Analysis of Lipolysis and Oxidation Ability of Fermentation Strains in Sterilized Pork Pulp

This study aimed to screen out the fermentation strains with high lipolysis and antioxidant ability, which provided the theoretical basis for development of new starter cultures.

The sterilized pork pulp was inoculated with Staphylococcus xylosus YSZ11, Staphylococcus xylosus YCC3, Staphylococcus saprophyticus YCC2, Macrococcus caseolyticus YZC2, and Macrococcus caseolyticus YZC3, respectively. The sterilized pork pulp without inoculation of strains was used as the control group. The changes of pH, peroxide value (POV), thiobarbituric acid reactive substances (TBARS), lipase activity, lipid composition and free fatty acid content were measured after 4 d fermentation.

5 fermentation strains could reduce the pH value of the pork pulp. The POV and TBARS values were 2.51-2.96 mmol∙kg^-1 and 0.21-0.24 mg/100g in pork pulp inoculated with fermentation strains, which were significantly lower (P<0.05) than that in CK group. The activity of neutral lipase, acid lipase and phospholipase were all detected in the groups inoculated with the fermentation strains, while higher activity of acid lipase and phospholipase were found in the groups inoculated with the fermentation strains than that of neutral lipase. After 4 d of fermentation, the phospholipid content decreased significantly (P<0.05), while the free fatty acid content increased by 21.1%-73.7% in the groups inoculated with the fermentation strains. At the same time, the amount of saturated fatty acids decreased significantly, while the amount of unsaturated fatty acids especially the content of palmitoleic (C_16:1), oleic (C_18:1) and linoleic acids (C_18:2) increased significantly, and the linolenic acid (C_18:3) was also detected.

This study showed that five fermentation strains could inhibit lipid oxidation, and promoted lipid hydrolysis by secreting lipase, which led to the increase of the content of free fatty acids, especially unsaturated fatty acids. Staphylococcus saprophyticus YCC2 and Staphylococcus xylosus YCC3 had better lipolysis and antioxidant ability, and showed a more prominent promoting effect on improving the quality of fermented meat products.