Screening Of Probiotics From Traditional Fermented Foods And Application In Cheese Processing

In this study, the traditional fermented food sources of Lactobacillus as the object of study, through a serirs of experiments on bile and acid resistance, surface hydrophobicity, cholesterol-lowering effect, in vitro antioxidant activity and proteolytic ability, we screened out one strain with excellent probiotic characteristics as an auxiliary starter to be used in the fermentation process of cheese, then researched and evaluated the probiotic cheese products. The main findings are shown as follows:(1) 6 strains of Lactobacillus plantarum showed excellent tolerance at pH 3.0 and their survival rate reached more than 70% after 3 h. 3 h after cultured at pH 2.0, S72 strain showed the best acid resistance, where the viable count was 6.74 Log CFU / mL; 6 strains exerted different tolerance to bile salt, where S72 strain could achieve viable count of 6 Log CFU/mL or more in MRS broth at a concentration of 1.0% bile salt; 6 strains had different hydrophobic characteristics, S72 and C26 showed strong hydrophobic ability to p-xylene, ethyl acetate and chloroform.(2) 6 strains of L. plantarum exhibited different scavenging activity to the cholesterol in medium, after being cultivated for 48 h, the scavenging rate was varied from 36.64% to 78.83%, where S72 showed stronger cholesterol-lowering ability; In aspect of in vitro antioxidant capacity, 6 strains have certain radical scavenging ability, where S72 and C62 showed stronger scavenging ability to hydroxyl radicals and superoxide anion, S72 and C40 exerted stronger scavenging ability to DPPH free radical; S72 showed significantly high proteolytic activity than other strains, where the value of free amino acids could reach 51.389 μg/mL. Moreover, S39 and C40 also had higher proteolytic activity.(3) When L. plantarum S72 was used as an auxiliary starter in the processing of Gouda, the results showed that supplementation of probiotics in Gouda cheese, had no significant effect on the protein, fat, moisture, pH and salt content(P>0.05). During cheese processing and storage, had no significant effect on the fermentation of Lactococcus lactis. During the mature period, the proteolysis index, free amino acids contents, free fatty acid content, texture and sensory indicators were analyzed, and the results showed that S72 neither had adverse effects on the overall quality of the cheese, nor produced undesirable flavor.To sum up, L. plantarum S72 has good prohiotic features and proteolytic ability and can be used as an auxiliary starter in cheese processing to make Gouda, but it has no adverse effect to various indicators of Gouda.