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Identification and application of effectors promoting asexual sporulation of Antrodia cinnamomea in aqueous extract of Cinnamomum kanehirae Hay

Hua-Xiang LI

FOOD SCIENCE 0, (): 0-0.

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In order to determine the substance in aqueous extract of Cinnamomum kanehirae Hay (CWE) that promotes the asexual sporulation of Antrodia cinnamomea in submerged fermentation. Firstly, the CWE was isolated by alcohol precipitation and fractional extraction with different organic solvents, and the sporulation was used as the index to study the influence of different components on the sporulation of A. cinnamomea. It was showed that 30 μg/mL of chloroform extract of supernatant from alcohol precipitation of CWE (LFE) and 50 μg/mL of ethyl acetate extract (YZE) had a remarkable effect on promoting sporulation of A. cinnamomea, indicating that the effectors mainly existed in LFE and YZE; Subsequently, LC-MS/MS was used to analyze the components of different extracts of CWE, and combined with their effects on sporulation of A. cinnamomea, it was judged that the effector was probably erythritol; Finally, the commercial erythritol with purity of 98% was used to verify its effect on sporulation of A. cinnamomead. It was showed that erythritol did significantly promote the sporulation of A. cinnamomea, and the sporulation increased by 55.17% compared with Control at the optimal concentration of 1 μg/mL. Meanwhile, 1 μg/mL of erythritol can also significantly promote the growth and the synthesis of intracellular polysaccharides (IPS) for A. cinnamomea in submerged fermentation, and the biomass and yield of IPS were increased by 18.65% and 260.13%, respectively. However, erythritol has no significant effect on the synthesis of triterpenes. This study can greatly improve the industrial production efficiency and benefits of submerged fermentation for A. cinnamomea, and have great development value and good application prospects.

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Influence mechanism of Saccharomyces cerevisiae on microbial community succession during Nongxiangxing Baijiu fermentation

Huibo Luo Chuan SONG Dan Huang Hui-Bo LUO

FOOD SCIENCE 0, (): 0-0.

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Abstract: The changes of microbial niche and community assembly of fermented grains during Nongxiangxing Baijiu fermentation by Saccharomyces cerevisiae were analyzed to explore its influence mechanism on microbial succession of fermented grains. In this study, a strain of Saccharomyces cerevisiae screened from Nongxiangxing Baijiu was inoculated into fermented grains for fermentation experiment, and the microbial community structure of fermented grains in control group and experimental group was studied by high-throughput sequencing technology, and the niche changes of control group and experimental group were studied by statistical analysis method, and the assembly mechanism of microbial community was analyzed by zero model. The results showed that compared with the control group, the diversity and species composition of microbial communities in the experimental group decreased, the niche width of microbial communities in the experimental group decreased, and the relative content of specialized species groups increased. In the co-occurrence network, the relative abundance of specialized species in the main modules of the experimental group network increases, and the network complexity increases. The assembly of microbial communities in the control group and the experimental group is mainly dominated by random processes, but the importance of ecological drift and homogeneous diffusion in the experimental group is reduced, which makes the microbial community succession more certain. This study will further reveal the ecological function of Saccharomyces cerevisiae in the process of Nongxiangxing Baijiu fermentation, which has an important impact on Baijiu fermentation.

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Succession of Microbial Community Structure and Its Correlation Analysis with Physicalchemical Indicators in Fermented Grains during Nongxiangxing baijiu Fermentation

