A comprehensive review on bioactive compounds, health benefits, and potential food applications of onion (Allium cepa L.) skin waste

By-products of agricultural waste are now utilized in the food industry rather than being thrown away. Onion is a spicy vegetable that is an everyday ingredient in most residential kitchens for its unique flavor and is used extensively over the world for therapeutic purposes. Onions produce a lot of waste due to their widespread production and use around the world, which has inspired new studies with potential approaches for reusing these by-products. This review aims to draw attention to the significant advances made in the identification of onion by-products as valuable sources of bioactive compounds, the techniques used to extract these bioactives, the potential health benefits of onion by-products, and the exploration of their potential diverse applications in a circular bioeconomy perspective. This paper contains information regarding the phytochemical composition, extraction methods, therapeutic properties, food and industrial applications of onion by-products. The current study has shown that onion waste is a rich source of nutrients and phytochemicals with bioactive properties that are beneficial to human health. The skins of onions are a valuable source of bioactives like flavonoids, phenolic acids, fructooligosaccharides, organosulfur compounds, and phenolic glycosides. Numerous health advantages of these compounds, including antioxidant, anti-inflammatory, anti-diabetic, anti-microbial, and anti-cancer capabilities, have been demonstrated. This review can be used as a starting point to investigate potential applications for bioactives onion skins in the functional food industry. It also suggests that further study may help to maximize the use of this resource.