Chen Jiajia, Pitchai Krishnamoorthy, Birla Sohan, Negahban Mehrdad, Jones David, Subbiah Jeyamkondan
Dept. of Biological Systems Engineering, Univ. of Nebraska-Lincoln, Lincoln, NE 68583, U.S.A.
J Food Sci. 2014 Oct;79(10):E1991-2004. doi: 10.1111/1750-3841.12636. Epub 2014 Sep 15.
A 3-dimensional finite-element model coupling electromagnetics and heat and mass transfer was developed to understand the interactions between the microwaves and fresh mashed potato in a 500 mL tray. The model was validated by performing heating of mashed potato from 25 °C on a rotating turntable in a microwave oven, rated at 1200 W, for 3 min. The simulated spatial temperature profiles on the top and bottom layer of the mashed potato showed similar hot and cold spots when compared to the thermal images acquired by an infrared camera. Transient temperature profiles at 6 locations collected by fiber-optic sensors showed good agreement with predicted results, with the root mean square error ranging from 1.6 to 11.7 °C. The predicted total moisture loss matched well with the observed result. Several input parameters, such as the evaporation rate constant, the intrinsic permeability of water and gas, and the diffusion coefficient of water and gas, are not readily available for mashed potato, and they cannot be easily measured experimentally. Reported values for raw potato were used as baseline values. A sensitivity analysis of these input parameters on the temperature profiles and the total moisture loss was evaluated by changing the baseline values to their 10% and 1000%. The sensitivity analysis showed that the gas diffusion coefficient, intrinsic water permeability, and the evaporation rate constant greatly influenced the predicted temperature and total moisture loss, while the intrinsic gas permeability and the water diffusion coefficient had little influence.
This model can be used by the food product developers to understand microwave heating of food products spatially and temporally. This tool will allow food product developers to design food package systems that would heat more uniformly in various microwave ovens. The sensitivity analysis of this study will help us determine the most significant parameters that need to be measured accurately for reliable model prediction.
开发了一个耦合电磁学、传热传质的三维有限元模型，以了解500毫升托盘中微波与新鲜土豆泥之间的相互作用。通过在额定功率为1200瓦的微波炉中的旋转转盘上对25°C的土豆泥进行3分钟加热来验证该模型。与红外热像仪获取的热图像相比，土豆泥顶层和底层的模拟空间温度分布显示出相似的热点和冷点。光纤传感器在6个位置采集的瞬态温度分布与预测结果吻合良好，均方根误差在1.6至11.7°C之间。预测的总水分损失与观测结果匹配良好。几个输入参数，如蒸发速率常数、水和气体的固有渗透率以及水和气体的扩散系数，对于土豆泥来说不易获得，且难以通过实验轻松测量。生土豆的报告值用作基线值。通过将基线值分别改变为其10%和1000%，评估了这些输入参数对温度分布和总水分损失的敏感性分析。敏感性分析表明，气体扩散系数、固有水渗透率和蒸发速率常数对预测温度和总水分损失有很大影响，而固有气体渗透率和水扩散系数影响较小。
食品产品开发人员可以使用该模型在空间和时间上了解食品的微波加热情况。这个工具将使食品产品开发人员能够设计出在各种微波炉中加热更均匀的食品包装系统。本研究的敏感性分析将帮助我们确定为进行可靠的模型预测而需要准确测量的最重要参数。
