Abstract

One of the most significant advancements in food technology recently is the management of natural antioxidants produced from plant waste to address issues with its sustainable production. The aim of the present study is to determine the chemical compositions, total tannin, phenolic, α-tocopherol, and antioxidant yields of red onion skin and pomegranate peel. Polyphenols compounds were identified by HPLC. Moreover, Sunflower oil was treated with aqueous and ethanolic extracts of red onion skin, and pomegranate peel as natural antioxidants at various concentrations compared with synthetic antioxidants (BHT and Catachin) at 80 °C for five hours each day for seven days. According to the findings, pomegranate peel and red onion skin had higher antioxidant yields from ethanol than from aqueous solution; also, pomegranate peel has a higher content of total tannin, and phenolic, while, red onion skin has a higher level of α-tocopherol. In comparison to these chemicals from red onion skin extract, the pomegranate peel extract utilizing HPLC contained the highest amounts of Syringic acid, Ferulic acid, Protocattechuic acid, Salicylic acid, and Resorcinol, respectively. On other hand, red onion skin extract contained the highest amounts of Coumarin, Caffic acid, P-Coumaric acid, Vanilne, Cinnamic acid, Quercetin, and Kaempferol. With time, lower acid values, peroxide values, and TBARS, also, higher iodine numbers were noticed than without it when sunflower oil was treated with increasing concentrations of extracts (ethanol and aqueous). The best results were noticed at 500ppm concentration. Pomegranate peel and red onion skin antioxidant extracts gave the best or the same effects recorded by synthetic antioxidants. It is therefore advised to use these edible extracts (natural antioxidants) extracted from onion skin and pomegranate peel instead of these toxic synthetic antioxidants.

Keywords:Red onion skin; Pomegranate peel; Antioxidants; Sunflower oil; HPLC; BHT; TBABS; Peroxide value

Abbreviations: BHT: Butylated Hydroxyl Toluene; TBARS: Thiobarbituric Reactive Substances; TBHQ: Tert-Butyl Hydroquinone