Bioactive Metabolites and Antioxidant Potential of Yellow Passion Fruit (Passiflora edulis f. flavicarpa) Rind

Abstract

Yellow passion fruit rind (Passiflora edulis f. flavicarpa) is a major by-product of fruit processing and a potential source of dietary fibre, pectin and phytochemicals. This study evaluated the physicochemical composition, metabolite profile and antioxidant properties of yellow passion fruit rind. Fresh rind was analysed for proximate composition, cellulose, titratable acidity and pectin content, while a methanolic extract was used for phytochemical and antioxidant assays. The rind contained 76.00% moisture, 2.04% crude protein, 0.16% fat, 9.70% carbohydrate, 7.77% crude fibre, 7.48% cellulose and 1.68% titratable acidity. Pectin yield was 5.34% on a fresh-weight basis. Total phenolic and flavonoid contents were 6.77 mg gallic acid equivalents (GAE)/g and 4.70 mg quercetin equivalents (QE)/g, respectively. The extract exhibited total antioxidant activity of 7.82 mg ascorbic acid equivalents (AAE)/g extract and showed concentration-dependent reducing power and radical-scavenging activity. At 100 µg/mL, hydroxyl radical, nitric oxide and DPPH radical-scavenging activities were 25.40%, 44.90% and 6.28%, respectively. Metabolite profiling using LC-MS/MS and GC-MS/MS enabled the tentative assignment of several compounds, including flavonoids, phenolic acids, long-chain hydrocarbons and fatty alcohols. Putatively identified metabolites included kaempferol, kaempferitrin, genistein, neoastilbin, ferulic acid, tetracontane, pentacosane and triacontanol. The findings indicate that yellow passion fruit rind is a source of dietary fibre, pectin and diverse phytochemicals, with measurable in vitro antioxidant activity. However, metabolite identities require confirmation using authentic standards before biological significance or industrial applications can be fully established.