Table of Content

15 June 2024, Volume 45 Issue 11
Basic Research
Principal Component Analysis and Comprehensive Evaluation of Quality Traits in Post-ripening Corn Kernels
CAO Yong, XU Xiuying, CAI Dan, LIU Huimin, ZHANG Hao, ZHAO Chengbin, ZHENG Mingzhu, LIU Jingsheng
2024, 45(11):  1-7.  doi:10.7506/spkx1002-6630-20230724-264
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The purpose of this study was to evaluate the physiological characteristics and nutritional quality of corn kernels during the post-ripening stage. Using principal component analysis (PCA), this study analyzed and comprehensively evaluated 14 physiological and quality traits of post-ripening corn kernels from two varieties (Zhengdan 958 and Xianyu 335), including water content and state, respiratory rate, soluble sugar content, α-amylase activity, catalase (CAT) activity, peroxidase (POD) activity, hexokinase (HK) activity, isocitrate dehydrogenase (IDH) activity, fatty acid value, starch content, 1 000-grain mass and rapid digestible starch (RDS) content. The results showed significant variations in various quality traits of corn grains during the post-ripening process (P < 0.05). PCA extracted three principal components, namely storage intolerance factor, yield factor and digestive characteristic factor, which explained 53.436%, 18.466% and 12.857% of the total variance, respectively, 84.759% in total. The post-ripening quality and time of corn could be determined according to the changes of F-value. The post-ripening time of newly harvested corn grains from Zhengdan 958 and Xianyu 335 were 50 and 30 days, respectively. The results of this study could provide a reference for the evaluation of the post-ripening quality of newly harvested corn and the processing and utilization of corn.
Comprehensive Evaluation of Genetic Characteristics of Wheat Gluten Protein
JIANG Lanfang, MAO Hang, WANG Xue, CAO Yong, HAO Jianyu, MA Xiaofei, WANG Min, LI Xiaoli, ZHANG Dingyi, JI Hutai
2024, 45(11):  8-15.  doi:10.7506/spkx1002-6630-20230918-149
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In this study, 19 gluten protein traits of 44 wheat varieties were analyzed. Principal component analysis (PCA), correlation analysis (CA), membership function (MF) and stepwise regression (SR) were used for comprehensive evaluation of wheat gluten protein. The results showed that the variations of disulfide bond content ranged from 3.28 to 6.78 μmol/g, and the variations of sulfhydryl group content ranged from 13.30 to 16.66 μmol/g. The variation range of gluten protein traits was 4.74% to 89.46%, with larger variation coefficients being observed for stabilization time and farinograph quality index, indicating huge variation potential for protein quality traits. Three comprehensive factors were converted from the 19 protein traits by PCA, with contribution rates of 40.80%, 19.86% and 15.88%, respectively, and a cumulative contribution rate of 76.54%. PCA classified gluten proteins into three categories including gluten quality traits, aggregation traits and quantitative traits. The comprehensive evaluation value (D-value) of gluten was calculated using the MF method, and the average of the 12 traits with higher PCA loadings were found to be significantly correlated with D-values. Regression equations with seven traits including disulfide bond content, glutenin macropolymer (GMP) content, protein content, dry gluten content, gluten index, tensile area and peak maximum time (PMT) as independent variables were established using SR. There was a good linear relationship between bread quality indexes and D-value, with determination coefficient (R2) between 0.561 4 and 0.771 3, which verified the accuracy and feasibility of D-value. It could be concluded that wheat gluten protein with different gluten strengths exhibited abundant variation potential. It is feasible to comprehensively evaluate gluten protein quality by multivariate statistical analysis. The quantity and quality of gluten protein as well as the content of disulfide bonds in the gluten network could be used as key indexes for the evaluation and improvement of wheat quality.
Regularity and Reaction Mechanism of the Conversion of Sesamolin into Sesamol under High Temperature Conditions
YU Yumeng, MA Yuxiang, ZHANG Chenxia, WANG Xuede
2024, 45(11):  16-23.  doi:10.7506/spkx1002-6630-20231012-090
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This study investigated the effects of different factors on the conversion of sesamolin to sesamol under high temperature conditions, explored its conversion kinetics, and analyzed the relevant pathways by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results indicated that glycerol was an ideal medium for converting sesamolin into sesamol. Both the reaction temperature and time had a significant impact on the yield of sesamol. At temperatures between 160 ℃ and 200 ℃, the degradation of sesamolin followed first-order kinetics, and temperature was positively correlated with the reaction rate constant, but negatively correlated with the half-life and one-tenth-life. The activation energy of this reaction was calculated to be (104.50 ± 4.32) kJ/mol using the Arrhenius equation. The LC-MS/MS results revealed that the reaction system using sesamolin as the substrate included two conversion pathways: the generation and conversion of sesamol.
Transcriptomic Analysis of the Molecular Mechanism for High-Glucose Diet-Induced Aging of Caenorhabditis elegans
LI Rong, XU Yan, MIAO Yuanxin, TAO Mingfang
2024, 45(11):  24-30.  doi:10.7506/spkx1002-6630-20230904-023
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The aim of this study was to uncover the molecular mechanism for high-sugar diet-induced aging of Caenorhabditis elegans. Changes in the gene expression profile of C. elegans induced by a high-glucose (HG) diet were explored by transcriptomics. The results showed that the expression of 4 183 genes in C. elegans significantly changed after HG diet consumption. In addition, gene ontology (GO) enrichment analysis showed that differentially expressed genes (DEGs) induced by HG diet treatment were significantly enriched in aging, unfolded protein binding, response to stress, autophagy, transferase activity, catalytic activity, and heat shock protein binding. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the DEGs were also significantly enriched in longevity regulation of C. elegans, autophagy regulation, pyruvate metabolism, the forkhead box O (FOXO) signaling pathway, glycolysis/gluconeogenesis, glutathione metabolism, and the transforming growth factor-β signaling pathway. Furthermore, we found that high-glucose diet up-regulated the expression of DEGs involved in the insulin/IGF-1 signaling (IIS) pathway and of DEGs associated with glycolipid metabolism, and down-regulated the expression of DEGs related to heat stress resistance and antioxidant regulation. This study provides a theoretical basis for further elucidation of the molecular mechanism underlying the effects of HG diet on the longevity and metabolism of C. elegans.
Effects and Underlying Mechanisms of Lycium barbarum leaves Flavonoids on Lipid Metabolism in HepG2 Cells
YANG Chao, PEI Yufang, SUN Xiazhi, LIU Shuang, ZHANG Huiling, FAN Yanli
2024, 45(11):  31-40.  doi:10.7506/spkx1002-6630-20230904-018
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The aim of this study was to investigate the impact of Lycium barbarum leaves flavonoids (LBLF) on lipid accumulation in normal and oleic acid-induced HepG2 cells. The experiment was divided into six groups as follows: blank, model, positive control, low-, medium-, and high-dose LBLF. Oil red O staining was performed to assess the aggregation of lipid droplets in each group, and lipid levels and oxidative stress indicators were measured. Finally, real-time polymerase chain reaction (real-time PCR) and Western blot were used to detect the expression of mRNAs and proteins associated with lipid synthesis. The results indicated that LBLF could decrease the increase in the levels of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA) and reactive oxygen species (ROS) induced by oleic acid in HepG2 cells. It also could increase high-density lipoprotein cholesterol (HDL-C), superoxide dismutase (SOD), glutathione, and catalase levels. Additionally, Western blot results suggested that LBLF intervention could up-regulate phosphorylated adenosine 5’-monophosphate (AMP)-activated protein kinase (p-AMPK) and AMPK levels, and down-regulate the protein expression of sterol regulatory element-binding protein 1c(SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), and CCAAT enhancer binding protein alpha (CEBPα). Real-time PCR results indicated that LBLF intervention down-regulated the expression of genes such as ACC, FAS, SREBP-1c, SCD-1, PPARγ, and CEBPα. In conclusion, LBLF could partially alleviate lipid metabolism disorder in oleic acid-induced HepG2 cells by regulating the expression levels of lipid synthesis and oxidation-related genes.
