Effects of natural antioxidants extracted from Cameroonian ginger roots on the oxidative stability of refined palm olein

Abstract

The objective of this study was to evaluate the effect of ginger roots methanolic extract on the stability of palm olein during accelerated storage. After analysis of the extract by the measurement of its total phenolic content by colorimetry and detection of some of its phenolic antioxidants by HPLC-DAD (high performance liquid chromatography-diode array detector) and ESI-MS (Electrospray ionization-mass spectrometer), preliminary antioxidants tests have been conducted. After these tests, the extract has been added in refined palm olein at concentration 200–1800 ppm for investigating its effect on it oxidative stability. Butylated hydroxytoluene (BHT) at it legal concentration of 200 ppm served as positive control, while palm olein without additive served as negative control. Induction time, chemical indexes (peroxide, p-Anisidine, total oxidation, thiobarbituric acid and iodine values) and changes in linoleic acid profile (analyzed by gas chromatography coupled to a flame ionization detector) of oil samples were evaluated. Results of these investigations showed ginger roots methanolic extract to be rich in phenolic antioxidants. Ferulic acid and 6-gingerol were the antioxidants detected. The extract was also efficient in reducing palm olein oxidation on Rancimat and Schaal oven test of 30 days at 70 °C. Ginger roots extract might be a viable source of natural antioxidants for stabilization of palm olein.