Optimisation of soybean oil enriched with lipophilic antioxidants from Thai rice germs and their nanoparticles developed using complex coacervation

Abstract

Soybean oil contains high levels of polyunsaturated fatty acids, which are susceptible to lipid oxidation, negatively affecting on the stability of food products and human health. In this study, soybean oil was enriched with lipophilic antioxidants from various types of Thai rice germs with broken rice pieces. The ultrasonic-assisted extraction was optimised using response surface methodology. Under temperature of 40 °C, time of 40 min, and solvent-sample ratio of 5, the oils with high vitamin E and γ-oryzanol contents were achieved. Complex coacervation was applied to develop oil-loaded nanoparticles using soy protein isolate (SPI) and inulin as wall materials. The size of the obtained particles ranged from 170 to 240 nm, with an irregular continuous surface. FTIR spectra revealed electrostatic interactions between SPI and inulin. Moreover, the nanoparticles exhibited a greater release of lipophilic antioxidants and higher recovery of antioxidant activity than the unencapsulated oils.