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Table of Content

25 May 2024, Volume 45 Issue 10
Machine Learning
Hash Food Image Retrieval Based on Enhanced Vision Transformer
CAO Pindan, MIN Weiqing, SONG Jiajun, SHENG Guorui, YANG Yancun, WANG Lili, JIANG Shuqiang
2024, 45(10):  1-8.  doi:10.7506/spkx1002-6630-20231231-270
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Food image retrieval, a major task in food computing, has garnered extensive attention in recent years. However, it faces two primary challenges. First, food images exhibit fine-grained characteristics, implying that visual differences between different food categories may be subtle and often can only be observable in local regions of the image. Second, food images contain abundant semantic information, such as ingredients and cooking methods, whose extraction and utilization are crucial for enhancing the retrieval performance. To address these issues, this paper proposes an enhanced ViT hash network (EVHNet) based on a pre-trained Vision Transformer (ViT) model. Given the fine-grained nature of food images, a local feature enhancement module enabling the network to learn more representative features was designed in EVHNet based on convolutional structure. To better leverage the semantic information in food images, an aggregated semantic feature module aggregating the information based on class token features was designed in EVHNet. The proposed EVHNet model was evaluated under three popular hash image retrieval frameworks, namely greedy hash (GreedyHash), central similarity quantization (CSQ), and deep polarized network (DPN), and compared with four mainstream network models, AlexNet, ResNet50, ViT-B_32, and ViT-B_16. Experimental results on the Food-101, Vireo Food-172, and UEC Food-256 food datasets demonstrated that the EVHNet model outperformed other models in terms of comprehensive retrieval accuracy.
Detection of Dispersibility and Bulk Density of Instant Whole Milk Powder Based on Residual Network
DING Haohan, SHEN Song, XIE Zhenqi, CUI Xiaohui, WANG Zhenyu
2024, 45(10):  9-18.  doi:10.7506/spkx1002-6630-20240129-262
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To address the problems of the traditional international standard methods for milk powder quality detection such as subjectivity and lag, this study proposed a rapid method for the detection of the dispersibility and bulk density of milk powder based on residual network (ResNet). The dataset used in this study included 499 particle distribution images taken for 10 groups of instant whole milk powder samples under a 10 × optical microscope. Initially, these sample groups were tested for dispersibility and bulk density using the international standard methods, and classified into different levels of dispersibility and bulk density based on the test results. Subsequently, these microscopic images were used to train the ResNet to facilitate effective classification of different samples. Ultimately, the classification results were used to predict the dispersibility, loose density, and tapped density of instant whole milk powder. Additionally, this study compared the predictive performance of different deep learning models, including ResNet, EfficientNetV2, and Swin Transformer. The results indicated that the deep learning model based on ResNet 152 exhibited the best performance in predicting the dispersibility, loose density, and tapped density of instant whole milk powder, with accuracy rates of 97.50%, 98.75%, and 95.00%, respectively for the test set. The exceptional performance of these deep learning models in milk powder quality detection not only proves that this method can predict the dispersibility and bulk density of milk powder in real time and accurately, but also provides a new technological approach for online quality detection of milk powder.
Establishment and Evaluation of Support Vector Machine Model for Adulteration Discrimination of Camellia Oil Based on Low-Field Nuclear Magnetic Resonance Relaxation Characteristics
LIN Xiaolang, FU Libin, WANG Xin
2024, 45(10):  19-27.  doi:10.7506/spkx1002-6630-20240105-053
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The high commercial value of camellia oil entails the development of a rapid and accurate method for identifying camellia oil adulteration. In this study, the feasibility of using low-field nuclear magnetic resonance (LF-NMR) relaxation characteristics and support vector machine (SVM) to detect adulteration in camellia oil was investigated. The LF-NMR relaxation characteristics of raw and oxidized oils of camellia and three other species and their binary blends were compared. Furthermore, principal component analysis was carried out and then an SVM multi-classifier with a binary tree structure was designed. After feature screening by the ReliefF algorithm, an SVM model for identifying adulteration in camellia oil was established and evaluated. The results showed that the LF-NMR relaxation characteristics of oil samples were affected by oil type, oxidation degree and blending ratio. The SVM multi-classification model with 9 features exhibited the best performance, with an accuracy of 90.77%. Additionally, the average recall, precision and F1 score for camellia oil, blending type and ratio were 90.87%, 90.83% and 0.90, respectively. This study indicated that the SVM model based on LF-NMR relaxation characteristics could be employed for identifying adulteration in camellia oil.
Research Progress and Future Trends of Machine Learning in the Field of Food Flavor
CHEN Liang, YANG Jiahong, TIAN Xing
2024, 45(10):  28-37.  doi:10.7506/spkx1002-6630-20231123-181
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With the continuous improvement of living standards, people are concerned about not only whether foods are tasty or not, but also the combination of health elements and good flavor. Food flavor components are not only important factors in sensory quality, but also key indicators of the nutritional level of foods. At present, the traditional methods to evaluate and predict food flavor components are time-consuming and labor-intensive, and unable to handle large amounts of data. In contrast, machine learning (ML), the core of artificial intelligence, has incomparable advantages over traditional analytical techniques in distinguishing differences and finding commonalities, and has found good application in the field of food flavor analysis. In this context, this paper focuses on the current research status of ML in the field of food flavor, and introduces the principles and advantages of commonly used ML methods, as well as their latest applications and prospects in food flavor prediction and regulation. It also focuses on the advantages and future trends of modern intelligent sensory evaluation techniques combined with ML in the field of food flavor analysis, with a view to providing new ideas and theoretical foundations for food flavor analysis and prediction.
Basic Research
Effect of Basal Immunoglobulin on the Meat Quality of Qinchuan Cattle during Postmortem Maturation
SU Xiaofeng, LI Yalei, LUO Ruiming
2024, 45(10):  38-44.  doi:10.7506/spkx1002-6630-20230403-024
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To investigate the effect of basal immunoglobulin (BSG) expression during postmortem maturation on meat quality, changes in quality indicators such as pH, cooking loss and myofibril fragmentation index (MFI), as well as energy substance and BSG contents of Qinchuan cattle meat were measured after different periods (0, 2, 4, 6 and 8 days) of postmortem aging at 4 ℃. The proteomic changes were also analyzed using 4D-label free quantification (4D-LFQ). The results showed that during the postmortem storage period, the expression of BSG showed an overall trend of initially increasing and then decreasing. The levels of the energy substances ATP, ADP, AMP and NADH showed a decreasing trend; pH and cooking loss initially decreased and then increased; MFI showed a continuous increasing trend. The correlation analysis showed that the expression of BSG was significantly positively correlated with cooking loss (P < 0.01), but negatively correlated with pH, ATP and NADH levels (P < 0.05). However, it had no significant correlation with ADP or AMP contents. Therefore, the change of BSG expression in the Longissimus dorsi muscle of Qinchuan cattle during postmortem maturation was closely related to the quality and energy metabolism of beef. Proteomics identified that BSG and its associated differential proteins had catalytic activity, hydrolase activity and proton-transporting ATP synthase activity, bound to ATP, ribonucleotides and carbohydrate derivatives in cells, and were involved in the regulation of molecular functions and hydrogen ion transport across membranes. These biological effects caused mitochondrial damage and were involved in changes in meat tenderness through energy metabolism.
