourdough made with edible organic acids (SCA) as well as non-inoculated dough with erythromycin (CK) were used as controls. Gliadin was extracted from each sourdough and was evaluated for secondary and tertiary structures and immunoreactivity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FTIR), intrinsic fluorescence spectroscopy (IFS), enzyme linked immunosorbent assay (ELISA), and their correlation were analyzed by agglomerative hierarchical clustering (AHC). SDS-PAGE results indicated that protein hydrolysis in dough was mainly governed by lactic acid bacteria. High-molecular-mass glutenin (HMM-GS) and some gliadins in SLB02012 were more effectively degraded than in SL20998. Further, FTIR and IFS analyses indicated that the molecular flexibility of glutens in SLB02012 increased. Moreover, SLB02012 exhibited the most marked decrease in α-helix content and the smallest α-helix/β-sheet content ratio among the 7 doughs. In addition, SY, SLB02012 and SYLB02012 showed blue shifts of λmax, while SL20998 showed a red shift of λmax, implying that the tertiary structure of the proteins was extended. In terms of the immunoreactivity of gliadins as measured by ELISA , SLB02012 showed a decrease of 35% compared with CK, while no significant difference was noted for SCA and SL20998 increased by 29.5%. AHC showed a good correlation between the secondary and tertiary structures and the immunoreactiviity of gliadins for each of these sourdoughs. Taken together, Lactobacillus plantarum B02012 can be used as a dominant bacterium in low allergenic fermented foods, and this study provides theoretical support for understanding the mechanism of action of lactic acid bacteria in reducing allergenicity.
Effects of Two Feeding Patterns on Oxidation Stability of Sunit Sheep Meat
LUO Yulong, LIU Chang, LI Wenbo, WANG Bohui, DOU Lu, DU Rui, YAO Duo, ZHAO Lihua, SU Lin, JIN Ye
2019, 40(17):  30-35.  doi:10.7506/spkx1002-6630-20180727-328
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The objective of this study was to investigate the oxidative stability of meat from Sunit sheep fed on two different diets: pasture and forage supplemented with concentrate mixture. The amount of lipid oxidation products, thiobarbituric acid (TBA) value, antioxidant ability, antioxidant enzymes activities and the expression of antioxidant genes in Biceps femoris muscles from sheep slaughtered at 12 months of age were determined and compared between the two feeding groups. The results showed that TBA value of meat from grazed sheep was significantly lower than that of forage plus concentrate-fed sheep (P < 0.001). Hexanal, heptanal, nonanal, 1-octen-3-ol and 2,3-octanedione were the major lipid oxidation products in both meat samples and their values were lower in meat from grazed sheep than in forage plus concentrate-fed sheep (P < 0.05), indicating that the latter had a higher degree of lipid oxidation. As for antioxidant properties, total antioxidant capacity (T-AOC, P < 0.01) and cupric reducing antioxidant capacity (CUPRAC, P < 0.05) of grazed sheep were significantly higher than those of forage plus concentrate-fed sheep. The same was true for the antioxidant enzymes, superoxide dismutase (SOD, P < 0.001), catalase (CAT, P < 0.05) and glutathione peroxidase (GPx, P < 0.05). These observations suggest that meat from pasture-fed sheep has higher antioxidant enzymes activities and as a result, its lipid oxidation can be effectively inhibited. Furthermore, the gene expression of SOD (P < 0.001), CAT (P < 0.05) and GPx (P < 0.05) in pasture-fed sheep was significantly higher than in forage plus concentrate-fed sheep, while the opposite was true for the gene expression of lipoxygenase (P < 0.001). In conclusion, this study provides molecular evidence that antioxidant capacity in meat from pasture-fed sheep was better than in forage plus concentrate-fed sheep.
Quality Change and Aroma Formation in Cured Fish during Traditional Sun Drying Processing
GU Saiqi, TANG Jinjing, ZHOU Xuxia, ZHENG Haoming, ZHOU Hongxin, DING Yuting
2019, 40(17):  36-44.  doi:10.7506/spkx1002-6630-20180716-201
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This study investigated the quality changes and aroma formation in cured grass carp during traditional sun drying processing. For this purpose, aerobic plate count (APC), total volatile basic nitrogen (TVB-N) content, acid value (AV), peroxide value (POV), thiobarbituric acid (TBA) value, color, texture, fatty acid composition as well as volatile flavor components were analyzed. The results showed that APC and TVB-N values of curded fish samples both increased with the expansion of sun drying time, reaching the maximum values of 4.73 (lg (CFU/g)) and 28.39 mg/100 g after four days, respectively, which shows the safety of cured fish products. In addition, with the increase of sun drying time, both AV and TBA values increased consistently, while POV increased at first and then decreased. According to the results of color and texture, the brightness of cured fish fell, while the redness and yellowness became higher during the sun drying processing. At the same time, the hardness and chewiness increased, likely contributing to the unique ‘dry’ aroma of cured fish. After 4 days, the relative percentage of polyunsaturated fatty acids (PUFA) in various lipid components obviously decreased in the following order: free fatty acids > phospholipids > triglycerides. A total of 70 volatile compounds belonging to 7 chemical classes were identified in cured fish samples, out of which 14 odor-active compounds including hexanal were selected. The summation of odor activity value (OAV) of volatile compounds increased from an initial level of 156.67 (salted fish without drying) to 252.88 after the completion of the sun drying, indicating that sun drying treatment may be crucial to aroma formation in traditional cured fish products. This study could provide a theoretical basis for improvement of the traditional production process of cured fish.
Effect of Adenosine Monophosphate-Activated Protein Kinase (AMPK) Activity on Glycolysis, Intramuscular Environment and Quality of Beef during Postmortem Aging
GAO Yongfang, GONG Yuxia, YANG Yayuan, HAN Ling, YU Qunli, ZHU Yueming, HAN Guangxing, BO Wenxi
2019, 40(17):  45-52.  doi:10.7506/spkx1002-6630-20180923-249
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With the aim of exploring the effect of adenosine monophosphate (AMP)-activated protein kinase (AMPK) on glycolysis, intramuscular environment and quality during the postmortem aging of beef muscle, changes in the transcription of AMPKα genes (PRKAA1 and PRKAA2), the expression of phosphorylated AMPK (P-AMPK) gene, AMPK activity, glycolysis, and quality traits in Longissimus dorsi muscle samples injected with 0.50 mol/L 5-amino-4-imidazolecarboxamide (AICAR) were measured during postmortem aging at 4 ℃. The results showed that between 24 and 120 h postmortem, AMPKα transcription, P-AMPK expression and AMPK activity in the AICAR treatment group were significantly higher than in the control group (P < 0.05); between 72 and 168 h, pH value and muscle glycogen content in the treatment group were significantly lower than in the control group (P < 0.05), whereas the reverse was true for lactic acid content (P < 0.05); between 12 and 168 h, L* and b* values, and the contents of ATP, ADP, AMP and IMP in the treatment group were higher than in the control group (P < 0.05), while a* value was significantly lower in the control group (P < 0.05); from 24 to 120 h, the treatment group exhibited a significant increase in cooking loss and myofibril fragmentation index but a significant decrease in shear force than did the control group (P < 0.05). These results showed that AICAR accelerated the postmortem aging process by activating AMPK and augmenting postmortem glycolysis, thus affecting intramuscular environment, meat color, shear force and muscle fiber microstructure. This indicates that AMPK activity has an important effect on muscle glycolysis and quality changes during postmortem aging, and meat quality can be controlled by regulating AMPK activity in postmortem muscles.
Effects of Different Temperatures on Lactate Metabolic Network Flux in Bow-Bound Carp and Bow-Bound Catfish
YUAN Shuai, PANG Guangchang
2019, 40(17):  53-58.  doi:10.7506/spkx1002-6630-20190414-178
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In this experiment, we studied the effects of different temperatures on the central metabolic network flux in bow-bound carp and catfish and determined their survival time without water at the optimum temperature determined in this study. Besides, we also explored the feasibility of low temperature dormancy and waterless live fish transportation for carp and catfish. At temperatures of 0, 4, 6, 10 and 15 ℃ (gradual cooling to each of the temperatures), the metabolic fluxes in the glycolytic pathway, the tricarboxylic acid cycle and the pentose phosphate pathway were determined in the serum of fish. The results showed that the pentose pathway flux, representing anabolism, was the highest among the central metabolic pathways for bow-bounded carp at 6 ℃ and for bow-bounded catfish at 4 ℃, while the lactate metabolism flux, representing catabolism and respiratory intensity, was the lowest which provides evidence that 6 ℃ is the optimal storage temperature and dormancy temperature for carp, and 4 ℃ for catfish. Furthermore, the survival experiment showed that the survival time of carp was 48.93 h on average and 77 h at best, while the survival time of catfish was 38.14 h on average and 70 h at best. The above results indicated the feasibility of waterless storage and transportation for live bow-bound fish. This study provides a new method and theoretical basis for inducing hibernation and sleep in fish.
