The effect of rice bran extract on the quality indices, physicochemical properties and oxidative stability of soybean oil blended with various oils

Abstract

Soybean oil (SBO) is an edible vegetable oil of importance although, prone to degradation owing to its low oxidative stability. Blending of soybean oil with potentially stable oils and incorporation of antioxidants from low-cost resources such as rice bran is a potential channel of improving oil stability. The study evaluated the effect of partial blending (20, 40%) of SBO with sesame oil (SSO) and or cashew nut oil (CNO), the effect of incorporating rice bran extract in oil and exposure to repeated high temperature during use for frying on the physicochemical properties, oxidation parameters, fatty acid profile and color attributes of the oil blends using standard methods. Results showed that blending of soybean oil with either sesame and or cashew nut oil significantly improved the properties and quality of crude soybean oil as shown in the reduced peroxide value, free fatty acid (12.20 meq O2/kg, 12.78% in SBO, 7.90 to 8.90 meq O2/kg, 11.04 to 11.66% in blended oils respectively). Oleic (41.91%) and linoleic acid (15.57%) are the most abundant unsaturated fatty acids in SBO, blending significantly increased their values to 62.41% (SBCS - 60% SBO, 20% SSO, 20% CNO), 63.78% (SBS - 80% SBO, 20% SSO) and 20.03% (SBCS), 21.17% (SBS) respectively in blended oils. Also, inclusion of 500 ppm ethanolic rice bran extract was most appropriate in enhancing the stability of oil. In conclusion, blending of SBO with SSO and or CNO as well as incorporation of rice bran extract to blended oils has potential to reduce oxidative indices and improve thermal stability of composite oil.