Abstract：
Microbial thermal inactivation in low moisture foods is challenging due to enhanced thermal resistance of microbes and low thermal conductivity of food matrices. In this study, we leveraged the body of previous work on this topic to model key experimental features that determine microbial thermal inactivation in low moisture foods. We identified 27 studies which contained 782 mean D-values and developed linear mixed-effect models to assess the effect of microorganism type, matrix structure and composition, water activity, temperature, and inoculation and recovery methods on cell death kinetics. Intraclass correlation statistics (I2) and conditional R2 values of the linear mixed effects models were: E. coli (R2-0.91, I2-83%), fungi (R2-0.88, I2-85%), L. monocytogenes (R2-0.84, I2-75%), Salmonella (R2-0.69, I2-46%). Finally, global response surface models (RSM) were developed to further study the non-linear effect of aw and temperature on inactivation. The fit of these models varied by organisms from R2 0.88 (E. coli) to 0.35 (fungi). Further dividing the Salmonella data into individual RSM models based on matrix structure improved model fit to R2 0.90 (paste-like products) and 0.48 (powder-like products). This indicates a negative relationship between data diversity and model performance.
摘要：
由于微生物的耐热性增强和食品基质的低热导率,低水分食品中的微生物热灭活具有挑战性。在这项研究中,我们利用了先前关于这个主题的工作来模拟确定低水分食品中微生物热失活的关键实验特征。我们确定了27项研究，其中包含782个平均D值，并开发了线性混合效应模型来评估微生物类型的影响，矩阵结构和组成，水活动,温度,以及接种和恢复方法对细胞死亡动力学的影响。线性混合效应模型的组内相关统计量（I2）和条件R2值分别为：大肠杆菌（R2-0.91，I2-83％），真菌（R2-0.88，I2-85%），L.单核细胞增多症（R2-0.84，I2-75％），沙门氏菌(R2-0.69,I2-46%)。最后,建立了全局响应面模型（RSM），以进一步研究aw和温度对失活的非线性影响。这些模型的拟合程度因R20.88(E.大肠杆菌)到0.35(真菌)。进一步将沙门氏菌数据划分为基于基质结构的单个RSM模型,改进模型拟合R2为0.90(糊状产品)和0.48(粉末状产品)。这表明数据多样性与模型性能之间存在负相关关系。