波曾静文 Huang Zhi-Guo

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Abstract：The formation of Nongxiangxing Baijiu flavor is inseparable from the microbial metabolism which influences the physicochemical environment of the fermented grains. In order to clarify the succession law and potential function of microbial in the fermented grains of Nongxiangxing Baijiu. High-throughput sequencing was borrowed to reveal the succession of microbial community structure , and the relationship between microbial community structure and physicalchemical indicators was analyzed in different fermentation stages. PICRUSt analyse was used to predict the potential function of bacterial community in the fermented grains. The results showed that Firmicutes, Proteobacteria, Actinobacteriota, Ascomycota, and Basidiomycota were the dominant phylums in the fermented grains. The dominant microorganisms were Lactobacillus、Bacillus、Staphylococcus、Thermoactinomyces、Kazachstania、Wickerhamomyces、Penicillium、Candida、Aspergillus、Meyerozyma、Debaryomyces，Lactobacillus、Kazachstania and Wickerhamomyces being absolutely dominant. The correlation analysis between physicochemical indicators and microbial diversity showed that reducing sugar and starch have a significant positive correlation with 8 bacteria. Acidity and moisture have a significant negative correlation with 10 bacteria. Some fungi are significantly correlated with physicalchemical indicators.PICRUSt analysis showed that the relative abundance of functional enzymes at different fermentation stage was significantly different, and the dominant microbial in the fermented grains participate in glycolysis, acid metabolism and ethanol synthesis to form a complete metabolic chain, indicating that the succession of the microbial community of the fermented grains is the main reason for the differences in metabolism at different fermentation nodes. This study analyzes the succession law of microbial community structure in the fermented grains and their metabolism in the fermentation process, which provides a theoretical basis for the study of the metabolic mechanism of baijiu brewing microorganisms.

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Effect of Saccharomyces cerevisiae on quality and flavor of fermented sausage

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In order to improve the quality and flavor of fermented sausage, Saccharomyces cerevisiae Y-8 was inoculated to explore the effects of different proportions of S.cerevisiae Y-8 and Lactiplantibacillus plantarum Z43 on the physical and chemical properties, volatile flavor compounds and fatty acids of fermented sausage. The volatile flavor compounds and fatty acid were determined by Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) and Gas Chromatography-Mass Spectrometry (GC-MS), respectively. The results showed that the addition of S. cerevisiae Y-8 could promote the production of esters and alcohols, reduce acetic acid content, increase the final pH, enheance the proportion of oleic acid, and rapidly reduce the number of enterobacteria. The model was established using Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA), 17 differential volatile flavor substances (VIP > 1) were identified, which could effectively distinguish the sausages fermented with different proportional combinations of S. cerevisiae Y-8 and L. plantarum Z43. The combination of L. plantarum Z43 and S. cerevisiae Y-8 in a ratio of 20:1(the inoculum of L. plantarum Z43 was 107CFU/g) had the highest comprehensive sensory evaluation, the highest chrominance value, and the hardness value were significantly higher than the other groups (P < 0.05), the contents of 3-hydroxy-2-butanone and isoamyl alcohol monomer were significantly higher than those in the other groups. Inoculation with S. cerevisiae Y-8 can give fermented sausage rich mellow and ester flavor, effectively eliminate sour taste, improve the quality and safety of fermented sausage, and provide useful reference for the application of S. cerevisiae in fermented meat products.

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Study on Improving the Quality of Liupao Tea by Fungal Solid Fermentation

null

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Abstract （58）

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In this study, the Cangwu population species Liupao hairy tea was used as raw material, and 20 strains of fungi isolated from Liupao hairy tea were inoculated into sterilized Liupao hairy tea for solid-state fermentation. Through sensory review, biochemical component detection and principal component analysis, the fermentation effects of different fungi were explored, so as to screen out the dominant solid-state fermentation fungi that can significantly improve the quality of Liupao tea or give Liupao tea new flavor.The results showed that 9 kinds of fungi with excellent fermentation performance were selected by sensory evaluation, which were Aspergillus tubingensis, Aspergillus niger, Penicillius manginii, Aspergillus keratitidis, Aspergillus ruber, Aspergillus intermedius, Penicillius commune, Aspergillus amstelodami and Trichomonascus ciferrii. The results showed that inoculation with Aspergillus tubingensis, Aspergillus niger, Penicillius commune and Aspergillus amstelodami could significantly change the content of 18 chemical components in tea. Penicillius commune and Aspergillus amstelodami were identified as excellent fermentation fungi.The research can provide excellent strain resources for the later period of human industrial fungal fermentation of Liupao tea, and provide scientific theoretical basis for the fermentation process improvement, product research and development innovation and quality improvement of Liupao tea.