Purification and Identification of Novel Antioxidant Peptides from Sheep Hemoglobin Hydrolysate and Their Protective Effect on H2O2-Induced Oxidative Injury in Caco-2 Cells
MA Zehao, GENG Yukun, WANG Jingyun, LU Shiling, CAO Doudou, LIU Xingyu
2024, 45(11):  41-51.  doi:10.7506/spkx1002-6630-20230905-030
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In this study, antioxidant peptides derived from sheep hemoglobin were prepared from fresh sheep blood. Sephadex G-25 chromatography, DEAE Sephadex A-50 chromatography, reverse phase high performance liquid chromatography (RP-HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to separate, purify, and identify peptides from the hydrolysate of sheep hemoglobin. The antioxidant activity of the obtained peptides was evaluated by their free radical scavenging capacity, stability against simulated gastrointestinal digestion and protective effect on H2O2-induced oxidative injury in Caco-2 cells. The results indicated that three novel antioxidant peptides, Ala-Tyr-Glu-Val-Asp (AYEVD), Phe-His-Thr-Met-Glu (FHTME) and Ser-Phe-Met-Tyr-Glu-Lys (SFMYEK), were purified and identified from the hydrolysate, with molecular masses of 595.60, 663.74 and 803.92 Da, respectively. Among them, AYEVD had the strongest scavenging capacity to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and AYEVD showed stronger antioxidant activity after simulated gastrointestinal digestion. In addition, AYEVD inhibited H2O2-induced oxidative injury in Caco-2 cells, significantly reduced the accumulation of reactive oxygen species (ROS), suppressed early cell apoptosis and the formation of malondialdehyde (MDA), and increased the activity of intracellular antioxidant enzymes. Therefore, this study could provide a theoretical basis for the application of novel antioxidant peptides from sheep hemoglobin in functional foods.
Food Chemistry
Effect of Salt Addition at Different Processing Stages on the Quality and Volatile Flavor Components of Marinated Crayfish Tails
WANG Ziling, ZHANG Zihao, ZENG Luyao, LAO Mengtian, WANG Haibin, WANG Qi, PENG Lijuan, LU Hongyan, ZOU Shengbi
2024, 45(11):  52-60.  doi:10.7506/spkx1002-6630-20231009-058
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In this study, the effects of the addition of different amounts of salt (0%, 1%, 2% and 3%) at five stages of processing: raw shrimp, blanching, marination, soaking for 2 h and soaking at 4 ℃ for 24 h, on the quality and volatile flavor compounds of marinated crayfish were investigated. The results showed that L* values increased and then decreased as the processing stages proceeded, while a* and b* values both continued to increase. But salt addition had little effect on the color difference. Additionally, moisture content decreased and then increased, and was affected little by salt addition. For 1%, 2% and 3% salt addition, hardness, elasticity, chewiness and adhesion showed an initial increasing and subsequent decreasing trend. Without salt addition, hardness and chewiness continued to increase. For each group, elasticity and cohesiveness increased and then did not show any significant change. The electronic nose results could be roughly divided into four parts, raw shrimp and blanching, marination, soaking for 2 h, and soaking at 4 ℃ for 24 h. There were also some differences between the less and more salt addition groups. The electronic tongue results showed that as salt addition increased or the processing stages proceeded, saltiness, astringency, and umami taste increased, and other taste attributes changed little. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis showed that salt addition and marination had a positive effect on the volatile flavor of crayfish. However, excessive salt addition and too long processing time were detrimental to volatile flavors. In conclusion, the addition of salt and processing stages can affect the quality and flavor of marinated crayfish.
Effect of Covalent Coupling with Rosmarinic Acid on the Structure and Properties of β-Lactoglobulin
YANG Qing, SHANG Jieli, ZENG Haolong, WANG Xuanpei, CHEN Yijie, LIU Xin, GONG Zhiyong, XU Lin
2024, 45(11):  61-67.  doi:10.7506/spkx1002-6630-20231101-001
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The present study aimed to investigate the effect of covalent coupling with the dietary polyphenol rosmarinic acid (RA) on the structure and properties of β-lactoglobulin (β-LG). β-LG-RA complexes were prepared using the free radical and alkaline methods. The structural changes of β-LG after coupling with RA were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FTIR) spectroscopy, ultraviolet (UV) absorption spectroscopy, fluorescence spectroscopy, and circular dichroism (CD) spectroscopy. The antioxidant activity of β-LG and its complexes with RA was assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation scavenging methods. Furthermore, their binding capacity to serum-specific immunoglobulin G (IgG) were evaluated using enzyme-linked immunosorbent assay (ELISA). The results revealed that the secondary structure of β-LG transformed from α-helix to β-sheet and random coil after RA covalent conjugation. The protein underwent changes in its secondary and tertiary structures. Additionally, compared to β-LG, the β-LG-RA covalent conjugates showed significantly enhanced antioxidant activity and reduced binding ability with serum specific IgG. In conclusion, covalent coupling with RA led to a significant improvement in the antioxidant activity of β-LG and a significant decrease in its binding capacity to serum-specific IgG by introducing phenolic hydroxyl groups.
Enhancing Effect of Cooking of Fermented Tomato Sour Soup with Added Oil on Lycopene cis/trans Isomerization
YANG Zhiyi, LIU Na, JIA Yulong, QIN Likang, BAO Aiming, QIN Weijun, LIANG Xiaoyang
2024, 45(11):  68-74.  doi:10.7506/spkx1002-6630-20230914-120
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In this study, we evaluated the cis/trans-lycopene content in commercial ketchup, and investigated the effect of cooking of fermented tomato sour soup added with one of seven oils including peanut oil (PO), sesame oil (SO), corn oil (CO), tung seed oil (TSO), olive oil (OO), Litsea cubeba oil (LCO), and mustard oil (MO) on lycopene isomerization. The results showed significant differences in the contents of total lycopene and cis-lycopene among six brands of ketchup (P < 0.05), with cis-lycopene accounting for only 20.84%-24.56% of the total lycopene. The contents of total lycopene and cis-lycopene were significantly different among the seven cooked fermented tomato sour soup samples (P < 0.05), and their proportions of cis-isomers (51.40%-78.23%) were 1.2-1.9 times higher than that of the blank group and 2.09-3.75 times higher than those of the six brands of ketchup. Specifically, the sample with added MO had the highest proportion of cis-lycopene (78.23%), followed by those with SO and PO (75.34% and 71.65%, respectively). The total lycopene and cis-lycopene contents of the sample with added PO were 6.6 and 11.4 times higher than those of the blank control group, respectively, indicating that the former has great market potential. Therefore, the results of this study could provide a scientific basis for the further processing of fermented tomato sour soup for high-value functional products.
Changes in Growth and Muscle Quality of Largemouth Bass (Micropterus salmoides) Reared in Recirculating Aquaculture System
ZHOU Xiuzhen, ZHANG Yi, ZHOU Qin, DING Xueyan, LI Ming, JIA Jia, HUANG Ju, WANG Yang
2024, 45(11):  75-83.  doi:10.7506/spkx1002-6630-20231018-144
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In order to investigate the effect of a recirculating aquaculture system on the body indexes, texture, nutrient composition and earthy odor substances of largemouth bass (Micropterus salmoides), this study determined texture characteristics of fish meat such as hardness, springiness and chewiness, and used conventional biochemical methods, an amino acid automatic analyzer, and gas chromatography (GC) to detect the contents of moisture, ash, crude protein, crude fat, fatty acids, and amino acids. Meanwhile, gas chromatography-mass spectrometry (GC-MS) and electronic tongue were used to analyze the earthy odor substances and taste of fish meat. The results showed that the ratio of liver to body mass decreased significantly with rearing time; after rearing for up to 20 days, the hardness, cohesiveness, chewiness, springiness, adhesiveness and gumminess of fish meat were improved compared with those before rearing. The crude fat content initially increased and then decreased with rearing time, while the moisture content showed an opposite trend. The contents of protein, ash, flavor amino acids, essential amino acids, and monounsaturated fatty acids in fish meat increased after 15 days of rearing. The contents of sum of eicosapentaenoic acid methyl ester, docosahexaenoic acid methyl ester and ω-3 fatty acids significantly increased after 5 and 15 days. In addition, the contents of water-soluble protein and non-protein nitrogen in fish meat also increased significantly; with increasing rearing time, fish meat showed an increase in flavor differences, and the content of earthy odor substances decreased, which was below the sensory threshold from day 15 onward. Taking into account the body indexes, nutrient composition and earthy odor substances of largemouth bass muscle, a rearing period of 15 days in the recirculating water system is recommended.
