Abstract:

In order to investigate the effect of frozen storage on lipid composition in different tissues and organs of mini-pig, subcutaneous fat, longissimus dorsi muscle and livers from three mini-pigs of the same age were subjected to frozen storage at－ 18℃for 150 days. Pre- and post-storage samples were determined for their lipid content, lipid composition, fatty acid composition and malonaldehyde content. No obvious change in the lipid content of all the tested tissues and liver before and after storage was observed. However, phospholipid content exhibited a significant decrease (P＜0.01) in all the samples and the biggest decrease (from 45.61% to 34.96%) in the liver of mini-pig was observed. After 150 days of frozen storage, subcutaneous fat, muscle and liver tissues showed 6.6-, 7.7- and 9.1-fold increases in fatty acid contents, respectively. In addition, an obvious difference of fatty acid compositions was observed among different tissues. The content of saturated fatty acids (SFA) in neutral lipid increased (P＜0.01), whereas that of polyunsaturated fatty acids in phospholipid decreased (P＜0.01), and that of saturated fatty acids decreased to the largest extent (P＜0.01). The TBARS values of subcutaneous fat, muscle and liver tissues were 0.7, 16.7 mg/kg and 120.5 mg/kg, respectively, which revealed a significant difference (P＜0.01). The above results also suggested that the lipolysis of SFA was slower than that of non-SFA during frozen storage. Lipids in liver were the most susceptible to oxidation, followed by those in muscle, and the oxidative stability of subcutaneous fat was the best under the condition of frozen storage.

Key words: mini-pig, subcutaneous fat, muscle, liver, frozen storage, fatty acids, lipid oxidative stability