Solar drying modes of saladette tomatoes slices on phytochemicals and functional properties

Abstract

The paper analyses three solar drying modes for tomatoes slices, correlating drying kinetics with their concentration of phytochemicals and functional properties, such as inhibition of free radicals and digestive enzymes. The solar drying included direct drying by a greenhouse (DD), indirect solar dryer operating in continuous (IC) and discontinuous (ID) modes, and all were compared to those obtained by lyophilization (control). For DD, IC and ID, the drying time and drying constant were 30 h:0.0028, 25 h:0.0054, and 8.5 h:0.0061. The IC had the lowest drying time, ID represented only 36.2% and 62.0% of solar heating by DD and IC. Both indirect methods were important for phytochemical content. Proanthocyanidins, soluble and insoluble dietary fiber were highly correlated to the drying method and functionality of dried tomato. The effect of the solar drying method on critical functional components may allow obtaining functional food additives based on dehydrated tomatoes, with an air heating expenditure of 2.1–5.8 kWh/kg.