Valorization of pomelo ( Citrus grandis Osbeck) peel: A review of current utilization, phytochemistry, bioactivities, and mechanisms of action

Citrus grandis Osbeck, commonly known as "pomelo" or "shaddock," is the largest citrus fruit, the peel of which is a well-known agricultural residual waste. Pomelo peel offers a wide range of components such as essential oils, polysaccharides, and phytochemicals with potential food applications. Utilization of pomelo peel to recover these components is an important step toward agricultural sustainability. This review covers pomelo peel utilization opportunities beyond conventional composting and animal feed production, and critically examines value-added uses via the recovery of potentially bioactive components. The peel of pomelo accounts for approximately 30% of the total fruit weight and contains phytochemicals, including aroma-active volatiles, pectin, flavonoids, phenolic acids, carotenoids, coumarins, and polysaccharides. Recovery of these phytochemicals offers an opportunity for value-added utilization such as the development of enriched or functional foods and nutraceuticals. The health-promoting and therapeutic potential of pomelo peel extracts and isolated pure compounds have been evaluated through numerous in vitro and in vivo studies that revealed a wide range of bioactivities, including hypolipidemic, hypoglycemic, antioxidant, antimicrobial, anti-inflammatory, and anticancer effects. Preclinical evidence highlights multifaceted molecular and signaling events that possibly underlie the said bioactive potential. Overall, the pomelo processing industry offers a great opportunity to recover or produce valuable products from the large amounts of residual wastes it generates. It is envisaged that a thorough understanding of the bioactive components of pomelo peel, their functional and nutraceutical applications, and mode of actions will benefit the food industry.