Soymilk Processing Properties of Soybean Varieties Based on Fuzzy Sensory Evaluation
JIN Xuehua, GUO Shuntang, CHEN Chen, LUAN Xiaoyan, ZHANG Hui
2019, 40(17):  59-64.  doi:10.7506/spkx1002-6630-20180805-042
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Six soybean varieties from Heilongjiang province were selected to determine their own physicochemical characteristics (100-seed mass as well as protein, fat, calcium and phosphorus contents) and those of soymilk made from each of them (including yield). The sensory quality of soymilk was analyzed by fuzzy logic. Besides, the correlation between seed mass and soymilk sensory quality and soybean physicochemical indexes was analyzed. Soymilk made from ‘Zhonglong 606’ had the best sensory quality as demonstrated by its high sweetness, strong soybean-like flavor, good color, and weak beany odor and astringency. The varieties containing less than 40% protein content and higher oil content were more suitable to processing high-quality soymilk.
Molecular Mechanism of Rapid Gelatinization of Rabbit Skin Collagen
FENG Xin, SU Xianbo, MA Mingsi, MA Liang, DAI Hongjie, YU Yong, GUO Ting, ZHOU Hongyuan, ZHANG Yuhao
2019, 40(17):  65-71.  doi:10.7506/spkx1002-6630-20180903-023
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In order to analyze the molecular mechanism of rapid gelatinization of rabbit skin collagen, its acid-induced gelatinization process was simulated by YASARA software. The root mean square deviation (RMSD) indicated that acid treatment promoted the dissociation of non-helical subunits from the collagen molecules, while it had little influence on the conformation of single subunits. During the initial stage of acid treatment, the hydrogen bonds present in the triple helix region of rabbit skin collagen were rapidly destroyed in a short time. After simulation for 50 ns, the number of hydrogen bonds remained relatively stable, showing consistency with the actual results. Because of the destruction of hydrogen bonds during the initial stage of acid treatment, the triple helix structure was transformed into other secondary structures. With the increase of simulation time, the total relative content of α-helix and β-sheet increased firstly and then decreased, and the best degree of gelatinization was obtained at its highest level.
Rheological and Gelling Properties of Tremella fuciformis Polysaccharide and Gellan Gum Mixtures
LIU Tingting, YANG Jiadan, CAO Chenyu, ZHANG Yanrong
2019, 40(17):  72-78.  doi:10.7506/spkx1002-6630-20190122-257
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Rheological and gelling properties of Tremella fuciformis polysaccharide (TFP) and gellan gum (GG) at different concentrations (2.0, 1.6, 1.2, 0.8 and 0.4 g/100 mL) as well as their mixtures at different mass ratios (1.6:0.4, 1.2:0.8, 0.8:1.2 and 0.4:1.6) were studied, and the interaction mechanism between them was discussed. The results showed that the apparent viscosity and dynamic viscoelasticity of the TFP-gellan mixtures with increasing proportion of TFP, and so did the storage modulus (G’) and loss modulus (G”) increased. The area of thixotropic loop decreased with increasing proportion of TFP, indicating that TFP could improve the thixotropy of the mixtures. Texture profile analysis and water holding capacity (WHC) tests showed that gellan gum was the decisive factor for the gel strength and hardness of the mixed gels. TFP contributed significantly to the springiness, stickiness and WHC. Fourier-transform infrared (FTIR) spectroscopy showed that there was an interaction between gellan gum and TFP in their mixed system, and a gel network structure was formed as observed by cryogenic scanning electron microscopy.
Isolation, Identification and Antioxidant Activity of Stilbene Derivatives from Fermentation Broth of Photohabdus temperata SN259
WANG Baojuan, WANG Yu, SHI Danshu, XI Xuedong, YU Zhiguo
2019, 40(17):  79-84.  doi:10.7506/spkx1002-6630-20180821-226
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In an effort to search for efficient antioxidants from natural resources, nine compounds were purified from the fermented broth of Photohabdus temperata SN259 using solid phase extraction, column chromatography, preparative high performance liquid chromatography by bioassay-guided fractionation. Their structures were identified by nuclear magnetic resonance (NMR) and high performance liquid chromatography-mass spectrometry through comparison with literature data. Compound 1 was a new one, and compounds 2 and 3 were isolated and purified for the first time. The antioxidant activity of compounds 1–9 was evaluated by their effect on the oxidation stability of peanut oil. Compounds 1, 8 and 9 showed 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical-scavenging activity with half maximal effective concentration values of (4.95 ± 0.11), (6.17 ± 0.09) and (4.55 ± 0.07) μg/mL, respectively.
Effects of Different Glutinous and Japonica Rice Blends on Gelation Behavior and Quality of Rice Cake
HU Wenxuan, CHEN Jie, XU Fei, CHEN Ling
2019, 40(17):  85-95.  doi:10.7506/spkx1002-6630-20190115-157
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The gelatinization properties, rheological properties, Fourier transform infrared spectroscopy (FTIR) spectra and microstructure of glutinous (G) and japonica (J) rice blends at different ratios were studied. The gelation behavior was explored by analyzing storage modulus (G’), gelation velocity (?g) and gelation acceleration (αg) of the blend gels. The relationship of rice cake quality changes with the characteristics of the blend system was analyzed. The results indicated that the blend system was a weak gel system. The stability of hot paste and the gelling ability of cold paste considerably changed with the increase of glutinous rice, and the viscosity, breakdown and setback value decreased significantly (P < 0.05); the dynamic rheological properties G’ and ?g declined under both non-isothermal and isothermal conditions, whilst the opposite was true for the phase tangent (tan δ), activation energy (Ea) and αg. Meanwhile, in the frequency sweep, the tan δ curves of the blend systems with G/J ratio of 1:2.5–1:2.0 gradually became smooth in the low frequency range, while for the low-glutinous rice systems (G/J ratio = 1:3.0–1:5.0), the changes in gel properties reached a critical value at G/J ratio of 1:3.0, leading to the formation of a better network structure with higher water absorption rate and better gel stability. With increased proportion of glutinous rice, the consistency coefficient (K) from the Power-Law model and the thixotropic loop area decreased, and the flow characteristic index (n) increased, indicating good shear stability and thixotropy. As a result, in the gelatinization degree of rice cake decreased continuously, reaching a critical value of 90.48% at G/J ratio of 1:3.0. As indicated by the changes in peak area ratio at 997 cm-1/1 155 cm-1, 1 020 cm-1/1 155 cm-1, and 1 654 cm-1/1 155 cm-1 in the FTIR spectra, increased proportion of glutinous rice could enhance the water-binding capacity of the blend system, and the bound water molecules led to changes in the gelation behavior by interacting with the single helix structure of amylose and expanding the amorphous region. Therefore, the G/J ratio of 1:3.0 blend system formed a dense gel network structure without needle-like morphology and with uniform pore size distribution, and the resulting rice cake had the highest water absorption rate and elasticity.
