TOTAL PHENOLIC CONTENTS AND ANTIOXIDANT ACTIVITY OF PALM OILS AND PALM KERNEL OILS AT VARIOUS REFINING PROCESSES

Oil palm is one of the richest sources of antioxidants such as carotenoids, tocopherols, tocotrienols and phenolic compounds. This study quantified the amount of total phenolic content (TPC) and the antioxidant activity of crude to refined palm oil and palm kernel oil products obtained from palm oil mills. The TPC of the oil extracts was determined using Folin-Ciocalteau method expressed as gallic acid equivalent (GAE). Aqueous oil extraction with methanolic solvent was efficient and extract from crude palm oil (CPO) had the highest concentration of TPC. A reduction in trend was observed along the various stages of the refining steps probably due to losses through absorption of bleaching earth, volatilisation and degradation during the refining processes. The antioxidant activity was determined using 2,2-diphenyl-1-picrylhdrazyl (DPPH) assays. Results showed that the effect of antioxidants on DPPH radical scavenging activity decreases in the order of oil extracts CPO > CPKO > RPO > RPKO > RPOo > PKOo. Overall, it was found that CPO extract exhibited the highest antioxidant activity due to high TPC compared to other extracted oil samples.