Mechanism of Action of Capsaicin and Quercitrin in Regulating Lipid Metabolism in HepG2 Cells through EGFR/PI3K/Akt Signaling Pathway
ZHU Wenxuan, SHI Quanying, WANG Xianghong, YANG Ruili, CHENG Xinying, MI Si
2024, 45(10):  45-53.  doi:10.7506/spkx1002-6630-20230906-051
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The objective of this study was to investigate the molecular mechanism behind the regulatory effect of capsaicin combined with quercitrin on liver lipid metabolism. The effects of capsaicin alone or in combination with quercitrin on the survival rate of HepG2 cells with oleic acid-induced lipid accumulation were investigated. Oil red O staining was used to observe lipid accumulation in HepG2 cells. Meanwhile, the levels of total triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total bile acid (TBA) were determined. Moreover, the expression levels of epidermal growth factor receptor (EGFR), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), farnesoid X receptor 1 (FXR1), cholesterol 7α-hydroxylase (CYP7A1) and fibroblast growth factor 19 (FGF19) were determined by Western blotting. The results showed that the proliferation rate of HepG2 cells in each treatment group was greater than 75%, demonstrating no significant cytotoxicity. The results of oil red O staining showed a reduction in lipid accumulation in both single and combined treatment groups. The application of capsaicin alone or combined with quercitrin reduced the contents of TG, TC and LDL-C, increased the contents of HDL-C and TBA, and up-regulated the protein expression levels of EGFR, PI3K, Akt, FXR1 and FGF19. In summary, capsaicin combined with quercitrin exerted a synergistic regulatory effect on lipid metabolism in HepG2 cells, with the most pronounced effect being observed at a 3:1 ratio.
Cysteine Oxidation Sites in Tan Lamb Meat Proteins at Different Storage Temperatures: Identification and Effect on Meat Tenderness
ZHANG Rui, TAO Yingmei, GAO Yurong, WANG Suye, LIU Dunhua
2024, 45(10):  54-61.  doi:10.7506/spkx1002-6630-20230403-015
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The shear force and textural properties (hardness, elasticity and chewiness) of Ningxia Tan lamb meat stored at −80 ℃ (control), −2, −18 or 4 ℃ for 7 days were determined by cysteine oxidative modification proteomics. Meanwhile, the cysteine oxidation sites were identified, and the Pearson’s correlation was used to analyze the correlation between the oxidation intensity of significantly differential oxidation sites (SDOS) and the quality indicators of refrigerated Tan lamb meat. The results showed that compared with the control group, the shear force and texture characteristics of lamb meat in the experimental groups were significantly reduced (P < 0.05), and 25 SDOS proteins (including 10 structural proteins, 8 metabolic enzymes, 2 degradative enzymes and 5 other proteins) were significantly correlated with at least one quality indicator (P < 0.05), which could be used as potential biomarkers to evaluate changes in the tenderness and texture of lamb meat during storage.
Quantum Chemical Calculation of the Formation Mechanism of the Sugar Smoking Pigment 5-(α-D-glucopyranosyl-(1-6)-α-D-glucopyranosyloxymenthyl)-2-furancarboxaldehyde
YE Guoqing, NIU Yumin, FAN Chaoxia, YANG Hui, LIU Dengyong
2024, 45(10):  62-71.  doi:10.7506/spkx1002-6630-20230515-128
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In order to explore the formation pathways of 5-(α-D-glucopyranosyl-(1-6)-α-D-glucopyranosyloxymenthyl)-2-furancarboxaldehyde (5-GGMF), a pigment formed during the process of sugar smoking, the thermal decomposition reaction site of sucrose, the dehydration reaction modes between glucose and 5-hydroxymethylfurfural (5-HMF) and between two molecules of glucose, and the formation pathways of 5-HMF and 5-GGMF were analyzed by quantum chemical calculation. The results showed that the initial position of thermal decomposition of sucrose was the cleavage of fructosyl-oxygen bond. van der Waals force played a leading role in the complexes formed by the interaction between glucose and 5-HMF and between two molecules of glucose, and the intermolecular dehydration reaction was promoted by strong hydrogen bonding. The formation of 5-HMF from the glucose moiety formed after the pyrolysis of sucrose needed more activation energy than from the fructose moiety formed with a lower reaction rate, indicating that the fructose moiety was more prone to form 5-HMF. Among the two formation pathways of 5-HMF from the fructose moiety, pathway 5 was more prone to occur than pathway 4, because pathway 5 showed obvious advantages in energy and reaction kinetics. In the formation pathways of 5-GGMF from sucrose, the energy barrier of the transglycosylation pathway was overall lower, which was more favorable than the disaccharide dehydration and trisaccharide dehydration pathways. Among them, pathway C2, including three steps: the pyrolysis of sucrose to produce fructose and glucose, the reaction of glucose with 5-HMF to form 5-glucosyloxymethylfurfural (5-GMF), and the reaction of 5-GMF with a molecule of free glucose to produce 5-GGMF, was most conducive to the generation of 5-GGMF from both an energy barrier and kinetic perspective. The results of this study can provide a theoretical basis and reference for controlling and intervening in the color of sugar smoked products in the future.
Food Chemistry
Effect of Whole Common Buckwheat Flour on the Rheological Properties of Wheat Dough and the Quality of Fresh Noodles
YAN Minghuan, HE Jialiang, WANG Libo, CHEN Jing, REN Yanjuan, ZHANG Hengyun, ZHANG Bin, LIU Wenchao, WANG Haoran, WU Weijing, LUO Denglin
2024, 45(10):  72-79.  doi:10.7506/spkx1002-6630-20230911-081
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The present study tested the effect of addition of whole common buckwheat flour on the rheological properties of wheat dough, and the textural characteristics, water distribution, secondary structure and molecular mass distribution of proteins, microstructure, and color of fresh noodles. The results demonstrated that the dough with 30% whole common buckwheat flour had a higher G’ (5.3 × 105 Pa) and a minimum tan δ value of 0.50. The resulting noodles had a maximum elasticity of 0.97, a maximum α-helix content of 28.30%, and a denser and more homogenous microstructure. According to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) data, the band intensities of buckwheat protein subunits increased with increasing addition of whole common buckwheat flour. Compared with the control group, the addition of whole common buckwheat flour caused partial transformation of tightly bound water to weakly bound water and free water. As the addition of common buckwheat flour increased, the L* value of noodles decreased significantly, the a* and b* values increased to varying degrees, and as a result the overall color turned reddish and yellow. In conclusion, the addition of 30% whole common buckwheat flour can improve the mechanical properties and processing quality of fresh noodles.
Preparation and Properties of Passion Fruit Seed Oil Pickering Emulsion Stabilized by β-Lactoglobulin-Polyphenol Nanoparticles
JIANG Tingting, ZHENG Lili, AI Binling, YANG Yang, ZHENG Xiaoyan, WANG Shenwan, XIAO Dao, YANG Jinsong, SHENG Zhanwu
2024, 45(10):  80-88.  doi:10.7506/spkx1002-6630-20230712-143
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In this study, a passion fruit seed oil Pickering emulsion stabilized by β-lactoglobulin nanoparticles loaded with a ternary mixture of ferulic acid, quercetin and vanillic acid (β-LGCNPs) was prepared by an ultrasonic method. The particle size, stability, and microstructure, and antioxidant, digestibility, rheological properties and lipid oxidation products of Pickering emulsions prepared under varying conditions of nanoparticle concentration and oil phase ratio were investigated. The results showed that the Pickering emulsion was a stable oil-in-water (O/W) emulsion with β-LGCNPs adsorbed at the oil-water interface. The particle size of the emulsion was directly proportional to the particle concentration and inversely proportional to the oil phase ratio. The average particle size of the Pickering emulsion prepared at β-LGCNP concentration of 1.5% and 30% oil phase was (5.78 ± 0.10) μm. The emulsion had good stability under different ionic strength and pH conditions, showing stronger antioxidant properties than passion fruit seed oil. The free radical scavenging capacity was dependent on β-LGCNP concentration. After intestinal digestion for 2 h, the release rate of free fatty acids from the Pickering emulsion was (65.17 ± 1.52)%, which was 26.65% higher than that from passion fruit seed oil. The rheological results showed a shear-thinning phenomenon, indicating that the emulsion is a non-Newtonian fluid, and the elastic and viscous moduli increased with the increase in shear frequency. During 15 days of storage, the amount of lipid oxidation products including hydroperoxide and malondialdehyde (MDA), and the rate of lipid oxidation in the Pickering emulsion decreased. In summary, the Pickering emulsion stabilized with β-LGCNPs improved the stability, antioxidant activity, digestibility and lipid oxidation of passion fruit seed oil, which is conducive to expanding the application of passion fruit seed oil in the food field.