Evolution of Aroma Components and Key Gene Expression during Postharvest Ripening of Banana (Musa ABB Pisang Awak)
ZHU Xiaoyang, LI Qiumian, LUO Jun, CHEN Weixin, LU Wangjin, LI Xueping
2019, 40(17):  96-103.  doi:10.7506/spkx1002-6630-20190101-007
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With the aim of gaining insights into the evolution of quality characteristics of banana (Musa ABB Pisang Awak) during postharvest ripening, the cultivar ‘Guangefen 1’ was used to investigate the changes in physiological quality, the changes in volatile aroma components with maturity and the changes in the expression patterns of the gene related to aroma synthesis during postharvest storage at room temperature (25 ℃). The results showed that fruit firmness decreased sharply within 2 days after harvest, and the contents of total soluble solids (TSS) and soluble sugar increased significantly. Full ripening was reached on the 6th day of storage. On the 8th day, fruit firmness was reduced to a very low level, and the contents of TSS, and total aroma substances were maximized while the maximum contents of TSS and amino acid occurred on the 6th day. A smaller number of volatile compounds were detected in immature bananas at lower levels, consisting mainly of C6–C9 aldehydes and alcohols along with a lesser amount of esters. The content of volatile compounds increased significantly with fruit ripening, including isoamyl isobutyrate, hexyl acetate, isoamyl acetate as esters, contributing to the unique aroma of Pisang Awak bananas. Expression analysis of the key genes involved in fruit aroma synthesis revealed that the expression of LOX (lipoxygenase), AAT (alcohol acyltransferase), ADH (alcohol dehydrogenase), BCAT (branched chain amino acid transferase) and HPL (hydroperoxide lyase) genes increased with fruit ripening and softening, and then rapidly decreased. However, the expression level of PDC (pyruvate decarboxylase) was higher during the earlier and later storage periods, but lower at the mid-ripening stage, which may closely relate to the high contents of aldehydes and alcohols in unripe and overripe bananas. This present work preliminarily revealed the change profiles of the main volatile substances during banana fruit ripening process and its relationship with fruit physiological activities, which could provide a theoretical basis for postharvest quality maintenance of Pisang Awak bananas.
Material Characteristics and Eating Quality of Trachinotus ovatus Muscle
XIONG Tian, WU Yanyan, LI Laihao, LIN Wanling, YANG Xianqing, HU Xiao, YANG Shaoling
2019, 40(17):  104-112.  doi:10.7506/spkx1002-6630-20180720-255
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In order to explore the material characteristics and eating quality of Trachinotus ovatus muscle, various indicators including body parameters, proportion of each body part and meat yield as well as myofibril diameter, texture, color, cooking loss percentage, drip loss percentage, water loss percentage, pH, basic chemical composition, protein composition, mineral element contents, fatty acid composition, amino acid contents and volatile flavor substances were measured and analyzed. The results showed that Trachinotus ovatus had high fullness but low meat yield, and so it had more processing wastes. The diameter of myofibrils was (77.84 ± 4.94) μm, and the meat was tender. Abdominal muscle had significantly higher hardness and chewiness than back and tail muscle as well the highest whiteness, thus being more suitable for the processing of ready-to-eat fish fillets. The moisture and crude fat contents in Trachinotus ovatus muscle were (71.65 ± 0.55)% and (8.74 ± 0.55)%, respectively. The contents of sodium and magnesium in Trachinotus ovatus muscle were slightly higher than in other fish. Meanwhile, Trachinotus ovatus muscle had a ratio among saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids close to 1:1:1, and an essential amino acid index of 93.51. Hexanal, furfural and 2-ethylhexanol were the major components of Trachinotus ovatus muscle. This study provides a rationale for diversified processing and utilization of Trachinotus ovatus.
Antimicrobial Activity of Citral against Vibrio parahaemolyticus
GUO Du, SUN Huihui, SUN Zheng, SUN Yi, XIA Xiaodong, SHI Chao
2019, 40(17):  113-120.  doi:10.7506/spkx1002-6630-20180727-330
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Effective prevention and control of Vibrio parahaemolyticus contamination in foods are of great significance for safeguarding public health. In this study, the minimum inhibitory concentrations (MICs) of seven plant-derived compounds (syringic acid, ferulic acid, chlorogenic acid, sulfur acid, protocatechuic acid, protocatechuic aldehyde and citral) against V. parahaemolyticus were measured by agar dilution method. Subsequently, citral was selected to investigate its effect on the growth curve, cell membrane potential, intracellular ATP concentration, cell membrane integrity and cell morphology of V. parahaemolyticus. The possible antimicrobial mechanism was deciphered. The results showed that citral had more potent antimicrobial effect against V. parahaemolyticus than the other six plant-derived compounds, and its MICs against V. parahaemolyticus ranged from 0.10 to 0.60 mg/mL. It could cause cell membrane depolarization, a decrease in intracellular ATP concentration and cell membrane integrity, and cell shrinkage and deformation. These findings suggest that citral can effectively inhibit the growth of V. parahaemolyticus and will have potnetial aplication in the food industry.
Effect of Citral on Mitochondrial Morphology and Function in Geotrichum citri-aurantii
LIU Miao, TAO Nengguo, XU Lingchun, WU Yufan, YANG Wenhao, JING Guoxing
2019, 40(17):  121-126.  doi:10.7506/spkx1002-6630-20181030-355
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This study investigated the effect of citral on mitochondrial morphology, adenosine triphosphate (ATP) content and the tricarboxylic acid (TCA) cycle in Geotrichum citri-aurantii. Scanning electron microscopy showed the mitochondria of G. citri-aurantii were distorted, collapsed and even ruptured after citral treatment, leading to leakage of intracellular ATP and a consequent increase in extracellular ATP. The activity of citrate synthase (CS), α-ketoglutarate dehydrogenase (α-KGDH), isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) as well as the content of citric acid, all of which are associated with the TCA cycle, decreased after citral treatment at its minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC). In short, citral can affect mitochondrial morphology and function in G. citri-aurantii, but the underlying mechanism needs to be further explored.
Effect of High-Humidity Thawing under Different Temperatures on Physicochemical Characteristics and Protein Properties of Frozen Pork
ZHU Mingming, PENG Zeyu, LU Sen, MA Changming, HE Hongju, WANG Zhengrong, MA Hanjun, KANG Zhuangli, ZHAO Shengming
2019, 40(17):  127-133.  doi:10.7506/spkx1002-6630-20180925-259
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This study was conducted to analyze the effect of different thawing temperatures (0, 4, 8 and 12 ℃) under high relative humidity (RH 90%) on the quality characteristics of frozen pork. Fresh pork and conventional low temperature thawing (4 ℃, RH 65%–73%) were considered as control. Thawing rate as well as physicochemical characteristics including water-holding capacity (WHC), tenderness, color, lipid oxidation (2-thiobarbituric acid reactive substances (TBARS) content), pH and freshness were measured and compared among various groups. Protein thermal denaturation and rheological properties were examined as well by a differential scanning calorimeter (DSC) and a rheometer, respectively. The results showed that compared with the conventional low temperature thawing, high-humidity low-temperature thawing could improve the thawing efficiency. The WHC, color and tenderness were improved and lipid oxidation was inhibited significantly (P < 0.05). Also, protein denaturation was reduced. As a result, high-humidity low-temperature thawing provided the best maintenance of fresh pork quality, and thawing at 4 and 8 ℃ was significantly better than at 0 and 12 ℃ as evidenced by improved WHC, color and tenderness, reduced lipid oxidation, lower degree of protein denaturation, and higher storage modulus G’. Therefore, thawing at 90% humidity and 4–8 ℃ could enhance the thawing efficiency, and maintain pork quality and could be more suitable for frozen pork.
Physicochemical Properties and Anticoagulant Activity of Heparin from Different Marine Organisms
DU Zhenxing, ZHOU Siyi, ZHONG Saiyi, CHEN Guanlan, CHEN Jianping,, CHEN Suhua,, HONG Pengzhi,
2019, 40(17):  134-140.  doi:10.7506/spkx1002-6630-20180903-027
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In this study, crude heparin was extracted from 9 marine organisms by enzymatic hydrolysis and then alcohol precipitation. The physicochemical properties and monosaccharide composition of the heparins were analyzed by ultraviolet spectroscopy, Fourier transform infrared spectroscopy and high performance liquid chromatography, and their anticoagulant activities were analyzed by in vitro experiments. The results showed that the heparin contents of the 9 crude heparin samples were 339.92 μg/mg for Penaeus vannaei heads, 239.15 μg/mg for Mactra antiquata, 234.85 μg/mg for Tegillarca granosa, 218.29 μg/mg for Sinonovacula constricta, 214.78 μg/mg for Meretrix meretrix L., 212.194 μg/mg for Tapes dorsatus, 68.52 μg/mg for Argopecten irradias, 61.48 μg/mg for Panopea abrupta, and 24.29 μg/mg for Ruditapes philippinarum. All of them, having pyranose rings, contained glucosamine, iduronic acid, and galacturonic acid. The in vitro experiments showed that the titers of the crude heparin samples were 67.1 U/mg for Mactra antiquata, 59.3 U/mg for Penaeus vannaei heads, 44.0 U/mg for Meretrix meretrix L., 39.2 U/mg for Tapes dorsatus, 35.0 U/mg for Sinonovacula constricta, 29.6 U/mg for Tegillarca granosa, 27.2 U/mg for Panopea abrupta, 27.1 U/mg for Argopecten irradias, and 24.1 U/mg for Ruditapes philippinarum. They exerted different anticoagulant activities through different pathways. This study provides a basis for the development of heparin from marine resources.