Analysis of the Differences in the Composition and Properties of Crude and Refined Wheat Starches from the Front, Middle and Back Flour Mill Streams
WANG Yi, ZHENG Xueling
2024, 45(11):  84-90.  doi:10.7506/spkx1002-6630-20230524-233
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Crude starches (C-S-1, C-S-2, C-S-3 and C-S-4) were prepared the dough method from wheat flours with different processing degrees from the wheat processing line, the front (S-1), middle (S-2 and S-3) and back (S-4) flour mill streams, and refined starches (R-S-1, R-S-2, R-S-3 and R-S-4) were obtained after the removal of yellow waste slurry. The effects of the retention or removal of yellow waste slurry on physicochemical indexes, pasting properties, gelatinization properties, granular morphology and crystal structure of wheat starch were investigated. It was shown that the particle size of the crude starches was larger than that of their refined counterparts (D10 7.51–8.26 μm versus 6.46–7.70 μm). High contents of impurities, specifically ash, crude protein and pentosan, were found in the crude starches than their refined counterparts. X-ray diffraction analysis showed that both crude and refined starches had an A-type crystalline structure, and the relative crystallinity of the latter was higher than that of the former. Their paste properties were significantly different. The refined starches had higher transparency, peak viscosity, final viscosity and trough viscosity but lower solubility and swelling strength than the crude starches. There was no significant difference in textural properties between the crude and refined starch gels, except that the hardness and gel strength of the back-stream starch were higher than those of the front- and middle-stream starches.
Effect of Component Migration during the Extraction Process on Functional Properties of Seed Storage Proteins from Camellia oleifera Abel.
YANG Xiaoli, ZHOU Jisong, SHANG Wei, PENG Dengfeng, DENG Qianchun, JIN Weiping
2024, 45(11):  91-99.  doi:10.7506/spkx1002-6630-20231011-084
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In this study, the effect of component migration and interaction with concomitant saponins on the composition and functional properties of the seed storage proteins from Camellia oleifera Abel., a typical woody oil crop in China, was investigated using proteomics and molecular docking. The results showed that the optimal parameters for alkaline extraction were solid/liquid ratio 1:10 (g/mL) and pH 8.0, which resulted in an extraction rate of 75.8%, and a saponin-to-protein ratio of 2.60. The 11S globulins were precipitated at pH 4.5 with a saponin-to-protein ratio of 0.36. Albumin accounted for 69% of the total storage proteins, and coexisted with saponin during the extraction process, thus resulting in a high saponin-to-protein ratio of 3.73. The foaming properties of albumin and globulin from C. oleifera Abel. seeds were larger than 200%, and the emulsifying activity index was 16.7 m2/g. The interaction between saponins and proteins significantly improved the emulsion stability. This study provides theoretical support for the high-value utilization of proteins from C. oleifera Abel. and the development of functional food ingredients.
Effects of Three Microorganisms on Volatile Substances during Fermentation of Douchi
FENG Liang, ZHONG Risheng, WANG Shuqi, CHEN Haitao
2024, 45(11):  100-109.  doi:10.7506/spkx1002-6630-20231017-136
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The effect of the use of Aspergillus oryzae, lactic acid bacteria (LAB) and Wickerhamomyces anomalus as starter cultures on volatile substances during the fermentation of Douchi. The results showed that the contents of total volatile compounds in the uninoculated control, A. oryzae, LAB, A. oryzae + LAB, and W. anomalus inoculation groups were 5 145.88, 13 972.15, 9 006.07, 4 359.72 and 5 169.42 μg/kg, respectively. The contents of alcohols, organic acids, ketones and esters were increased by A. oryzae; the contents of alcohols and organic acids were increased by LAB; the contents of alcohols and organic acids were increased by the mixture of A. oryzae and LAB, but its effect was less pronounced than that of pure culture fermentation; the contents of alcohols and organic acids were increased by W. anomalus. Compared with the control group, the contents of pyrazines and phenolics in each inoculated fermentation group were decreased. Taken together, A. oryzae was the most suitable for the fermentation of Douchi, and the other strains could assist in regulating the production of volatile compounds during the fermentation of Douchi. Our findings from this study could provide some theoretical references for the industrial production of Douchi with traditional Chinese flavor.
Non-targeted Metabolomics Analysis of the Inhibitory Effect of Trichoderma erinaceum Volatile Substances on Alternaria alternata Isolated from Postharvest Korla Fragrant Pear
HUANG Wei, WANG Ning, LIU Fengjuan, SONG Bo, Reyilai KUERBAN, WANG Suling, Gulimire NURE, QIN Xinzheng, TANG Qiyong, ZHANG Lijuan, WANG Wei
2024, 45(11):  110-117.  doi:10.7506/spkx1002-6630-20231013-103
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In this study, the effects of Trichoderma erinaceum M6-5 volatile components on metabolites, respiration and energy metabolism of Alternaria alternata from postharvest Korla fragrant pear were investigated. Non-targeted metabolomics based on liquid chromatography-mass spectrometry (LC-MS) was used to determine the changes of metabolites in A. alternata after treatment with M6-5 volatile substances. At 0, 3, 5 and 7 days after fumigation with M6-5 volatile substances, the respiratory rate of A. alternata was measured, and the respiration inhibition rate were calculated. The levels of ATP, ADP, AMP and energy charge in the M6-5-treated and control groups as a function of culture time were determined by liquid chromatography (LC). The results showed that among the identified differential metabolites, 6-amyl-2h-pyrano-2-one (6pp), 4-ethylbenzaldehyde, 3,4-dimethylbenzoic acid, 4-phenylbutyric acid and 2-methoxyresorcinol were up-regulated, while 6-aminonicotinamide, 11-ketoacetyl cholesterol, 3-hydroxyconilone, jasmonic acid and benzoylsphenine were down-regulated by M6-5 volatile substances. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the significantly differential pathway was involved in the biosynthesis of secondary metabolites. At the end of the 7 day incubation period, the respiration inhibition rate of A. alternata by M6-5 volatile substances was (49.64 ± 2.04)%. Compared with the control group, treatment with M6-5 volatile substances significantly reduced the levels of ATP, ADP, AMP and energy charge, indicating that it can keep the energy charge at lower levels, thereby resulting in imbalanced energy metabolism and inhibited respiratory rate and affecting metabolite changes.
Selection of Lactobacillus with High Bile Salt Hydrolase Activity and Its preventive and therapeutic effects against Neonatal Jaundice in Rats
ZHANG Huimin, LI Binbin, PAN Xiaohua, SUN Jia
2024, 45(11):  118-127.  doi:10.7506/spkx1002-6630-20231015-116
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This study aimed to select Lactobacillus with high bile salt hydrolase (BSH) and to explore its protective role against neonatal jaundice. The LBS selective medium supplemented with 25 U/mL nystatin was used to screen and identify Lactobacillus strains isolated from the feces of healthy newborns and breast milk. L. rhamnosus (LGG) was used as a positive control to evaluate the in vitro probiotic properties and bile salt hydrolase activity of the Lactobacillus strains. Thereafter, the protective effect and mechanism of the selected isolates with high bile salt hydrolase activity against phenylhydrazine hydrochloride (PHZ)-induced neonatal jaundice in rats were investigated by analyzing serum bilirubin levels, hepatotoxicity, and the expression of inflammatory cytokines and nuclear transcription factors in the liver. The results showed that compared with the LGG, L. gasseri FWJL-5, which was isolated from infant feces, exhibited outstanding in vitro probiotic properties and higher bile salt hydrolase activity than LGG. L. gasseri FWJL-5 significantly alleviated the increase in serum bilirubin levels, liver tissue swelling and hemolysis in PHZ-treated neonatal rats, reduced the release of hepatic enzymes, inhibited the secretion of proinflammatory cytokines, and promoted the expression of UGT1A1, pregnane X receptor (PXR), and farnesol X receptor (FXR). Taken together, L. gasseri FWJL-5 could regulate bilirubin metabolism in the liver by up-regulating the expression of FXR/PXR and UGT1A1, thereby alleviating neonatal jaundice in rats. Our findings may provide new ideas for the prevention and treatment of neonatal jaundice by L. gasseri.
