Analysis of Deodorized Palm Kernel Oil Using Optical And Conventional Techniques

Abstract

ABSTRACT Palm kernel oil has been deodorized using medicinal plants (fresh and dry cinnamon leaves, fresh lemongrass) and the changes monitored using optical (absorbance (ABS), surface reflectance (SR), laser induced fluorescence (LIF)) and conventional (phosphor molybdate method using ascorbic acid) techniques. Changes were again monitored when the oil was exposed to sunlight with samples protected and not protected from ultraviolet radiation (UV). The ABS measurements were conducted using a spectrophotometer while for the SR measurements, white light source was focused into a two- way optical fibre probe and the reflected light channelled into a spectrometer on to the sample. The LIF was measured at longer wavelengths using a spectrometer at 90o to a 445 nm laser source. Principal component analysis was computed using the fluorescence data in discriminating between the refined deodorized and refined non-deodorized oils. The ABS increased with increasing deodorant mass while the SR decreased. The conventional technique established an increase in antioxidant capacity (AC) as deodorant mass increased. This corresponded to an increase in vitamin E and chlorophyll contents, associated with longer wavelengths in the fluorescence emission spectrum. Correspondingly, increase in deodorant mass resulted in increase in florescence intensity (FI) at longer wavelengths. The fresh cinnamon and the lemongrass deodorant had 169 % and 78 % in AC respectively. There was reduction 91 % in AC after exposure to sunlight protected and not protected from UV, with the reduction of 91.4 % being greater for samples not protected. FI peaks at longer wavelength of the samples decreased after exposure to sunlight