Recovery and Valorization of Bioactive and Functional Compounds from the Discarded of Opuntia ficus-indica (L.) Mill. Fruit Peel

This work focused on the recovery and application of bioactive and functional compounds (BFC) from a waste matrix, the Opuntia ficus-indica (L.) Miller fruit peel (OFP), using different extraction methods: maceration and Extractor Naviglio®. The presence of BFC was initially evaluated by following the extraction yields and antioxidant activity using the Folin-Ciocȃlteu reagent and the DPPH method, respectively. The quali-quantitative content of BFC was also verified with UHPLC/UV-ESI-HRMS profile of OFP extracts. The evaluation of the BFC yields is aimed at using extract components, such as betanins, in the technological application as textile dye based on natural pigments: we evaluated the stability of the extracted dyes, tested the dyeing power and assessed the stability of the dye on the textile material. The results showed different compositions depending on the polarities of the solvents. The ethanol-water mixture extracts obtained using Naviglio method revealed an important presence in terms of total phenolic compound yields. Wool, linen and cotton fibers were chosen for the dyeing tests. Rock alum and lemon juice, two etching methods, were used. Results suggest that the OFP may be of great interest as a natural source of BFC for food, nutraceutical and technological applications in the sustainability context.