Effect of different concentration of soy flour on the quality of gluten-free bread containing rice flour

Gluten-free formulations are often supplemented with proteins to improve their quality. The objectives of this work were to assess the impact of different concentration of soy flour in addition to 2% of carboxy methyl cellulose on gluten-free bread quality parameters. Therefore, soy flour and rice flour were combined respectively in concentrations: 0% & 100%, 10% & 90%, 20% &80%, and 30% & 70%. Soy flour addition had had positive effect on farinograph properties of dough such as water absorption. Adding soy flour up to 10% caused positive and significant differences in physical properties of bread such as specific volume, crumb hardness, and porosity. Colorimetric factors, except for L*, were not influenced by soy flour. Pictures obtained from SEM showed that bread containing 10% of soy flour had the best texture and rice bread (100% rice flour) in the next order showed suitable and porous structure. Best score from organoleptic test was related to bread containing 10% soy flour getting the highest score in total acceptability. Generally, adding 10% soy flour resulted in reduction of undesirable properties of rice bread. However, increasing concentration resulted in negative effects on qualitative and sensory properties of bread.