全豆豆腐中腐败菌分离、鉴定及货架期研究

Study on isolation, identification of spoilage bacterium and shelf life in whole-soybean curd

全豆豆腐是保留大豆中营养物质的新型豆腐,研究全豆豆腐中腐败菌及货架期,可提高农产品利用效率。文章对全豆豆腐中腐败菌16S r DNA作序列分析,利用Logistic方程和Modified Gompertz方程拟合腐败菌生长动力学曲线,在一级模型基础上,采用延滞期模型和平方根模型分析温度对腐败菌延滞期(Lag time)和最大比生长速率(μmax)影响,采用一级模型研究并评估全豆填充豆腐货架期。结果表明,全豆豆腐中腐败菌经鉴定为Bacillus cereus和Bacillus subtilis。15~30℃下,Modified Gompertz模型拟合精度高于Logistic模型。豆腐贮藏温度由30℃降至15℃,腐败菌最大比生长速率(μmax)降低,延滞期(Lag time)增大。Modified Gompertz方程延滞期模型和平方根模型拟合度(R2)依次为0.98和0.99,拟合精度高于Logistic方程,相对误差低于Logistic方程。15℃下Logistic方程和Modified Gompertz方程计算实际货架期为41.38和40.73 h,10℃下Modified Gompertz方程预测全豆豆腐货架期为143.96 h(5.99 d)。结果表明,Modified Gompertz方程更适用于全豆填充豆腐货架期预测。

Researches on the identification of spoilage bacteria and shelf life prediction of wholesoybean curd, an innovative soybean curd that almost retains all the nutrients in soybean seeds, will enhance the utilization of agricultural products. In the present research, 16 S r DNA sequencing technology was applied to identify spoilage bacteria isolated from spoiled whole-soybean curd that had been stored at37 ℃ for 24 h. Based on predictive microbiology theory, kinetics growth models of spoilage bacteria were set up by Logistic and modified Gompertz equations and the effects of temperature on the maximum specific growth rate and lag time were described by lag time and square root models, the shelf life of the wholesoybean curd was calculated and predicted, followed by an accuracy assessment to evaluate the precision of the primary model. The experimental results indicated that spoilage bacteria isolated from spoiled wholesoybean curd was identified as Bacillus cereus and Bacillus subtilis, respectively, growth curves of spoilage bacteria among 15 ℃ to 30 ℃ were better described by modified Gompertz equation and it was observed that the maximum growth rate increased with increasing temperature while changes of lag time showed opposite trend. The temperature dependence of the maximum growth rate and lag time calculated from modified Gompertz equation was modeled using lag time and square root models, the calculated nonlinear correlation coefficient between temperature and the maximum growth rate, lag time was 0.98 and 0.99,respectively, which was better than that of Logistic equation. The observed shelf life of the whole-soybean curd stored at 15 ℃ calculated by Logistic equation and modified Gompertz equation was 41.38 h and40.73 h, respectively, and the predicted shelf life at 10 ℃ was 143.96 h（5.99 d）. To conclude, obviously, the shelf life of the whole-soybean curd could be predicted availably by modified Gompertz equation in our research.