Screening Of Bacteria In Fermented Sausage And Its Effects On Physical And Chemical Properties Of Fermented Sausage

In order to screen out the sausage fermenterer with excellent performance and suitable for the taste of Chinese consumers,four strains were isolated from the Italian spicy sausages and preliminary identified by enotypic characteristics observation and physiological and biochemical methods.The selected lactic acid bacteria were added to the sausage fermentation,according to its fermentation process and the quality of the final product of sausage research,access to China's consumer taste of fermented sausage fermentation agent.Major contents were as following:1.Two strains of Gram-positive bacilli and two Gram-positive cocci were isolated and purified from MRS medium from three kinds of sausages.The four strains of lactic acid bacteria were found to be resistant to 6%NaCl,150 mg/kg nitrite,and no glucose,H₂S,and H₂O₂ were produced in the culture,and amino acid decarboxylase test was negative,Litmus milk test was positive,VP reaction was negative,acetyl methyl methanol test negative.RY500,RY175 were Bacillus cereus,RY75 was Lactobacillus fermentum,and RY25 was Lactobacillus plantarum.The results showed that RY500 could be used as a result of the observation of phenotypic characteristics and physiological and biochemical characteristics.The growth of three lactic acid bacteria was measured at 20?,24?,28?,32?and 36?.Three strains of Lactobacillus grew fastest at 32?.The growth rate and acid production rate of three strains of lactic acid bacteria were good,and the growth rate and acid production rate of RY25 were higher than those of other strains.Three strains of lactic acid bacteria were tested by filter paper method,and RY500 and RY25 had no antagonistic effect on each other.Therefore,it could be used as a mixed starter for the production of fermented sausages.2.Use the selected lactic acid bacteria to process fermented sausages and detect the changes of microorganisms and physicochemical indexes of sausage during sausage fermentation and maturation.Lactobacillus was the dominant strain in the process of sausage fermentation and ripening,and lactic acid bacteria inhibited the growth of Enterobacteriaceae in fermented sausage.Lactobacillus reduced the pH value and water activity of fermented sausage,and inhibited the increase of peroxide value and volatile base nitrogen.Lactic acid has a weak degradation effect on sodium nitrite in fermented sausages.3.The quality analysis of the final product of fermented sausage shows that lactic acid bacteria have a certain effect on improving the hardness,chewiness and elasticity of sausage,improving the color of sausage and improving the flavor of fermented sausage.The volatile flavor substances of five fermented sausages were analyzed by SPME-GC-MS,and 137kinds of volatile substances were detected.Most of volatile substances were acid,esters and aldehydes.Combined with sensory evaluation,through this study found that mixed fermentation than single strains of fermentation can improve and enhance the sensory flavor of fermented sausage.