Addition of red palm oilein as natural antioxidant to sunflower oil : effects on frying quality

Abstract: There is an increasing demand for the use of natural antioxidants in the food industry as a result of consumer concerns of toxicity and safety of common synthetic antioxidants used to stabilise edible oils. The study was aimed to investigate the effect of adding red palm olein (RPO) as a natural antioxidant to sunflower oil (SFO) on the physicochemical characteristics of resultant oil blends and sensory quality of fried potatoe chips. Commercially available sunflower oil red palm olein blend used as the standard, while samples analysed for the study were formulated in blends of sunflower oil (SF): red palm olein (RPO) as follows; 100:0, 95:5, 90:10, 85:15, 80:20, 75:25, 50:50, 25:75 and 0:100 respectively. Physicochemical characteristics analysed included free fatty acid (FFA), peroxide value (PV), colour (Red Unit), Oxidative stability (OSI), iodine value (IV), fatty acid composition (C18:2), and total polar compound (TPC). A sensory panel was used to evaluate different sensory attributes of fried chips. Data obtained from the study indicated that increasing the amount of red palm olein added to sunflower oil resulted in an increased degree of saturation of the oil blend over five days of frying. The highest FFA content was observed in a blend of 95SF5RPO (0.93%) compared to that of 100SF (0.39%) on fifth days of frying. The control sample (100SF) showed the highest PV vales (12.4 mEqO2/kg) compared to samples blended with red palm olein. The highest oxidative stability was recorded for blend 25SF75RPO (7.59) and the lowest oxidative stability was recorded for blend 95SF5RPO (0.82) on fifth days of frying. Linoleic acid a known predominant polyunsaturated fatty acid in sunflower oil decreased in 100SF than in the SFO: RPO blends over the five days of frying. The gradual increase in TPC was noticed in blend 25SF75RPO throughout frying. Sensory evaluation data showed that chips fried with all oil blends were acceptable to the consumers, however, the commercial blend (STD) fried chips had higher scores for all the attributes tested and the overall acceptability compared to sunflower oil red palm olein blends. This study has shown that the addition of red palm olein as a natural antioxidant to sunflower oil can improve the physicochemical properties such as stability and sensory properties of unsaturated oil blends.M.Sc. (Food Technology