Abstract:

Protein in heat stable defatted rice bran (HSDRB) was extracted with subcritical water at various temperatures
(100–200 ℃) and various extraction durations (0–30 min). The extracts were analyzed for protein and total carbohydrate
contents, amino acid composition, molecular mass distribution and color parameters. The results showed that the highest
yields of protein and amino acids were 50% and 48.6 mg/g HSDRB, respectively at 175 ℃ for 30 min. Under these
conditions, the average hydrophobicity of amino acids and the essential amino acids content were the highest, reaching 1.84 kJ/mol and
14.8 mg/g HSDRB, respectively. The color parameters were significantly different at various temperatures. L* values were
negatively correlated with protein content while a* values were positively correlated with protein content. The hydrophilic
fraction of the extracts mainly contained low-molecular-mass substances.

Key words: heat-stable defatted rice bran (HSDRB), subcritical water extraction (SWE), protein, total carbohydrates, amino acids