Taghian Dinani Somayeh, Jenn Alina, Kulozik Ulrich
Chair of Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany.
Foods. 2021 Aug 25;10(9):1986. doi: 10.3390/foods10091986.
In this study, the effect of different horizontal and vertical orientations of a model sample (cuboid gellan gel samples containing Maillard reactants) on microwave heat processing was investigated in the solid-state and magnetron microwave systems. To achieve this target, seven orientations inside both microwave cavities were defined. Two of the investigated sample orientations were in a vertical position with and without turntable rotation, and five in a horizontal position. Furthermore, samples at horizontal orientations were put at an angle position without turntable rotation. To analyze the microwave heating patterns, infrared (IR) pictures and photographs of the gellan gel samples were taken after processing to document IR-based thermal and Maillard color changes, respectively. Three main factors for improvement of the heating homogeneity were identified: first, processing samples in the solid-state microwave system; second, position variation of the sample by turntable activated; and third, horizontal orientation. In addition, it was observed that placing the gellan gel samples in a vertical position in the magnetron microwave system resulted in considerably more absorbed power and a more uniform microwave heat processing compared to other horizontal orientations in this system. This indicated a non-uniform microwave field distribution. The results of this study can also confirm the importance of designing suitable food packaging: a vertical shape for more microwave energy absorbance and thus, more energy efficiency, and a horizontal shape for more uniform microwave heat processing.
在本研究中，在固态和磁控管微波系统中研究了模型样品（含有美拉德反应物的长方体结冷胶样品）不同水平和垂直取向对微波热处理的影响。为实现这一目标，在两个微波腔体内定义了七种取向。所研究的样品取向中有两种处于垂直位置，一种有转盘旋转，一种无转盘旋转，另外五种处于水平位置。此外，处于水平取向的样品处于无转盘旋转的角度位置。为了分析微波加热模式，在处理后拍摄了结冷胶样品的红外（IR）图片和照片，分别记录基于红外的热变化和美拉德颜色变化。确定了提高加热均匀性的三个主要因素：第一，在固态微波系统中处理样品；第二，通过启动转盘改变样品位置；第三，水平取向。此外，观察到在磁控管微波系统中将结冷胶样品垂直放置与该系统中的其他水平取向相比，会导致吸收的功率显著增加，微波热处理更加均匀。这表明微波场分布不均匀。本研究结果还可以证实设计合适食品包装的重要性：垂直形状可吸收更多微波能量，从而提高能量效率，水平形状可实现更均匀的微波热处理。
