Rana Yadwinder Singh, Eberly Philip M, Suehr Quincy J, Hildebrandt Ian M, Marks Bradley P, Snyder Abigail B
Department of Food Science, Cornell University, Ithaca, NY 14850, USA.
Department of Food Science, The Ohio State University, Columbus, OH 43210, USA.
Foods. 2021 Sep 13;10(9):2162. doi: 10.3390/foods10092162.
The effect of moderate-temperature (≤60 °C) dehydration of plant-based foods on pathogen inactivation is unknown. Here, we model the reduction of O157:H7 as a function of product-matrix, , and temperature under isothermal conditions. Apple, kale, and tofu were each adjusted to 0.90, 0.95, or 0.99 and inoculated with an O157:H7 cocktail, followed by isothermal treatment at 49, 54.5, or 60.0 °C. The decimal reduction time, or -value, is the time required at a given temperature to achieve a 1 log reduction in the target microorganism. Modified Bigelow-type models were developed to determine -values which varied by product type and level, ranging from 3.0-6.7, 19.3-55.3, and 45.9-257.4 min. The relative impact of was product dependent and appeared to have a non-linear impact on -values. The root mean squared errors of the isothermal-based models ranged from 0.75 to 1.54 log CFU/g. Second, we performed dynamic drying experiments. While the isothermal results suggested significant microbial inactivation might be achieved, the dehydrator studies showed that the combination of low product temperature and decreasing in the pilot-scale system provided minimal inactivation. Pilot-scale drying at 60 °C only achieved reductions of 3.1 ± 0.8 log in kale and 0.67 ± 0.66 log in apple after 8 h, and 0.69 ± 0.67 log in tofu after 24 h. This illustrates the potential limitations of dehydration at ≤60 °C as a microbial kill step.
植物性食品中温（≤60°C）脱水对病原体灭活的影响尚不清楚。在此，我们模拟了等温条件下O157:H7的减少量与产品基质、水分活度和温度的函数关系。将苹果、羽衣甘蓝和豆腐分别调整至水分活度0.90、0.95或0.99，接种O157:H7菌液混合物，然后在49、54.5或60.0°C下进行等温处理。D值，即十进制减少时间，是在给定温度下使目标微生物数量减少1个对数所需的时间。我们开发了改良的Bigelow型模型来确定D值，其因产品类型和水分活度水平而异，范围为3.0 - 6.7、19.3 - 55.3和45.9 - 257.4分钟。水分活度的相对影响因产品而异，并且似乎对D值有非线性影响。基于等温模型的均方根误差范围为0.75至1.54 log CFU/g。其次，我们进行了动态干燥实验。虽然等温实验结果表明可能实现显著的微生物灭活，但脱水机研究表明，中试规模系统中产品温度低和水分活度降低的组合导致微生物灭活极少。在60°C下进行中试规模干燥8小时后，羽衣甘蓝仅减少3.1±0.8个对数，苹果减少0.67±0.66个对数，24小时后豆腐减少0.69±0.67个对数。这说明了≤60°C脱水作为微生物杀灭步骤的潜在局限性。