Reconstitutability and Flavor Characteristics of Pea Peptide-Incorporated Soymilk Powder
LÜ Wenqing, SUN Jingru, ZHANG Shu, CAO Rong’an, DIAO Jingjing, WANG Changyuan
2024, 45(10):  89-97.  doi:10.7506/spkx1002-6630-20231019-152
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To enrich the flavor and nutritional efficacy of soymilk powder, this study investigated the effects of adding different ratios of pea peptides on the quality, nutrition and flavor of soymilk powder. The reconstitutability of soymilk powder was examined based on solubility and caking rate, and its in vitro bioactive functions were evaluated in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and cholesterol scavenging capacity. The changes in the structural properties and flavor quality of soymilk powder caused by addition of pea peptides were explored by Fourier transform infrared (FTIR) spectroscopy, nanoparticle size analyzer, confocal laser scanning microscopy (CLSM), and headspace solid phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS). The results showed that the addition of 30% pea peptides to soymilk powder increased the protein content by 13.05% and solubility by 11.23%, decreased the caking rate by 4.20%, enhanced the DPPH radical and cholesterol scavenging capacity by 19.84% and 21.25%, respectively, and significantly improved the reconstitutability in hot water at 70 ℃. The structural analysis results revealed that pea peptide addition altered the secondary structure of proteins, reduced the average particle size, and resulted in more uniform particle size distribution in reconstituted soymilk, thereby improving the solubility of soymilk powder. Additionally, pea peptide addition changed the concentrations of the key flavor components geranylacetone, myristic acid, 3-methylthiopropanal, 2-methylpyrazine and 2,5-dimethylpyrazine in reconstituted soymilk, while decreasing the concentrations of off-flavor substances, such as hexanal, trans-2-nonenal, nonanal, n-hexanol, 1-octen-3-ol and naphthalene.
Bioengineering
Debittering and Antioxidant Activity of Fermented Grapefruit Juice with Lactiplantibacillus plantarum 1-1-2
LI Hui, WANG Yixuan, LI Long, XU Qianqi, HAN Rubing, WU Zhengyan, ZHANG Yan
2024, 45(10):  98-107.  doi:10.7506/spkx1002-6630-20230706-054
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Grapefruit juice was debittered by cleaving the bitter compound naringin through fermentation with lactic acid bacteria with strong ability to metabolize functional oligosaccharide. The experimental results showed that the content of naringin in the fruit juice was reduced by Lactiplantibacillus plantarum 1-1-2 fermentation, while the content of naringenin was significantly increased, and the content of total phenols and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity were also significantly increased. DPPH radical scavenging activity was positively correlated with the contents of total phenols and naringenin. These findings prove that L. plantarum 1-1-2 can hydrolyze naringin into naringenin, with significantly higher antioxidant activity. The sensory evaluation score of fermented grapefruit juice was higher than that of unfermented grapefruit juice. This study can provide a theoretical basis for improving the taste of grapefruit juice and developing functional probiotic fermented products.
Selection of Enzyme-Producing Microorganisms from Jiuqu and Their Influence on the Quality of Fermented Rice Wine
ZOU Yuting, HE Zihan, XU Bitao, CHEN Lanchai, ZHANG Qing
2024, 45(10):  108-117.  doi:10.7506/spkx1002-6630-20230922-208
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Generally, commercial rice wine has stable quality with bland flavor, while traditional rice wine has a mellow taste but is unstable in quality. In order to solve this problem, the influence of mixed culture fermentation with monocultures of culturable fungi producing amylase, protease and esterase isolated from Jiuqu from different regions in China and commercial sweet wine koji on the quality of rice wine was assessed. According to the enzyme-producing characteristics and 18S rDNA gene sequence analysis, the five obtained strains were identified as Rhizopus oryzae, Mucor circinelloides, M. lanceolatus, and two strains of Saccharomycopsis fibuligera (XG and HB). The addition of S. fibuligera HB increased the contents of ethanol and amino nitrogen, enriched the types and contents of organic acids, reduced the contents and percentage of bitter amino acids, and increased the contents of volatile compounds when compared with the control group (commercial sweet wine koji alone). More importantly, the contents of phenethyl alcohol and ethyl acetate were significantly higher than those in the other groups. Therefore, S. fibuligera HB can significantly improve the quality of rice wine, suggesting its application potential in multi-strain Qu for rice wine.
Analysis of Bacterial Diversity in Lufeng Aromatic Vinegar with Different Storage Years
ZHAO Ruihuan, CHEN Qianrui, GU Dahai, XU Zhiqiang
2024, 45(10):  118-125.  doi:10.7506/spkx1002-6630-20230711-141
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In this study, high throughput sequencing technology was used to analyze the bacterial diversity of Lufeng vinegar stored for different periods (produced in 2017, 2018, 2019 and 2020). The results showed that the composition of bacterial flora in samples with different storage years was significantly different. In Lufeng vinegar produced in 2017, 2018 and 2019, the diversity of bacterial flora was higher, and the dominant phyla were Firmicutes, Proteobacteria and Actinobacteriota. The dominant genera were Herbaspirillum, Acinetobacter, Hafnia-Obesumbacterium, Enterobacter and Bosea. The dominant bacterial phyla in Lufeng vinegar produced in 2020 were Firmicutes and Proteobacteria, and the dominant bacterial genera were Lactobacillus, Ralstonia and Lactobacillus_homohiochii. Linear discriminant analysis effect size (LEfse) analysis and correlation analysis consistently showed that the diversity of bacterial flora was related to storage time. Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway analysis showed that the beneficial flora in Lufeng vinegar could play an important role in the relationship between primary and secondary metabolism, which needs further study. Our findings in this study may lay the foundation for the analysis of bacterial diversity in Lufeng aromatic vinegar, the breeding of high-quality strain resources and the industrial production of vinegar.
Selection of Antimicrobial Peptide DB16 from Bacillus cereus and Its Antibacterial Mechanism against Staphylococcus aureus
YANG Zhiyuan, JIN Ritian, LIANG Duo, QIU Xujian, YANG Shen, LIN Rong
2024, 45(10):  126-134.  doi:10.7506/spkx1002-6630-20231016-128
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In this study, it was found that when co-cultured with Bacillus cereus, the growth of Staphylococcus aureus was inhibited. The antimicrobial peptide DB16 (RKLLQFAKKLGIVFTK) was predicted and selected from the ATP-dependent RNA helicase of B. cereus by bioinformatics. The minimum inhibitory concentration (MIC) of the antimicrobial peptide DB16 against S. aureus was 31.25 μg/mL, which could completely inhibit the growth of S. aureus within 0.5 h. DB16 presented a random coiled structure in phosphate buffered saline (PBS), and turned into an α-helix structure in sodium dodecyl sulfate (SDS). Fluorescence probe, flow cytometry, transmission electron microscopy (TEM), DNA gel electrophoresis and circular dichroism (CD) spectroscopy were used to explore the antibacterial mechanism of DB16 against S. aureus. The results showed that the antibacterial peptide DB16 could change the permeability of the bacterial cell membrane, thereby causing the leakage of cellular contents, while entering the cells to combine with the genomic DNA of S. aureus, affecting normal DNA replication, and finally inhibiting the growth and reproduction of bacteria. In addition, DB16 at 8 × MIC showed no hemolysis on mammalian red blood cells. In conclusion, the antimicrobial peptide DB16 from B. cereus has great potential for the prevention and control of S. aureus.