Effect of Chitosan-Tannic Acid Coating on the Microbial Diversity of Jiaohuaji Chicken
ZHANG Xiaoqian, SU Wei, LIU Xiaoli, HU Genhe, ZHOU Jianzhong, FAN Linlin
2024, 45(11):  128-135.  doi:10.7506/spkx1002-6630-20231013-107
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In order to explore the effect of chitosan-tannic acid coating on the quality of Jiaohuaji chicken during storage, the microbial diversity of Jiaohuaji chicken with and without the coating treatment was evaluated. The changes in total bacterial count (TBC), pH, thiobarbituric acid reactive substances (TBARS) and total volatile basic nitrogen (TVB-N) values during storage were analyzed as well. The results of high-throughput sequencing analysis showed that Bacillus, Streptophyta, and Prevotella were the dominant genera during the storage period of Jiaohuaji chicken. The abundance of Bacillus increased to 99.04% on the fifth day of storage (37 ℃), indicating it to be dominant. After the coating treatment, the abundance of Bacillus in Jiaohuaji chicken decreased by 13.53% whereas the abundance of Prevotella and other genera increased. In addition, the results of microbial and physicochemical analysis showed that the coating treatment kept the TBC below 5.0 (lg (CFU/g)) for 8 days (4 ℃), significantly reduced the pH, and decreased the TBARS and TVB-N values by 22.28% and 28.15%, respectively at the end of storage (4 ℃) compared with the blank control group. To sum up, the chitosan-tannic acid coating treatment changed the composition of the bacterial flora, inhibited the growth of spoilage bacteria to some extent, delayed lipid and protein oxidation, and prolonged the shelf life of Jiaohuaji chicken.
Nutrition & Hygiene
Adlay Seeds Fermented by Lactobacillus plantarum NCU137 Regulates Immunity and Intestinal Mucosal Barrier Function in Immunosuppressed Mice
YIN Hongmei, XIA Shengkun, ZHONG Yadong, SHI Xiaodan, HU Jielun, NIE Shaoping, XIONG Tao, XIE Mingyong
2024, 45(11):  136-143.  doi:10.7506/spkx1002-6630-20230613-110
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Objective: To compare the regulatory effects of adlay (Coix lachryma-jobi L.) seeds fermented and not fermented by Lactobacillus plantarum NCU137 on immune and intestinal mucosal barrier function in mice induced by cyclophosphamide (CTX). Methods: BALB/c mice were randomly divided into four groups, including normal, CTX-induced model, non-fermented adlay seed (NFC) and fermented adlay seed (FC) treatment. The mice in the normal and CTX groups were orally administrated with 0.2 mL of physiological saline for 10 days, while those in the NFC and FC groups 0.2 mL of non-fermented and fermented adlay seeds for 10 days, respectively. The immunosuppressed mouse model was established by daily intraperitoneal injection of 100 mg/kg of CTX for the last three days of the administration period, while the normal group was intraperitoneally injected with the same volume of normal saline. Spleen index, the number of spleen T lymphocyte subsets, and the levels of cytokines and immunoglobulin were measured, histopathological examination of the small intestine was performed and intestinal mucosal barrier function was detected. Results: Compared with the CTX group, fermented adlay seeds significantly increased the spleen and thymus indexes of immunosuppressed mice, up-regulated the cluster of differentiation (CD) 4+/CD8+ ratio of spleen T lymphocytes, down-regulated the levels of spleen pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), and increased serum immunoglobulin (Ig) M and IgG levels. Moreover, fermented adlay seeds repaired small intestinal mucosal structure and up-regulated the gene expression of occludin and E-cadherin, and the effect was more pronounced than that of non-fermented adlay seeds. Conclusion: Coix lachryma-jobi L. seeds fermented by L. plantarum NCU137 have the potential to regulate immune and intestinal mucosal barrier function, which are expected to be developed into a novel health food with immunomodulatory function.
Anti-aging and Antioxidant Activities of Hydrolysate Fraction from Spherical Sea Cucumber (Phyllophorus proteus) in Caenorhabditis elegans
CHEN Kexin, SHI Linfan, REN Zhongyang, WENG Wuyin
2024, 45(11):  144-151.  doi:10.7506/spkx1002-6630-20230620-158
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To explore anti-aging and antioxidant activities of Phyllophorus proteus hydrolysate fraction (PPHF) on Caenorhabditis elegans, the physiological and biochemical indicators of C. elegans fed 0.5, 2.0 mg/mL and 8.0 mg/mL PPHF were determined. The results showed that PPHF was beige in color, and its L* and b* values were 81.28 and 15.88, respectively. The proportion of oligopeptides with molecular mass of 180–1 000 Da in PPHF was 63.76%, and the proportions of glutamic acid and glycine were 19.50% and 15.34%, respectively. After being fed 0.5, 2.0, and 8.0 mg/mL PPHF, the lifespan of C. elegans was increased by 22.43%, 54.60%, and 78.89%, respectively, under normal conditions, and also increased under thermal or oxidative stress. The body length of C. elegans was increased significantly by feeding 0.5 mg/mL PPHF, while the swallowing frequency was significantly increased by feeding 2.0 mg/mL PPHF. The body bending frequency of C. elegans fed 0.5 and 8.0 mg/mL PPHF was increased by 7.75% and 43.71%, respectively, when compared with the control group on the second day of incubation. PPHF significantly reduced the content of reactive oxygen species (ROS) in C. elegans, and increased the antioxidant enzyme activity, glutathione content and total antioxidant capacity in a dose-dependent manner. These results indicated that PPHF could improve the physiological function and prolong the lifespan by enhancing antioxidant capacity in C. elegans.
Oxidative Damage Caused by Trimethylamine Oxide to Human Skin Fibroblasts and Protective Effect of Vitamin C against It
SUN Bin, XIAO Ying, YU Ling, XU Haojie, PAN Liang, ZHOU Yiming, LIU Xiaojie
2024, 45(11):  152-162.  doi:10.7506/spkx1002-6630-20230515-142
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This study aimed to clarify the oxidative damage in human skin fibroblasts (HSF) treated with trimethylamine oxide (TMAO) and to elucidate its pro-aging effect in skin cells in terms of antioxidant indicators, levels of inflammatory cytokines, levels of collagen and matrix metalloproteinases, and mRNA expression of related genes. The results showed that TMAO treatment significantly increased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and decreased the content of reduced glutathione, superoxide dismutase (SOD) activity, and total antioxidant capacity (TAC) in HSF cells (P < 0.05). TMAO treatment was found to significantly elevate the mRNA levels of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and matrix metalloproteinase-1 (MMP-1), and decrease the mRNA transcript levels of collagen synthesis-related genes and the inducible nitric oxide synthase (iNOS) gene by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). Western blot analysis showed that the protein expression level of phosphorylated p65 (p-p65) significantly increased (P < 0.05). Vitamin C (VC) was able to protect against TMAO-induced oxidative stress in HSF cells, and reduce inflammation and collagen loss. These results indicated that TMAO can produce oxidative stress in HSF cells, which may activate the signaling pathway of nuclear factor kappa-B (NF-κB), promote NF-κB phosphorylation in HSF cells, induce inflammatory responses, reduce collagen synthesis, and accelerate collagen degradation, thus possibly promoting skin cell aging.
