Effect of Low Sodium Salt on Lipid Oxidation and Volatile Flavor Compounds of Naturally Fermented Yak Meat Sausage under Different Ripening Conditions

To explore the effect of reducing the sodium content on the lipid oxidation and flavor quality of naturally fermented yak meat sausages, low-sodium and control sausages were prepared by adding 2% and 4% sodium salt and natural ripening or constant temperature ripening, respectively. Physicochemical indicators were measured during the ripening process. The results showed that regardless of the ripening method used, the water content, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and hydroxyl radical scavenging capacity of the low-sodium group were significantly lower than those of the control group (P < 0.05), and the pH was significantly higher than that of the control group (P < 0.05). The degrees of lipid hydrolysis and oxidation in the four treatment groups increased with ripening time, being significantly higher in the low-sodium group than in the control group for each ripening method (P < 0.05). There was no significant difference in lipoxygenase activity between the two groups of natural maturation (P > 0.05), while at the late stage of constant-temperature ripening, the lipoxygenase activity in the low-sodium group was significantly higher than that in the control group (P < 0.05). In addition, a total of 69 volatile flavor compounds were detected from the sausages, and the cumulative contribution rate of the first three principal components was as high as 96.206%. Principal component analysis (PCA) showed that on the 9th and 17th (end) day of maturation, the relative contents of alcohols, aldehydes and other substances generated by lipid oxidation in the low-sodium group were higher than those in the control group. Different sodium contents had a significant effect on the hydrolysis and oxidation of lipids in sausage. Directly reducing the sodium content to 2% may promote the oxidation of lipids.