Nutrition & Hygiene
Effect of Yak Milk on Intestinal Microbiota and Metabolism in Mice
SHU Senbiao, ZHANG Jinchao, YANG Jie, WANG Wenhan, LUO Zhang, LI Liang, LIU Zhendong
2024, 45(10):  135-146.  doi:10.7506/spkx1002-6630-20230906-053
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In order to investigate the effect of long-term consumption of yak milk on the intestinal flora and metabolism and to explore the correlation between acclimation to monodiet and yak milk intake in high-altitude pastoral areas, this study used metagenomics and metabolomics to evaluate the gut microbial community structure and metabolites of mice fed yak milk or Holstein cow milk. Results showed that compared with the control group (normal saline solution), at the phylum level, ingestion of yak milk improved the relative abundance of Actinobacteria (33.27%), Bacteroidetes (24.31%) and Verrucomicrobia (11.08%), while ingestion of Holstein cow milk increased the relative abundance of Firmicutes (43.74%) and Bacteroidetes (24.75%). At the genus level, yak milk consumption increased the relative abundance of Ackermania (11.80%), Bacteroides (6.09%) and Limosilactobacillus (4.77%), while Holstein cow milk consumption increased the relative abundance of Lactobacillus (28.62%), Duncaniella (6.15%) and Limosilactobacillus (6.49%). Both yak and Holstein cow milk up-regulated carbohydrate and nucleotide metabolism. Furthermore, yak milk significantly up-regulated amino acid metabolism, cofactor and vitamin metabolism, energy metabolism, the biosynthesis of secondary metabolites, and the biosynthesis and metabolism of peptidoglycan. Metabolomics revealed that yak milk increased the contents of metabolites such as VB1, (+/-) 12 (13)-DiHOME, coenzyme Q2 and sulfonymethazine, as well as steroid hormone biosynthesis, cofactor biosynthesis, 2-oxyarboxylate metabolism, VB6 metabolism and phenylalanine metabolism in mice. Investigation of intestinal tissue morphology showed that the intestinal wall became thicker with increasing diversity and richness of the gut microbiota and the intestinal villi became longer and denser without deformity or breakage. In conclusion, yak milk has a positive effect on the intestinal flora and metabolism in mice, and this study provides a scientific basis for further development and utilization of yak milk.
Exploring the Action Mechanism of Rosa roxburghii Fruit Flavonoids in the Intervention of Ulcerative Colitis Based on Network Pharmacology, Molecular Docking and Experimental Verification
PU Xian, YUAN Meng, TAN Shuming, XIE Guofang, TAO Yun, LOU Jienan, LU Guanglei, XU Haoran
2024, 45(10):  147-157.  doi:10.7506/spkx1002-6630-20230717-196
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The aim of this study was to investigate the core components and mechanism of action of Rosa roxburghii fruit flavonoids in the intervention of ulcerative colitis (UC) using network pharmacology and molecular docking. We extracted flavonoids from R. roxburghii fruit by an ethanol-cellulase method and used liquid chromatography-mass spectrometry (LC-MS) to identify the major chemical components of the flavonoid extract, and then we selected 34 active flavonoid components and 146 targets in the intervention of UC on an analytical platform and constructed a “R. roxburghii flavonoids-active components-intersecting targets-UC” network. The results of gene ontology pathway analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the intervention of R. roxburghii flavonoids in UC mainly involved the arachidonic acid signaling pathway, the nuclear factor-kappa B signaling pathway, and cancer pathways. Molecular docking was performed on the major active ingredients and the key targets selected from the network, with docking energies all less than −6.0 kcal/mol, indicating a strong binding affinity between the core active ingredients and the key targets for UC treatment. So, the network analysis results are reliable. The results of animal experiments showed that intervention with R. roxburghii flavonoids could effectively alleviate the body mass loss and colon pathological changes of UC mice, and significantly inhibit the expression of inflammatory cytokines such as tumour necrosis factor-α, interleukin (IL)-1β and IL-6 in the UC model group (P < 0.05). The results of Western blot showed that R. roxburghii flavonoids could effectively inhibit the expression of the key target proteins associated with the metabolic pathway of arachidonic acid, such as cyclooxygenase-2 and 5-lipoxygenase. In conclusion, R. roxburghii flavonoids can intervene in UC through a multi-component, multi-target and multi-pathway mechanism. The results of this research can provide a theoretical basis for the development and utilization of functional foods from R. roxburghii.
Component Analysis
Evaluation of Wine Fermentation Characteristics of Guizhou’s Five Specialty Fruits Based on the Composition of Organic Acids and Polyphenols
CHEN Qiuzhu, XIE Hanyi, HE Jiaojiao, WU Fang, WANG Chunxiao
2024, 45(10):  158-166.  doi:10.7506/spkx1002-6630-20230715-176
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To evaluate the fermentation potential of Guizhou’s specialty fruits, the contents of organic acids and polyphenols juices in juices and laboratory prepared wines from crystal grapes, brier grapes, kiwifruits, golden prickly pears and blueberries grown in Guizhou were analyzed and compared with those of commercial wines. The results showed that the contents of organic acids and polyphenols varied significantly among the five fruit juices, with the highest contents of organic acids (72.30 g/L), total phenols (2 457.16 mg/L), and tannins (1 112.84 mg/L) being found in golden prickly pear juice and the lowest values (organic acids 7.63 g/L, total phenols 8.52 mg/L, and tannins 7.45 mg/L) in crystal grape juice. During the fermentation process, the contents of organic acids and polyphenols changed. The content of total organic acids significantly decreased in all wine samples, the contents of total phenols and anthocyanins increased in blueberry and brier grape wine, and the contents of total phenols and tannins decreased in kiwifruit and golden prickly pear wine but did not change significantly in crystal grape wine. Resveratrol was only detected in commercial red wine and blueberry wine at low levels ranging from 0.29 to 5.98 mg/L. Compared with commercial wines, laboratory prepared golden prickly pear wine had higher contents of organic acids, total phenols and tannins, and laboratory prepared kiwifruit wine had higher contents of organic acids. The anthocyanin content in laboratory prepared brier grape wine was the highest, which was two to three times higher than that of all commercial wines. To sum up, each of the specialty fruits from Guizhou has their own unique characteristics in the composition of organic acids and polyphenols, and their organic acid and polyphenol composition change differently after fermentation into wine. This study provides a theoretical basis for the selection of different technological methods such as maceration in wine processing from Guizhou’s specialty fruits and for the design of wine body from mixed fruit juices.
