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目的建立单核细胞增生李斯特菌、阪崎肠杆菌和蜡样芽胞杆菌在复原乳中的生长动力学模型。方法将3种致病菌分别接种于复原乳中,分别在低温(4℃、8℃)、适温(25℃、37℃和42℃)条件下储藏不同时间,参考国标GB 4789.2—2010对菌落总数进行计数,采用修正的Gompertz模型和平方根模型模拟3种致病菌在低温和适温条件下的一级和二级生长动力学模型,并验证模型的有效性。结果修正的Gompertz模型能较好地拟合3种致病菌的生长曲线,拟合的R2范围在0.97~1.00。平方根模型能较好地拟合温度与3种致病菌最大比生长速率μmax的线性关系,其R2范围为0.93~0.99之间,经验证3种细菌的生长动力学模型的Bf和Af均在可接受范围内。结论本研究建立了复原乳中3种致病菌一级和二级生长动力学模型,该模型为开展复原乳中3种致病菌的风险评估和预警提供了理论基础。
Objective To establish a kinetic model for the growth of Listeria monocytogenes, Enterobacter sakazakii and Bacillus cereus in reconstituted milk. Methods Three kinds of pathogenic bacteria were inoculated into reconstituted milk separately and stored at low temperature (4 ℃, 8 ℃) and suitable temperature (25 ℃, 37 ℃ and 42 ℃) for different time. Reference to national standard GB 4789.2-2010 The total number of colonies was counted. The modified Gompertz model and square root model were used to simulate the primary and secondary growth kinetic models of three kinds of pathogenic bacteria at low temperature and moderate temperature, and the validity of the model was verified. Results The modified Gompertz model fitted well the growth curves of three kinds of pathogenic bacteria, and the R2 range of fitting was 0.97-1.00. The square root model can well fit the linear relationship between temperature and the maximal specific growth rate μmax of three kinds of pathogenic bacteria, and the R2 range is between 0.93 and 0.99. The Bf and Af of the three kinds of bacteria growth dynamics models are validated Acceptable range. Conclusion This study established the primary and secondary growth kinetic models of three kinds of pathogenic bacteria in reconstituted milk. This model provides the theoretical basis for the risk assessment and early warning of three kinds of pathogenic bacteria in reconstituted milk.