Agro-industrial by-products represent a sustainable and underutilized source of bioactive compounds with potential applications in human health. Among them, papaya (Carica papaya L.) peel, typically discarded during industrial processing, constitutes a promising and underexploited matrix for carotenoid recovery and valorization. In this study, different extraction strategies were evaluated and compared to identify the most efficient approach for carotenoid recovery. Total carotenoid contents of 7.13 ± 0.32, 5.35 ± 0.24, and 4.44 ± 0.38 µg β-carotene/100 g dry weight (DW) were obtained, respectively. The conventional extraction was further optimized using response surface methodology (RSM) to maximize carotenoid recovery and antioxidant activity. The extracts obtained under the optimized conditions were characterized by spectrophotometric analysis, HPLC-DAD, and in vitro antioxidant assays (DPPH and ORAC-FL), exhibiting antioxidant capacities of 528.4 ± 43.3 µmol TE/100 g DW and 5.0 ± 0.5 mmol TE/100 g DW, respectively. The carotenoid profile revealed lutein as the predominant compound (1414.28 µg/100 g fresh weight (FW)), followed by violaxanthin (629.55 µg/100 g FW), zeaxanthin (624.58 µg/100 g FW), β-cryptoxanthin (531.23 µg/100 g FW), and β-carotene (278.82 µg/100 g FW), while lycopene was not detected. The predominance of xanthophylls, particularly lutein, highlights the potential of papaya peel as a source of carotenoids that have been associated with visual health in previous studies, supported by its significant antioxidant activity. Overall, papaya peel is confirmed as a valuable and sustainable source of carotenoids, particularly xanthophylls associated with visual health, supporting its potential use in the development of functional ingredients. These findings contribute to circular economy strategies and support the sustainable production of bioactive compounds with potential applications in functional food and nutraceutical formulations.
Barroso-Torres et al. (Fri,) studied this question.