Thin-layer catalytic far-infrared radiation drying and flavour of tomato slices

Abstract

A far-infrared radiation (FIR) catalytic laboratory dryer was designed by us and used to dry tomato. The kinetics of drying of tomato slices with FIR energy was dependent on both the distance from the heat source and the sample thickness. Numerical evaluation of the simplified Fick’s law for Fourier number showed that the effective moisture diffusivity increased from 0.193×10<sup>–9</sup> to 1.893×10<sup>–9</sup> m<sup>2</sup>/s, from 0.059×10<sup>–9</sup> to 2.885×10<sup>–9</sup> m<sup>2</sup>/s, and, from 0.170×10<sup>–9</sup> to 4.531×10<sup>–9</sup> m<sup>2</sup>/s for the 7, 9, and 11 mm thick slices as moisture content decreased. Application of FIR enhanced the flavour of the dried tomatoes by 36.6% when compared with the raw ones. The results demonstrate that in addition to shorter drying times, the flavour of the products can be enhanced with FIR. Therefore, FIR drying should be considered as an efficient drying method for tomato with respect to minimization of processing time, enhancement in flavour, and improvements in the quality and functional property of dried tomatoes.