Physical, Chemical And Microbial Property Of Sichuan Sausage During Processing And Selection And Application Of Staphylococcus

Fermented sausage, with the largest yield, is a first class fermented meat product, which is nutritious, with a long shelf-life and special flavor. And so the fermented sausage is popular in the occident. However, traditional sausage in our country is a batch of questions with poor hygienic quality, long production period, poor safety. Reflecting on the unavoidable disadvantages above, product are focusing on starter culture to achieve effective control and ensure safety and stability of product quality. Currently,our main purpose is to find out the predominant strains in the source of traditional fermented meat products to achieve fermented meat products.Sichuan sausage was used for current study. The changes of microflora was analyzed during the processing and storage of Sichuan sausage. And the relationship between microflora and quality of Sichuan sausage was also studied. Moreover, the application in Sichuan fermented sausage of the predominant Staphylococcus was analyed, which can provide a theory for the research of multiple starter cultures and the application of mixed starter cultures. The major researches and experimental results were as follows:1. The lowest pH of the Sichuan sausage was about 5.84 during the ripening process. Aw was 0.73 and moisture content was about 20% in final products. The acidity value, peroxide value and TBA value increased gradually during the natural air-drying. The major free fatty acids in Sichuan sausage were oleic acid, palmitic acid, stearic acid, linoleic acid. The proteolysis indexes (P.I.) had an upward tendency during the ripening process in Sichuan sausage, the contents of non-protein nitrogen and amino-acid nitrogen in the ripened product were significantly higher than the raw meat (P＜0.05). Asparaginic acid, serine, cystine were not detected in Sichuan sausage, and the amount of other individual free amino acid in the ripened product among which Ala, Pro and Glu were dominant in concentration had increased to differing degrees than the raw meat. The residual nitrite was in the range of 0.148-27.399mg/kg not beyond the government standard during ripening process. A total of 62 volatile compounds were identified in Sichuan sausage, and the major components were consisted of terpenes (79.4%) and esters (11.47%). The odor was mainly the smell of the meat and the spice in sausage before ripeness, the sausage aroma formed after the ripening process of 18 days, and the good aroma always existed during the first 60 days of storage.2. During the three months of Sichuan sausage storage, the value of pH had no significant change, moisture content and Aw decreased slightly. TBA and acidity value increased gradually, and peroxide value rise and fall alternately. The total nitrogen content of sausage change were few during storage, and the protein mainly had the hydrolysis in the first 40 days of storage. The amino-acid nitrogen and volatile salt base nitrogen assumed the ascending trend in the process of storage. But the content of nitrite decreased gradually during storage.3. Results of the microbial property displayed that the predominant microorganisms in Sichuan sausage were Staphylococcus, Micrococcus and Lactobacillus. Dring the storage, counts of Lactobacillus were about 107 cfu/g; counts of Staphylococcus and Micrococcus were about 106 cfu/g, which was lower than Lactobacillus; the change of counts of yeasts and moulds were few.4. A strain named S25 was isolated and screened from traditional Sichuan sausage. S25 was identified as Staphylococcus saprophyticus by examining its biochemical characteristics and the 16S rDNA sequence. The optimal temperature for its growth was 35℃, and its salt and nitrite tolerance was better.5. S25 was used for the production of Sichuan fermented sausage in present study. The odour of sausage fermented with S25 was better than fermented without starter culture in the early days of ripening (P< 0.05); and after the 15th day, the odour of the two products had not diffenrence (P＞0.05). The strain named S25 had better aroma production, and the other sensory of sausage with S25 had not an advantage over the sausage without stater culture.