Variations in Chemical Quality among Spring and Summer Tea Made from Six Cultivars Grown in Motuo County, Tibet
MAO Juan, WANG Wenhai, Lobsang, ZHANG Liyong, WANG Fatong, WANG Bin, LI Qing, Tsering Choezom, WANG Wenhua
2024, 45(10):  167-174.  doi:10.7506/spkx1002-6630-20230922-204
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The water extract contents, polyphenol compositions, total free amino acid contents, caffeine (CAF) contents, amino acid compositions and catechin compositions of spring and summer tea made from six varieties planted in Motuo, namely Tezao 213, Zhuyeqi, Zhongcha 302, Tieguanyin, Yinghong 9 and Fenghuang Dancong were determined and compared. The results indicated significant differences between spring and summer tea in all quality components except tea polyphenols. The average phenol/ammonia ratio of spring and summer tea was 4.60 and 7.99, respectively, indicating summer tea to be suitable for processing into green and black tea. Altogether 18 amino acids were detected in the six cultivars, and the contents of different groups of amino acid were in the decreasing order of umami amino acids > sweet amino acids > bitter amino acids > aromatic amino acids. The contents of umami and sweet amino acids in spring tea were significantly higher than those in summer tea. Correlation analysis revealed that the synthesis of various metabolites were highly correlated. Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) showed that season had a more significant effect on tea metabolites than variety. A total of 16 compounds were identified as differential metabolites between spring and summer tea, including 7 amino acids, 8 catechins and CAF, which could be used as potential markers to distinguish spring and summer tea. This study provides a valuable reference for tea processing.
Classification of Phenotypic Traits, Identification of Volatile Compounds and Characteristic Aroma Analysis of Canarium album Fruit
XIE Qian, ZHAO Qingqing, JIANG Lai, CHEN Qingxi
2024, 45(10):  175-185.  doi:10.7506/spkx1002-6630-20240103-035
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The phenotypic characteristics (including single fruit mass, longitudinal diameter, transverse diameter, and fruit shape index) of 59 varieties of Chinese olive fruit were assessed and categorized based on probability. 15 Chinese olive varieties with varying fruit shape indexes and genetic backgrounds were selected for analysis of volatile compounds using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results indicated a wide range of variation in four phenotypic traits, with coefficients of variation (CV) between 10.70% and 26.67%. The Kolmogorov-Smirnov (K-S) test showed that the data of fruit shape index, longitudinal diameter, and transverse diameter followed a normal distribution, allowing for their categorization based on probability. A total of 886 volatile compounds were identified including 186 terpenoids, 157 heterocyclic compounds, 146 esters, 73 ketones, 64 hydrocarbons, 64 alcohols, 53 aldehydes, 51 aromatic hydrocarbons, 21 acids, 21 amines, 20 phenols, and 30 other compounds at concentration levels ranging from 1 881.70 to 6 727.40 μg/g of fresh mass. Terpenes were the dominant volatile compounds in Chinese olive fruit, accounting on average for 52.49% of the total volatile compounds. The most abundant terpene was α-pinene, with a relative content of 7.13% (309.66 μg/g of fresh mass). A total of 181 characteristic aroma components were identified using odor activity value (OAV) analysis, contributing to the overall aroma profile of Chinese olive fruit. Among these components, the heterocyclic compound 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone was the biggest contributor with the highest OAV of 2 468 148.28, being responsible for sweet aroma. Utilizing principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) analysis, 6 differential characteristic aroma components were identified among different varieties of Chinese olive fruit. Notably, α-farnesene had the highest variable importance in the projection (VIP) value with an OAV of 19.71, being responsible for floral and fruity aromas. These findings serve as a valuable reference for the quality grading of Chinese olive fruit, as well as for future investigations into its aroma formation mechanism and quality improvement.
UPLC-QE-MS Analysis of the Differences in Milk Metabolites from Guanzhong Dairy Goats at the Peak and Late Lactation Stages
YU Mengqi, YUAN Yuxin, CHEN Lu, SHARI Akang, REN Xinyang, QU Yingxin, LI Guang
2024, 45(10):  186-193.  doi:10.7506/spkx1002-6630-20230710-100
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In order to explore the dynamic changes of metabolites in goat milk during different lactation periods, the differential metabolites in milk from Guanzhong dairy goats at the peak and late lactation stages were investigated by ultra-high performance liquid chromatography-quadrupole electrostatic field orbitrap mass spectrometry (UPLC-QE-MS). A total of 90 differential metabolites were identified using P < 0.05, variable importance in the projection (VIP) > 1.00, and fold change (FC) > 2 or < 0.5 as criteria. Compared with late-lactation milk, 50 differential metabolites were up-regulated and 40 down-regulated in peak-lactation milk. Metabolic pathway analysis showed that these differential metabolites were significantly correlated with the biosynthesis of secondary bile acids. According to the VIP, uridine diphosphate-N-acetylglucosamine and phosphatidylethanolamine (PE, 12:0/22:2(13Z,16Z)) could be considered as potential biomarkers for the differential changes of milk metabolites from Guanzhong dairy goats during the two lactation periods, but this needs further research to be confirmed.
Establishment of an Improved Acetyl Chloride-Methanol Method for the Determination of Fatty Acids in Infant Foods for Special Medical Purpose Based on Simulation Experiments
LI Jie, TIAN Qiyan, LIU Yanming, WANG Yanli, LI Haixia, ZHANG Hui, LIANG Xiuqing, LI Fangfang, JU Xiang, WANG Jun, HU Mei
2024, 45(10):  194-200.  doi:10.7506/spkx1002-6630-20230715-179
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An improved acetyl chloride-methanol method was established for the rapid and accurate determination of linoleic acid, α-linolenic acid, docosahexaenoic acid (DHA) and arachidonic acid (ARA) in infant foods for special medicinal purpose with deeply hydrolyzed milk proteins and amino acids. The results showed that the optimal pretreatment conditions were 6 mL of reaction reagent, reaction for 60 minutes, and use of isooctane as extraction solvent. The linear range of linolenic acid and α-linolenic acid were 0.8–8.0 and 0.2–2.0 mg/mL, respectively. The linear ranges of DHA and ARA were 0.02–0.40 mg/mL, and the determination coefficients for all analytes were greater than or equal to 0.999 7. The limits of detection (LOD) and limits of quantitation (LOQ) of the developed method were 2 and 5 mg/100 g, respectively. This method was characterized by good repeatability (relative standard deviation (RSD) ≤ 3.3%), high precision (RSD ≤ 3.8%), good stability (RSD ≤ 2.6%), and high spiked recovery (ranging from 93.1% to 101.7%). Compared with its original version, the developed method could effectively solve the problem of incomplete reaction due to caking, with an at least 100% higher working efficiency.
Food Engineering
Effects of Different Radio Frequency Polar Plate Spacings on the Structural and Physicochemical Properties of Potato Starch and 3D Printing Performance of Its Gels
MA Shu, BAO Yanru, YANG Yang, ZHANG Meng, WANG Xinxin, JIANG Hao
2024, 45(10):  201-209.  doi:10.7506/spkx1002-6630-20230911-090
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In this study, the changes in the amylose content, crystalline structure, Fourier transform infrared (FTIR) properties, pasting properties, and rheological properties of potato starch were explored after radio frequency (RF) treatment at different polar plate spacings (90, 100, 110, 120, and 130 mm). The appropriate RF parameters for 3D printing of potato starch gels were determined. The results revealed that under low plate spacing, the content of amylose decreased and the crystalline form of starch transformed from B-type to C-type. We found that the starch gel with RF treatment at a plate spacing of 90 mm had the best morphology in terms of transparent line uniformity and high retention rate. To sum up, we can conclude that RF treatment at low polar plate spacings is an effective method for preparing 3D printed starch gels.
