鲜切紫薯中酵母菌和乳酸菌货架期模型的构建

Shelf Life Establishment of Fresh-Cut Purple Sweet Potatoes by Use of Predictive Microbiological Models for Yeast and Lactic Acid Bacteria

用Gompertz模型对不同温度条件下真空包装鲜切紫薯中酵母菌和乳酸菌的生长曲线进行一级模型拟合,并通过计算准确因子(Af)和偏差因子(Bf)验证的生长模型的准确性;利用平方根模型和Arrhenius模型构建酵母菌和乳酸菌的二级模型,比较两种模型的优劣性;依据真空紫薯感官评价判定紫薯的腐败限控量,对其货架期预测模型进行构建和验证。结果表明,Gompertz模型能较好地拟合不同温度条件下2种菌的生长情况(R2在0.9左右),数学检验参数Af、Bf接近1.0,均在接受范围;通过不同二级模型动力学参数的比较,2种菌均为用平方根模型拟合二级模型较优;紫薯选用酵母菌作为指示菌预测货架期较好,其腐败限控量为6.64(lg(CFU/g)),选定4℃条件构建并验证货架期预测模型可靠性,实测值为7.0 d,预测值为7.737 d,预测效果良好。

Primary models(Gompertz) and secondary models(square root and Arrhenius) were built to describe the growth of yeast and lactic acid bacteria in vacuum-packed fresh-cut purple sweet potatoes at different temperatures. The accuracy of models was verified by accuracy factor(Af) and bias factor(Bf). The advantages of two secondary models were compared. According to sensory evaluation, the spoilage limit for purple sweet potatoes was determined. Then the predictive model for the shelf life of sweet potatoes was built and verified. The results showed that the growth of yeast and lactic acid bacteria could be well described by the Gompertz models, with correlation coefficients R2 near 0.9; the mathematical parameters(Af and Bf near 1.0) were both in acceptable range. For both microbial species, the square root models were better than the Arrhenius models in terms of mathematical parameters. Yeast was a better indicator of the shelf life of purple sweet potatoes than lactic acid bacteria. The spoilage limit of yeast was 6.64(lg(CFU/g)). A predictive model for the growth of yeast at 4 ℃ was established and validated. The measured shelf life of purple sweet potatoes at 4 ℃ was 7.0 d, while that obtained from the mode was 7.737 d. The good agreement indicated that this model is reliable.