Review on the Study of Dielectric Properties of Food Materials

Abstract

Dielectric properties of foods are used to explain interactions of foods with electric fields. It determines the interaction of electromagnetic waves with matter and defines the charge density under an electric field. For engineering point of view, dielectric properties are the foremost important physical properties related to radio frequency and microwave heating, it is critical to possess knowledge of the dielectric properties of materials in products and process development and, within the modern design of dielectric heating system for the need of desired process. Dielectric properties are often categorized into two: dielectric constant and dielectric loss factor. Dielectric constant is the ability of a material to store microwave energy and dielectric loss factor is the ability of a material to dissipate microwave energy into heat. Dielectric properties of food materials are required for various applications in food industry like microwave (at 915 or 2450 MHz), radio wave (at 13.56, 27.12 or 40.68 MHz) and magnetic field processing. In this review, the dielectric properties of various food groups were listed such as; Cereal grains and oilseeds, Bakery product, Dairy products, Poultry products, Fruits and vegetables. Dielectric properties are utilized in fruit drying processes, protect food materials from insects that already present in dried fruits, pasteurization, sterilization, tempering of concentration of liquid foods such as fruit juices, identification, processing, quality monitoring of fats and oils and improvement during oil processing and storage. The dielectric studies of food materials are an important tool to identify the quality of food materials and to improve dielectric heating uniformity. Frequency, moisture content, phase change, storage time and temperature are main factors that influence the dielectric properties of food material.