老腊肉加工过程中脂质水解及氧化的变化研究

以重庆城口改进型老腊肉为研究对象,分别提取腌制前、腌制后、电热烘烤、烟熏5 d、10 d、15 d共6个阶段的试样,通过测定酸价、过氧化值、TBA、脂肪酶活力及脂肪酸组成等指标,分析其在加工过程中脂质水解及氧化的变化。结果表明:酸价在腌制后显著上升,在其他工艺阶段变化缓慢,TBA和过氧化值均在电热烘烤后显著上升,但过氧化值在烟熏阶段呈下降趋势而TBA变化不显著;脂肪水解酶的活力在腌制后显著上升,经电热烘烤阶段后不断下降;受脂肪酶水解酶活性的影响,磷脂和游离脂肪酸的组成成分在烟熏前期变化显著,其中磷脂和游离脂肪酸的含量及两者脂肪酸组成的变化尤其是多不饱和脂肪酸的变化趋势相反,而甘油酯的含量及其脂肪酸组成的相对含量保持稳定,说明磷脂在腊肉加工过程中水解作用显著,游离脂肪酸主要来源于磷脂的水解。

Lipolysis and Lipid Oxidation During the Process of Chinese Traditional Bacon Development

Here, modified Chongqing Chengkou bacon was studied using samples collected before and after salting, roasting via electric heat, and smoking for 5, 10, and 15 h to assess changes in lipolysis and lipid oxidation during the processing by measuring acid value (AV), peroxide value (POV), thiobarbituric acid (TBA), lipase activities, and fatty acid composition. The results showed that AV increased sharply after salting, but exhibited slow changes during other phases of processing. TBA and POV values increased markedly after roasting with electric heat, with POV exhibiting a downward trend and insignificant changes in TBA during the smoking phase. Lipase activities were significantly enhanced after salting before a continuous decline during roasting with electric heat. The compositions of phospholipids and free fatty acids varied considerably during the early stage of smoking due to the influence of lipase activity. Changes in the content and fatty acid composition of phospholipids showed opposite trends from those of free fatty acids, especially, polyunsaturated fatty acids; however, the content of triacylglycerols and the relative content of their fatty acids was stable, suggesting that phospholipids play an important role in hydrolysis duringthe processing, and that phospholipid hydrolysis may be the main source of free fatty acids.