Detection of Defected Potato Tubers from Intact One Using Microwave

Potato faced with various pests and damages during growth and storage. Some of these damages caused by environmental conditions or different mechanical tensions. Although these damages do not have any traces on potato surface, but have bad effect on potato quality. There are some methods for determining these damages. One of these methods is applying microwave. Therefore, the aim of this research was the probability of recognition of healthy and unhealthy potato by using microwave, based on dielectric constant.
For preparing defected potato samples, healthy samples were stored in nylon bag at 25 0C and 40% relative air humidity for 4 months to get unfavorable surface quality. Also a 20.6 * 13.1 millimeter brazen cylindrical in connector were used for measuring the samples impedance. High-frequency wave telecom was sent to the given sample, some of these waves were absorbed by the sample and the rest were returned. The amount of wave absorption sent by the sample depended on the texture temperature and frequency of the initial wave. By analysis of this parameter, samples dielectric constant could be measured. In this research, for measuring dielectric constant of three varieties of Agria, Arinda and Savalan potato, short circuit transmission line system was used. Dielectric constants of both healthy and unhealthy potatoes were measured at two temperature levels of 0 0C and 25 0C and three frequency levels of 915, 1800, and 2450 MHz .
The results showed that different levels of temperature and frequency had significant difference (p Generally, for unhealthy potatoes, the mean values of dielectric constant is 1-2 units lower than that of corresponding values. The dielectric constant increases with increasing temperature. Missing of moisture content in storage period is the main reason of this behavior. Also due to different texture of potato variety, Arinda, Savalan and Agria get the maximum score of dielectric constant respectively. Therefore, this character is very good option for quality sorting, packing and so on.