Component Analysis
Difference in Flavor among Boletus edulis Dried by Different Drying Methods Analyzed in Terms of Aroma and Taste Substance Characteristics
LI Weilan, YANG Hao, ZI Luxi, XU Ningmeng, GUO Lei
2024, 45(11):  163-174.  doi:10.7506/spkx1002-6630-20231105-028
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This study aimed to understand the flavor and taste characteristics of dried Boletus edulis products prepared by different drying methods and to explored the difference in flavor among the dried products. The volatile flavor substances and non-volatile taste substances of B. edulis dried by three different drying methods including hot air drying (HAD), vacuum freeze drying (VFD) and vacuum drying (VD) were measured and analyzed. Totally 64 and 85 volatile organic compounds (VOCs) were identified by gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS), respectively. The fingerprint analysis results showed large differences among the dried products, the most significant differential characteristics being found in the VD dried product. Orthogonal partial least squares-discriminate analysis (OPLS-DA) selected 17 and 22 differential characteristic markers based on the results of GC-IMS and GC-MS, respectively. Relative odor activity value (OAV) analysis showed that the key VOC was 1-octen-3-ol. The analysis of non-volatile taste substances indicated that the highest contents of both free amino acids (FAAs) and 5’-nucleotides were found in the HAD-dried product, which were 234.57 and 27.870 mg/g, respectively. Among the 16 free amino acids (FAAs), glutamic acid was the major contributor to umami taste. In summary, HAD is more conducive to the accumulation of taste substances in B. edulis, while VD results in a higher number and amount of flavor compounds. This study could provide a reference for the selection of a method for the postharvest drying of fresh B. edulis.
Analysis of Volatile Composition and Key Aroma Compounds in Toddalia asiatica Lam. Honey
JIANG Ao, LI Hongxia, LIU Zhaolong, SONG Mei, LI Na, CHEN Lanzhen
2024, 45(11):  175-185.  doi:10.7506/spkx1002-6630-20230919-178
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In order to clarify the volatile composition and aroma characteristics of Toddalia asiatica Lam. honey, a Chinese specialty herbal honey, this study determined its selected physicochemical indexes such as water content, sugar content, amylase activity, and antioxidant capacity by using an Abbey refractometer, high-performance liquid chromatography (HPLC), and ultraviolet-visible spectrophotometry, respectively. Meanwhile, its volatile components were qualitatively and quantitatively analyzed using headspace-solid phase microextraction combined with gas chromatography-quadrupole time-of-flight mass spectrometry (HS-SPME-GC-Q-TOF-MS). The results showed that T. asiatica Lam. honey contained (18.71 ± 1.49)% moisture, (35.92 ± 2.70)% fructose and (35.85 ± 2.51)% glucose, and could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical with half-maximum inhibitory concentration (IC50) values of (57.18 ± 7.62) and (247.68 ± 40.50) mg/mL, respectively, and its amylase activity was (11.84 ± 3.38) mL/(g·h). A total of 176 volatile substances were identified from the honey, mainly including 52 hydrocarbons, 29 esters, 21 alcohols, 21 terpenes, 17 aldehydes, and 12 aromatics. Among them, the contents of benzaldehyde, phenylethanol and 1-octene-3-alcohol were high (8 181.9, 4 483.1 and 4 239.5 μg/kg, respectively). Totally 42 key aroma compounds, with odor activity values (OAV) greater than 1, were identified, including damastone, methyl phenylacetate and α-cresine, which contributed significantly to the aroma composition of T. asiatica Lam. honey. Among them, violonone had a violet flower-like aroma, being responsible for the unique violet- and raspberry-like aroma notes of T. asiatica Lam. honey. Overall, T. asiatica Lam. honey was dominated by floral aromas, along with fruity, chemical, and green aromas. In summary, the physicochemical indexes of the honey meet the relevant standards, and it contains a variety of volatile components. This study could provide data support for the quality evaluation of T. asiatica Lam. honey, as well as research ideas for the excavation of other Chinese specialty herbal honeys.
Analysis of Flavor Characteristics of Roasted Cololabis saira with Different Pretreatments by Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry and Electronic Tongue
ZHAO Ling, WANG Lin, CAO Rong, LIU Qi, WANG Shanyu, HU Mengyue
2024, 45(11):  186-191.  doi:10.7506/spkx1002-6630-20230711-126
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An electronic nose and solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) were used to analyze the volatile flavor substances of roasted Cololabis saira with different pretreatments: fresh fish, brining and ultraviolet radiation (UVR) followed by cold air drying (CAD). Their taste and flavor characteristics were determined using an electronic tongue and sensory evaluation, respectively. The electronic nose results showed that the three groups had completely different odor profiles. A total of 38 volatile flavor compounds were detected, including 11 aldehydes, 4 alcohols, 5 ketones, 13 hydrocarbons and nitrogenous compounds, contributing to the flavor characteristics of roasted C. saira dominated by fatty as well as grassy and fishy aromas. There were significant differences in the contents of key flavor compounds among the three groups. More volatile flavor compounds were accumulated in the UVR-CAD group, which enriched the flavor characteristics with unique refreshing and burnt aromas. The electronic tongue results showed that saltiness, umami and umami aftertaste were important taste indicators of roasted C. saira, and UVR-CAD enhanced the taste of roasted C. saira by enriching its saltiness and umami aftertaste. The results of sensory evaluation showed that the appearance, smell, taste and mouthfeel of roasted C. saira pretreated by UVR-CAD were improved, which was characterized by golden color, compact texture, rich fatty aroma, pleasant taste and aftertaste. As a result, the sensory acceptability was significantly improved. In summary, UVR-CAD brought a richer flavor to roasted C. saira than the fresh control and brining pretreatment.
Food Engineering
Effect of High-Pressure Homogenization Modified Bamboo Shoot Dietary Fiber on Gelation Properties and Chemical Interactions of Shrimp Surimi
LIU Xin, JIANG Pengfei, FU Baoshang, QI Libo, YANG Jingqi, SHANG Shan
2024, 45(11):  192-200.  doi:10.7506/spkx1002-6630-20230504-023
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The effects of high-pressure homogenization (HPH) at different pressures (30, 40, 50 and 60 MPa) on the hydration properties and crystallinity of bamboo shoot dietary fiber (BSDF) were studied as well as the effect of HPH-treated BSDF on the gel strength, water-holding capacity (WHC), protein secondary structure, chemical interactions and microstructure of heat-induced gels from shrimp surimi. The results showed that the WHC, oil-holding capacity (OHC), and swelling capacity of BSDF were positively correlated with homogenization pressure (P < 0.05). However, too small size of fiber particles affected its combination with hydrophilic groups, which could reduce the water absorption and swelling properties. X-ray diffraction (XRD) and scanning electron microscopic (SEM) results demonstrated that the crystallinity of BSDF decreased after medication, and the fiber bundle structure was destroyed, becoming loose and porous. Compared with the surimi added with unmodified BSDF, the gel strength of shrimp surimi added with BSDF treated at 30, 40, 50, and 60 MPa were increased by 10.04%, 17.87%, 28.76%, 28.49%, and WHC increased by 3.48%, 5.74%, 13.04%, and 12.70%, respectively. Fourier transform infrared (FTIR) spectral analysis showed that the contents of α-helix and random coil in the modified BSDF-supplemented shrimp surimi gel decreased, while the contents of β-sheet and β-turn increased significantly, suggesting more stable secondary structure of proteins. The results of chemical interaction analysis showed that modified BSDF promoted the hydrophobic interactions and the formation of disulfide bonds in shrimp surimi gel, with a more pronounced effect being observed with BSDF treated at 50 and 60 MPa. SEM results showed that shrimp surimi gel added with BSDF treated at 60 MPa had a more uniform and denser three-dimensional network structure. These results showed that HPH treatment could improve the hydration properties, and reduce the crystallinity of BSDF, and HPH-treated BSDF could significantly enhance the gelation properties of heat-induced shrimp surimi, which will provide a theoretical basis for improving the application of BSDF in shrimp surimi gels.