Effect of Pre-drying on Oil Penetration and Textural Characteristics of Deep-Fried Battered and Breaded Fish Nuggets
SHU Jing, CHEN Jiwang, ZHAI Jinling, ZHAI Jiahao, TENG Zongna, LIAO E
2024, 45(10):  210-216.  doi:10.7506/spkx1002-6630-20230710-124
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This purpose of this study was to evaluate the effect of pre-drying on the oil penetration and texture characteristics of deep-fried battered and breaded fish nuggets. Battered breaded fish nuggets (BBFNs) were dried in a drying oven and dried at 40 ℃ for 3, 4.5, 6, 7.5 and 9 h and deep fried at 180 ℃ for 60 s. Moisture state in dried BBFNs and deep-fried BBFNs was measured, and the oil content and distribution, microstructure and texture characteristics of deep-fried BBFNs were analyzed. The absorption of oil during deep-fat frying was simulated. The results showed that after deep-fat frying, the contents of strongly bound water (T21), weakly bound water (T22) and free water (T23) in the crust, the content of strongly bound water in the fish nuggets, the content of weakly bound water inside muscle fibers, and the content of free content outside muscle fibers were reduced. As the drying time increased, the starting time of peak T22 for the deep-fried crust gradually decreased, indicating declined freedom degree of water, and the signal intensity of peaks T21 and T22 decreased, suggesting that the bound water was converted to free water. In addition, only fish nuggets with 9 h drying showed a left shift in peak T22. The surface oil (SO) and total oil (TO) contents of deep-fried BBFNs decreased while the penetrated surface oil (PSO) content increased. The crust structure was first tight and then became rough, and the surface of the fish was smooth first and then exhibited cracks and holes. The fluorescence intensity of the crust became weaker gradually. The Sudan red-dyed region in the crust decreased while that of the junction between the crust and the fish nuggets increased gradually. The hardness and crispiness of the crust first decreased and then increased, while the elasticity and chewiness of the fish nuggets presented the opposite trend. These results indicated that pre-drying alleviated the freedom degree of moisture in BBFNs, and changed the microscopic structure of deep-fried BBFNs, thereby affecting the oil penetration and texture characteristics. The study may provide a theoretical basis and scientific guidance for the large-scale production of low-fat deep-fried BBFNs.
Effect of Extrusion Treatment on the Microstructure and Physicochemical Properties of Corn Flour
HOU Jingyao, XING Jiayue, YIN Fuyu, WEI Chaoyue, LIU Jingsheng, WU Yuzhu, XU Xiuying
2024, 45(10):  217-223.  doi:10.7506/spkx1002-6630-20230912-098
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In order to improve the processing characteristics of corn flour, the effect of twin-screw extrusion on the microstructure and physicochemical properties of corn flour was evaluated under different conditions of moisture content (15%, 18%, 21%, and 24%) and extrusion temperature (100, 120, 140, and 160 ℃). The results showed that after extrusion, the morphology of starch granules was destroyed, resulting in water absorption and swelling of the starch and gel network formation, significantly improving the hydration characteristics, cold paste viscosity and pseudoplasticity of corn flour (P < 0.05). With increasing extrusion temperature or moisture content, the damage degree of starch crystalline zone and double helix structure became more and more serious. At a moisture content of 18% and an extrusion temperature of 120 ℃, the maximum tensile distance of (28.95 ± 0.66) mm was recorded, indicating the strongest pseudoplasticity. Taken collectively, extrusion modification could effectively improve the problem of the difficulty in molding corn flour due to the lack of gluten protein, which will provide a technical basis for the processing of whole corn staple foods.
Packaging & Storage
Effect of Ultrasound Treatment on Quality Maintenance of Fresh-Cut Broccoli
DING Jiao, TANG Jing, DONG Xiaopan, JIN Peng, ZHENG Yonghua
2024, 45(10):  224-231.  doi:10.7506/spkx1002-6630-20230919-180
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This study aimed to investigate the effect of ultrasound (US) treatment on the quality maintenance of fresh-cut broccoli during storage. Fresh-cut broccoli was treated ultrasonically at 40 kHz and different power levels (200, 250, 300, 350 and 400 W) for 10 min and then stored at 10 ℃ for up to 96 h. The changes of appearance and microbial load were measured to determine the optimum parameters of US treatment for fresh-cut broccoli. Furthermore, the effect of the optimum US treatment on chlorophyll degradation and the changes in bioactive components in fresh-cut broccoli was studied. The obtained data indicated that US treatments at all power levels tested delayed the increase of yellowing index, L* value, total mold and yeast count and total bacterial count, and inhibited the decrease of H value, the 300 W power being the most effective in maintaining the appearance and microbial quality of fresh-cut broccoli. US treatment at 300 W effectively inhibited the activities of chlorophyllase and Mg-dechelatase, contributing to maintaining higher contents of chlorophyll a, chlorophyll b and total chlorophyll of fresh-cut broccoli. Meanwhile, this treatment maintained higher contents of bioactive ingredients such as vitamin C, total phenols, total glucosinolates and sulforaphane, and improved the scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals. Therefore, these results indicated that US treatment could not only effectively slow down the yellowing of fresh-cut broccoli, but also maintain higher contents of bioactive compounds, thus playing a fresh-keeping role.
Preparation of Polylactic Acid/Chitosan/Cinnamaldehyde One-Way Moisture Barrier Bilayer Film and Its Application in the Preservation of Pleurotus geesteranus
CHEN Xiumei, LIN Yan, CHEN Junyu, TAN Xiaoli, CHE Jinxin, TAO Nengguo
2024, 45(10):  232-241.  doi:10.7506/spkx1002-6630-20231001-002
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Pleurotus geesteranus, being rich in nutrients and moisture, easily loses water and wilts after harvest, reducing its commercial value. Furthermore, film packaging leads to excessive humidity in the internal environment, causing products to decay. In this study, polylactic acid (PLA) and chitosan (CS) were used as film-forming substrates to prepare a one-way moisture barrier bilayer film containing 0.25% cinnamaldehyde nano-emulsion (CANE). The microstructure, physical properties, optical properties, mechanical properties, moisture barrier properties and sustained release behavior of the film were investigated and its application in the preservation of P. geesteranus was evaluated. The results showed that the combination between PLA and CS could effectively make up for the defects of the monomer film, and the layers in the composite film with 0.25% CANE were tightly bound to each other, with a retention rate of 42% for cinnamaldehyde (CA). The film had strong ultraviolet resistance and the smallest settling speed of water droplets. The P layer had good water vapor barrier properties, and the C layer had good hydrophilicity. Compared with polyethylene (PE) film packaging, the 0.25% CANE-PLA-CS bilayer film significantly inhibited the browning and respiratory intensity of P. geesteranus during postharvest storage, delayed the increase in mass loss, soluble solids content, browning degree, electrical conductivity and malondialdehyde (MDA) content, reduced the activities of polyphenol oxidase (PPO) and peroxidase (POD) and maintained higher superoxide dismutase (SOD) activity. These results indicated that the one-way moisture barrier bilayer film could effectively delay the browning and aging of P. geesteranus and maintain its commercial value. This study provides theoretical support for the preparation of novel packaging materials for mushrooms and is of guiding significance to the reduction of post-harvest loss of P. geesteranus.
Effect of ε-Poly-L-lysine on Disease Resistance in Guava Fruit Infected by Neopestalotiopsis clavispora
CHEN Hongbin, CHEN Leiyi, XIAO Yumin, JIANG Xuanjing, LIN Yuzhao, ZHENG Jinshui, ZHENG Zongping
2024, 45(10):  242-248.  doi:10.7506/spkx1002-6630-20230421-211
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The effect of ε-poly-L-lysine (ε-PL) treatment on the occurrence of postharvest fruit rot caused by Neopestalotiopsis clavispora and disease resistance-related substance metabolism in guava were explored. Freshly harvested guavas (cv. Xiguahong) were soaked in sterile distilled water as a control or 2.0 g/L ε-PL solution for 10 min, inoculated with N. clavispora, and then stored at (28 ± 1) ℃ and a relative humidity of 90% for up to seven days. During the whole storage period, lesion diameter, cell membrane permeability, lignin content and disease resistance-related enzyme activities in guava fruit were measured every day. The results showed that compared with the control group, ε-PL could reduce the lesion diameter and cell membrane permeability, and maintain higher lignin content and higher activities of disease resistance-related enzymes including β-1,3-glucanase, cinnamate-4-hydroxylase, 4-coumarate CoA ligase, peroxidase, phenylalanine ammonia-lyase, chitinase and cinnamyl alcohol dehydrogenase. Therefore, we conclude that ε-PL enhanced the lignin level and the activities of disease resistance-related enzymes and consequently maintained cell membrane stability, which in turn enhanced the postharvest disease resistance of guavas and delayed the occurrence of guava fruit rot caused by N. clavispora.
