Effect of turmeric root extract on the oxidative stability of palm oil, African walnut oil and their 50:50 and 60:40 blends during accelerated storage

Abstract The objective of this study was to evaluate the preservative effect of turmeric root extract on Palm oil, African walnut oil and their 60:40 and 50:50 blends during accelerated storage. Turmeric antioxidants were extracted with ethanol and their total phenolic content and antioxidant activity evaluated. The oils used in this study were palm oil, African walnut oil and their 50:50 and 60:40 blends. Turmeric extract was added in each oil at concentrations 500, 1000 and 1500 ppm. Curcumin and butylated hydroxytoluene were used at concentrations 200 ppm and served as positive controls while oils without additives served as negative controls. Oils were stored in the oven at 65°C for 21 days. Oil samples were collected every 7 days for analysis. Results showed that the total phenolic content of turmeric is similar to that of pure curcumin. Turmeric extract exhibited good antioxidant activities. Turmeric root extract significantly delayed oil oxidation during accelerated storage. Turmeric root extract could be used as a natural source of antioxidants for the stabilization of palm oil, African walnut oil and their 50:50 and 60:40 blends during storage and processing. This can be a good alternative to the use of synthetic antioxidants and hydrogenation reactions in oils.