Physicochemical Properties of Spray-Dried Microcapsules Prepared with Gamma Oryzanol Pre-encapsulated in Zein Nanoparticles and Maltodextrin as a Drying Agent

Gamma oryzanol (GO) is a bioactive compound found naturally in rice bran oil and is known for its antioxidant properties. However, GO is sensitive to environmental stresses such as light, oxygen, and temperature. Encapsulation is employed to enhance the stability and dispersibility of the GO. The present work was aimed at producing and characterizing spray-dried microcapsules of GO facilitated by pre-encapsulation in zein nanoparticles and maltodextrin (MD) as a drying agent. Pre-encapsulation of GO was conducted by liquid–liquid dispersion at the highest homogenization speed of 15,000 rpm, leading to GO-loaded zein nanoparticles (GOZNs) with a Z-average diameter of 234 nm. The effects of MD concentration (0, 50, 100, and 150% mass of zein) and inlet air temperature (120, 140, and 160 °C) on physicochemical properties of the spray-dried powders were investigated. The highest retention of 84.97 ± 2.39% was observed at a zein to MD to GO mass ratio of 1:0.5:0.3 and an inlet air temperature of 160 °C. Increments in both inlet air temperature and MD concentration reduced the hygroscopicity of spray-dried powders, while the addition of MD significantly improved the solubility of spray-dried powders. The primary spray-dried particles exhibited irregular shapes, varied dimensions, surface shrinkages, dents, and absence of cracks. The retention of GO in spray-dried powders was 87.06 ± 0.42% and 77.89 ± 0.81% after storage at 4 °C for 6 and 12 months, respectively, which was significantly higher than 59.14 ± 1.37% and 37.71 ± 0.72% for pristine GO. The improved storage stability of GO and improved powder solubility may allow future applications in the food and beverage industries.