Effect of Vacuum Precooling on the Lignification and Related Enzyme Activities of Tricholoma matsutake
ZHAO Zhuoran, WANG Fengling, WANG Xuan, GUAN Wenqiang, HU Xin, LIU Zhenguo, YAO Gang, LU Peng
2024, 45(10):  249-256.  doi:10.7506/spkx1002-6630-20230710-115
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In order to investigate the effect of vacuum precooling treatment on the lignification of Tricholoma matsutake during storage, the changes in the hardness of cap and stalk, pulp firmness, lignin, chitin and cellulose contents, and the activities of cellulase (CX), phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO) were studied during storage. The results showed that compared with the control group, vacuum precooling treatment could significantly inhibit the decline in the hardness of cap and stalk and pulp firmness, effectively inhibit the degradation of chitin and the increase of CX activity in the cell wall, maintain a higher cellulose content, and delay the accumulation of lignin. In addition, it could decrease the peak PAL activity of cap and stalk by 8.2% and 2.9%, the peak POD activity by 10% and 3.7%, and the peak PPO activity by 23.1% and 5.2%, respectively. In addition, compared with the cap, the peak time of lignification in the stalk was earlier, and lignification phenomenon was more likely to occur in the stalk. Therefore, vacuum precooling treatment can delay the lignification process and maintain the quality of T. matsutake.
Safety Detection
Detection of Ochratoxin A Using Immunoaffinity Chromatography Combined with Enzyme-Linked Immunosorbent Assay
ZHANG Yunzhe, ZHANG Xianzhou, YUAN Yaowu, ZHANG Wei
2024, 45(10):  257-264.  doi:10.7506/spkx1002-6630-20231015-119
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Ochratoxin A (OTA) in samples was captured and concentrated by immunoaffinity chromatography (IAC) and detected by enzyme-linked immunosorbent assay (ELISA). The anti-OTA monoclonal antibodies used in IAC and ELISA came from different clone strains, belonging to different idiotypes, and there were differences between their selectivity for binding to OTA targets. The combined use of IAC and ELISA could effectively filter out the interference from OTA analogues, thus improving the specificity and sensitivity of immunological analysis. The limit of detection (LOD) for OTA in spiked samples was 0.2 ng/g, the quantification limit was 0.4 ng/g, and the average recovery was 75.9%. Although the recovery of the IAC-ELISA method was slightly lower than that of ELISA, the sensitivity was increased by 60 times. For 49 real samples, the proportion of samples that tested positive by this combined method was 100% consistent with the result of the national standard method, with a missed detection rate of 0%. Therefore, the developed method exhibited significant advantages in accuracy. As a comprehensive immunoassay, this method does not require any large-scale instruments or equipment, and has no strict requirement on the operating environment, thereby making it easy for grassroot laboratories to analyze OTA in samples.
Preparation and Application of SERS Wipe Paper Based on Nano-Silver Loading to Nondestructive Detection of Ferbam Residue on the Surface of Fruits and Vegetables
ZHANG Chaofan, ZHAO Yanan, WANG Shiyao, ZHANG Qi, CHEN Yisheng
2024, 45(10):  265-271.  doi:10.7506/spkx1002-6630-20231012-089
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A flexible wipe paper for rapid nondestructive detection of ferbam residues on the surface of fruits and vegetables by surface-enhanced Raman scattering (SERS) was prepared using filter paper as the substate by a simple soaking method. The synthesis and storage conditions were optimized to ensure that the SERS method has excellent performance. The results showed that concentration factor of silver nanoparticles (AgNPs), soaking time in AgNP solution and drying method greatly affected the performance of the SERS wipe paper. The performance under the condition of soaking for 8 h in a 5-fold concentrate of AgNP solution was significantly better than that under other conditions. The SERS wipe paper prepared by vacuum drying had better performance that those prepared by other drying methods. After 9 days of storage at −20 ℃, the optimized substrate retained approximately 50% of the original peak value. Besides, it exhibited good sensitivity, uniformity, and repeatability. The limit of detection (LOD) for ferbam on a glass plate was 4.07 × 10-6 mg/mL, and the LOD for ferbam on the surface of spinach and nectarine were 0.043 and 0.062 mg/kg, respectively. This study provides an excellent basis for the development and utilization of SERS wipe paper.
HS-SPME-GC-MS Analysis of Volatile Compounds in Whole-Fat Cow and Goat Milk Powder during Accelerated Oxidation
XUE Haiyan, LI Xinyu, MENG Yi, HE Baoyuan, ZHANG Lei, LIU Xiaofeng, MA Jun
2024, 45(10):  272-280.  doi:10.7506/spkx1002-6630-20230929-262
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In order to investigate the changes of flavor substances in whole-fat cow and goat milk powder during storage, the volatile compounds of whole-fat cow and goat milk powder during accelerated oxidation were analyzed using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPEM-GC-MS). The results indicated that 56 and 63 volatile substances were identified in whole-fat cow and goat milk powder, respectively, mainly including acids, alcohols, carbonyls, esters, aromatics and heterocyclic compounds. Ten significantly differential volatile compounds were identified between whole-fat cow and goat milk powder by principal component analysis (PCA) and cluster analysis (CA). The relative content of butyric acid decreased and the relative content of 2-nonanone and 1-chloropentane increased in whole-fat cow milk powder during accelerated storage. The relative contents of nonanaldehyde, octanoic acid, propionic acid, and butylhydroxytoluene decreased, and the relative contents of benzaldehyde, 2-heptanone, and allyl n-propyl ester increased in whole-fat goat milk powder.
Non-destructive Determination of Body Composition of Cultured Live Large Yellow Croaker by Bioimpedance
LI Zengwei, LU Jinghong, YU Menghai, WU Jie, YANG Min, LIANG Yan, DENG Shanggui, YUAN Pengxiang
2024, 45(10):  281-289.  doi:10.7506/spkx1002-6630-20231027-222
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The body composition of cultured live large yellow croaker (Pseudosciaena crocea) is extremely difficult to detect. In order to solve this problem, we analyzed the relationship between the impedance measured at 2, 5, 20, 50, 100 kHz for the dorsal and ventral muscles of live large yellow croaker and their key components (protein, fat and moisture). The optimal models (r = 0.830–0.922, P < 0.001) for non-destructive evaluation of the muscle protein and water contents as well as the fat content in live fish was established using the impedance at 2 and 100 kHz frequencies, and their accuracy was verified by experiments (r ≥ 0.900). The correlation among muscle composition, microstructure and impedance indicated that the average area of muscle fiber increased with increasing protein content and decreasing moisture content and was positively correlated with the impedance at 2 kHz; in contrast, the density of muscle fiber and the area of extracellular space decreased with increasing protein content and decreasing moisture content and was negatively correlated with the impedance at 2 kH. The diameter and volume of adipocytes increased with the deposition of fat, and had a significant relationship with the impedance at 100 kHz. This study can rapidly evaluate the composition of fat, protein, water and so on of cultured live large yellow croaker by using biological impedance, and clarify the internal reasons for predicting the composition of live fish by impedance. The findings of this study can help aquaculture enterprises with targeted breeding and and help consumers to choose the optimal products.
