含水量
电介质
介质加热
热导率
微波食品加热
材料科学
无线电频率
水分
穿透深度
脱水
分析化学(期刊)
介电损耗
热的
复合材料
化学
热力学
电气工程
光电子学
色谱法
光学
生物化学
物理
岩土工程
量子力学
工程类
作者
Shunqin Bai,Li Liu,Haibo Yu,Xiangyu Guan,Rui Li,Lixia Hou,Bo Ling,Shaojin Wang
出处
期刊:Foods
[MDPI AG]
日期:2022-11-24
卷期号:11 (23): 3796-3796
被引量:2
标识
DOI:10.3390/foods11233796
摘要
Knowledge of the thermal and dielectric properties of wolfberries is essential for understanding the heat transfer and the interaction between the electromagnetic field (10-3000 MHz) and the sample during radio frequency (RF) and microwave (MW) drying. The thermal and dielectric properties of wolfberries were determined as influenced by moisture content from 15.1% to 75.2%, w.b.) and temperature from 25 to 85 °C. The results showed that as the moisture content increased from 15.1% to 75.2% (w.b.), the true density of wolfberries decreased, but the specific heat capacity and thermal conductivity increased with increasing temperature and moisture content. The dielectric properties (DPs) of wolfberries decreased with increasing frequency from 10 to 3000 MHz. The dielectric constant increased with increasing temperature at lower a moisture content (below 45% w.b.) but decreased with increasing temperature at a high moisture content (above 60% w.b.). The cubic and quadratic polynomial models (R2 = 0.977 - 0.997) were best for fitting the dielectric constant and loss factor at four representative frequencies of 27, 40, 915, and 2450 MHz, respectively. The penetration depth increased with the decreased frequency, temperature, and moisture content, and was greater at RF frequencies than MW range, making the RF heating more effective for drying bulk wolfberries. These findings offered essential data before optimizing RF or MW dehydration protocols for wolfberries via computer simulation.
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