Evaluation of Juice Quality of Mid-Early Ripening Peach Varieties Based on Principal Component Analysis and Cluster Analysis
ZHANG Chunling, LIU Hui, LIU Jiechao, Lü Zhenzhen, YANG Wenbo, WANG Lirong, JIAO Zhonggao
2019, 40(17):  141-149.  doi:10.7506/spkx1002-6630-20190222-137
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The purpose of this study was to investigate the effects of different varieties and maturities of peach on the yield and quality of peach juice and to select the optimal variety for juice processing. A total of 45 peach juices from 15 mid-early ripening cultivars harvested at 3 maturities (I, II and III) were measured for 15 quality indicators including sugar, acid, total phenols and browning degree and comprehensive evaluation of their quality was investigated by conventional descriptive statistics, principal component analysis (PCA) and cluster analysis (CA). The results showed that quality indicators varied significantly among different peach cultivars and maturities. A total of 5 principal components were extracted through PCA, which represented 80.333% of the total variability. The first and second principal components (PC1 and PC2) were related to total sugar and acid concentrations. The third and fourth principal components (PC3 and PC4) were related to juice yield and color. The fifth principal component was related to total phenolic concentration and browning degree. In the PC1 versus PC2 score plot, the cultivars with higher comprehensive scores were clearly separated from those with lower comprehensive scores. In the PC1 versus PC3 score plot, the three maturities were clearly discriminated. CA classified the 45 samples into 6 groups on the basis of the measured parameters and the results were consistent with the PCA. The white-fleshed nectarine cultivar ‘Zhongyoutao 12’ harvested at maturity III ranked first in terms of comprehensive score among all these samples, while the white-fleshed peach cultivar ‘Zhongtao 1’ harvested at maturity I ranked last. Overall, peach juice from the yellow-fleshed cultivars had better quality, and the mid-ripening varieties had better quality than the early-ripening varieties. The quality of peach juice was better at higher maturity levels.
Hot-Air Drying of Red-Fleshed Pitaya: Kinetic Modelling and Quality Changes
CHU Wenjing, SHENG Danmei, ZHANG Nan, YU Yan, ZHANG Feng, YE Shuangshuang
2019, 40(17):  150-155.  doi:10.7506/spkx1002-6630-20190415-196
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In order to improve the hot-air drying efficiency and the product quality, the drying characteristics and quality changes of red-fleshed pitaya were evaluated at different slice thicknesses (6, 8, 10 and 12 mm) and drying temperatures (50, 60, 70 and 80 ℃). The results showed that higher temperature and thinner slices led to higher drying rate and shorter drying time. The Page model could well reflect the change of moisture ratio with thickness and drying temperature during hot air drying. The effective moisture diffusion coefficient of red-fleshed pitaya ranged from 3.537 4 × 10-10–19.942 6 × 10-10 m2/s. The hot-air drying activation energy for 6, 8, 10, and 12 mm thick pitaya slices were 32.985 7, 27.086 1, 26.889 4 and 17.792 9 kJ/mol, respectively. Higher total phenol content and antioxidant activity were observed for the dried product obtained at drying temperature of 70 ℃, slice thickness of 6 mm and drying time of 6 h. Drying temperature and slice thickness had no significant effect on the color of the product.
Food Engineering
Effects of Different Homogenization Processes on Fat Globule Membrane Protein Composition of Pasteurized Milk
ZHANG Ruiming, LIU Mengxia, WANG Yi, LIU Xiaohui, YU Jinghua
2019, 40(17):  156-161.  doi:10.7506/spkx1002-6630-20180927-306
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Changes in milk fat globule size and membrane protein composition determine the stability of fat globules, thereby affecting the stability of pasteurized milk during storage. In the present study, the effects of different preheating temperatures (50, 60 and 70 ℃) and homogenization pressures (20, 30, 40 and 45 MPa) on milk fat globule membrane (MFGM) proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis-polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the relationship between changes in MFGM protein composition and stability was explored using a stability analyzer. The results showed that homogenization affected the amounts but not types of MFGM proteins. The lowest levels of xanthine dehydrogenase/oxidase (XO) activity, butyrophilin (BTN) and adipophilin (ADPH) and the highest content of mucin 1 (MUC1) were obtained after preheating at 60 ℃. The contents of fatty acid binding protein (FABP) and periodic acid Schiff 6/7 (PAS6/7) decreased with the increase of preheating temperature, whereas the opposite was observed for cluster of differentiation 36 (CD36). XO, PAS6/7, BTN, ADPH and FABP reached the lowest values at a homogenization pressure of 40 MPa, and CD36 decreased with the increase of homogenization pressure. The analysis of MFGM protein composition showed that the contents of bovine serum albumin (BSA), αs1-casein (CN) and β-CN increased, with the largest increase being observed for BSA. From the above results, it can be inferred that homogenization can lead to the involvement of BSA, αs1-CN and β-CN in the composition of MFGM and have a positive effect on the stability of milk fat globules.
Preparation of Anthocyanin-Loaded Nanoparticles from Lycium ruthenium Murr. and Its Protective Effect on Oxidative Damage of EAhy926 Cells Induced by Oxidized Low-Density Lipoprotein
RAN Linwu, MI Jia, LU Lu, CHEN Fei, LUO Qing, LI Xiaoying, YAN Yamei, CAO Youlong, HUANG Qingrong
2019, 40(17):  162-168.  doi:10.7506/spkx1002-6630-20180710-134
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In order to improve the stability and activity of anthocyanins from Lycium ruthenicum Murr., chitosan (CS) and casein phosphopeptide (CPP) composite gel system was used to prepare anthocyanin-loaded CS-CPP nanoparticles. The preparation conditions were optimized to be sequential addition of an equal volume of 2 mg/mL anthocyanins followed by 0.20–0.30 mg/mL CS to 0.5% CPP solution at pH 4 with stirring at room temperature. As a result, the CS-CPP nanoparticles containing anthocyanins were spontaneously formed by ionic gelation, which had an average particle size of 215.3 nm, surface potential of 36 mV and encapsulation efficiency of 65.0%–72.2%. The in vitro release test showed that the release percentage of anthocyanins from the nanoparticles was 24.3%–64.2% at pH 7.0. The in vitro cell test demonstrated that the nanoparticles with anthocyanin concentrations of 100–200 μg/L significantly elevated the survival rate of EAhy926 cells exposed to oxidized low-density lipoprotein (ox-LDL) (P<0.05). Therefore, the CS-CPP composite gel system can encapsulate anthocyanins from Lycium ruthenicum Murr., and the nanoparticles containing anthocyanins have good antioxidant effect in vitro.
Effect of High-Pressure Homogenization on Vesicle Characteristics and Stability of Liposomes
TAI Kedong, ZHAO Sumao, YANG Ziheng, MAO Like, GAO Yanxiang, YUAN Fang
2019, 40(17):  169-177.  doi:10.7506/spkx1002-6630-20180916-158
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In order to investigate the effects of high-pressure homogenization and cholesterol on vesicle characteristics and stability of liposomes, liposomes were prepared by the traditional thin film hydration method combined with high-pressure homogenization. The vesicle size, polydispersity index, zeta potential and centrifugal stability of liposomes were determined as a function of homogenization pressure and cycles and cholesterol content, and a fluorescence probe and a transmission electron microscope were applied to explore the effect of cholesterol content on the membrane characteristics and morphology. The results indicated that increased homogenization pressure and cycles could significantly reduce the vesicle size and improve the centrifugal stability of liposomes. However, excessive pressure and cycles had no effect in further reducing the vesicle size and changing the zeta potential of liposomes. The lower the cholesterol content, the smaller the vesicle size and the denser the membrane structure of liposomes. Besides, cholesterol significantly decreased the micropolarity and surface hydrophobicity, and it reduced the membrane fluidity of liposomes as evidenced by increased degree of polarization. The centrifugal stability of liposomes decreased dramatically with the incorporation of too much cholesterol (soybean lecithin:cholesterol = 2:1, m/m) (P < 0.05). In conclusion, liposomes loading an appropriate amount of cholesterol (soybean lecithin:cholesterol = 3:1, m/m) have good centrifugal stability due to the stable microstructure of liposomal vesicles, which provides useful information for the encapsulation of bioactive compounds in the future.
