Recent developments in the value-addition of pomegranate fruit in South Africa: from edible to non-edible fruit parts

Prior to the past decade, nutritionists and processors focused more on the juice extracted from pomegranate arils. As a result, pomegranate peel, seeds, and their constituents were underutilised and wasted after processing. Literature has shown that all the fruit parts contain compounds with health benefits. For example, the juice and peels contain punicalagin, hydrolysable tannins, anthocyanins, and ellagic acid, while pomegranate seeds are a rich source of oil high in tocopherols, polyphenols, sterols, and punicic acid. Furthermore, 20 to 40% postharvest losses of pomegranate limit fruit supply and consumption despite high local and export demands for pomegranate. Recent research in South Africa has focused on agro-processing and value-addition in the quest to support commercial processing and product development from pomegranate fruit parts under three subthemes: pomegranate aril dehydration (PAD), pomegranate seed oil recovery (PSOR), and pomegranate peel valorisation (PPV). Under subtheme PAR, recent research highlight the potential of blanch-assisted drying of pomegranate arils. Blanching at 85 or 100°C for 30 s increased the moisture loss and drying rate of pomegranate arils without compromising the quality of the end product. The effects of harvest maturity, cultivar, and storage of whole fruit before drying have provided new insights into developing an integrated drying protocol for pomegranate arils. A further study on the storage of dried arils revealed that a blanching pretreatment helps retain aril quality parameters. A study on the development of value-added pomegranate juice powder showed that maltodextrin-encapsulated juice powder appeared 44% redder (a*), with 54% more anthocyanin content than gum arabic-encapsulated powder. The PSOR subtheme established protocols for the extraction of value-added seed oil. For example, pretreatments, including blanching, microwave- and enzyme-assisted oil extraction, significantly improved oil yield, stigmasterol, punicic acid, and the seed oil’s total phenolic content and antioxidant capacity. Under the PPV research subtheme, hot water blanching was established to extract fruit peel antioxidant compounds, providing an opportunity for waste utilisation. Overall, our research efforts provide science-based information to promote the value addition of pomegranate fruit into speciality products valuable in the cosmetic, food, nutraceutical, and pharmaceutical industries.