二肽酰肽酶Ⅳ在金华火腿加工过程中的活力变化

 以浙江兰溪长白×金华猪杂交猪后腿为原料，按传统工艺加工金华火腿，分别在腌制前、腌制结束、晒腿结束、成熟中期、成熟结束和后熟结束6个工艺点随机取5条腿的股二头肌，测定了各样品的常规理化指标和二肽酰肽酶Ⅳ（dipeptidyl peptidase Ⅳ, DPPⅣ）在pH7.0和温度37 ℃条件下的潜在活力；借助Design-experts 6.0软件，用响应曲面法研究了温度、食盐含量、硝酸钠含量和pH值对DPPⅣ活力的影响，并用响应曲面回归方程对金华火腿加工各阶段结束后的肌肉DPPⅣ实际活力进行了预测。结果表明，在金华火腿加工过程中，随加工温度和股二头肌pH逐渐升高，食盐含量持续增加，DPPⅣ潜在活力持续下降；DPPⅣ实际活力受加工温度、肌肉pH和食盐含量的显著影响(P<0.05)，DPPⅣ在金华火腿整个加工过程中一直保持较高的潜在活力，但其实际活力一直很低，最高为其潜在活力的3.12%。

Changes of Dipeptidyl Peptidase Ⅳ in the Processing of Jinhua Ham

Sixty experimental Jinhua hams were processed according to typically traditional processing technology with fresh hams from hind legs of local hybrid pigs of Lanxi, Zhejiang Province, China. Biceps femoris was sampled from 5 hams randomly taken each time from one of the 6 processing stage, namely, green ham before salting, end of salting, end of sun-drying, mid-aging, end of aging and end of post-aging. Sample potential DPPⅣ activity at pH 7.0 and temperature 37℃ as well as some general physical and chemical indices were determined. The effects of temperature, sodium chloride content, sodium nitrate content and pH value on muscle DPPⅣ activity were evaluated with Response Surface Method by Design-experts 6.0 software, and muscle actual DPPⅣ activity after each processing stage of Jinhua ham was predicted with response surface regression equation. The results showed that during Jinhua ham processing, processing temperature, biceps femoris pH value and sodium chloride content increased gradually while biceps femoris potential DPPⅣ activity decreased gradually. The actual DPPⅣ activity was significantly influenced by processing temperature, muscle pH value and sodium chloride content (P < 0.05). Though muscle DPPⅣ could keep rather high potential activity during Jinhua ham processing, its actual activity was always very low and only 3.12% of the potential activity could be expressed at most, which therefore indicated that DPPⅣ's role in the formation of Jinhua ham flavor was quite possibly limited.