Effect of Microfluidization on Protein Structure and Solubility of Soymilk Powder
LI Liang, ZHOU Yan, WANG Dongmei, FAN Jinyuan, WU Changling, ZHU Ying, LI Yang, JIANG Lianzhou, WANG Zhongjiang, FAN Zhijun
2019, 40(17):  178-182.  doi:10.7506/spkx1002-6630-20180918-199
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Microfluidization was introduced into the traditional wet process for preparing soymilk powder. After okara separation, soymilk was microfluidized at pressures of 0, 42.5, 89.0, 123.5 or 152.0 MPa. Our aim was to study the effect of microfluidization on the structure and solubility of soymilk powder protein. The results demonstrated that free sulfhydryl content, volume average particle size and surface hydrophobicity of the microfluidized samples were significantly higher than those of the untreated ones (P < 0.05). At a microfluidization pressure of 123.5 MPa, the protein surface hydrophobicity reached its the maximum value, an increase of 1.6 times compared with that of the untreated samples. Similarly, the content of free sulfhydryl groups reached its maximum level of 7.62 μmol/g, an increase of 24.96% compared with that of the untreated samples. Moreover, the soymilk powder produced had the smallest volume average particle size and particle size distribution width, and its maximum solubility was 79.47%. However, when the pressure was increased to 152.0 MPa, the solubility of the soymilk powder decreased.
Effect of Twin-Screw Extrusion on Physicochemical Properties and Quality Characteristics of Corn Flour
XIE Tian, SUN Hongrui, KANG Lining, LI Fenglin, TIAN Zhigang, LIU Xiangying
2019, 40(17):  183-189.  doi:10.7506/spkx1002-6630-20180714-180
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In order to study the effect of twin-screw extrusion on the physicochemical properties and quality characteristics of corn flour, a model SLG-30 twin-screw extruder was used to extrude 17 varieties of corn in Jilin province. Changes in the physicochemical properties and quality characteristics were analyzed before and after extrusion. The results showed that all varieties exhibited a decrease in protein content by 11.32%, in fat content by 29.88%, and in amylose content by 5.11% on average, as well as an increase in freeze-thaw stability by 58.90%, in gelatinization degree by 88.62%, in water-absorbing capacity by 77.03%, in water solubility by 73.57%, and in swelling power by 87.51% on average after extrusion. Correlation analysis showed that the degree of gelatinization was negatively correlated with fat, amylose and protein contents in extruded corn, but was extremely significantly positively correlated with water-absorbing capacity and water solubility (P < 0.01); amylose and fat contents were both extremely significantly negatively correlated with freeze-thaw stability, gelatinization degree, water-absorbing capacity and water solubility (P < 0.01). Therefore, extrusion treatment has a negative impact on the physicochemical properties of corn flour, but it can significantly improve the processing properties and eating characteristics of the product.
Effect of High-Voltage Electrostatic Field on Bioactive Components and Antioxidant Activity of Peanut Sprouts
ZHANG Qian, ZHENG Yaying, LI Yan, JIANG Zhengqiang, LIU Haijie
2019, 40(17):  190-195.  doi:10.7506/spkx1002-6630-20180706-087
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The effect of high-voltage electrostatic field (HVEF) treatment on the contents of bioactive components and antioxidant activity in peanut sprouts during germination was investigated in this study. The results indicated that the average hypocotyl length of peanut sprouts treated by 400 kV/m HVEF was significantly greater than that of the control. The total phenol content of peanut sprouts treated with 400 kV/m HVEF was enhanced by 22.09% when compared with the control on the 7th day of germination. The maximum total flavonoid content appeared on the 5th day. At this time, the total flavonoid content of peanut sprouts treated with 300 kV/m HVEF was 19.91% higher than that of the control (P < 0.05). The resveratrol contents of peanut sprout treated with 400 and 450 kV/m HVEF were significantly increased by 32.46% and 20.94% relative to the control (P < 0.05), respectively. The antioxidant capacity of peanut sprouts subjected to HVEF treatment at 300 and 400 kV/m was stronger than that of the control during the whole germination period. Hence, HVEF pretreatment could improve the contents of several bioactive compounds and consequently health benefits in peanut sprouts.
Nutrition & Hygiene
Antioxidant Activity and Immunomodulatory Effect of Betalain in Mice
BAO Xiaowei, HAN Haixia, DU Guangming, WEI Chenye, ZHU Xuan, REN Wei, ZENG Lanjun, ZHANG Yatao
2019, 40(17):  196-201.  doi:10.7506/spkx1002-6630-20180930-344
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Objective: To explore the regulatory effect of betalain on antioxidant status and immune function in mice. Methods: Betalain was extracted and separated from red beet (Beta vulgaris var. rubra). Three groups of male KM mice were used: blank group and high, medium and low-dose betalain groups. After 15 days of oral administration, the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and the concentration of malondialdehyde (MDA) in serum were determined in each group. The changes in immune organ index, splenic lymphocyte proliferation, serum hemolysin, natural killer (NK) cell activity and the phagocytic function of peritoneal macrophages were measured. The results showed that the activities of SOD and GSH-Px in the serum of mice were significantly increased in the high and middle-dose groups and MDA concentration was significantly decreased compared with the blank group (P < 0.05). The thymus index of mice in each dose group was higher than that in the blank group (P < 0.05), and the spleen index and corrected clearance index of mice in the high and medium-dose groups were both significantly higher than those in the blank group (P < 0.05). Also, the splenic lymphocyte proliferation ability, serum hemolysin and NK cell activity in the two dose groups were significantly different from those in the blank group (P < 0.05). It was concluded that betalain could significantly improve antioxidant status and specific and nonspecific immunity of mice.
Immunoregulatory Effect of Soybean Protein Isolate-Pleurotus eryngii Polysaccharide Conjugate on RAW264.7 Cells
WU Yiliang, ZHONG Lei, MA Ning, PEI Fei, MA Gaoxing, HU Qiuhui
2019, 40(17):  202-207.  doi:10.7506/spkx1002-6630-20190320-267
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In the present study, we investigated the effect of a covalent conjugate between soybean protein isolate (SPI) and Pleurotus eryngii polysaccharide (PEP) conjugate on cell viability, neutral red phagocytosis activity, nitric oxide content, and the secretion and mRNA expression of cytokines in RAW264.7 cells. Untreated cells as well as those treated with lipopolysaccharides (LPS), PEP or an SPI-PEP physical mixture were used as controls. The results showed that SPI and PEP as well as their conjugate and mixture at concentrations of 0–50 μg/mL had no significant effect (P > 0.05) on the cell proliferation rate. The conjugate increased neutral red phagocysis activity, NO production and the secretion and mRNA expression of tumor necrosis factor α, interleukin 1β (IL-1β) and IL-6 at 100 μg/mL. In conclusion, soybean protein isolate-Pleurotus eryngii polysaccharide conjugate could enhance immune functions in RAW264.7 cells in a dose-dependent manner. The glycosylation modification of soybean protein can provide a basis for the deep processing and development of cereal proteins.
