Northwest A&F University, College of Mechanical and Electronic Engineering, Yangling, Shaanxi, 712100, China.
Northwest A&F University, College of Mechanical and Electronic Engineering, Yangling, Shaanxi, 712100, China; Department of Biological Systems Engineering, Washington State University, 213 L.J. Smith Hall, Pullman, WA, 99164-6120, USA.
Food Microbiol. 2021 May;95:103682. doi: 10.1016/j.fm.2020.103682. Epub 2020 Nov 21.
In recent years, radio frequency (RF) heating is getting popular as an alternative pasteurization method for agricultural commodities and low moisture foods. Computer simulation is an effective way to help understand RF interactions with food components and predict temperature distributions among food samples after RF treatments. In this study, a computer model based on Joule heating and thermal inactivation kinetic of A. flavus was established to predict both temperature distribution and microbial reduction among peanut kernels after RF processing. For the process validation, three 2-g peanut samples inoculated with 40 μL A. flavus were placed at three representative locations among 2.17 kg peanut kernels and subjected to various processing conditions in a 27.12 MHz, 6 kW RF heating unit together with hot air system. Results showed that the average difference of the sample temperature and microbial reduction between simulation and experiment was small with RMSE values of 0.009 °C and 0.012 °C, and 0.31 log CFU/g and 0.42 log CFU/g for peanut moisture contents of 7.56% and 12.02% w. b., respectively. Nonuniform RF heating resulted in the least lethality of A. flavus at the cold spot. The validated computer model was further used to estimate microbial reduction distributions at other target temperatures based on predicted temperature profiles. This computer model may help design the RF pasteurization protocols for peanut kernels without extensive experiments in food industry.
近年来，射频（RF）加热作为一种替代巴氏杀菌方法，在农业商品和低水分食品中越来越受欢迎。计算机模拟是帮助理解 RF 与食品成分相互作用以及预测 RF 处理后食品样品温度分布的有效方法。在这项研究中，建立了一个基于焦耳加热和 A. flavus 热失活动力学的计算机模型，用于预测 RF 处理后花生仁中的温度分布和微生物减少。为了进行工艺验证，将三个 2 克的花生样本接种 40 μL 的 A. flavus，放置在 2.17 公斤花生仁中的三个代表性位置，并在 27.12 MHz、6 kW 的 RF 加热单元中与热空气系统一起进行各种处理条件。结果表明，模拟和实验之间的样品温度和微生物减少的平均差异较小，RMSE 值分别为 0.009°C 和 0.012°C，对于花生水分含量为 7.56%和 12.02%（w.b.）的样品分别为 0.31 log CFU/g 和 0.42 log CFU/g。不均匀的 RF 加热导致冷点处 A. flavus 的致死率最低。经过验证的计算机模型进一步用于根据预测的温度分布估计其他目标温度下的微生物减少分布。该计算机模型可帮助设计花生仁的 RF 巴氏杀菌方案，而无需在食品工业中进行广泛的实验。
