Phytochemicals in the tissues of Australian-grown papaya cultivars

The phytochemical composition of the edible fruit and leaf parts of Australian papaya cultivars and the impact of maturity on these functional compounds was investigated. The pulp, peels and leaves of commercially grown Australian papaya cultivars (red and yellow) at 4 different stages of maturity (immature to fully ripened) were analysed for phytochemical content (carotenoids, ascorbic acid and polyphenols by HPLC) and antioxidant capacity (total phenolic content (TPC) and ORAC)). Carotenoid levels in the pulp ranged from 0.28-0.99 mg β-carotene, 0.18-0.42 mg β-cryptoxanthin and 0-1.06 mg lycopene 100 g^-1 fresh weight (FW), respectively. Ascorbic acid (AA), TPC and ORAC were up to 61.2 mg 100 g^-1 FW, 3.6 mg gallic acid equivalents 100 g^-1 FW and 50.9 µM Trolox equivalents g^-1 FW, respectively. Mid-mature and/or fully ripe fruits exhibited the highest ORAC activity as well as AA and carotenoid content. Overall, the highest antioxidant capacity was found in leaves (young and mature) followed by peels and pulp. Polyphenols such as quercetin, gallic acid, kaempherol, chlorogenic acid and coumarin compounds were identified in papaya leaves. These data will assist in assessing the nutritional value of Australian papaya cultivars as well as evaluating the potential benefit of papaya fruit and leaf consumption.