Production of milk analogues from rice bran protein hydrolysate using the subcritical water technique

Abstract

Subcritical water treatment is a useful technique for the extraction of active compounds from biomass materials due to its short processing time, low cost, and environmental sustainability. Defatted rice bran is a by-product of rice bran oil, which still contains protein. In this study, rice bran protein was extracted using subcritical water treatment at temperatures of 120, 140, 160, and 180 °C and reaction times of 30, 45, and 60 minutes to determine the effects of following parameters on the production of milk analogues. At higher temperatures, the protein content and emulsifying activity index (EAI) increased, and the nitrogen solubility index (NSI) ranged from 87-100%. The emulsifying stability index (ESI) reduced when the reaction time was increased, while the molecular weight of the protein was less than 50 kDa. These temperatures and reaction times were shown to have direct impacts on both protein extraction and the molecular size of rice bran protein, which significantly increase the production of milk analogues. The results showed that milk analogues appeared to be more viscous than cow’s milk, as evidenced by the shear thinning. In sensory evaluation, the color, texture, taste, and acceptability of cow’s milk scored higher in comparison to milk analogues. All of the sensory parameters analyzed, except odor, were significantly different (P ≤ 0.05).