Effect of Radio Frequency Treatment on Thawing Efficiency of Frozen Chicken Breast
CHENG Teng, XUE Dong, ZHAO Jiale, XIANG Qisen, BAI Yanhong
2024, 45(11):  201-209.  doi:10.7506/spkx1002-6630-20230916-147
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The objective of the study was to investigate the effect of radio frequency parameters on the thawing time and the uniformity. During the radio frequency thawing of frozen chicken breast at 27.12 MHz and 6 kW, the effects of operating parameters such as electrode gap (8, 9, 10, and 11 cm), voltage (70%, 75%, and 80%) and sample thickness (4, 5, and 6 cm) on the pattern of temperature rise and the uniformity were examined. The results showed that with decreasing electrode gap and increasing voltage and sample thickness, the temperature rise accelerated and the uniformity index decreased. The optimum parameters were determined as 9 cm and 75% for electrode gap and voltage, respectively based on the thawing time and temperature distribution. Compared with thawing at ambient temperature (20 ℃, 6 h), the thawing time with radio frequency was shortened to 54.67 min, and the total viable count, the drip loss and total volatile basic nitrogen (T-VBN) content were significantly reduced (P < 0.05). The results of this study provide a theoretical basis and technical support for the practical application of radio frequency technology in the field of meat thawing.
Bactericidal Effect of Combined Slightly Acidic Electrolyzed Water and Ultrasonic Treatment against Escherichia coli on Fresh-Cut Lettuce
GAO Qing, LIU Peihong, RAN Ran, FAN Jiangping, HE Jinsong
2024, 45(11):  210-216.  doi:10.7506/spkx1002-6630-20230701-004
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This study aimed to investigate the bactericidal effect and dynamics of slightly acidic electrolyzed water (SAEW) combined with ultrasonic (US) treatment on Escherichia coli on fresh-cut lettuce. Fresh-cut lettuce was treated with SAEW-US under different conditions of solid/liquid ratio (1:5, 1:10 and 1:15 (g/mL)) and temperature (25, 35 and 45 ℃). The colony number of E. coli on lettuce was determined by the plate counting method, and the synergistic effect of combined treatment with SAEW and US on reducing the colony number of E. coli was determined and kinetically analyzed. The sublethal damage of SAEW-US treated E. coli was detected by flow cytometry and the double-layer culture counting method. The results showed that the efficacy of SAEW-US treatment in killing E. coli was significantly better than that of SAEW treatment (p < 0.05), and increased with treatment time, solid/liquid ratio and temperature. SAEW-US treatment had a synergistic effect on killing E. coli, and the sterilization process followed a first-order kinetic model. Moreover, SAEW-US treatment reduced the rate of sublethal damage of E. coli. The results of this study will provide a theoretical basis for the sterilization of fresh agricultural products.
Optimization of Separation Parameters of Wheat Aleurone Layer Flour and Their Influence on Characteristics of Wheat Flour and Dough
LUO Dan, MA Junzhe, SANG Ziqing, XIE Qiang, CHEN Chen, WANG Jianying, XUE Wentong
2024, 45(11):  217-225.  doi:10.7506/spkx1002-6630-20230614-122
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To effectively obtain high-quality wheat aleurone layer flour suitable for food processing, the effects of milling speed and mesh size on the nutritional and functional components of wheat aleurone layer flour were investigated, and the optimal separation parameters were developed by grey correlation analysis (GCA). The effects of adding 0%–30% wheat aleurone layer flour (based on the weight of wheat flour) on the nutritional composition and thermodynamic characteristics of wheat flour, and the thermomechanical and dynamic rheological properties of dough were studied. The results showed that the optimal separation parameters for wheat aleurone layer flour were 4 000 r/min and 80-mesh, which provided a high yield of wheat aleurone layer flour, rich in crude protein, total dietary fiber and alkyl resorcinol. With increasing addition of wheat aleurone layer flour from 0% to 30%, the contents of moisture and starch continuously reduced, and the contents of ash, crude protein, total dietary fiber, crude fat, total polyphenol and alkyl resorcinol increased. Moreover, addition of wheat aleurone layer flour improved the gelatinization stability and viscoelasticity of flour and delayed the retrogradation of dough, consequently improving its processing properties. The findings of this study contribute to maximizing the development of the nutritional and processing properties of wheat aleurone layer flour, improving its processing performance and promoting the utilization of wheat by-products.
Effects of Addition of Different Types and Amounts of Citrus Fibers on the Yield and Quality of Sauced Beef
ZHANG Mingcheng, CHANG Guangqiang, WANG Zu, ZHENG Duoduo, JIA Na, LU Jiafeng, LÜ Guang, HUANG Yunxia, LIU Dengyong
2024, 45(11):  226-234.  doi:10.7506/spkx1002-6630-20231009-057
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In this study, we studied the effect of the addition of citrus fibers on the yield and quality of sauced beef. Sauced beef added with different types of citrus fibers (CF100L80, CF400L80 and CF100H60) by tumbling at different amounts (0.5%, 1.0% and 1.5%) was prepared and evaluated for yield, moisture distribution, pH, residual citrus fiber, color, texture, distribution of citrus fiber and sensory evaluation. The results demonstrated that the incorporation of citrus fibers significantly enhanced the yield of sauced beef, with the highest values of 78.73% and 78.35% being observed in sauced beef supplemented with 1.5% CF400L80 and 0.5% CF100H60, respectively. Furthermore, it was found that the addition of citrus fibers improved the water retention capacity of sauced beef not through pH changes but rather through water adsorption of residual citrus fiber in the meat. Among the prepared samples, sauced beef with the addition of 1.5% CF400L80 and 1.0% CF100L80 had the highest residual rate of citrus fiber of 68.57% and 66.31%, respectively. The scanning electron micrograph (SEM) results showed that citrus fibers accumulated on the surface of the muscle bundles and increased the yield of sauced beef through water adsorption and swelling. Also, the addition of citrus fibers decreased the hardness, stickiness and chewiness of sauced beef (P < 0.05). The sensory evaluation results demonstrated that the incorporation of citrus fibers significantly enhanced the texture and taste attributes of sauced beef, with the highest sensory evaluation score being observed for the samples with the addition of 0.5% CF100H60. In conclusion, the addition of 0.5% CF100H60 citrus fibers was the most effective in enhancing both the yield and sensory quality parameters of sauced beef.
Effect of Ultrasonic-Assisted immersion Freezing with Different Ultrasonic Powers on Beef Quality
LI Junguang, YUE Xiaonan, SUN Chenhao, ZHAO Jiansheng, CHEN Bo, LIU Sihao, BAI Yanhong
2024, 45(11):  235-242.  doi:10.7506/spkx1002-6630-20231023-180
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In this study, the effects of ultrasonic-assisted immersion freezing (UIF) with different ultrasonic powers on beef quality were measured. The changes in freezing rate, cooking loss, thawing loss, tenderness, color difference, moisture distribution and microstructure of beef were analyzed after traditional air cooling or ultrasonic-assisted freezing at different ultrasonic powers (0, 200, 400 and 600 W). Fresh beef was used as control. The results showed that UIF could significantly increase the freezing rate of beef, affect the color and water state, and reduce the structural destruction of muscle tissue and quality deterioration during the freezing process. At an ultrasonic power of 400 W, the fastest freezing rate was obtained, as well as the lowest cooking loss and thawing loss of 32.44% and 1.66%, respectively, and shear force closest to that of the fresh meat. In addition, the minimum freezable water of 51.11% was observed. Low-field nuclear magnetic resonance (NMR) analysis showed that the amplitude of T21 was the highest, and the amplitude of T22 was relatively small, indicating a more uniform water distribution. Microscopic observation showed that an appropriate ultrasonic power reduced the structural damage caused by freezing to muscle fibers, thereby improving the quality of frozen meat.
