Microwave Temperature Measurement Methods in Food Processing Industry

Microwaves, a category of non-ionizing electromagnetic radiations with a frequency range of 300 MHz to 300 GHz, are increasingly utilized to process food and agricultural products both domestically and commercially to enhance food quality and shelf life. It offers an excellent substitute for conventional techniques in several applications, including drying, heating, pasteurization, and sterilization. This chapter has elaborated the background, underlying principles, benefits, and drawbacks of its application. The primary limiting issue preventing its commercial adoption is the nonhomogeneous temperature distribution that causes hot and cold spots in microwave-processed food, endangering food safety and product quality and limiting reproducibility. To ensure consistent heating and optimized temperature distribution over the food volume during microwave-assisted food processing, various temperature sensing techniques have been investigated in the literature and are extensively discussed in this chapter. The traditional methods of measuring temperature incorporate thermometers, thermocouples, thermistors, resistance temperature detectors (RTDs), and more sophisticated techniques, including optic fiber sensors, silicon diode, and infrared thermometer, which have all been analyzed along with their methodology and underlying working principles. Their unique benefits and drawbacks have been highlighted, and the applicability of each technique for various situations has also been evaluated. The chapter concludes with recommendations about selecting appropriate temperature measurement techniques for temperature sensing applications in microwave-assisted food processing.