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Microbial community of chilled goose breast and its effect on its volatile flavor

Li-Zhen WU

FOOD SCIENCE 0, (): 0-0.

Abstract （10）

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In order to establish an effective mechanism for predicting spoilage of chilled goose breast meat, ghe microbial community structure was investigated by high-throughput sequencing and volatile flavour compounds of chilled goose breast meat were determinated by using as chromatography-ion mobility spectrometry (GC-IMS) and gas-phase(GC-IMS) and gas chromatography-mass spectrometry (SPME-GC-MS) techniques during fresh and spoilage. Results shown that the diversity of flora was richer in the pre- and post-storage periods during the cold storaget. At the phylum level, the dominant phylum during storage of cold fresh goose breast meat was Amoeba, and at the genus level, the main dominant spoilage flora was Pseudomona. large lots of Pseudomonas was observed from day 3 and reached a peak of 96.79% on day 9. The addition of dominant spoilage bacteria had a significant effect on the composition of volatile components of goose breast at the end of storage, and spoiled goose breast having a higher proportion and higher levels of esters and ketones than those of fresh goose breast. Combining the substance concentrations and OPLS-DA analysis, methyl palmitoleate, methyl palmitate, ethyl oleate, methyl linoleate, ethyl linoleate, ethyl palmitoleate, 3-hydroxy- 2-butanone, methyl transoleate, ethyl transoleate and Neopentyl hexanoate were the main contributors to the volatile flavour of spoiled goose breast . These results can provide some theoretical basis for the quality control of goose breast .

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BSG on MAPK signaling pathway and apoptosis during post-slaughter maturation of Qinchuan cattle

null

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Abstract （24）

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In order to explore the effect of basigin (BSG) on MAPK signaling pathway and apoptosis during post-slaughter maturation of Qinchuan cattle, the changes of BSG and its differential proteins were analyzed by 4D-label free quantification (4D-LFQ). The BSG inhibitor thinomycin was injected into the longest dorsal muscle of Qinchuan beef after slaughter, and the expression level of key proteins of MAPK pathway during storage at 4°C was determined by western blotting. The apoptosis detection kit was used to determine the viability change of caspase-3. In this way, the effects of BSG inhibitors on MAPK signaling pathway and apoptosis were analyzed. The results showed that the expression of BSG increased first and then decreased during the storage period of Qinchuan cattle. KEGG pathway analysis was used to show that BSG and its differential proteins were significantly annotated in oxidative phosphorylation pathway, calcium signaling pathway and MAPK signaling pathway, indicating that BSG played a role through MAPK pathway. In addition, the relative expression of key proteins of the MAPK pathway in the thinomycin group was significantly down-regulated, indicating that BSG inhibitors inactivated the MAPK signaling pathway. This lays a good foundation for studying the effect of BSG on the MAPK signaling pathway. After inhibiting the expression of BSG, the activity of caspase-3 in the hiromycin group increased significantly, indicating that apoptosis was an important link in cell damage, and thinomycin acted on the N-terminal structure of BSG to deglycosylation of proteins. By inhibiting the folding of proteins within cells, their biological activity is inhibited, thereby inducing apoptosis in cells.

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Study on the inhibition of linalool against Pathogens of Fusarium wilt

丽荣周玲玲张

FOOD SCIENCE 0, (): 0-0.

