Changes in physical and chemical properties of palm olein during heating

Abstract

This study evaluated some changes occurring in double fractionated (DF) palm olein during heating. DF palm olein was heated at 180°C for 60 hr (4hr/day) with no added source of water. Heated oil samples were analyzed for refractive index (Rl), viscosity, colour change, dielectric constant change (DCC), acid value (AV), peroxide value (PV), iodine value (IV) and unsaponifiable matter (UM) constituents. The results indicated that, viscosity, colour, DCC and AV gradually increased, while IV gradually decreased with increasing heating time. The study showed also that heating times correlated with increases in DCC, viscosity and AV. PV increased ca 17-fold, reached a maximum at 16 hr, then gradually decreased to remain relatively constant through the last 20 hr of heating. Chromatographic analysis illustrated that UM components changed qualitatively and quantitatively due to the heating treatment.

Keywords

• chemical properties
• heating
• palm olein
• physical properties