Effects of soybean oil and whey protein complexation by temperature treatments on the structural, physicochemical and digestive characteristics of autoclaved rice

To further reduce the digestibility of autoclaved rice, autoclaved rice flour (ARF) was added to soybean oil (SO) and whey protein (WP) and treated at different temperatures. The results showed that the treatment temperatures had a profound effect on the morphologies of the ARF; the addition of SO and WP had a protective effect on the morphologies of the ARF particles when they were subjected to thermal treatment. With increasing complexation temperature, the relative crystallinities of both the ARF and ARF-SO-WP displayed a pattern of decreasing first and then increasing. The hydrolysis rates of the ARF increased gradually with the increase of the treatment temperatures, while the hydrolysis rates of the ARF-SO-WP decreased with the increase of the treatment temperatures first, then the hydrolysis rate increased when the temperature was further increased to 70 °C. Compared with the HI and EGI of the ARF, those of the ARF-SO-WP became much lower. We could conclude that protein and lipid addition could lower the EGI of autoclaved rice.