Sweet potato flour decreases firmness of gluten-free rice bread

Abstract

Rice flour of the rice cultivar "Mizuhochikara" is suitable for making gluten-free bread without additives such as hydrocolloids or enzymes, but the bread becomes firm more rapidly than wheat bread. The firming rate of rice bread can be reduced by partially replacing the rice flour with sweet potato flour. Herein, when the replacement ratio or β-amylase activity in sweet potato flour was higher, the firming rate was lower. Rice bread made by 5% replacement of rice flour with sweet potato flour with the highest β-amylase activity had a firming rate that was more than three times slower than that of rice bread without replacement. The replacement of more than 5% of rice flour by sweet potato flour produced inferior shaped bread. Therefore, replacing up to 5% of rice flour with sweet potato flour with high β-amylase activity is a better way to reduce the firming rate of gluten-free bread.