Submitted to: Journal of Food Processing and Preservation Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2016
Publication Date: 10/15/2016
Citation: Alfaro, L., Zhang, J., Chouljenko, A., Scott, R., Xu, Z., Bankston, D., Bechtel, P.J., Sathivel, S. 2016. Development and characterization of emulsions containing purple rice bran and brown rice oils. Journal of Food Processing and Preservation Research. doi:10.1111/jfpp.13149. Interpretive Summary: Oxidized oil can produce a rancid flavor which can be detected by consumers. Most food emulsions contain antioxidants to prevent or reduce lipid oxidation. Using purple rice bran oil as an ingredient in food emulsions may improve the nutritional profile of the emulsion and provide natural antioxidants that could reduce lipid oxidation. The aims of this study were to characterize and compare emulsions containing purple rice bran oil. A nano-emulsion (NE) containing purple rice bran oil was produced by ultrasonication followed by ultra-shearing, and a control emulsion (CE) was made from the same ingredients using sonication only. The droplet size of NE was significantly smaller than that of the CE. The NE had more oxidation than the control emulsion (CE) when stored at both 4 and 40 degree C. This increase in oxidation could be due to the higher surface area of the oil droplets in the nano-emulsion. This study demonstrated a nano-emulsion with minimum oxidation could be produced with purple rice bran oil using a sonication process.
Technical Abstract: The aims of this study were to characterize purple rice bran oil (PRBO) as extracted from the bran, and to produce and characterize a nano-emulsion containing purple rice bran oil. An emulsion was prepared using PRBO (10%), sodium caseinate (5%) and water (85%). The mixture was sonicated followed by ultra-shearing to produce the nano-emulsion (NPRBO). A control emulsion using the same proportion of ingredients and from the same source as NPRBO was prepared by sonication only. PRBO was extracted and the physicochemical properties, such as; free fatty acids (FFA), peroxide value (PV), moisture, and antioxidant contents (vitamin E vitamers and gamma oryzanol) were determined. NPRBO was analyzed for stability, particle size, microstructure, peroxide value, thiobarbituric-acid-reactive-substances (TBARS), rheological properties, and antioxidant contents (vitamin E vitamers and gamma oryzanol). The droplet size and microstructure of NPRBO was significantly (p<0.05) smaller (199 nm) than that of the control emulsion. The oxidative stability analyses of the emulsions indicated that NPRBO and the control emulsion had only marginal oxidation during storage at 4 °C and an increased amount of oxidation during storage at 40 oC. NPRBO had more oxidation than the control emulsion when stored at both storage temperatures. This study describes the development and characterization of a nano-emulsion containing purple rice bran oil.