Reviews
Microbial Diversity and Its Influence on Quality Development in Chinese Traditional Fermented Vegetables: A Review
LIU Xin, WANG Jiawang, SUI Yumeng, KONG Baohua, YUE Xiqing, CHEN Qian
2024, 45(10):  290-297.  doi:10.7506/spkx1002-6630-20230701-006
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Chinese traditional fermented vegetables are made from fresh vegetables through microbial metabolism and a series of chemical reactions. During the fermentation process, the microbial community structure is complex, and the dominant microorganisms at different stages play different roles, which has a great impact on the quality, flavor and safety of fermented vegetables. Based on this, this article reviews the effect of the microbial diversity on the quality, flavor, and safety of Chinese traditional fermented vegetables as well as the abiotic factors affecting the microbial diversity, aiming to provide a theoretical basis for improving the quality and safety of fermented vegetables.
Research Progress on Influential Factors of and Control Technologies for Aldehyde Formation in Cooking oil Fume
FU Gui, FAN Zhenyu, SUN Yating, ZHAO Yueliang, WANG Mingfu
2024, 45(10):  298-309.  doi:10.7506/spkx1002-6630-20230630-243
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Gaseous oil fume is complex in composition and contains a large number of harmful volatile organic compounds (VOCs), which are one of the major pollutants in indoor air and also the major source of oil fume odor, with aldehydes accounting for the major proportion. This paper reviews the formation and composition of cooking oil fume, the hazards of and the detection methods for volatile aldehydes in cooking oil fume, and the factors influencing their formation. It also summarizes the current techniques to control the formation of aldehydes in cooking oil fume to provide a theoretical basis for the scientific regulation of aldehydes pollution from cooking oil fume.
Research Progress on Closed Solid-State Fermentation System and Its Application in Vinegar Brewing
CHENG Siyuan, YU Yongjian, TANG Ruijun, LIU Jiaxin, YE Xiaoting
2024, 45(10):  310-319.  doi:10.7506/spkx1002-6630-20230529-270
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The brewing of solid vinegar is traditionally carried out in an open solid-state fermentation system, which is susceptible to environmental factors, leading to unstable flavor quality, low degree of mechanization and low labor productivity. Compared with the traditional open solid-state fermentation system, the closed solid-state fermentation system is not disturbed by external environmental factors, and allows mechanized and automated vinegar brewing, which is beneficial for stabilizing product quality, improving labor productivity, and promoting the modernization of the vinegar industry. In recent years, the closed solid-state fermentation system has been widely used in the field of vinegar brewing, which has brought significant improvement to the production efficiency of solid-state fermented vinegar. This article introduces the structure, characteristics, and regulatory measures of common closed solid-state fermentation systems. Besides, the factors affecting the fermentation performance of the closed solid-state fermentation system are summarized, the application of the closed solid-state fermentation system in vinegar brewing is briefly discussed, and an outlook on future trends in the development of an automatic and intelligent closed solid-state fermentation system is given. We hope that this review can provide a reference for the development of a new closed solid-state vinegar system in the future.
Research Progress on the Directed Enzymatic Preparation and Structure-Function Relationship of Alginate Oligosaccharides
CUI Yongyan, YANG Min, LIU Nan, WANG Shanshan, SUN Yong, SUN Guohui, ZHOU Deqing
2024, 45(10):  320-329.  doi:10.7506/spkx1002-6630-20230512-109
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Alginate oligosaccharides (AOS) are low molecular mass linear polymers containing 2–10 monosaccharides obtained by the degradation of alginate. They have various bioactivities including anti-inflammatory, antibacterial, antioxidant, antitumor, and immunomodulation. Thus, AOS have a wide range of applications in the fields of medicine, food, feed and agriculture. The bioactivity of AOS is closely related to its structure, including mode of degradation, degree of polymerization, ratio of mannuronic acid to guluronic acid, non-reducing end structure, and modification. Directed enzymatic degradation of alginate produces functional AOS with specific monomer composition and polymerization degree. Furthermore, the sources, properties and reaction conditions of enzymes affect the product distribution. In this article, the enzymatic preparation of functional AOS and its influential factors are systematically reviewed, and the structure-function relationship of functional AOS is discussed. It is expected that this review will provide a theoretical reference for the directed preparation and application of AOS.
Research Progress on Glycemic Control Effect and Mechanism of Tea Catechins
WANG Linghui, XU Na, YANG Qiannan, HUANG Jinbao, WANG Yijun, WAN Xiaochun
2024, 45(10):  330-341.  doi:10.7506/spkx1002-6630-20230626-198
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As people’s diet structure changes in modern society, diabetes and its complications have become a global public health concern. China has the world’s largest number of diabetics. Modern science has proved that tea is an important source of natural hypoglycemic polyphenols and plays an important role in the dietary treatment of diabetes as a healthy drink. Tea catechins are the key functional substances in tea, which can effectively regulate blood glucose levels through various pathways, such as inhibiting exogenous carbohydrate hydrolysis, regulating glucose transfer, promoting oxidative decomposition of glucose, inhibiting gluconeogenesis, regulating glycogen synthesis and decomposition, promoting insulin secretion, rescuing insulin resistance and reducing oxidative stress status. Beginning with a summary of recent studies on the effects of tea catechins on obesity, diabetes and metabolic syndromes, this paper moves on to review the latest knowledge on the physiological mechanism of blood glucose stabilization by tea catechins, hoping to provide a theoretical basis for the precise development and application of tea catechins.
Research Progress on the Effects of Parameters of Alkali Extraction and Acid Precipitation on the Denaturation, Aggregation, and Rheological Characteristics of Soybean Protein Isolate
MENG Ang, LUAN Binyu, GUO Boli, ZHANG Bo, YU Wenhua, CUI Kai
2024, 45(10):  342-354.  doi:10.7506/spkx1002-6630-20230515-127
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pH, NaCl and temperature are important process parameters for the manufacturing of soybean protein isolate (SPI). pH and NaCl affect protein aggregation by modifying the surface charge and electrostatic repulsion, whereas temperature affects protein aggregation by changing the surface hydrophobicity and/or disulfide bonding, which in turn changes the particle size and compactness and then the rheology and downstream application characteristics of SPI. This paper reviews the effects and possible mechanisms of pH, NaCl, and temperature on the denaturation, aggregation, and rheological properties of SPI and its components glycinin and β-conglycinin with respect to interaction, thermal stability, degree of aggregation, and gelling properties. The relationship between the degree of protein aggregation, gel strand thickness, gel strand curvature and gel network continuity and gel strength is discussed, and the differences among the effects of pH, NaCl and temperature on protein aggregation are summarized for the purpose of providing an assistance in regulating the degree of SPI aggregation by preparation parameters.
Research Progress on the Active Substances of Sea Cucumber Ovum
WANG Qiuting, SUN Zuli, CHEN Juan, LI Mingbo, SUN Leilei
2024, 45(10):  355-363.  doi:10.7506/spkx1002-6630-20230628-223
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As an important component of sea cucumber viscera, sea cucumber ovum contains polypeptides, polysaccharides, saponins, and so on, which has biological activities such as enhancing immunity, antioxidant, antitumor, and improving reproductive function, and has high protein, polysaccharide and phospholipid contents. Although rich in nutrition, sea cucumber ovum is discarded as a byproduct of sea cucumber processing. In this article, the nutritional components, the composition, extraction and purification of bioactive substances in sea cucumber ovum are summarized. The biological activities and the current status of the development and utilization of sea cucumber ovum are reviewed, which will provide a scientific basis for the comprehensive utilization of sea cucumber ovum.