The purpose of the study was to determine influences of dielectric properties (DPs) on radio frequency (RF) heating rate and uniformity and provide essential information for developing effective pasteurization processes of wheat flour. DPs of the wheat flour as a function of frequency, moisture content (MC), wheat bran content (WBC) and temperature were determined using an impedance analyzer. A 27.12 MHz, 6 kW pilot-scale RF system at an electrode gap of 100 mm was used to evaluate the heating rate and temperature distribution in each wheat flour-bran mixture. The results showed that DPs of wheat flour increased with increasing temperature and MC but with decreasing WBC due to high fat content in wheat bran, and their relationship can be represented by cubic or quadratic models. The heating rate of wheat flour decreased first and then increased with increase in MC while decreased with decreasing WBC due to the increasing difference between dielectric constant (ε′) and loss factor (ε″). Decreased WBC also resulted in decreasing uniformity index (λ) value. Reducing MC and WBC in wheat flour-bran mixtures could help to improve RF heating uniformity.

该研究的目的是确定介电性能（DPs）对射频（RF）加热速率和均匀性的影响，并为开发有效的小麦粉巴氏杀菌工艺提供重要信息。使用阻抗分析仪确定小麦面粉的DP随频率，水分含量（MC），麦麸含量（WBC）和温度的变化。电极间隙为100 mm的27.12 MHz，6 kW中试规模RF系统用于评估每种小麦粉糠混合物中的加热速率和温度分布。结果表明，由于小麦麸皮中脂肪含量高，小麦粉的DPs随温度和MC的升高而增加，但随着WBC的降低而降低，其关系可用三次或二次模型表示。ε '）和损耗因子（ε “）。WBC降低也导致均匀度指数（λ）值降低。降低小麦粉糠混合物中的MC和WBC可以帮助改善RF加热均匀性。