Microwave-Assisted Extraction of Phenolic Compounds from Pineapple Peel Using Deep Eutectic Solvents

Abstract

Approximately half of the world’s pineapple production is marketed as a processed product, leading to the generation of a significant quantity of industrial waste, mainly composed of pineapple peels, cores, and crowns. This study evaluated deep eutectic solvents (DESs) for the assisted microwave extraction of phenolic compounds from pineapple peels and their antioxidant capacity. DESs are considered environmentally friendly solvents characterized by their low toxicity and high capacity for the extraction of bioactive compounds. DESs (choline chloride-glycerol and choline-chloride-malic acid) were used for phenolic compound extraction and compared with traditional solvents such as water, ethanol, methanol, ethanol-water (50%), and methanol-water (50%). A higher concentration of phenolic compounds was achieved using choline chloride-glycerol than traditional solvents as an extraction solvent (7.98 mg eq of gallic acid/g of dry weight). In all the treatments, the antioxidant capacity was higher than 85%. The process variables (drying temperature, extraction time, and solvent/solid ratio) were optimized using choline chloride-glycerol as a solvent. It was found that a drying temperature of 67 °C, an extraction time of 87 s, and a solvent/solid ratio of 60.5 mL/g allow maximizing the content of phenolic compounds and the antioxidant capacity of the extract.