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Development and characterization of emulsions containing purple rice bran and brown rice oils

Alfaro, Luis, Zhang, Jie, Chouljenko, Alexander, Scott, Ronson, Xu, Zhimin, Bankston, David, Bechtel, Peter J., Sathivel, Subramaniam
Journal of food processing and preservation 2017 v.41 no.5
antioxidants, bioactive compounds, brown rice, cholesterol, droplet size, food industry, free radicals, humans, immune system, ingredients, microstructure, nanoemulsions, nutrient content, oryzanol, oxidation, oxidative stability, particle size, polyunsaturated fatty acids, rheological properties, rice bran, rice bran oil, storage temperature, thiobarbituric acid-reactive substances, tocopherols, tocotrienols, ultrasonics
The aims of this study were to use extracted purple rice bran oil (PRBO) to produce oil‐in‐water (O/W) emulsions and to compare the emulsions to emulsions of conventional brown rice bran oil (BRBO). Four emulsions were produced: (1) a PRBO emulsion produced with ultrasonic processing (Emulsion I PRBO), (2) a BRBO emulsion produced with ultrasonic processing (Emulsion I BRBO), (3) Emulsion II PRBO produced from Emulsion I with an ultrashearing homogenizer and (4) Emulsion II BRBO produced from Emulsion I with an ultrashearing homogenizer. The emulsions were analyzed for stability, particle size, microstructure, thiobarbituric‐acid‐reactive‐substances (TBARS) and rheological properties. The droplet size and microstructure of Emulsions II were significantly (p < .05) smaller (199 and 170 nm for Emulsion II PRBO and Emulsion II RBO, respectively) than that of the Emulsions I. The oxidative stability analyses indicated that Emulsions II had more oxidation than the Emulsions I when stored at 40C storage temperature. PRACTICAL APPLICATIONS: Rice bran oil has gained more importance in the recent years due to its health benefits. Purple rice bran oil (PRBO) is balanced in saturated, monounsaturated and polyunsaturated fatty acids, which makes it an excellent nutritional oil source according to the American Heart Association (AHA). PRBO rich in antioxidants such as Tocopherols (vitamin E), Tocotrienols and Gamma Oryzanol provide health benefits such as lower cholesterol, immune system enhancement and the ability to control free radicals in the human body. Lately, the food industry has had a strong interest in nanoemulsions due to their benefits such as better delivery of bioactive components, and greater stability and functional performance. Using PRBO as an ingredient in a food emulsion will not only improve the nutritional profile of the emulsion but will also substantially increase the natural antioxidant content. This study describes the development and characterization of emulsions containing PRBO.