Changes in lipids of surface, middle and inner layer from Sichuan sausage during processing and storage

According to the closeness when the sausage was exposed to the air, Sichuan sausage was divided into outer, middle and inner layers. Acid value, peroxide value, TBA value and free fatty acids of the sausage were determined during processing and storage. Results showed that water activities and moisture contents in the surface layer of Sichuan sausage were lower than the sausage inner layer. Moisturer contents of the surface and the inner of the sausage were individually 9.32% and 12.51%, while water activities were 0.62 and 0.51seperately at the end of the storage phases. On the 120th day, the acid value, peroxide value and TBA value in the surface layer of Sichuan sausage were 9.08mg KOH/g, 18.33meq/kg and 1.52mg MDA/kg, respectively, which were both higher than the middle and the inner layers. In the end of storage, the content of MUFA from 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.