Abstract （16）

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In order to study the antifungal mechanism of linalool on Fusarium oxysporum, we systematically investigated the effects of linalool on spores and mycelium, cell membrane damage and control efficacy . The results showed that linalool could significantly inhibit the mycelial growth of F. oxysporum, the EC50 value and the minimum inhibitory（MIC）were 1.183 and 2 g/L, respectively, moreover the inhibitory effect was dose-dependent with the amount of linalool. The spore number of F. oxysporum treated with MIC linalool for 6 h (1.43 ± 0.12) was 104 spores/mL, which was significantly lower than that of control (5.79 ± 0.19) (P <0.05), and the spore germination rate of F. oxysporum treated with MIC- for 12 h was (5.83 ± 2.16)% and significantly lower than that of control (95.12 ± 3.78)% (P <0.05). At the same time, treatment with 1/2 MIC and MIC- damaged the integrity of the cell membrane, resulting in a significant increase in nucleic acid, relative conductivity leakage and MDA content in mycelium but significant decrease in ergosterol content. And 1/2 MIC and MIC linalool weakened the pathogenicity of the bacteria, no diseased spots were produced on the ginger blocks after MIC linalool treatment for 3 d. In conclusion, linalool affects its normal physiological function by inhibiting the spore germination and mycelial growth of F. oxysporum, disrupts cellular structures, which provides a new idea for the effective control of Fusarium wilt.

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Screening and identification of in vitro anti-allergic active probiotics based on the degranulation inhibition of RBL-2H3 cells

MA Ding Qin Shuangxia

FOOD SCIENCE 0, (): 0-0.

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To investigate the anti-allergic activity of lactic acid bacteria, this paper screened probiotics with anti-allergic activity by traditional isolation technique of lactic acid bacteria and in vitro evaluation of probiotics, combined with RBL-2H3 cell degranulation inhibition test. The results showed that the four strains isolated from fermented vegetables exhibited good probiotic properties and safety; the selected four strains showed high inhibition of β-Hexosaminidase release from RBL-2H3 cell degranulation, and the four strains showed high inhibition of Histamine, Histamine release from RBL-2H3 cell degranulation, Histamine, Histamine release from RBL-2H3 cell degranulation, and Histamine release from RBL-2H3 cell degranulation, The four strains were identified by 16S rDNA sequencing as Lactobacillus plantarum, Lactobacillus fermentum and Lactobacillus paracasei.

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Antibacterial activity and mechanism of spores of Bacillus cereus by rhamnolipids

Ming YiSun Yong-Wu NIU Shan Qiao

FOOD SCIENCE 0, (): 0-0.

Abstract （101）

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Rhamnolipids(RLs) is a non-toxic glycolipid biosurfactant. RLs has been reported to show broad-spectrum antibacterial properties and has promising applications. However, the mechanism of RLs inactivation of spores has rarely been reported. In the study, Bacillus cereus spores were used as the target. The antibacterial activity and mechanism of RLs against Bacillus cereus spores were analyzed from the aspects of appearance, morphology and membrane state. The results showed that minimum inhibitory concentration and minimum bactericidal concentration of RLs was 80.0 mg/L and 160.0 mg/L, respectively. Both concentrations of RLs caused severe wrinkling and depression of spores’ appearance, disrupted the integrity and permeability of spores’ cell membrane, leaded to the leakage of spores’ electrolytes, DNA and proteins. At the same time, RLs inhibited and inactivated Bacillus cereus spores by decreasing resistance, generating oxidative stress, reducing surface adhesion, and binding and interfering with DNA molecules. The results of the study will contribute to the development and application of RLs in the field of food safety.

