Study On The Mechanism Of Lactic Acid Bacteria On Proteolysis In Fermented Sausage

In order to explore the mechanism of lactic acid bacteria on the protein hydrolysis of fermented sausage,this study screened strains with proteolytic ability from traditional fermented foods in Inner Mongolia,and utilized high-throughput sequencing and widely targeted metabolomics technology to analyze bacterial community structure,metabolites and functional pathway prediction of fermented sausage,which could explore mechanism of their influence on the quality characteristics of fermented sausage.It provided some theoretical support for fully exploiting Inner Mongolia characteristic strain resources and improving the quality of fermented meat products.This study screened two strains of lactic acid bacteria with great fermentation performance and protein decomposition ability from traditional fermented foods in Inner Mongolia and identified them as Lactiplantibacillus plantarum(YXAR-7,XAR-10).The study on the influence of different environmental factors on proteolytic ability of strain YXAR-7 and XAR-10 to decompose muscle protein showed that the decomposition ability of sarcoplasmic protein and myofibrillar protein was different under different p H values,temperature,salt concentration and nitrite concentration system.When the initial p H of fermentation system was low(p H4.5,p H5.5),the decomposing ability of myofibrillar protein was significantly lower than that of sarcoplasmic protein(P<0.05).The decomposition ability of myofibrillar protein was significantly stronger than that of sarcoplasmic protein(P<0.05)under different temperature,salt concentration and nitrite concentration system.The application of strains YXAR-7 and XAR-10 as starter cultures in fermented sausages could effectively reduce the water activity,p H value,TVB-N,TBARS and nitrite residues to improve the safety of fermented sausages.The strain had positive effects on the content of redness(a*),amino nitrogen(AN),non-protein nitrogen(NPN)and protein hydrolysis index of fermented sausage.The gel electrophoresis results of fermented sausages showed that strain XAR-10 had a strong ability to decompose low and medium molecular weight sarcoplasmic protein,while strain YXAR-7 had a strong ability to decompose heavy meromyosin(HMM),actin(AC)and tropomyosin(TM)during processing.The analysis of microbial flora structure of fermented sausage showed that the microbial diversity of starter group(YXAR-7 group and XAR-10 group)decreased gradually with increasing time,and the core microbial community was mainly Firmicutes and Lactiplantibacillus during processing.Widely targeted metabonomics analysis showed that the addition of strains YXAR-7 and XAR-10 mainly affected the production and metabolic pathway of amino acids such as arginine and tyrosine in fermented sausages,which promoted the relative content of amino acids such as L-arginine and other amino acids in fermented sausages to show an upward trend.Correlation analysis of different flora and different metabolites showed that Lactiplantibacillus was positively correlated with different metabolites such as Met-Arg and Phe-Ala-Pro.In conclusion,the addition of strains YXAR-7 and XAR-10 had a positive effect on the protein decomposition of fermented sausage,and effectively regulated the production and metabolic pathway of amino acids such as arginine in protein decomposition,which promoting the formation of flavor compounds such as phenylalanine and arginine.