Dielectric spectroscopy in agrophysics

Abstract

A b s t r a c t. The paper presents scientific foundation and some examples of agrophysical applications of dielectric spectroscopy techniques. The aim of agrophysics is to apply physical methods and techniques for studies of materials and processes which occur in agriculture. Dielectric spectroscopy, which describes the dielectric properties of a sample as a function of frequency, may be successfully used for examinations of properties of various materials. Possible test materials may include agrophysical objects such as soil, fruit, vegetables, intermediate and final products of the food industry, grain, oils, etc. Dielectric spectroscopy techniques enable non-destructive and non-invasive measurements of the agricultural materials, therefore providing tools for rapid evaluation of their water content and quality. There is a limited number of research in the field of dielectric spectroscopy of agricultural objects, which is caused by the relatively high cost of the respective measurement equipment. With the fast development of modern technology, especially in high frequency applications, dielectric spectroscopy has great potential of expansion in agrophysics, both in cognitive and utilitarian aspects.K e y w o r d s: agrophysics, dielectric spectroscopy, food quality INTRODUCTIONAgrophysics is a specialized scientific field derived from the branch of the agricultural sciences (Micha³ek, 2006). Its aim is to apply physical methods for studies of properties of materials and processes occurring in production and processing of crops and food of agricultural origin. Dielectric properties of all materials existing in Nature are dependent on their molecular structure. Specifically, they depend on the distribution of electric charges, which are either constantly embedded within the molecules or become temporarily induced on their surfaces. It is also known that the molecular structure of objects determine their physical and chemical properties. Therefore, one may suppose that the dielectric properties of mixtures of various molecules constituting a given material will uniquely identify it. It means that dielectric properties can successfully diversify physical and chemical properties of a tested material. This idea is presented in Fig. 1. The crucial point of the application of the dielectric spectroscopy measurement techniques in agrophysics is the utilization of their advantages for rapid and non-destructive assessment of the quality of the agricultural objects. It may be done by searching for dependencies between the dielectric properties and other physical and chemical properties of tested materials of agricultural origin.Behaviour of any material in the electric field is unique, because of the unique molecular structure of each material. On the other hand, physical and chemical properties of materials determine their quality, which in the case of food products is closely related to their commercial and nutritional value. Therefore, it is reasonable to assume that the dielectric properties, uniquely describing each...

Dielectric Spectroscopy of Grape Juice at Microwave Frequencies

“…The dielectric properties of food materials are therefore those electrical properties which are responsible for the polarization of food molecules and measure the interaction of food with electromagnetic fields (Ahmed et al, 2007). Dielectric spectroscopy, which describes the dielectric properties of a sample as a function of frequency, has been successfully used for examining the behaviour of materials in radio and microwave frequency regions of electromagnetic spectrum (Skierucha et al, 2012). Electrical properties of food materials are finding increasing application in agriculture and food processing industries (Jha et al, 2011), as they are important in processes like moisture measurement in crops, protection of seeds and destruction of insects in fruits and nuts by selective heating on one hand and in processing of foods using microwave heating and for finding better processing conditions leading to better quality of foods on the other (Barbosa-Canovas et al, 2006).…”

Dielectric power spectroscopy as a potential technique for the non-destructive measurement of sugar concentration in sugarcane

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