大黄鱼腐败细菌鉴定及PLFAs初级模型的建立

Identification of Spoilage Bacteria in Pseudosciaena crocea and Primary Model Establishment for PLFAs

摘要:

为研究既定工艺条件下大黄鱼腐败状况，对大黄鱼腐败细菌进行分离、鉴定及加工过程中PLFAs初级动力学模型的建立，结果表明：14株分离的细菌中共确认3种主要腐败菌，分别为彭氏变形杆菌(Proteus penneri)、克雷伯菌(Klebsiella)、产气肠杆菌(Enterobacter-aerogenes)，均属肠杆菌科，能较好利用含氮物质。其NaCl浓度敏感区间为0~4%，最适生理活性浓度为1%。三种细菌的PLFAs比例稳定，其中16:0、16:1ω6c和16:1ω7c比例显著高于其他的PLFAs。通过修正Gompertz和修正Logistic两种模型对大黄鱼加工过程中三种PLFAs变化进行拟合比较，16:0的修正Logistic模型拟合度最优，方程为：y=5.151+2.322/[1+exp(3.831-0.090t)]，校验参数R2、RMSE、Af、Bf分别为0.9781、0.0948、1.1994、0.9909。其响应值与TVBN值显著相关（p<0.01），证明该模型具有实际价值。确定腐败细菌最大比生长速率时间点为t=42.57h，因此可在此处建立腐败细菌的HACCP。

Abstract:

Spoilage bacteria from Pseudosciaena crocea were isolated and identified, and a primary kinetic model for the presence of specific Phospholipid Fatty Acids (PLFAs) was established. The results showed that three main spoilage bacteria, which were good at utilizing nitrogenous substances, were identified from a total of 14 isolated strains, and belonged to the family Enterobacteriaceae. These three major spoilage bacteria were identified as Proteus penneri, Klebsiella II, and Enterobacter aerogenes. The range of NaCl concentration, to which these bacteria were sensitive, was between 0-4%, with the most suitable physiological concentration being 1%. The proportions of PLFAs in the three bacteria were stable, and the proportions of 16:0, 16:1ω6c, and 16:1ω7c were significantly higher than those of other PLFAs. The response value curves for the three selected PLFAs were fitted by modified Gompertz and Logistic models, and the subsequent comparison was performed. The modified Logistic model for 16:0 showed the best fit. The equation was y=5.151+2.322/[1+exp(3.831-0.090t)], and the model evaluated parameters, such as coefficient of determination (R2), root mean square error (RMSE), accuracy factor (Af), and bias factor (Bf) as 0.9781, 0.0948, 1.1994, and 0.9909, respectively. The model proved to have practical value due to a strong correlation between the response value of 16:0 and the value of the total volatile basic nitrogen (TVBN) (p < 0.01). The corresponding time point for the maximum specific growth rate of the spoilage bacteria was determined to be t = 42.57 h, which can be used to establish the hazard analysis and critical control point (HACCP) of spoilage bacteria.