Effect of Thermoresponsive Xyloglucan on the Bread-Making Properties and Preservation of Gluten-Free Rice-Flour Bread

This study clarified the effect of adding thermoresponsive xyloglucan on the bread-making properties and preservation of gluten-free rice-flour bread. The thickening polysaccharides used for preparing gluten-free rice-flour bread were modified tamarind gum (MTG; thermoresponsive xyloglucan), tamarind gum (TG), and xanthan gum (XT). The mechanical properties of the added polysaccharide thickener solutions and bread dough, the mechanical properties and sensory characteristics of rice-flour bread, and the aging properties of rice-flour bread were measured. The results showed that the MTG solution exhibited solification at 40 °C and gelation below 40 °C, which affected the dynamic viscoelasticity of the dough. The addition of MTG to gluten-free rice-flour bread reduced the specific volume, increased the moisture content, and reduced the stress at 70% compression. Therefore, the bread with MTG added was soft, moist, and preferred over other those with other additives. In terms of preservation, the addition of 0.5-0.75% of polysaccharides inhibited the hardening and aging of beard with MTG added. This indicates that the addition of MTG at low concentrations is effective in preserving gluten-free rice-flour breads. We found that the thickening polysaccharides had to be added in appropriate concentrations to improve the bread-making properties and achieve the preferred effect.