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Effect of Basigin on the Mitogen Activated Protein Kinase Signaling Pathway and Apoptosis in Qinchuan Cattle Muscle during Postmortem Maturation

SU Xiaofeng, LI Yalei, LUO Ruiming

FOOD SCIENCE 2024, 45 (6): 48-54. DOI: 10.7506/spkx1002-6630-20230519-194

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In order to explore the effects of basigin (BSG) on the mitogen activated protein kinase (MAPK) signaling pathway and apoptosis in Qinchuan cattle muscle during postmortem maturation, the changes in BSG and related differentially expressed proteins were analyzed by 4D-label free quantification (4D-LFQ). The BSG inhibitor tunicamycin was injected into the longissimus dorsi of Qinchuan cattle after slaughter, and the expression levels of key proteins in the MAPK signaling pathway during storage at 4 ℃ were determined by Western blotting. An apoptosis detection kit was used to determine the change in the activity of caspase-3. The results showed that the expression of BSG increased first and then decreased during the postmortem storage period of Qinchuan cattle muscle. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, it was found that BSG and related differentially expressed proteins were significantly annotated to the oxidative phosphorylation pathway, calcium signal pathway and MAPK signaling pathway, indicating that BSG played an important role through the MAPK signaling pathway. In addition, for the tunicamycin group, the relative expression of the key proteins in the MAPK signaling pathway was significantly down-regulated, indicating that BSG inactivated the MAPK signaling pathway. This finding lays a good foundation for exploring the effect of BSG on the MAPK signaling pathway. After inhibiting BSG expression, caspase-3 activity in the tunicamycin group increased significantly, indicating that apoptosis was an important link in cell injury mechanism, and tunicamycin acted on the N-terminal structure of BSG to deglycosylate the protein and inhibited the folding of intracellular proteins and consequently their biological activity, thereby inducing cell apoptosis.

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Screening and Identification of Probiotics with in Vitro Anti-Allergic Activity Based on the Degranulation Inhibition of RBL-2H3 Cells

Ma Ding, Qin Shuangxia, Hao Huichao, Deng Fangming, Zhao Lingyan

FOOD SCIENCE 2024, 45 (6): 55-63. DOI: 10.7506/spkx1002-6630-20230613-098

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To investigate the anti-allergic activity of lactic acid bacteria, lactic acid bacterial strains were obtained from fermented vegetables by the traditional isolation technique and screened for in vitro allergic activity by the degranulation inhibition assay against RBL-2H3 cells. The results showed that all four isolates exhibited good probiotic properties and safety and had a strong inhibitory effect on β-hexosaminidase released from RBL-2H3 cells after degranulation. Moreover, they showed significant down-regulation effects on the release of histamine, tumor necrosis factor-α and interleukin-4 from RBL-2H3 cell after degranulation, suggesting their potential as anti-allergic probiotics. The four strains were identified by 16S rDNA sequencing as two strains of Lactobacillus plantarum, one strain of L. fermentum and one strain of L. paracasei.

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Screening of Fungal Strains for Single-Culture Solid-State Fermentation of Liupao Tea

WU Xinhui, DU Jinjie, LIU Xiaochun, LIAO Kaibin, QIN Yuna, LIANG Weijie, ZHANG Lingzhi, LONG Zhirong, QIU Ruijin

FOOD SCIENCE 2024, 45 (6): 64-71. DOI: 10.7506/spkx1002-6630-20230608-075

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In this study, 20 fungal strains isolated from Liupao tea were used for solid-state fermentation of sterilized raw Liupao tea from Cangwu Quntizhong. The fermentation performance of these strains was explored by sensory evaluation and biochemical analysis combined with principal component analysis (PCA) and strains that are able to significantly improve the quality of Liupao tea or impart new flavor to the tea were selected. The results showed that nine fungi with excellent fermentation performance were obtained, namely, Aspergillus tubingensis, A. niger, Penicillius manginii, A. keratitidis, A. ruber, A. intermedius, P. commune, A. amstelodami and Trichomonascus ciferrii. Moreover, A. tubingensis, A. niger, P. commune and A. amstelodami could significantly change the contents of 18 chemical components in tea samples. P. commune and A. amstelodami were identified as excellent starter cultures for Liupao tea fermentation. This study could provide a theoretical basis for the improvement of the fermentation process of Liupao tea and the development, innovation and quality improvement of tea products.

