Effect Of Lacticaseibacillus Rhamnosus R7970 On The Quality Of Fermented Milk

In this study,Lacticaseibacillus rhamnosus R7970(Lacticaseibacillus rhamnosus R7970,R7970)and commercial fermentor PYS-010 were combined to ferment cow’s milk as the experimental group,and Lacticaseibacillus rhamnosus Probio-M9(Lacticaseibacillus rhamnosus Probio-M9,Probio-M9)and PYS-010,PYS-010 alone were fermented as the control group,and the fermented milk quality was comprehensively evaluated by micro-rheological properties,storage stability,extracellular polysaccharide content,and microstructure,while non-targeted metabolomics was applied to identify the different metabolites between the experimental group and the control group followed by pathway enrichment analysis,and functional characterization of the different metabolites The results are as follows.The specific results are as follows:(1)Using R7970(inoculum 5×10~6CFU/m L)with PYS-010(inoculum 0.03‰),Probio-M9(inoculum 5×10~6CFU/m L)with PYS-010(inoculum 0.03‰),and PYS-010(inoculum 0.03‰)for 37°C fermentation of cow’s milk,compared with the control group,the experimental group’s micro The rheological properties showed that it had lower elasticity factor and higher solid-liquid equilibrium value,and although there was no effect on viscosity factor and flow factor,the experimental group could reach the gel point faster and shorten the fermentation time.(2)During the storage period,there was no significant difference in acidity test results between the experimental group and the control group,but the experimental group could significantly improve the number of viable bacteria,viscosity,water holding capacity,texture characteristics and sensory score of fermented milk(P<0.05).At the same time,the microstructure of the experimental group was the most stable during the whole storage period,and the content of extracellular polysaccharide was significantly higher than that of the control group,reaching 448 mg/L at 14 d,which was helpful to enhance the quality of fermented milk.(3)Through pathway enrichment analysis of the differential metabolites of the three groups of fermented milk during storage,the most important differential metabolic pathways between the experimental and control groups were identified as the metabolism of amino acids such as arginine,glycine,serine and threonine and the metabolism of glycerophospholipids,and the differential metabolites such asγ-aminobutyric acid and betaine with potential health effects were enriched.In summary,the fermentation of R7970 in combination with PYS-010 shows that R7970is beneficial to enhance the quality of fermented milk,which not only can confer excellent fermentation characteristics and storage stability,but also has potential probiotic efficacy.This study provides some theoretical data to support the development and commercial application of this strain in high viscosity fermented milk products.