低温热处理对超高温灭菌乳中假单胞菌脂肪酶Ⅷ的活性影响

Effect of low temperature heat treatment on the activity of lipase Ⅷ from Pseudomonas Species in UHT milk

摘要: 通过分析不同因素对假单胞菌脂肪酶Ⅷ活性的影响以及假单胞菌脂肪酶Ⅷ活性与超高温灭菌(UHT)乳脂肪上浮的关系，研究了控制UHT乳中假单胞菌脂肪酶Ⅷ活性和延缓脂肪上浮现象的措施。结果表明pH值对假单胞菌脂肪酶Ⅷ的活性有显著性影响(P<0.01)，50、55、60℃(20 min)的低温热处理能显著降低假单胞菌脂肪酶Ⅷ的活性(P<0.01)。贮藏试验表明低温热处理对控制UHT乳在贮存过程中的假单胞菌脂肪酶Ⅷ活性水平(P<0.01)和脂肪上浮现象(P<0.05)有明显的作用，而55℃和15 min的低温热处理对缓解UHT乳在贮藏过程中的脂肪上浮现象最为有效。

Abstract: The factors influencing the activity of lipase Ⅷ from Pseudomonas Species and the effect of lipases on fat separation of UHT milk were determined to investigate the means for controlling the activity of lipase and inhibiting the fat separation in UHT milk. The results show that the pH value has significant influence on lipase activity(P<0.01), low temperature heat treatment at 50, 55, 60℃ for 20 minutes are effective to inactivate the lipase Ⅷ(P<0.01). It is found that the activity of lipase Ⅷ(P<0.01) and the extent of fat separation(P<0.05) during storage of UHT milk are significantly reduced by the low temperature heat treatment. It is suggested that the optimum condition for inhibiting the fat separation of UHT milk is heating at 55℃ for 15 minutes.