Effects of Feeding and Delivery Modes on Intestinal Flora of Infants of different Ages Investigated by High-Throughput Sequencing
YANG Li, GE Wupeng, LIANG Xiuzhen, ZHANG Jing, WANG Xining, ZHANG Xue, CUI Xiuxiu, GONG Sheng
2019, 40(17):  208-215.  doi:10.7506/spkx1002-6630-20180612-182
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High-throughput sequencing technology was used to analyze the difference in the intestinal flora of infants of different age groups (I: 0–6 months old, II: 6–12 months old, III: 12–36 months old) subjected to different feeding methods (breast milk, goat milk, and cow milk) and different delivery modes (vaginal delivery and cesarean section). A total of 54 fecal samples were collected and used to determine the composition of intestinal flora with a special focus on the influence of goat milk infant formula on the intestinal flora. Meanwhile, the abundance and diversity of intestinal flora were analyzed and the abundance of dominant bacteria was compared. By doing so, this study aimed to provide technical support for the development of new infant formulas and scientific feeding of infants. The results showed that different delivery modes had different effects on the intestinal microbiota of infants of the same age with the same feeding pattern. At the phylum level, the relative abundance of Actinobacteria, Firmicutes, Bacteroidets and Proteobacteria were 43.74%, 25.48%, 17.93% and 9.71%, respectively in breasted infants vaginally delivered, and 40.83%, 44.31%, 3.81% and 11.01%, respectively in those born by caesarean section in the 0 to 6 month age group; 41.44%, 43.84%, 8.38% and 6.27%, respectively in goat milk infant formula-fed infants vaginally delivered, and 60.76%, 24.85%, 8.66% and 5.70%, respectively in those born by cesarean section in the 6 to 12 month age group; 26.58%, 47.73%, 24.07% and 1.58%, respectively in infant formula-fed infants vaginally delivered, and 34.77%, 51.94%, 11.10% and 2.16% in those born by cesarean section in the 12 to 36 month age group. For the same delivery mode and the same age, the composition of intestinal flora in infants fed on goat milk infant formula was more diverse and the abundance of dominant bacteria was higher, Actinobacteria accounting for 62.98% and 43.74% of the total abundance in vaginally delivered infants fed on goat milk infant formula and breastmilk in the 0 to 6 month age group, respectively, and Bacteroidets accounting for 43.84% and 35.71% for those in the 6 to 12 month age group, respectively. For infants delivered by the same route and fed by the same method, the composition of intestinal flora changed significantly with age (P < 0.05). The intestinal flora in the 6 to 12 month age group was more diverse than in the other age groups and Lactobacillales had the highest relative abundance in this age group and was the dominant bacteria, with significant differences being observed compared with other bacteria detected. This study provides a rationale to protect infant health and defend against metabolic diseases.
Anti-fatigue Effect of Glutathione in Mice and Its Underlying Mechanisms
NIU Zhenzhen, GUO Yaoyao, ZHAO Xinling, JIN Hong, GONG Yanling
2019, 40(17):  216-222.  doi:10.7506/spkx1002-6630-20180606-058
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This study explored the anti-fatigue effect of glutathione (GSH) in mice and its underlying mechanisms. Mice were randomly divided into normal control, exercise-induced fatigue, GSH treatment and American ginseng (AG) control groups. The mice in the treatment groups were intragastrically administered with GSH (0.2, 0.4 and 0.8 g/kg mb) and AG (0.6 g/kg mb) daily before exercise, respectively, while the mice in the remaining groups were given normal saline. The experiment lasted for 10 days. The mice were sacrificed immediately after exhaustive swimming on the last day of the experiment to determine biochemical markers. The number of c-fos positive cells in the paraventricular nucleus (PVN) of the hypothalamus was measured by immunohistochemically. Compared with exercise-induced fatigue group, both GSH and AG significantly prolonged exhaustive swimming time (P < 0.05). Furthermore, the levels of blood lactic acid (LAC), lactic dehydrogenase (LDH) activity, blood urea nitrogen (BUN) and creatine phosphokinase (CK) activity in serum as well as malondialdehyde (MDA) content in liver decreased significantly (P < 0.05), while glycogen content and superoxide dismutase (SOD) activity in liver significantly increased in the GSH-treated mice (P < 0.05). With regard to central fatigue, GSH significantly increased dopamine (DA) content (P < 0.05), and decreased 5-hydroxytryptamine (5-HT) content in the hypothalamus and induced the over-expression of c-fos positive cells in the PVN. While the anti-fatigue effect of high-dose GSH was not significantly different from that of AG (P > 0.05), GSH had obvious anti-fatigue effect in mice via peripheral and central mechanisms, and could be used as a drug candidate for relieving exercise-induced fatigue.
Effects of Quercetin, Kaempferol, and Rutin on High-Fructose and High-Fat Diet Induced Metabolic Syndrome in Rats
LI Bowen, ZHAO Liang, WANG Yong, ZHAO Nan, JI Baoping, CHENG Qian, ZHOU Feng
2019, 40(17):  223-233.  doi:10.7506/spkx1002-6630-20180601-015
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In the present study, the protective effects of flavonoids against metabolic syndrome (MS) in rats were investigated. Quercetin, kaempferol, and rutin were chosen because of their similar molecular structures. Rats were divided into five groups according to their diets: basal diet, high-fructose and high-fat diet (HFFD) (model group (MG)), HFFD with quercetin (2.6 mmol/kg mb), HFFD with kaempferol (2.6 mmol/kg mb), and HFFD with rutin (2.6 mmol/kg mb). Diet intervention lasted for 13 weeks. Serum biochemical indicators, hepatic antioxidant capacity, pro-inflammatory cytokines, and hepatic histological changes were determined. Quercetin significantly reduced the level of alanine transaminase to (25.00 ± 0.67) U/L compared with MG ((33.00 ± 0.67) U/L) (P < 0.05). Kaempferol was effective in reducing body mass gain and fat accumulation. The final body mass of kaempferol-treated rats decreased by 10.7% at average relative to MG. Rutin decreased the area under the curve (AUC) during oral glucose tolerance test (OGTT) from (13.80 ± 0.45) mmol/(L·min) in MG to (12.10 ± 0.13) mmol/(L·min) (P < 0.05). Dietary flavonoids can be used in the prevention of MS, but these compounds play different biological roles in spite of their similar structures.
Packaging & Storage
Effect of Temperature Change on Quality of Turbot (Scophthal musmaximus) under Simulated Logistics Conditions
SHANG Feifei, LI Tingting, YANG Yaru, YU Haifeng, WANG Dangfeng, XIE Jing, LI Jianrong
2019, 40(17):  234-239.  doi:10.7506/spkx1002-6630-20180913-124
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Two cold chain logistics processes for frozen turbot including business to customer (B2C, model I) and business to business (B2B, model II) were simulated. Changes in the whiteness, water-holding capacity (WHC), thiobarbituric acid (TBA) value, total volatile basic nitrogen (TVB-N) content, sensory score and texture of vacuum-packaged and air-packaged turbot were measured during 24 days. The results showed that model I was more conducive to the quality of turbot, and vacuum packaging was better than air packaging, while model II could not maintain the quality of turbot due to frequent temperature fluctuations. Accordingly, model I was a better cold chain logistics process, involving 20-day cold-chain storage and transportation at ?20 ℃ followed by 3-day selling at ?4 ℃ and then 1-day refrigerated storage at 4 ℃, and vacuum packaging could maintain better freshness of turbot.
Effects of Thawing in NaCl and CaCl2 Solutions at Different Concentrations on the Quality of Frozen Tuna
YU Wenhui, WANG Jinfeng, XIE Jing
2019, 40(17):  240-246.  doi:10.7506/spkx1002-6630-20190303-026
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NaCl and CaCl2 solutions at different concentrations were used to thaw frozen tuna pieces. In order to explore the effects of the thawing methods on tuna quality, the thawing time, color difference, salt soluble protein content and texture were analyzed, and the microstructure of tuna meat after thawing was observed. The results showed that with the increase of salt concentration, the thawing rate and salt infiltration rate increased gradually for each salt. Tuna thawed in 3% CaCl2 had good water retention, desired salt-soluble protein content and texture, and its microstructure was best maintained. To sum up, thawing in 3% CaCl2 had a reduced effect on the quality and could maintain better freshness of tuna.
