Comparative assessment of energy analysis, drying kinetics, and biochemical composition of tomato waste under different drying conditions

Abstract

Food industry generates devastating amount of waste, and it is not easy to handle such huge quantities. Tomato industry also generates tons of waste materials and drying is commonly used for waste tomatoes. This study was conducted to investigate the effect of drying methods on drying kinetics, energy aspects, rehydration, shrinkage, and chromatic parameters of waste tomato samples. The β-caroten, lycopene, antioxidant, antiradical activity, total phenolics, flavonoids, ascorbic acid, fatty acid, and mineral contents of dried samples were also evaluated. Jena&Das model best estimated the drying process of tomato. The greatest color change values were obtained from air-convective (28.40) drying and the lowest from hybrid (16.03) drying. The highest rehydration capacity was determined in greenhouse (4.06) drying. Microwave drying was identified as the most efficient system in terms of energy (8.67%) and thermal efficiency (7.49%). Effective moisture diffusivity values ranged from 5.54×10–11 to 1.30×10–8 m2s–1. The highest total phenolics and ascorbic acid values were obtained from greenhouse drying. The greatest β-carotene and fatty acid contents were recorded in air convective drying. Microwave drying had the highest FRAP and flavonoid content.