冷冻是肉类和肉类产品的重要储存方法，本试验研究了反复冻融5次对猪背最长肌肉营养成分的影响，分析猪肉冻融过程中蛋白质、脂肪、氨基酸、脂肪酸和微量元素含量的变化。结果显示：随着冻融次数的增加，猪肌肉水分、粗脂肪、粗蛋白含量均显著降低（P<0.05）；灰分含量无显著变化（P>0.05）；WTAA、WEAA和WNEAA含量均极显著下降（P<0.01），氨基酸组成WEAA/WTAA在40％左右，WEAA/WNEAA在60％以上；冻融处理一次的第一限制性氨基酸为Met+Cys，其余冻融次数均为Val，必需氨基酸指数（EAAI）为73.71~77.42；SFA和PUFA在第一次解冻后变化不显著（P>0.05），在第二次解冻后极显著降低（P<0.01），而MUFA无显著变化（P>0.05）；除了必需微量元素Mn和Mo含量未发生显著变化（P>0.05），其余元素含量均呈显著下降趋势（P<0.05），但与冻融次数有关。因此，反复冻融会显著影响猪肉的营养价值。

Frozen storage is an important preservation method for meat and meat products. In this study, we investigated the effects of freeze-thaw cycles on the nutrient composition of porcinelongissimus dorsimuscle, and analyzed the changes of protein, fat, amino acid, fatty acid and trace element in the process of pork freeze-thaw cycles. The results showed that the contents of water, crude fat and crude protein were significantly decreased (P< 0.05) with freeze-thaw cycles, and the contents of ash did not change significantly (P> 0.05).WTAA,WEAAandWNEAAwere significantly decreased (P< 0.01),WEAA/WTAAwas about 40% andWEAA/WNEAAwas more than 60%. The first limiting amino acid for first freeze-thaw treatment was Met + Cys, and the remaining freeze-thaw cycles treatment were Val, the essential amino acid index (EAAI) was 73.71 ~ 77.42. SFA and PUFA did not change significantly in the first freeze-thaw (P> 0.05), and decreased significantly after the second freeze-thaw (P< 0.01), while MUFA did not change significantly (P> 0.05). The contents of Mn and Mo did not change significantly (P> 0.05), and the contents of other trace elements were significantly decreased (P< 0.05). Therefore, freeze-thaw cycles significantly affected the nutritional value of pork.