Packaging & Storage
Effect and Underlying Mechanism of Melatonin Treatment on Rhizopus Rot in Postharvest Peach Fruit
DONG Xiaopan, TANG Jing, DING Jiao, JIN Peng, ZHENG Yonghua
2024, 45(11):  243-249.  doi:10.7506/spkx1002-6630-20230918-160
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The protective effect and underlying mechanism of melatonin (MT) treatment against Rhizopus stolonifer in postharvest peach fruit (Prunus persica (L.) Batsch cv ‘Xiahui 8’) were studied. Freshly harvested peaches were inoculated with R. stolonifer following pretreatment with different concentrations of MT (0, 0.05, 0.10, 0.50 and 1.00 mmol/L) and then stored at 20 ℃ for up to 60 h. Disease development was measured to determine the most effective MT concentration. Subsequently, the effects of MT treatment on quality parameters, total phenol and lignin contents, disease resistance-related enzyme activity and gene expression in peaches during postharvest storage, and the in vitro growth of R. stolonifer were investigated. The results showed that 0.50 mmol/L MT treatment could most significantly reduce the occurrence of Rhizopus rot and maintain postharvest fruit quality. Furthermore, compared with either of them alone, R. stolonifer inoculation after MT treatment exhibited stronger disease resistance response, resulting in a marked increase in the activities of chitinase (CHI), β-1,3-glucanase (GLU), phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), peroxidase (POD) and polyphenol oxidase (PPO), the contents of total phenols and lignin, and the expression levels of defense-related genes such as those encoding CHI (PpCHI), GLU (PpGLU), PAL (PpPAL) and POD (PpPOD). Moreover, MT treatment had no significant inhibitory effect on the growth of R. stolonifer in vitro. Taken together, these results indicate that MT can initiate defense responses to pathogenic infection indirectly by priming defense, thereby reducing the occurrence of peach postharvest diseases.
Preparation of Natural Wax-Based Oleogels and Their Effect on the Fluctuating Temperature Storage of Chocolate
LI Pengyan, WANG Zhiguo, ZHANG Wendi, JIANG Xueming, CAO Jun
2024, 45(11):  250-257.  doi:10.7506/spkx1002-6630-20230710-113
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In this study, in order to investigate the effect of gelation on the hardness, oil-holding capacity and rheological properties of oils and fats, oleogels were prepared by mixing coconut oil and/or palm kernel oil as oil base with candelilla wax. The results showed that candelilla wax enhanced the hardness and oil-holding capacity of oils and fats, and it could overall increase the apparent viscosity and modulus, indicating strong gelation. Furthermore, in order to clarify the effects of wax-based oleogels on chocolate quality, chocolate was made with the oleogels as oil base and stored at fluctuating temperatures of 25/32 ℃. The fatty acid and triglyceride composition, color, crystal form and micromorphology of chocolate were analyzed. It was found that gelation resulted in the generation of a new β’ crystal form, and the formation of feather-shaped and spherical crystals inside the crystal; the oil was encapsulated in the dense crystalline network, preventing its migration, retarding the blooming of chocolate and making the chocolate system more stable. In conclusion, this study provides a theoretical basis for the construction of wax-based oleogels and a reference for the development and application of fat substitutes for chocolate.
Effect of Near-Freezing Temperature Storage on Postharvest Quality and Antioxidant Activity of Jabuticaba
HU Kaixue, QIU Qiuping, LIU Shunzhi, JIANG Xuebin, GUAN Zehong, HU Weirong
2024, 45(11):  258-266.  doi:10.7506/spkx1002-6630-20231011-083
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In this study, ‘Sabará’ jabuticaba fruit were stored at (5.0 ± 0.2) ℃ or near-freezing temperature ((0.0 ± 0.2) ℃), and evaluated for changes in quality attributes and antioxidant activity after 18 days. The results showed that compared with storage at 5 ℃, near-freezing temperature treatment could effectively reduce the rate of mass loss and decay rate, maintain the contents of soluble solids, titratable acid and vitamin C (VC), and inhibit the activities of pyruvate decarboxylase and ethanol dehydrogenase in the fruit. Moreover, near-freezing temperature treatment delayed the decrease in the contents of total phenols and flavonoids, improved the activity of superoxide dismutase (SOD), slowed down the decline in the activity of peroxidase (POD) and catalase (CAT), delayed the increase in superoxide anion radical (O2−·) production rate and hydrogen peroxide (H2O2) content, and retarded the accumulation of malondialdehyde (MDA) and the increase in the permeability of the cell membrane. Therefore, near-freezing temperature storage could delay ethanol fermentation and improve antioxidant properties of jabuticaba fruit, thereby maintaining its storage quality.
Effects of Combined Treatment with L-Ascorbic Acid and Ultrasound on Storage Quality of Fresh-Cut Taro
CHEN Lin, HU Xingcheng, LUO Ziwei, WANG Mian, TU Xiaoyuan, CHEN Bingzhi, JIANG Yuji
2024, 45(11):  267-277.  doi:10.7506/spkx1002-6630-20231017-135
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To investigate the effect of combined treatment with L-ascorbic acid (AA) and ultrasound (US) (AS) on the storage quality of fresh-cut taro, the present study measured changes in the sensory quality and browning-related enzyme activities during storage of Yongding grown fresh-cut Liuyuehong taro soaked in 2% AA solution for 15 minutes, followed by US treatment (53 kHz and 400 W for 10 minutes). Compared with the control group, combined treatment with AS could reduce the water loss rate of fresh-cut taro, maintain higher hardness, delay the increase in browning index, reduce cell membrane permeability, inhibit the accumulation of malondialdehyde (MDA), and suppress surface microbial growth, thereby maintaining higher sensory quality of fresh-cut taro. In addition, AS treatment could also maintain higher activities of catalase (CAT) and superoxide dismutase (SOD), decrease the activities of peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL), inhibit the consumption of phenolic substances, slow down the loss of nutrients such as starch, soluble proteins, and soluble solids, suppress the accumulation of soluble quinones, and delay the flavor deterioration of fresh-cut taro during storage. These results indicated that AS treatment could maintain better storage quality of fresh-cut taro.
Safety Detection
A Digital Polymerase Chain Reaction Method Based on Figwort Mosaic Virus 35S Promoter (FMV 35S) for Quantitative Detection of Genetically Modified Crops
LIU Yijun, YAN Wei, LONG Likun, MA Yue, HE Yuxuan, ZHAO Ning, LI Feiwu, ZHANG Sitong
2024, 45(11):  278-284.  doi:10.7506/spkx1002-6630-20231027-225
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Using genetically modified (GM) soybean MON87705 containing the figwort mosaic virus 35S promoter (FMV 35S) as a marker gene, a quantitative method for detecting transgenic crops was established based on real-time fluorescent quantitative polymerase chain reaction (real-time PCR) and digital polymerase chain reaction (dPCR). The amplification system was tested by real-time PCR, revealing that the developed method was highly specific to FMV 35S. By determining quantitative parameters using duplex droplet digital PCR (ddPCR), it was found that within the genomic DNA concentration range of 0.005–20 ng/mL, the measured copy number of the target gene had a good linear correlation with the theoretical copy number; the limit of detection (LOD) and the limit of quantification (LOQ) of dPCR for FMV 35S were as low as 5 copies and 0.1%, respectively. Blind samples with different contents of MON87705 were tested on two dPCR platforms, indicating that accurate, reliable and reproducible results were obtained in the duplex and triple detection using a combination of internal reference genes and foreign specific fragments. Therefore, the quantitative dPCR method, which can meet the parameter requirements of the quantitative detection standard for genetically modified components with improved detection efficiency, represents an accurate and simple technology for the quantitative detection of genetically modified crops.
