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).

摘要：亚临界水处理（Subcritical Water Treatment）凭借处理周期短、成本低廉且环境可持续的优势，成为从生物质原料中提取活性成分的实用技术。脱脂米糠作为米糠油加工的副产物，仍留存有蛋白质组分。本研究通过设置120、140、160及180℃的反应温度，与30、45、60分钟的反应时长，采用亚临界水处理法提取米糠蛋白，以考察各参数对仿乳饮品生产的影响。结果表明，随着反应温度升高，蛋白含量与乳化活性指数（Emulsifying Activity Index, EAI）均有所提升，氮溶指数（Nitrogen Solubility Index, NSI）介于87%至100%之间；而延长反应时长则会导致乳化稳定性指数（Emulsifying Stability Index, ESI）下降，且所得米糠蛋白的分子量均低于50千道尔顿（kDa）。上述反应温度与时长参数对蛋白提取效果及米糠蛋白的分子尺寸均存在直接影响，可显著提升仿乳饮品的产率。研究发现，仿乳饮品的黏度高于牛乳，这一特性可通过剪切变稀现象得到验证。在感官评价环节中，牛乳在色泽、质地、风味与可接受性方面的得分均高于仿乳饮品；除气味指标外，其余所有被分析的感官评价参数均存在显著性差异（P ≤ 0.05）。