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Inhibitory Effect of Linalool against the Ginger Fusarium Wilt Pathogen

ZHOU Lirong, ZHANG Lingling, XIONG Shijie, MA Jiawei, ZHU Yongxing, SUN Chong, ZHU Xuedong, LIU Yiqing

FOOD SCIENCE 2024, 45 (6): 72-79. DOI: 10.7506/spkx1002-6630-20230512-108

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To study the antifungal effect and mechanism of linalool against Fusarium oxysporum FOX-1, the causative agent of ginger Fusarium wilt, the damaging effects of different concentrations of linalool on the mycelial growth, spore germination and cell membrane of F. oxysporum FOX-1, and its control effect on ginger Fusarium wilt were systemically investigated. The results showed that linalool could significantly inhibit the mycelial growth of F. oxysporum FOX-1 in a concentration-dependent manner, and the half maximal effective concentration (EC50) and the minimum inhibitory concentration (MICs) were 1.183 and 2 g/L, respectively. The spore concentration of F. oxysporum FOX-1 treated with linalool at MIC for 6 h was (1.43 ± 0.12) × 104 spores/mL, which was significantly lower than that of the control group ((5.79 ± 0.19) × 104 spores/mL) (P < 0.05), and the spore germination rate of F. oxysporum FOX-1 treated with linalool at MIC for 12 h was (5.83 ± 2.16)%, which was significantly lower than that of the control group ((95.12 ± 3.78)%) (P < 0.05). Treatment with linalool at 1/2 MIC and MIC damaged the integrity of the cell membrane, resulting in a significant increase in relative electrical conductivity and nucleic acid leakage in the mycelial suspension and malondialdehyde (MDA) content in the mycelium, and a significant decrease in ergosterol content, finally weakening the pathogenicity of the fungus. No lesions appeared on ginger pieces after treatment with linalool at MIC for 3 days. In conclusion, linalool affects the normal physiological function of F. oxysporum FOX-1 by inhibiting its spore germination and mycelial growth and destroying its cellular structure. This study provides a new direction for the effective control of Fusarium wilt.

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Antibacterial Activity and Mechanism of Rhamnolipids against Bacillus cereus

NIU Yongwu, QIAO Shan, SUN Yiming, WANG Yuchen, ZHAO Renyong, TIAN Shuangqi

FOOD SCIENCE 2024, 45 (6): 80-86. DOI: 10.7506/spkx1002-6630-20230215-144

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The antibacterial activity and mechanism of rhamnolipids (RLs) against Bacillus cereus spores were analyzed from the aspects of appearance, morphology, and cell membrane state. The results showed that minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of RLs were 80.0 and 160.0 mg/L, respectively. Both concentrations of RLs caused severe shrinkage and depression on the surface of spores, and disrupted the integrity and permeability of the spore cell membrane, leading to the leakage of intracellular electrolytes, DNA and proteins. In addition, RLs inhibited and inactivated B. cereus spores by various mechanisms such as decreasing heat resistance, generating oxidative stress, reducing surface adhesion, and binding to and interfering with DNA molecules. The results of this study will contribute to the development and application of RLs in the field of food safety.

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Microbial Community of Chilled Goose Breast and Its Effect on Volatile Flavor Components