Effect of Different Freezing Methods on the Quality of Freshwater Fish
ZHOU Junpeng, ZHU Meng, ZHANG Wei, WANG Lan, SHI Liu, ZHANG Yi, HUANG Huang, XIONG Guangquan, WU Wenjin, LI Xin, QIAO Yu, DING Anzi, LIAO Li
2019, 40(17):  247-254.  doi:10.7506/spkx1002-6630-20180913-137
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In order to study the effects of different freezing methods on the quality of freshwater fish, channel catfish, Lateolabrax japonicus and mandarin fish were frozen by plate freezing at –30 ℃ (treatment 1), in a refrigerator at –80 ℃ (treatment 2) or with liquid nitrogen at –80 ℃ (treatment 3). The thawing loss percentage of frozen fish was measured as well as pressure-induced water loss percentage, cooking loss percentage, pH, color, toughness, microstructure, water distribution after thawing. The results showed that the thawing loss rate, pressure-induced water loss percentage and cooking loss percentage as well as the space between cells in each fish species with freezing treatments 1, 2 and 3 decreased in that order, whereas the toughness increased. Nevertheless, there was no significant difference in pH among the three treatments. Treatment 1 showed the highest whiteness, yet there was no significant difference between the other two treatments (P > 0.05). Low-field nuclear magnetic resonance (NMR) showed that the content of bound water (T22) in each fish species with treatment 1 was decreased compared with the remaining treatments, whereas the content of free water (T23) was significantly increased (P < 0.05). For each treatment, there were no significant differences in all parameters investigated among fish species. From the viewpoint of both freezing rate and quality maintenance, freezing in a refrigerator at –80 ℃ and with liquid nitrogen at –80 ℃ were more suitable for freshwater.
Inhibitory Mechanism of Natamycin on Browning of Fresh-Cut Agaricus bisporus
XU Dongying, GU Sitong, ZHOU Fuhui, CHEN Chen, JIANG Aili, HU Wenzhong
2019, 40(17):  255-262.  doi:10.7506/spkx1002-6630-20180926-284
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In order to explore the physiological mechanism for the inhibition of its browning by natamycin, fresh-cut Agaricus bisporus was dipped in deionized water, 0.1 g/kg natamycin alone or in combination with 10 g/kg D-sodium ascorbate for 5 min, and then stored at 4 ℃. Physiological indexes?such as polyphenol oxidase (PPO) and tyrosinase (TYR) activities, and free radical scavenging capacity were analyzed during storage. The results showed that natamycin alone and in conjunction with D-sodium ascorbate effectively suppressed the decrease of hardness and the increase of mass loss, respiratory intensity and relative conductivity in fresh-cut mushroom, reduced the total number of molds and yeasts, and delayed the increase of PPO and TYR activities. Meanwhile, both treatments maintained the contents of VC, and reduced glutathione (GSH), total phenols and hydroxyproline (HYP) and the activities of glutathione reductase (GR) and phenylalanine ammonialyase (PAL). Hence, the two treatments were able to maintain higher levels of antioxidant enzyme activity, free radical scavenging capacity and total antioxidant capacity, thereby inhibiting browning and?prolonging the shelf-life of fresh-cut Agaricus bisporus. The combined treatment was more effective than natamycin alone.
Effect of Cinnamaldehyde Fumigation on Antioxidant Capacity and Polyamines in Shiitake Mushroom
QIAN Xiaochen, LIN Kaili, HUANG Qi, WEN Xiaoli, JIANG Tianjia, ZHENG Xiaolin
2019, 40(17):  263-269.  doi:10.7506/spkx1002-6630-20180918-192
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In order to explore the effect of cinnamaldehyde fumigation on antioxidant capacity and free polyamines in Lentinus edodes, the cultivar ‘Xianggu 808’ was chosen to undergo cinnamaldehyde fumigation at different concentrations (0, 8, 40 and 80 nmol/L in 30% ethanol). The contents of total phenols and ascorbic acid (AsA), the activity of ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR), 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging capacity, total antioxidant capacity and free polyamine content were assayed in the samples. As a result, after storage for 30 days at 4 ℃, the activity of antioxidant enzymes (APX, CAT, SOD and GR), ABTS cation radical scavenging capacity and total antioxidant capacity of all treatment groups were higher than those of the control group, and the best effect was observed with 40 nmol/L cinnamaldehyde. However, cinnamaldehyde treatment had little effect on total phenol content. In addition, the free putrescine content of each treatment group was higher than that of the control group, while the contents of free spermidine and free spermine were lower than those of the control group. Therefore, cinnamaldehyde fumigation treatment can effectively improve antioxidant capacity and stress resistance in shiitake mushroom. This study provides a scientific basis for the application of cinnamaldehyde fumigation in browning control and preservation of fruits and vegetables.
Preparation of Chitosan/Curcumin/γ-Polyglutamic Acid Edible Composite Film and Its Preservative Effect on Bacon and Sausage
LI Tianmi, QU Sijia, HAN Junhua
2019, 40(17):  270-276.  doi:10.7506/spkx1002-6630-20180910-095
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Edible composite films were prepared from chitosan (CS) and γ-polyglutamic acid (γ-PGA) as film-forming materials with added curcumin (Cur). The thickness, water solubility, transparency and surface structure of the films were studied, and the antibacterial effect against bacteria on the surface of bacon and sausage was evaluated. The results showed that addition of γ-PGA reduced the film thickness and increased water solubility. Under scanning electron microscopy, the CS/Cur/γ-PGA film showed a compact surface. The Fourier transform infrared (FTIR) spectra of the pure and composite films indicated that there was an interaction among CS, Cur and γ-PGA in the mixed solution. The CS/Cur/γ-PGA composite film was applied to the surface coating of bacon and sausage, and it was found that the sensory quality of the samples treated with it was superior to that of commercially available wrap film packaging after storage under the condition of 28 ℃ and 50% relative humidity for 3 days. The total number of colonies in the composite film group was 1 (lg(CFU/g)) lower than the commercially available wrap film packaging group. The edible composite film has the potential to play a positive role in food preservation.
Effects of ε-Polylysine and L-Ascorbic Acid on the Quality of Fresh-Cut Spinach
YU Jie, XIE Jing
2019, 40(17):  277-283.  doi:10.7506/spkx1002-6630-20181225-299
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In order to investigate the effects of ε-polylysine and L-ascorbic acid treatments in preserving the quality of fresh-cut spinach, 16 treatment groups were designed with none, and ε-polylysine and/or L-ascorbic acid at different concentrations. Out of these, groups B (0.05 g/L ε-polysine), E (10 g/L L-ascorbic acid) and K (0.05 g/L ε-polylysine + 10 g/L L-ascorbic acid) were selected for their longer shelf life. The antimicrobial effects of the three treatments on the bacteria present on fresh-cut spinach were evaluated as well as their effects on the antioxidant enzyme activities and physicochemical quality of fresh-cut spinach. The results showed that antibacterial effects of the treatments were in the decreasing order of group K > group B > group E while their effects in regulating reactive oxygen metabolism were in the decreasing order of group K > group E > group B. In conclusion, the combined treatment had a synergistic effect and extended the shelf life of fresh-cut spinach up to 12 days, while 0.05 g/L ε-polylysine treatment prolonged the shelf life to 11 days through its antibacterial effect and 10 g/L L-ascorbic acid prolonged the shelf life to 10 days by improving active oxygen metabolism.
Phenolics in Wines II: Progress in Research on Copigmentation and Bioactivities
ZHAO Xu, ZHANG Xinke, CHEN Xinjun, ZHANG Shanshan, HE Fei
2019, 40(17):  284-294.  doi:10.7506/spkx1002-6630-20180916-160
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In recent years, the consumption of wine in China has remained a rapid growth, and wine is becoming one of the most popular alcoholic beverages. Besides its unique flavor, the appealing color and bioactivity of wine especially red wine also attract a lot of consumers. Different from other alcoholic beverages, wine contains plentiful phenolic compounds which contribute to the mellow taste and bright appearance. Phenolics in wine have been reported for their health benefits. This paper describes the bioactivity of main phenolic compounds in wine, and summarizes the phenomena of copigmentation that is vital for the color performance of red wine (with respect to history of research, typical types and influencing factors), in order to provide some practical and theoretical guidance for sustainable and healthy development of the wine industry in China.
Recent Progress in Development and Application of Proteins from Fish Viscera
ZHENG Ziyi, LI Lin, SU Dan, LI Guanghui
2019, 40(17):  295-301.  doi:10.7506/spkx1002-6630-20180923-248
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With the increased consumption of fish in China, a large number of by-products are generated. Fish viscera are one of the most important by-products of fish processing. In the present article, we review the state of the art of processing technologies for proteins and peptides from fish viscera. Meanwhile, the physicochemical properties and functional characteristics of the products developed such as active peptides, bacteriocins, biodegradable films, peptones and enzymes are summarized. Hopefully, this review will provide new ideas for the exploitation and utilization of fish viscera for their potential value.
