EFFECT OF DIFFERENT SOLVENTS AND DRYING CONDITIONS ON THE EXTRACTION OF PHYTOCHEMICAL BIOACTIVES FROM ORANGE PEEL

Abstract

Oranges (Citrus sinensis L.) are one of the most cultivated citrus fruits worldwide. Citrus peel is the main residue left after processing. The disposal of this agro-waste represents a problem for citrus industries, where the implementation of strategies for its valorization is essential. This study compared the effects of two different drying methods for leftover orange peel (C. sinensis var. Valencia) on extract yield, its chemical composition, and antioxidant capacity using two extraction solvents. The experimental design was completely randomized in a 3 × 2 factorial arrangement, including three types of peel: dehydrated peel at 60 °C pilot level (C60), dehydrated peel at 204 °C industrial level (CI), and fresh peel (CF), and two extraction solvents: 70 % ethanol and methanol. The extraction yield was higher (p < 0.05) using CF with 70 % ethanol. The content of total phenols (TPC), total flavonoids (TFC), and antioxidant capacity in orange peel was higher (p < 0.05) using CF with 70 % ethanol or methanol. The concentration of hesperidin was similar in all types of peel using methanol, and CF presented a higher amount of naringin than peels dehydrated using 70 % ethanol or methanol. The use of CF with 70 % ethanol or methanol as extraction solvents allowed a higher extraction yield (46 and 38 %), higher concentrations of TPC (12.31 and 14.03 mg GAE g^-1 DW), TFC (9.5 and 8.74 mg QE g^-1 DW), antioxidant capacity (273.9 and 272.69 µM TE g^-1 DW), and naringin (13.6 mg g^-1 DW) compared to dried orange peels.