Comparison of Gamma-Oryzanol Nanoemulsions Fabricated by Different High Energy Techniques

Gamma-oryzanol (GO) is a bioactive compound that, due to its biological characteristics, can be added to a food matrix. However, the bioactive compound is difficult to incorporate due to its low solubility and stability. A nanoemulsion allows substances to be packaged in nanometric sizes, improving their bioavailability. In this work, a GO nanoemulsion was developed using high-energy techniques. The methodological process began with the formulation of the coarse emulsion, where the emulsifiers (sodium caseinate and citrus pectin), diluent (rice bran oil), and pH were varied to find the most stable formulation. The coarse emulsion was subjected to four high-energy techniques (conventional homogenization, high-pressure homogenization, ultra-high-pressure homogenization, and ultrasonication) to reduce the droplet size. A physical-stability test, rheological-behavior test, image analysis, and particle-size-and-distribution test were conducted to determine which was the best technique. The formulation with the highest stability (pH 5.3) was composed of 87% water, 6.1% sodium caseinate, 0.6% citrus pectin, 6.1% rice bran oil, and 0.2% GO. The ultrasonic treatment obtains the smallest particle size (30.1 ± 1 nm), and the high-pressure treatment obtains the greatest stability (TSI < 0.3), both at 0 and 7 days of storage. High-energy treatments significantly reduce the droplet size of the emulsion, with important differences between each technique.