Change In Physical, Chemical And Microbial Of Surface, Middle And Inner Layer From Sichuan Sausage During Processing And Storage

The article regarded Sichuan sausage as research object, according to the closeness when the sausage was exposed to the air, Sichuan sausage was divided into outer, middle and inner layers to analysis sausage variation in protein, fat, microbial, endogenous enzymes during the processing and storage process. In order to provide a theoretical basis for improving the traditional craft of Sichuan sausage. The main results and conclusions are as follows:1. Results showed that water activities, moisture contents, salt and nitrite content in the surface layer of Sichuan sausage were lower than the sausage inner layer. Moisture contents of the surface and the inner of the sausage were individually 9.32% and 12.51%, while water activities were 0.615 and 0.511, respectively, salt content 4.75% and 4.95%, nitrite content 0.66 mg/100g and 1.25mg/100g at the end of the storage phases. At the early of storage phases, pH value of surface layer was higher than the inner surface. When the 55th day, pH value of the surface,the middle and the inner of the sausage were 6.21,6.15and 6.10. At the end of storage(55-120d), pH value of the surface layer became minimum, middle layer became maximum.2. During the course of sausage processing and storage, the potential activity of acid lipase and neutral lipase decreased and could be detected its activity in the 120th day. Sausage inner acid lipase’s potential activity was significantly higher than the surface layer during the early processing and storage (0-55d). On the 55th day, the potential activity of acid lipase in sausage surface and the inner were:47.66 U·g-1 and 96.49U·g-1.3. On the 120th day, the acid value, peroxide value and TBA value in the surface layer of Sichuan sausage were 9.08 mg KOH/g,18.33 meq/kg and 1.52 mg MDA/ kg, respectively, which were both higher than the middle and the inner layers. On the 90th day, the content of saturated fatty acids of neutral fat content in surface layer(38.45%)was higher than inner layer (35.12%). However, on the 120th day, the content of saturated fatty acid in the surface layer (36.65%) significantly lower than the inner layer (39.49%). Sausage in the surface, middle and inner layer, phospholipids monounsaturated fatty acid content in the late storage difference was obvious.On the 90th day, the monounsaturated fatty acids in the surface, middle and inner layer were:38.70%,42.32% and 46.04%, and on the 120th day were:40.29%, 43.96% and 40.44%. In the end of storage, the content of MUFA from free fatty acid of the sausage surface layer was highest,50.44%. The content of PUFA from the sausage inner was highest,21.23%. Results showed that during the processing and storage of the Sichuan sausage, lipid hydrolysis and lipid oxidation happened easily in the surface layer, and the oxidation of polyunsaturated fatty acids of the surface layer emerged easier than the middle and inner layer. In the late storage, sausage fat hydrolysis had a great relationship with microbial species and quantity.4. The cathepsin B and L of the potential activity decreased during the course of processing and storage in Sichuan sausage. The activity of cathepsin B in the raw meat was 376665.47U·g-1. Sausage in the surface, middle and inner layer residual activity of cathepsin B was about 20% of the raw meat at the end of storage. In the late processing, Cathepsin L had a rising trend of unknown cause, and it is in storage at the end of the residual activity of about 2% of the raw meat. The cathepsin B and L of the potential activity in the surface and inner layer had little differences of the Sichuan sausage.5. The total nitrogen and non-protein nitrogen content of raw meat were 3.79% and 0.29%(dry basis). At the early stage of the processing (0-7d), Sichuan sausage surface layer of total nitrogen and non-protein nitrogen content were on the decline, and the middle and inner were on the rise. On the 7th day, the total nitrogen of the sausage surface, middle and inner layer were:2.99%,3.74% and 4.12%, non-protein nitrogen content were:0.18%,0.41% and 0.32%. During the period of storage, the total nitrogen and nonprotein nitrogen content in surface were higher than inner. Throughout the course of processing and storage, the inner volatile base nitrogen sausage lining and all kinds of free amino acid content were higher than the surface. The protein bands in the sarcoplasmic protein which is more than 97.2KD had almost disappeared completely. While the protein bands between 44.3KD and 29KD had appeared different degree of degradation in the surface, middle and inner layer, in which the surface degraded fastest and the inner degraded slowest. Myofibrillar protein from the sausage inner degraded fiercely, but degraded slowly in middle and surface layers. Results showed that during the processing and storage of the Sichuan sausage, the degradation of protein of the surface layer emerged easier than the middle and inner layer.6. During the process of processing and storage of Sichuan sausage, microbial populations in the surface layer were higher than the inner.