Specific ratio of A- to B-type wheat starch granules improves the quality of gluten-free breads: optimizing dough viscosity and pickering stabilization

Abstract

Specific volume and crumb hardness, cohesiveness and porosity of gluten-free breads (GFBs) are still far from consumers’ expectations. Since additives are increasingly avoided by the consumers, a quality improvement of GFBs through the optimization of the starch source may provide important benefits. In this study, the effect of five different A- to B-type wheat starch ratios (100A-0B, 75A-25B, 50A-50B, 25A-75B, 0A-100B) on the quality of GFBs was investigated. The increase of the proportion of B-type granules (small ones) augmented the packing degree and uniformity of the continuous phase (starch-hydrocolloid matrix) as well as the Pickering effect (B-type granules being adsorbed onto the air-liquid interface), improving air bubble stabilization. In addition, 0A-100B dough displayed a more delayed crumb settling due to the higher pasting temperatures of B-type granules. Furthermore, the increase of the proportion of B-type granules also increased the apparent viscosity and viscoelastic moduli of doughs, which noticeable diminished bread expansion in 0A-100B sample. Interestingly, 75A-25B and 25A-75B doughs resulted in GFBs with the highest specific volume and crumb cohesiveness and lower crumb hardness, the former with open grain structure (fewer cells with larger size) and the latter with close grain structure (more cells with smaller size). For the first time, it is shown that a specific A- to B-type wheat starch ratio enables: 1) the simultaneous optimization of dough viscosity and Pickering stabilization to attain GFBs with improved physical quality and; 2) the modification of crumb porosity while maintaining specific volume and crumb texture.