冰箱贮藏猪里脊肉微生物变化规律研究

Research on Microbial Changes of Pork Tenderloin Stored in Refrigerator

为了解市售猪里脊肉携带微生物的种类,以及冰箱不同贮藏温度对其微生物种类和丰度的影响。以市售猪里脊肉为研究对象,样品在分割、包装和贮藏期间避免外界微生物污染,并分别于25、4、−3.5、−18、−32℃条件下贮藏24 h。用无菌牙签蘸取相同贮藏温度下样品表面微生物,并在细菌、酵母和霉菌3种选择性培养基上进行培养,从培养皿表面洗脱分别获得细菌、酵母和霉菌混合液。利用16S rRNA和ITS测序方法测定上述样品中的细菌、酵母和霉菌的种类,并分析其相对丰度。为了进一步研究上述猪里脊肉在家庭冰箱冷冻室(−18℃)的微生物种类,对−18℃贮藏样品的微生物进行了分离、纯化和测序,纯化得到的菌株可以为将来冰箱冷冻室杀菌研究提供目标菌株。结果表明:市售猪里脊肉含有众多微生物,以细菌居多,酵母菌次之,霉菌较少,并随着贮藏温度的变化,微生物种类和丰度也会发生较大变化;−18℃贮藏条件下纯化的微生物测序结果表明,猪里脊肉在冷冻条件下含有种类较少且耐冷的微生物,长期冷冻贮藏,仍然存在腐败变质的风险。

In order to investigate the types of microorganisms in commercially sold pork tenderloin,and the effects of different storage temperatures in refrigerators on the types and abundance of microorganisms,the commercial pork ten⁃derloin was taken as the research object and avoiding external microbial contamination during the period of segmenta⁃tion,packaging and storage,and then the samples were kept at 25,4,−3.5,−18,−32℃for 24 hours respectively.The microorganisms on the surface of the samples at same storage temperature were dipped with sterile toothpick,and cul⁃tured in three selective media of bacteria,yeast and mold,the mixture of bacteria,yeast and mold was obtained by washing from Petri dish.Using 16S rRNA and ITS sequencing methods to determine the types of bacteria,yeast,and mold in the above samples,and analyze their relative abundance.In order to further study the microbial species of the above pork tenderloin in the home freezer(−18℃),the microorganisms of the samples stored at−18℃were isolated,purified and sequenced.The isolated strains could provide target strains for future sterilization research in the freezer.The results showed that the marketed pork tenderloin contained many microorganisms,mostly bacteria,followed by yeast,and less mold.With the the change of storage temperatures,the species and abundance of microorganisms would also change significantly.The sequencing results of purified microorganisms at−18℃showed that pork tender⁃loin still contained a small number of cold resistant microorganisms under freezing conditions,and there was still a risk of spoilage in long-term frozen storage.