常温条件下白鱼中特定腐败菌的鉴定

摘要

通过分析常温条件下无菌白鱼鱼块（CK）以及接种不同腐败菌的无菌白鱼鱼块的感官评价、挥发性盐基氮（total volatile base nitrogen，TVBN）值、腐败菌生长动态以及pH值的变化，以腐败菌的生长动力学参数和TVBN产量因子（YTVBN/CFU）为定量指标，鉴定了常温条件下导致白鱼腐败的特定腐败菌（specific spoilage organism，SSO）。结果表明，在CK和接种葡萄球菌wf-1（Staphylococcus sp.wf-1）、摩根氏菌wf-1（Morganella sp.wf-1）、摩根氏菌wf-2（Morganellasp.wf-2）、变形杆菌wf-1（Proteus sp.wf-1）、变形杆菌wf-2（Proteus sp.wf-2）和变形杆菌wf-3（Proteussp.wf-3）的无菌白鱼鱼块中，以接种Morganellasp.wf-1的无菌白鱼鱼块达到感官拒绝点的时间最短，为15.16 h，此时鱼块的TVNB含量和菌落总数分别为29.98 mg/100 g和7.53（lg（CFU/g））。对这些腐败菌的生长动力学参数和YTVBN/CFU分析发现，Morganellasp.wf-1在无菌白鱼鱼块上的生长延滞期最短，为2.60 h；最大比生长速率最大，为0.3046 h－1；YTVBN/CFU最大，为6.27×10－9 mg TVBN/CFU。所有白鱼鱼块均出现pH值先下降后上升的过程，其中接种Morganellasp.wf-1和Morganellasp.wf-2的无菌鱼块在8～48 h之间的pH值远远高于CK和接种其他腐败菌的无菌白鱼鱼块。结合实验数据和SSO的概念，最终确定Morganella sp.wf-1为常温条件下导致白鱼腐败的SSO。%Sensory quality, total volatile base nitrogen (TVBN) value, the growth of spoilage bacteria and pH in sterile whitefish blocks (as control, CK) and those inoculated with different spoilage bacteria were analyzed, and growth kinetic parameters of spoilage bacteria and the yield factor for TVBN production (YTVBN/CFU) were used for quantitative measurements of microbial spoilage to identify the specific spoilage organism (SSO) of whitefish at room temperature. The results showed that the whitefish blocks inoculated with Morganellasp.wf-1 reached the limit (15.16 h) of sensory acceptability earlier than CK and whitefish inoculated with Staphylococcussp.wf-1,Morganellasp.wf-1,Morganellasp.wf-2,Proteussp.wf-1, Proteussp.wf-2 andProteussp.wf-3, and TVBN value and total bacterial count were 29.98 mg/100 g and 7.53 (lg(CFU/g)) at this time point, respectively. The analysis of growth kinetic parameters andYTVBN/CFU for these spoilage organisms showed thatMorganellasp.wf-1 had the shortest lag phase of growth, maximum specific growth rate andYTVBN/CFU, which were 2.60 h, 0.304 6 h-1 and 6.27 × 10-9 mg TVBN/CFU, respectively. The pH value tended to first decline and then rise for CK and all whitefish blocks inoculated with different spoilage bacteria. Notably, pH of whitefish blocks inoculated with Morganellasp. wf-1 andMorganella sp.wf-2 was much higher than that of CK and whitefish meat inoculated with other spoilage organisms at 8–48 h time points. In conclusion,Morganellasp.wf-1 was the SSO in whitefish at room temperature also taking into account the concept of SSO.