特定致腐菌对冷却猪肉的致腐作用机制

为研究特定致腐菌在冷却猪肉中的致腐作用机制，将韩国假单胞菌PS1（Pseudomonas koreensis PS1）和梭状芽孢杆菌J4（Bacillus fusiformis J4）分别接种到新鲜冷却猪肉中进行致腐实验，以不接种致腐菌的猪肉为对照，于4℃条件下贮藏，每隔1 d测定各组肉样的细菌总数、总挥发性盐基氮（total volatile basic nitrogen，TVB-N）含量、蛋白质含量以及脂肪酶、弹性蛋白酶、胰蛋白酶和胶原蛋白酶活力。结果表明：各组肉样细菌总数均呈现先上升后稳定的趋势，贮藏第5天，接种P. koreensis PS1、B. fusiformis J4的肉样细菌总数均超过8.0（lg（CFU/g）），明显大于对照组；接种特定致腐菌的2组肉样脂肪酶、弹性蛋白酶、胰蛋白酶和胶原蛋白酶活力均高于对照组，且呈现先上升后降低趋势，至贮藏第7天，弹性蛋白酶、胰蛋白酶和胶原蛋白酶活力均达到峰值，而脂肪酶活力在贮藏第5天达到峰值；同时，各组肉样蛋白质含量不断降低，产物TVB-N含量明显增加，贮藏第5天，接种特定致腐菌的2组肉样TVB-N含量均超出15mg/100g，明显高于对照组。

Mechanism by Which Inoculation with Specific Spoilage Organisms Caused Spoilage in Chilled Pork

Chilled fresh pork was inoculated with Pseudomonas koreensis PS1, Bacillus fusiformis J4 or nothing and stored at 4 ℃. Then, total viable count (TVC), total volatile basic nitrogen (TVB-N) content, protein content, and the activities of lipase, elastase, trypsin and collagenase in pork samples were determined. By doing so, we sought to explain the mechanism by which specific spoilage organisms (SSO) caused spoilage in chilled pork. The results showed that the TVC in all groups increased with storage time until reaching a plateau. The TVC in the two experimental groups exceeded 8.0 (lg (CFU/g)) on the fifth day, which was significantly higher than that of the control group. In the inoculated pork samples, the activities of the above four enzymes were higher than those in the control group, and showed a trend of increasing at first and then decreasing. The activities of elastase, trypsin and collagenase reached the peak on the seventh day, while the peak of lipase activity appeared on the fifth day. At the same time, the protein content decreased continuously in all groups, whereas the TVB-N content increased obviously. On the fifth day, the TVB-N content in the two experimental groups exceeded 15 mg/100 g, which was significantly higher than that of the control group.