Chiang Mai Journal of Science

                 The aim of this study was to evaluate the effects of palm olein (PO) addition on the thermooxidative degradation of canola oil (CO) during frying of potato pieces at 185 ± 5⁰C. The blends were prepared in the volume ratios of 20:80 (PO:CO, PC1) and 40:60 (PO:CO, PC2). Refractive index, free fatty acid content, peroxide value, p-anisidine value, total oxidation value, viscosity, specific extinction, polymer content, polar compounds, food oil sensor value and color of the oils all increased, whereas iodine value and C_18.2/C_16:0 ratio decreased as frying progressed. The percentage of linoleic and linolenic acids tended to decrease, whereas the percentage of palmitic, stearic and oleic acids, increased. In DSC analysis, addition of PO to CO altered the shapes of endo- or exotherm peaks of CO and became sharp; might be due to the change in fatty acid composition. Based on the most oxidative stability criteria investigated, it could be concluded that the frying process caused the formation of comparatively lower amounts of oxidation products in the blends compared to CO, indicating a lower extent of thermooxidative degradation of the blends. However, higher amounts of free fatty acids and higher color units were both detected in the blends compared to pure CO at the end of frying trial. It appeared that proper blending of highly unsaturated CO with PO could result in oil blends which could meet nutritional needs with improved stability for domestic cooking and deep-frying.