Effect of added Theobroma cacao Leaves Extract on the Oxidative Stability of Refined Palm Olein during Accelerated Storage

This study was conducted to evaluate the antioxidant potential of Theobroma cacao leaves extract on the oxidative stability of palm olein (PO). The plant material was extracted with methanol and its total phenolic, flavonoid contents and radical scavenging activity were evaluated, followed by the identification of some phenolic antioxidants by high-performance liquid chromatography (HPLC). The cocoa leaves extract was added in palm olein at concentrations of 500–2000 ppm. Oil containing butylhydroxytoluene (BHT) and oil without antioxidants served as positive and negative controls respectively. The oxidative stability of these oil samples was evaluated by determining their induction times on Rancimat (at 110°C) and measuring their oxidative state using the Schaal oven for a period of 46 days at 70°C (8 hours of heating per day) for measurement of their primary and secondary oxidation products. Results showed Theobroma cacao leaves extract to be rich in phenolic antioxidants and to be a good radical scavenger. Caffeic acid and vanillic acid were the phenolic antioxidants detected by HPLC. The induction times of palm olein supplemented with the extract were found to be ranged between 26.0 –27.99 hours, values significantly (p < 0.01) higher than that of the negative control. The extract, at all concentrations, were also found to be efficient in delaying oxidation of palm olein during 46 days storage at 70°C. It can be concluded that Theobroma cacao leaves extract can be a natural source of antioxidants for the stabilization of palm olein. Practical Application The research findings of this study can be useful to valorize waste products as cocoa leaves in the production of natural antioxidants who are supposed to be safer than synthetic antioxidants and their utilization as ingredient to limit palm olein oxidation.