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