Carica papaya biowaste valorization: Biorefinery advances and extraction optimization

Abstract

ABSTRACT Papaya (Carica papaya L.) is a tropical fruit, well recognized for its nutritional value and many health benefits. It is frequently used in the preparation of processed products and extraction of papain enzyme. All of these processes discard the papaya seeds and peels which can reach 20% of the fruit weight. Consequently, there has been increasing interest in recovering valuable chemical constituents from papaya biowastes and producing value-added products. Papaya seed has been well-characterized for its nutrients, particularly glucosinolates content which contribute to its health effects. Additionally, the seed represents a rich source of lipids, proteins, and dietary fibers. Likewise, the peel has extra proportion of fibers and carotenoids.This review outlines the phytochemical composition of papaya fruit biowastes, their biological functions, application in functional food, bioenergy, and other industrial uses. State-of-the-art valorization practices of papaya fruits biowastes are presented with suggestions for potential biorefinery applications. Different optimization techniques combining downstream biotechnology to develop maximal utilization of the non-edible parts of these major fruit crops are also reviewed for the first time. Abbrevations: Benzylglucosinolate (BG); Benzyl isothiocyanate (BITC); Dry weight (DW); Gallic acid equivalents (GAE); High voltage electrical discharges (HVED); Microwave-assisted extraction (MAE); Microwave power (MP); Microwave vacuum drying (MVD); Papaya seed oil (PSO); Polyunsaturated fatty acids (PUFAs); Pulsed electric field (PEF); Quercetin equivalent (QE); Response surface methodology (RSM), Solvent extraction (SE); Subcritical water extraction (SWE); Supercritical fluid extraction (SFE); Volatile organic compounds (VOCs).