酸化和渗透压不同处理顺序对肠炎沙门菌失活的影响

Effect of Processing Sequence of Acid and Osmotic Pressure on Salmonella enteritis Inactivation

为探讨酸化和渗透压不同处理顺序对肠炎沙门菌失活的影响,运用统计学模型模拟了最优处理条件下,肠炎沙门菌在不同初始接菌量下的失活过程。实验结果表明:在25℃和10 h内,先15%Na Cl再p H值4.5处理使肠炎沙门菌失活的效果大于相反顺序的处理、同时处理或者单独处理的效果。模拟结果表明:在最优处理条件下的各个阶段中,随着初始接菌量的增加,肠炎沙门菌分别达到0.986 4和0.993 9失活率时对应的失活时间的变异性逐渐降低。对于大量群体细菌,用确定性失活动力学一级模型拟合的D值是单一的定值;而对少量群体细菌,由于个体细胞本身的变异性,D值表现出较高的变异性,并且可用概率分布的形式表示。酸化和渗透压不同处理顺序的研究能为食品工业生产控制致病菌提供借鉴,且应用的统计学建模方法有助于从个体细胞的角度理解群体失活过程,提高风险评估的准确性。

To study the influence of different processing sequences of acid and osmotic pressure on the inactivation of Salmonella enteritis, a statistical model was used to simulate the inactivation of Salmonella enteritis with different initial inoculations under the optimal processing conditions. The experimental results demonstrated that the sequence of 15% NaC1 stress applied firstly and then pH value of 4.5 stress treatment made the number of Salmonella enteritis reduce faster than the reverse sequence or single stress or double stresses used simultaneously at 25% in 10 h. Moreover, the simulation results indicated that the variability of inactivation time was reduced gradually with the increase of initial inoculation when the inactivation rate of Salmonella enteritis reached 0. 986 4 and 0. 993 9, respectively, at all stages of the optimal processing conditions. In addition, the D value by the deterministic inactivation model was a single constant value for a large number of bacteria. However, the fitted D value showed high variability for a small group of bacteria due to the variability of the individual cells, and the D value could be described by the probability distribution. Consequently, the research of different processing sequences of acid and osmotic stress could provide reference of controlling pathogens for food industry production, and the applied statistical modeling method would help to understand the inactivation from the perspective of individual cells as well as to improve the accuracy of risk assessment.