Progress in Understanding the Mechanism of Exercise-Induced Fatigue and Its Regulation by Soybean Peptide
WU Liangwen, CHEN Ning
2019, 40(17):  302-308.  doi:10.7506/spkx1002-6630-20190118-219
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Health has aroused increasing concerns among people. More and more people have begun to take various exercises for health promotion. Therefore, exercise is becoming increasingly important in people’s daily life. All people, whether they are young or old, should take proper exercises based on their health status. However, excessive exercise can lead to physical discomfort and even physical fatigue, thereby influencing working efficiency, and even causing various physical injuries and damaging health. In this article, we describe the signaling pathways related to exercise fatigue at the molecular level. Meanwhile, we systematically discuss the association of exercise fatigue with the synthesis of skeletal muscle proteins, reactive oxygen species-mediated skeletal muscle protein degradation, and glycogen metabolism in skeletal muscles. Moreover, given the advantages of soybean polypeptide such as ease of absorption, rich nutrition, strong antioxidant capacity and rapid regulation on blood glucose level, we also present theoretical evidence for the potential of soybean polypeptide as a nutritional supplement to alleviate exercise fatigue on the basis of the existing experimental data.
Progress in Research of Functional Microbes in Xiaoqu, a Chinese Traditional Fermentation Starter for Liquor and Rice Wine
WANG Chunxiao, TANG Jiadai, WU Xinying, ZHOU Hongxiang, QIU Shuyi
2019, 40(17):  309-316.  doi:10.7506/spkx1002-6630-20180901-004
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The mining and application of functional microbes have become the focus of common concern to academia and industries in the field of brewing engineering. Of the articles regarding functional microbes in Jiuqu, a family of Chinese traditional fermentation starters for liquor and rice wine (including Daqu and Xiaoqu) that have been published over the past decade in the China National Knowledge Infrastructure (CNKI) and the Web of Science databases, more than 400 articles are about Daqu, while only less than 50 articles are about Xiaoqu. This review first summarizes the definition, history and current application of Xiaoqu. It then reviews the current status of studies on the species, screening methods, functional components and application value of functional microbes in Xiaoqu. The metabolic mechanisms of major functional components in functional yeasts are specially discussed. The aim of this review is to provide a rationale for further research and industrial application of functional microbes in Xiaoqu.
Recent Progress in the Application Shellac as a Natural Edible Wall Material in the Microencapsulation of Functional Ingredients
HUANG Xue, ZHANG Hui, PENG Shuyue, ZHAO Meng, FANG Yapeng
2019, 40(17):  317-324.  doi:10.7506/spkx1002-6630-20180917-182
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Shellac is an emerging wall material for the microencapsulation of functional ingredients, which is natural, non-toxic and biodegradable. It has special solubility (insoluble in neutral and acidic solutions, but soluble in alkaline solution), good film-forming ability and special thermal properties, which makes shellac an excellent material for acid resistance, moisture barrier and controlled release of functional ingredients in the intestine. This review first summarizes the chemical components and physiochemical properties of shellac. It then reviews the application of shellac in the microencapsulation of representative functional ingredients in the food and pharmaceutical industries including probiotics, vitamin, natural colorant, lipid, protein and drug, with focus on encapsulation techniques such as extrusion, emulsification, phase separation, electrospray and electrospinning. Finally, some directions for further studies of shellac and its encapsulation are presented.
Progress in the Understanding of the Mechanism by Which Inulin Regulates Energy Metabolism Disorders
HU Ting, LI Jian, ZHANG Yu, WANG Hongwei, ZHAO Xin, DING Yangping, SUO Huayi
2019, 40(17):  325-330.  doi:10.7506/spkx1002-6630-20180904-032
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Due to the popularity of high-fat diet, the global prevalence of obesity and its metabolic comorbidities has increased considerably over the past several decades and has become a major public health problem worldwide. Inulin plays an important role in preventing the occurrence and development of energy metabolism disorders and metabolic diseases. This paper focuses on the mechanism by which inulin regulates host energy metabolism disorders from four aspects, including improving intestinal flora imbalance, regulating intestinal microbial metabolites, reducing the host inflammatory state and influencing of related enzyme activities and gene expression. Hopefully, this paper will provide a basis for further research and applications of inulin.
Recent Progress and Application Prospects of Antifreeze Peptides in Food Industry
CHEN Xu, CAI Xixi, WANG Shaoyun, YANG Fujia, WU Jinhong
2019, 40(17):  331-337.  doi:10.7506/spkx1002-6630-20190303-025
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Antifreeze peptides are a class of small proteins or protein hydrolysates that can protect the organism from harm when it is frozen or sub-frozen. Antifreeze peptides have attracted great research interest in recent years because of their incomparable advantages over traditional commercial cryoprotectants and natural antifreeze proteins. This paper reviews the current status of research on antifreeze peptides with a focus on their properties, characteristics, mechanisms of action and applications in the food industry. Furthermore, some prospects for the future development and applications of antifreeze peptides are discussed.
A Literature Review of Ultrasonic Effects in Extraction of Phenolic Compounds from Fruits and Vegetables
WANG Pengxu, CHENG Chuanxiang, MA Yaqin, ZHANG Zhen, JIA Meng
2019, 40(17):  338-347.  doi:10.7506/spkx1002-6630-20180718-228
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The advantages of ultrasonic effects in enhancing the extraction of phenolic compounds from fruits and vegetables are reviewed in this paper, as well as the possible degradation reactions caused by it and its impact on the stability of phenolic compounds. In addition, the current commercial applications of ultrasound-assisted extraction of phenolic compounds from fruits and vegetables are also summarized. The aim of this review is to promote the effective application and rapid development of ultrasound-assisted extraction of phenolic compounds from fruits and vegetables in the food industry.
Recent Progress on Nanoparticles in Lateral Flow Immunochromatographic Strip
TIAN Yachen, WANG Shujuan, MA Lan, XIE Manman, XU Dongpo, LIU Cheng, DING Chengchao, GUO Liang, FANG Shuiqin, WANG Xiang, QIU Jingxuan, DONG Qingli, LIU Qing
2019, 40(17):  348-356.  doi:10.7506/spkx1002-6630-20180819-194
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Lateral flow immunoassay (LFIA), which combines the excellent separation ability of chromatography with the high specificity and sensitivity of conventional immunoassays, has served as an ideal platform for quantitative and sensitive on-site detection and played a significant role in food safety detection. The label is one of the key determinants of the sensitivity of LFIA. At present, the detection performance of LFIA is mainly enhanced by using nanoparticles (NPs) as labels including colored, luminescent and magnetic NPs. This paper is aimed to summarize the recent advances in the development of nanoparticle-based lateral flow immunochromatography. The application of various types of nanoparticles to improve the analytical performance is elaborated. This review is expected to provide powerful technical support for the selection of suitable nanoparticles for LFIA.
Current Status of Bacterial Contamination during Egg Storage and Its Effect on Egg Quality
CHEN Lili, SHEN Tianyu, LIU Jin, CHEN Huan, ZHANG Lizhao
2019, 40(17):  357-363.  doi:10.7506/spkx1002-6630-20180830-357
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As a natural nutritious food, egg is rich in proteins, amino acids, minerals, vitamins and other nutrients needed by the human body. However, the rich nutrients in egg make it a breeding ground for bacteria. The pathogenic bacteria of egg-borne infectious diseases such as Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes can produce poisonous and harmful substances that cause food poisoning and bring harm to human health. The non-pathogenic spoilage bacteria such as Enterobacter, Enterococcus and Pseudomonas can change food composition and reduce the nutritional value, the direct consumption value and the processing and application potential of foods. In this paper, the species and invasion pathways of bacterial contamination during egg storage, and the quality changes of contaminated eggs caused by bacterial growth, multiplication and metabolism are summarized, with the aim of providing further insights into the microbial and biochemical aspects of egg spoilage and also providing a rationale for developing specific strategies to control egg spoilage, prolong the shelf-life of eggs, and ensure food safety.