Re-Cycling of Cooking Oils and the Effect on the Quality and Stability

The quality and stability of industrially processed Palm (Korie & Safi) and Sunflower (Sundrop) oils as affected by repeated heating and cooling processes (re-cycling) were investigated. The oils were subjected to different cycles of heating and cooling and the variation in the stability and quality was determined after different numbers of cycles. The samples were analyzed for physicochemical properties in terms of acid value (AVs), free fatty acids (FFAs) and peroxide value (PVs) by titration method. Repeated heating and cooling showed pronounced increased values in peroxide values while the Acid value (AV) and Free Fatty Acids (FFAs) increased slightly. Relatively, higher range of PVs variations were detected in Safi oil that in which the highest levels went above the acceptable limit of 10meq/kg as set by the Tanzania Bureau of Standards (TBS). Among the three brands of oil tested, Sundrop stood to be the most stable after several cycles of heating and cooling processes, thus recommended for food frying over the other two oils. This study recommends more precautions in food frying processes to avoid the health effects due to formed auto oxidative compounds.