Optimization of Carotenoids and Other Antioxidant Compounds Extraction from Carrot Peels Using Response Surface Methodology

Carrots, scientifically known as Daucus carota L., are among the most popular and widely consumed vegetables. They are used for cooking and juice production, both industrially and in households, resulting in large amounts of waste each year, mainly from the peel. The peels are rich in antioxidant compounds that can be used either as cosmetics or as food and feed additives. Therefore, in this work, the extraction of these compounds was optimized using green techniques (pulsed electric field and/or ultrasonication) and solvents. Response surface methodology was applied to achieve the optimization. Under optimum conditions, the total polyphenol yield was 8.26 mg gallic acid equivalents per g dry weight (dw) and the total carotenoid content was 137.44 μg β-carotene equivalents per g dw. The optimum extract reportedly showed an antioxidant capacity of 76.57 μmol ascorbic acid equivalents (AAE) per g dw by FRAP assay and 63.48 μmol AAE per g dw by DPPH assay, while the total ascorbic acid content was 2.55 mg per g dw. Furthermore, chromatographic quantification of individual bioactive compounds through a diode array detector was performed, wherein catechin yielded the highest proportion (18.6%) of the total 6.88 mg/g dw. This study addressed inquiries regarding the valorization of bioactive compounds from carrot peels, as well as several strategies for recovering their diverse bioactive components using green procedures and solvents.