Valorization of commercial carrot discards through a dehydration and hydroalcoholic extraction process

Abstract

Carrot discards (Daucus carota L.)—rejected for visual flaws yet rich in carotenoids, phenolics, and fibre—offer a sustainable raw material. This study valorized non- commercial carrots via convective drying (50, 60, 70 °C) followed by hydroalcoholic extraction (50 %, 70 %, 100 % v/v ethanol; 40–60 °C; 1:10–1:30 w/v). A Box–Behnken design evaluated effects on carotenoid content, total phenolics, extraction yield, and productivity. Drying produced a fibre rich fraction (FF) and a carotenoid phenolic concentrate (CS) later freeze dried. Both products were analyzed for carotenoids, phenolics, antioxidant activity (DPPH, ABTS), sugars, dietary fibre (total, soluble, insoluble), and water/oil holding capacities. Ethanol concentration was the key driver: 100 % ethanol lowered carotenoid retention and yield in FF but improved carotenoid recovery in CS and overall yield. Optimal FF conditions (70 °C drying, 50 % ethanol, 50 °C extraction, 1:20 ratio) delivered 14.0 ± 4.7 mg carotenoids/100 g db and 12.0 ± 3.9% yield, plus high fibre, protein, and desirable hydration and fat binding properties. Best CS results (60 °C drying, 70 % ethanol, 40 °C extraction, 1:30 ratio) achieved 11.0 ± 0.2 mg carotenoids/100 g db and 649 ± 82 mg phenolics/100 g db, suitable for powdered functional extracts. The process converts edible waste into two value added ingredients: a techno-functional fibre matrix and a bioactive rich powder, supporting circular economy goals and reducing food waste.