风干牦牛肉品质形成与微生物变化规律研究

通过对风干牦牛肉加工过程不同阶段样品进行品质及微生物指标检测，研究了其品质形成与微生物变化规律。结果表明：产品的外观特征变化明显，失重率为76%；加工过程中TBA值逐渐上升，最终产品为0.48 mg/kg；水分含量和水分活度逐渐下降，水分含量除第0 d与第5 d差异不显著（P>0.05）外，其后各阶段差异显著（P<0.05），风干第10 d到第15 d是风干牦牛肉加工的主要失水阶段，风干第20 d和第25 d水分活度差异显著（P<0.05）；风干过程中pH变化范围较小；菌落总数在风干第5 d和第20 d变化显著（P<0.05），大肠菌群随着加工过程逐渐减少，未检出单增李斯特菌和金黄色葡萄球菌。风干过程中，水分活度的降低是菌落总数下降的主要原因，且较低的水分活度保证了产品的安全性，而失水速度是影响风干时间和产品酥松性的重要因素。

Studies on the Rule of Airing Yak Beef Quality Forming and Microorganism Changing

By detecting the quality and microorganism indicator of airing yak beef samples in different stages, we studied the rule of quality forming and changes of microorganism. The results showed that the appearance characteristics of the product change significantly and the weight loss rate was 76%; TBA value increased gradually in the processing process, and the final product was 0.48 mg/kg; the water content and water activity decreased gradually. Except the beginning day to the 5th day, change of moisture content was not significant (P>0.05), changes in the rest stages were significant (P<0.05). The 10thd to the 15th d was the major dehydration stage; water activity changes during the 20th d and 25th d were significant (P<0.05). In the airing period, the pH increased in a smaller changing range; change in the total number of colonies on the 5th d and 20th d were significant (P<0.05). The coliform reduced gradually in the process and no Listeria monocytogenes and Staphylococcus aureus were detected. In the drying process, the reduction of water activity was the main reason for the decline of total colonies number, and the lower water activity ensured the safety of products. The dehydration speed was the most important factor affecting air-dry duration and product crisp.