Effects of Water Soaking on Bread-Making Quality of Brown Rice Flour

We found that brown rice flour produced using a jet mill after soaking for more than 12 h yielded a better formulation of rice/gluten bread, giving an equivalent specific loaf volume (SLV) as bread made with white rice flour. Quality analysis of the brown rice flour showed that soaking for more than 12 h resulted in a lower damaged starch content. There was a significant inverse correlation between damaged starch content and SLV. Substitution of 10% white rice flour with rice bran had little effect on final SLV. Furthermore, endogenous α-amylase activity in brown rice flour produced after soaking was approximately 5 to 12 times higher than that of white rice flour, but there was no correlation with SLV. These results indicate that the improved SLV in brown rice/gluten bread was predominantly due to the decrease in damaged starch content, which depends on soaking time.