Plant-Based Yogurt Using Rice Bran and Grain of Green Rice: Increasing the Protein Content of Raw Materials by Enzymatic Protein Extraction

This study investigated rice bran and green Khao Dawk Mali 105 (KDML 105) rice grains as alternative protein sources for plant-based yogurt. However, there is a lack of systematic investigation on the application of enzyme-extracted proteins from green KDML 105 rice and rice bran in fermented yogurt systems. Proteins were obtained via enzyme-assisted extraction to enhance yield and bioactive compound release prior to formulation. Physicochemical, compositional, rheological, bioactive, and sensory properties were evaluated. Yogurts by green rice protein extract (GRE) and green rice bran protein extract (GBE) formed softer gel networks than soy yogurt, exhibiting lower water-holding capacity and higher syneresis, reflecting differences in protein aggregation during fermentation. Nevertheless, green rice (GR) and green rice bran (GB) yogurts contained significantly higher protein levels (1.93–2.47-fold) than the control. They also demonstrated enhanced bioactive properties, with increased total phenolic content (1.07–1.51-fold), total flavonoid content (2.10–4.35-fold), DPPH radical scavenging activity (1.07–1.16-fold), and FRAP values (1.46–1.98-fold). Sensory evaluation indicated good acceptability, particularly for GR formulations, which achieved a mean score of 7 with favorable texture and flavor attributes. These findings highlight the technological feasibility of utilizing green rice and rice bran proteins as primary ingredients in rice-based fermented yogurt alternatives with improved bioactive functionality.