Valorisation of Vegetables from the Northern Portugal Through Drying: Study of the Effect of Different Drying Methods on Texture, Colour and Physicochemical Properties

Abstract

Vegetables are often overproduced and discarded, generating large amounts of waste (vegetable surpluses that are not used for distribution and marketing). Vegetables have high moisture content and deteriorate over a short period. One possibility to take advantage of these products is through the drying process. The final vegetable quality is highly dependent upon the drying method, as well as their composition and physical properties. The aim of this study was to produce dehydrated vegetables from the Northern Portugal, tomato (Solanum lycopersicum), Turnip (Brassica rapa L.), Courgette (Cucurbita pepo L.) and Cucumber (Cucumis sativus L.), using two different drying methods: convective air-drying (T=60°C; 8h-tomato; 4h-turnip and cucumber, 6h-courgette) and freeze-drying (P/t=0.7Pa/48h). In this work moisture, ash, protein, carbohydrates and fibre content, water activity (aw), texture and color were determined. The analysis of variance (ANOVA) and the Tukey test were used to determine statistically different values at a significant level of p