金华火腿加工过程中内源脂肪酶活力变化特点研究

Studies on the Changing Characteristics of Endogenous Lipase during Processing of Jinhua Ham

以浙江兰溪两头乌杂交猪后腿为原料,按传统工艺加工金华火腿。分别在原料、腌制结束、晒腿结束、成熟中期、成熟结束、后熟-1和后熟-2七个工艺点随机取5条腿的股二头肌为样品,分别测定中性脂肪酶、酸性脂肪酶的活力变化,以及测定pH5.8时脂肪酶综合活力的变化;同时,利用响应曲面法研究温度、盐含量、硝酸盐含量、亚硝酸盐含量对脂肪酶活力的影响,并利用所得回归方程预测金华火腿加工过程中脂肪酶的实际表现活力。结果表明,加工过程中,脂肪酶活力持续降低,在后熟-1工艺点,酸性脂肪酶和中性脂肪酶活力残留分别是8.16%和3.0%,至后熟-2已测不到酶活;温度、盐含量及其交互项是脂肪酶活力的显著影响因子(P<0.05),硝酸盐和亚硝酸盐含量对脂肪酶活力影响不显著(P>0.05)。加工过程中,预测的脂肪酶实际表现活力在成熟中期工艺点之前低于酸性脂肪酶及中性脂肪酶的潜在活力,之后则高于潜在活力,其变化规律与酸性和中性脂肪酶完全不同。

Jinhua hams were processed with traditional method using green hams from local Liangtouwu cross-bred pigs＇ hind legs. Biceps femoris sampled from five hams randomly taken after each processing stages, i. e. , green ham, end of salting, end of sun-drying, middle of loft-aging, end of loft-aging, post-aging- 1 and post-aging-2, were used as samples to measure the potential activities of acid and neutral lipases and the integrative lipase activity at pH 5.8; the effects of temperature, salt content, nitrate content and nitrite content on the lipase activity were studied using response surface methodology （RSM） response surface regression equation was used to predict the actual lipase activity during processing. The results showed that during processing of Jinhua ham, lipase activity decrease gradually, about 8.16% and 3.0% of initial potential activity of acid and neutral lipases were left at the end of post-aging-1, espectively; no activity was measured for both acid and neutral lipases at the end of post-aging-2. Temperature, sodium chloride content and their interaction influenced the lipase activity significantly （ P d0.05） ; nitrate and nitrite contents showed insignificant effects （ P ）0.05）. During processing, the predicted actual activity, which changed in a different rule from the potential activities of acid and neutral lipases, was lower before the end of loft-aging and then higher after the end of loft-aging than the potential activities of acid and neutral lipases.