Rapid Determination of Residues and Migration of Seven Isocyanate Compounds in Food Composite Packaging Bags by Ultra-high Performance Convergence Chromatography
QIU Yue, LI Genrong, YU Qiuling, TAN Chaolan, LU Jiali, ZHANG Qing
2024, 45(11):  285-292.  doi:10.7506/spkx1002-6630-20231010-068
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An ultra-high performance convergence chromatography (UPC2) method was developed to rapidly determine the residues and migration of seven isocyanate compounds in food composite packaging bags. The separation was performed on an ACQUITY UPC2 HSS C18 SB column using gradient elution with a mobile phase consisting of CO2 and methanol. The column temperature was 40 ℃, and the system back pressure was 13.10 MPa. The analytes were detected by a photo diode array (PDA) detector and quantified by an external standard method. The results showed that under the optimal conditions, baseline separation of the seven isocyanate compounds could be achieved within 2 min. The detection limits were in the range of 1.0–3.0 μg/kg, and the quantitation limits were in the ranged from 5.0 to 10.0 μg/kg. At spiked levels of 10, 125 and 625 μg/kg, the recoveries of the isocyanate compounds ranged from 85.1% to 108.4%, and the relative standard deviations (RSDs) ranged from 0.7% to 6.5%. The developed method was used to determine 40 batches of food composite packaging bag samples. Isocyanate compounds residues were found in 7 batches, among which the contents of TDI and DPI residues were relatively high, but no isocyanates were found to migrate from these positive samples. The establishment of this method can provide technical support for the determination of the residues and migration of isocyanate compounds in food composite packaging bags.
A Review on the Application of Fluorescence Sensors Based on Fluorescence Resonance Energy Transfer Effect for Mycotoxins Detection
LU Meijun, WANG Tianlin, LI Tiange, QIAO Mingwu, MA Yan, HUANG Xianqing, FAN Jialin, SONG Lianjun
2024, 45(11):  293-300.  doi:10.7506/spkx1002-6630-20230619-149
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Mycotoxins are highly toxic and carcinogenic to humans and animals, and mycotoxin pollution in foods is difficult to prevent and control, which has sparked increasing concern. Therefore, it is necessary to detect mycotoxins in foods. Traditional mycotoxin detection methods, although accurate and reliable, require expensive equipment and long detection time, which do not meet the requirements of the rapid detection of mycotoxins. Thus, it is necessary to develop fast, sensitive, accurate, and economical methods for detecting mycotoxins. Fluorescent sensors based on the fluorescence resonance energy transfer (FRET) effect are widely used in the detection industry because of their simple operation, fast reaction speed, reliable results and low cost. This article mainly introduces the detection mechanism of fluorescence sensors based on the FRET effect, summarizes their applications in mycotoxin detection, and proposes existing problems and an outlook for future development trends, in order to provide a reference for the design of novel fluorescence sensors and the optimization of the sensitivity of mycotoxin detection.
Research Progress in Black Phosphorus-Based Electrochemical Sensors for Food Detection
PENG Gang, ZHANG Kaiwen, SUN Minghui, ZHANG Xu, YANG Han, DING Zhigang
2024, 45(11):  301-313.  doi:10.7506/spkx1002-6630-20230429-288
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In recent years, black phosphorus, a new two-dimensional nanomaterial, has been widely used in sensors and analytical instrumentation due to its tunable band gap, high electron mobility and large specific surface area. This article introduces the structure and properties of black phosphorus and its preparation methods, and reviews recent progress in the application of electrochemical sensors based on black phosphorus for the detection of nutrients and harmful substances in foods, harmful substances in food packaging materials. Finally, we summarize the problems in the application of black phosphorus-based electrochemical sensors and provides some suggestions to solve these problems.
Research Progress in the Application of Cold Plasma Sterilization Technology in Dairy Products
QI Geqi, ZHU Jun, DENG Haoguo, ZHANG Hai, XU Rihua
2024, 45(11):  314-322.  doi:10.7506/spkx1002-6630-20230517-170
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Cold plasma (or non-thermal plasma) is one of the popular non-thermal processing technologies in recent years. Cold plasma technology is expected to be used as a rapid non-thermal sterilization technology in dairy processing. However, an unoptimized cold plasma process may lead to quality deterioration of dairy products, such as lipid oxidation and odor generation. Therefore, this article provides a review of the classification and mechanism of cold plasma sterilization technology and its potential impact on dairy products, with the aim of offering theoretical support for the application of cold plasma sterilization technology in the dairy industry. Future studies on cold plasma need to consider the preservation of the quality and sensory acceptability of dairy products while effectively inactivating microorganisms.
Research progress in phenolic acid decarboxylase derived from microorganisms
CHEN Yinzhu, QIN Chi, LI Qin, HU Kaidi, LI Jianlong, LIU Shuliang
2024, 45(11):  323-332.  doi:10.7506/spkx1002-6630-20230517-163
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Phenolic acid decarboxylase (PAD) (lyase, EC catalyzes the conversion of phenolic acids such as coumaric acid, ferulic acid, caffeic acid, and glucosic acid that are widely distributed in plants into 4-vinyl derivatives. 4-Vinyl derivatives are not only high-grade fragrances, but also key precursors for the synthesis of other spices such as vanillin. Food spices are mainly chemically synthesized in the current market. By contrast, the biosynthesis method, which is characterized by single precursor substances, mild conditions and environmental friendliness, has broad application prospects, and biosynthesized spices are regarded as being equivalent to natural products. Therefore, using PAD for the biosynthesis of 4-vinyl derivatives is of great significance to supplementing the production pathway of this type of fragrance. In this article, PAD derived from microorganisms are summarized from five aspects: origins, molecular structure, catalytic mechanism and structure-function correlation, catalytic properties, and techniques to improve the catalytic efficiency.
Research Progress in Properties and Applications of Soybean Protein-Stabilized Emulsion Gels
ZHU Xiuqing, AN Yuexin, HE Yang, HUANG Yuyang, ZHU Ying
2024, 45(11):  333-342.  doi:10.7506/spkx1002-6630-20230704-027
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Emulsion gels, a complex colloid system in which the emulsion and the gel coexist with a unique three-dimensional network structure, are widely used in the pharmaceutical, cosmetic and food industries. As a high-molecular-mass protein, soybean protein has good functional and physicochemical properties. Soybean protein-stabilized emulsion gels can be prepared by various methods such as heat induction, salt induction, phosphorylation modification and enzyme induction, forming a core-shell structure with soybean protein-stabilized oil droplets, which have excellent gel-forming capacityand stability. Soybean protein-stabilized emulsion gels have been widely studied and applied as fat substitutes to reduce the content of animal protein and fat in the food system and as novel materials for three-dimensional printing. To better understand the research progress in soybean protein-stabilized emulsion gels, the classification of and the preparation methods for soybean protein-stabilized emulsion gels are reviewed. The structure and formation mechanism of emulsion gels stabilized by soybean protein alone or combined with polysaccharide are analyzed and summarized. The functional properties such as gelation, rheological properties and stability of soybean protein-stabilized emulsion gels are elucidated. Finally, the applications of soybean protein-stabilized emulsion gels are summarized to provide a theoretical basis for the processing and utilization of soybean protein-stabilized emulsion gel products.
Progress in Diets with Low Glycemic Index for the Nutritional Management of Type 2 Diabetes: Research and Current Applications
LI Aiqi, XIA Hui, SUN Guiju
2024, 45(11):  343-350.  doi:10.7506/spkx1002-6630-20230707-065
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Foods with a glycemic index (GI) equal to or less than 55 are known as low GI foods. A low GI diet refers to a dietary pattern in which low GI foods are primarily chosen, and cooking methods are adjusted to control the overall GI value of the diet. The application of a low GI dietary intervention in the nutritional management of diabetes helps to stabilize postprandial blood glucose, improve satiety, and reduce blood glucose fluctuations in diabetic patients. This article provides a systematic review of the application of low GI dietary patterns in the nutritional management for diabetes, elucidates the factors influencing dietary GI value, discusses the types and development of low GI foods, presents an outlook for future development trends, and proposes future research directions and potential challenges in the field of low GI foods.