IMPROVEMENT OF OXIDATIVE STABILITY OF RICE BRAN OIL EMULSION BY CONTROLLING DROPLET SIZE

Well-planned emulsification studies are needed to improve oxidative stability of rice bran oil. Factors that affect the droplet size during emulsification of rice bran oil include the amount of rice bran oil content, types of emulsifiers, power intensity and duration of sonication. In this study, the emulsions were prepared at different oil concentrations (10, 15 and 20%), using different emulsifiers (Tween 80 and its mixtures with Span 80), and subsequently sonicated at different durations (550min). Longer sonication time resulted in smaller-sized emulsion droplets. The emulsions with the mixture of Tween 80 and Span 80 formed smaller droplets and better oxidative stability than those with Tween 80 only. In conclusion, rice bran oil emulsion with smaller droplets improves oxidative stability. This study may be helpful for tailoring oxidative-stable emulsions with well-defined droplet size distribution. PRACTICAL APPLICATIONS Recently, food manufacturers have been interested in utilization of the polishing by-products such as rice bran. Rice bran oil contains well-balanced saturated and unsaturated fats and provides a good source of vitamin E, antioxidants, oryzanol and other micronutrients. However, food application of rice bran oil is limited because of lipid oxidation. One of the promising technologies is nanoemulsion fabrication, which is being applied to enhance the oral bioavailability and oxidative stability of the poorly water-soluble bran oils. Herein, attention is focused on improving oxidative stability by controlling droplet size through adding mixture of surfactants in the oil-in-water emulsion. Narrow size distribution of droplets is a challenge for improved oxidative stability. In this study, proper formulations such as a mixture of emulsifiers provide a resolution to overcome the oxidative stability limitations in utilization of rice bran oils.