WU Lizhen, LIAO Zhiqiang, SHI Yangkai, YU Limei

FOOD SCIENCE 2024, 45 (6): 87-96. DOI: 10.7506/spkx1002-6630-20230606-046

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In order to establish an effective mechanism for predicting spoilage of chilled goose breast meat, the microfloral succession was investigated by high-throughput sequencing and the dominant spoilage bacteria of chilled goose breast meat were determined. Meanwhile, the effects of three dominant spoilage bacteria on the volatile flavor substances of chilled goose breast meat were characterized by using gas chromatography-ion mobility spectrometry (GC-IMS) and solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). The results showed that the diversity of microflora was richer during the early and late storage periods. The dominant phylum was Amoeba, and the dominant spoilage bacterium was Pseudomona. Pseudomona began to grow significantly starting from day 3 and reached a peak with a relative abundance of 96.79% on day 9. Contamination with the dominant spoilage bacteria significantly affected the composition of volatile components in goose breast at the end of storage, resulting in higher proportions and contents of esters and ketones than fresh goose breast. Orthogonal partial least squares discrimination analysis (OPLS-DA) showed that methyl palmitoleate, methyl palmitate, ethyl oleate, methyl linoleate, ethyl linoleate, ethyl palmitoleate, 3-hydroxy-2-butanone, methyl trans-oleate, ethyl trans-oleate and neopentyl hexanoate were the major contributors to the volatile flavor of spoiled goose breast.

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Analysis of the Characteristics of Endochitinase with Antibacterial Oligosaccharide Preparation and Antifungal Activity

FOOD SCIENCE 0, (): 0-0.

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In order to develop chitin and chitosan bioconversion active oligosaccharides and achieve the application of chitinase in food preservation and biocontrol, chitinase (ChiA-Sa62) was isolated and purified from Streptomyces aureofaciens XZ-Sa62, and its bioconversion and antibacterial function were studied. ChiA-Sa62 was purified by Q-sepharose, Sephadex G-100 chromatography, and high-performance liquid chromatography (HPLC), with a purification factor of 41.3 times and a specific activity of 1119.8 U/mg. SDS-PAGE and Time-of-Flight Mass Spectrometry (MALDI-TOF/MS) showed that the enzyme is a single subunit protein with a molecular weight of 62.55 kDa. ChiA-Sa62 exhibits maximum activity at 50 ℃ and pH 4.5, and exhibits good stability below 80 ℃ and within the pH range of 3.0-9.0. Ca2+, Mn2+, Mg2+, and Co2+ activate enzyme activity. ChiA-Sa62 has a specific endonucleating hydrolysis activity on chitin and chitosan with a degree of deacetylation of 75%. Thin layer chromatography (TLC) shows that the hydrolysis products are 2-5 GlcNAc units of chitosan oligosaccharides and 2-4 GlcN units of chitosan oligosaccharides, respectively. The colloidal chitin was used as the substrate, with ChiA-Sa62 Km and Vmax values of 2.75 mg/mL and 64.52 U/mg, respectively. ChiA-Sa62 strongly inhibited the tested pathogenic fungi, and PI staining showed that ChiA-Sa62 disrupted the integrity of the cell membrane of Botrytis cinerea. The hydrolysate chitosan oligosaccharide had antibacterial activity against pathogenic G- bacteria (Escherichia coli and Pseudomonas aeruginosa) and G+ bacteria (Staphylococcus aureus and Bacillus cereus). LIVE/DEAD staining showed that chitosan oligosaccharide can cause Staphylococcus aureus to die. ChiA-Sa62 chitin and chitosan have great potential for application in biotransformation, food preservation, and biological control.

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Study on bioactivity of Monascus cheese and screening of ACE inhibitory peptides

Zhen MinLIU

FOOD SCIENCE 0, (): 0-0.

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This study investigates the impact of Monascus on bioactive peptides, particularly angiotensin-converting enzyme (ACE) inhibitory peptides during cheese maturation. The contents of soluble nitrogen, the inhibitory activities of α-glucosidase and angiotensin-converting enzyme (ACE) during the ripening process were investigated with cheese without Monascus as the control group. The peptide profile of Monascus cheese was identified. The potential active peptides were screened by bioinformatics and molecular docking, and the screened peptides were synthesized and evaluated. The results showed that compared with the control group, soluble nitrogen content of pH4.6 and trichloroacetic acid (TCA) increased by 57.98% and 38.34%, and α-glucosidase inhibitory activity and ACE inhibitory activity increased by 32.20% and 73.96%, respectively. A total of 1796 peptides were identified in the extract of Monascus cheese, including 51 ACE inhibitory peptides, 28 antioxidant peptides and 7 glucose-lowering peptides. Two ACE inhibitory peptides YPFPGPI and FPEVFGK were screened, and the IC50 values were 125.53 and 285.73 μmol/L, respectively. The enzyme inhibition types were non-competitive inhibition. This study provides a rapid screening method for ACE inhibitory peptides, and proves that the addition of Monascus in cheese can effectively improve the ACE inhibitory activity, which provides a reference for exploring the potential of functional properties of Monascus cheese.

