Effect of Dielectric Heating on the Quality and Shelf of Life of Tomato

Abstract

Tomato is a vegetable of nutritional and economic importance. It is an important part of the conventional diet and provides important vitamins for the body's development. With its short shelf life, achieving a long-term supply of tomatoes is crucial. Hence, there is a need to develop preservation technologies to improve its shelf life without significantly altering its nutritional quality. Over the years, several heating processes have been used for food preservation. These include steam and hot water heating, ohmic heating, microwave heating, and infrared processing. This study assessed the effect of radiofrequency heating on the shelf life and nutritional quality of tomatoes. The materials used were a radiofrequency signal generator (JDS6600 DDS Signal generator/counter), copper capacitance plates, plate holders, a conductivity meter (Conductometer TH27 in Siemens/m), and a few connecting wires. Fresh tomato samples were collected from farms and stored in a cool, sterile chiller during transit. Samples were chopped or shredded into a paste just before the analysis. The parallel plate capacitance method was used to determine the dielectric properties of the fruits. The dielectric properties of the fruit were measured, along with the exposure parameters, proximate analysis, and shelf life of the fruit. The work carried out shows that the frequency range to extend the shelf life of tomatoes was from 10 to 50 MHz, while the penetration depth for effective exposure at the same frequency was found to be between 0.05 m to 0.09 m. The effect of radiofrequency radiation on the proximate composition of tomatoes was found to be safe for consumption at 20 MHz with an extended shelf life of 11 days, with no significant impact on the proximate composition of the samples at the field of 55.37 – 73.43 V/m. The temperature rise for tomatoes was between 37°C to 39°C in 10 minutes.