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The Impact of Adding Green Tea to the Raw Materials on Bacterial Diversity and Physicochemical properties During the Fermentation Process of Daqu

Liang ZHAO

FOOD SCIENCE 0, (): 0-0.

Abstract （44）

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In this study, high-throughput sequencing technology and statistical analysis were employed to explore the effects of adding green tea at proportions of 10%, 20%, and 30% on the physicochemical characteristics, bacterial community diversity, and succession of daqu fermentation compared to wheat starter (control). The results showed that the addition of green tea significantly increased the bacterial diversity of the daqu community and improved its saccharification ability, moisture content, and acidity. However, the increase in tea addition proportion did not exhibit a proportional relationship with community diversity. The distinctive evolutionary structures of the community systems in different types of daqu were found to be the main factors influencing their physicochemical characteristics. During the fermentation process, the four types of daqu exhibited differentiation in community succession starting from the thermophilic stage, leading to the formation of unique community structures at the end of fermentation. The phyla Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria showed varying influences on the community succession of the four types of daqu, thus driving the appearance of different physicochemical characteristics in each type. Specifically, Pseudomonas was an important contributing bacterial genus in the control and 10% tea-added daqu, while Weissella and Pediococcus, genera of lactic acid bacteria, were important contributors in the 20% tea-added daqu. Bacillus was found to be a significant contributing bacterial genus in the 30% tea-added daqu. This study provides a theoretical basis for process optimization in the production of tea-added daqu and for the development of multi-raw material fermentation starters. It also has implications for improving the daqu preparation process and the application of tea in fermentation.

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Screening of highly efficient fermentation strains for semi-dry douchi and their fermentation performance evaluation

Liu Shu-liang Zhiyi Fan 李婷 Heng LI qisheng zhang Long LI

FOOD SCIENCE 0, (): 0-0.

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To select high-efficiency strains for semi-dry black douchi fermentation，this study compared and analyzed the effects of koji-making and fermentation quality differences of 6 strains of Aspergillus oryzae and one strain of Lichtheimia corymbifera with large differences in enzyme production capability. The results showed that HN3.042 and Aspergillus oryzae DM1 and DM2 have a strong ability to metabolize amylase, which is conducive to the formation of black color in douchi. Strains 24M-1, 30M-1, and PNM003 had a strong ability to produce protease, aminopeptidase, and carboxypeptidase, resulting in greater utilization of protein substrates and higher contents of total acid and amino nitrogen in the fermented douchi. In terms of volatile flavor substances, HN3.042, DM1, and DM2 had a relatively higher content of acid substances such as 1-octen-3-ol, isovaleric acid, and 4-methylpentanoic acid in the fermented soybeans. Strains 24M-1, 30M-1, and PNM003 had a relatively higher content of trans-2-nonenal, 3-octanone, and isophorone, resulting in a richer and better flavor quality of the fermented douchis and being more suitable for soybean processing. The strain QM3 had lower enzymatic activity compared to Aspergillus strains, resulting in lower physicochemical indicators, free amino acid contents, and volatile flavor substances in the fermented soybeans and poorer quality. The study suggests that the quality of fermented soybean paste is related to the enzyme production capacity of the koji strain used in fermentation. A koji enzyme system with amylase as the dominant enzyme is conducive to the formation of color and acidic flavor substances in fermented douchi, while a koji enzyme system with proteolytic enzymes as the dominant enzymes is conducive to the formation of amino acid nitrogen and good flavor quality in fermented douchi.

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