High amylopectin Cilembu sweet potato starch for structure formation in sorghum bread

Gluten-free bread often suffers from poor structure and hard texture due to the absence of gluten, which provides viscoelasticity. The use of starch as a structure forming ingredient in gluten-free foods has been recognized, but the influence of naturally high-amylopectin starches on bread structure and texture remains underexplored. This study investigates the potential of Cilembu sweet potato (CSP) starch, a local Indonesian starch rich in amylopectin, as a novel structure-forming agent for sorghum-based gluten-free bread. The effects of starch gelatinization state, concentration, and combination with hydrocolloids (HPMC, xanthan gum) on bread quality were systematically studied by analyzing baking characteristics, color and texture. Results showed that the incorporation of gelatinized CSP starch at 20% concentration produced sorghum bread with improved proofing percentage, higher specific volume, lower baking loss, as well as lower hardness and gumminess compared to formulations with non-gelatinized starch. Comparison with tapioca and maize starches was conducted by analyzing amylopectin content and starch-gel rheological properties, revealing the superior ability of CSP starch to provide viscoelasticity and stabilize the dough structure during gas entrapment. Furthermore, the combination of CSP starch with 3% xanthan gum yielded an optimal bread structure with textural properties closely approaching those of wheat bread. The findings highlight the critical role of amylopectin content, starch concentration, and starch–hydrocolloid interaction in achieving effective gluten substitution. Moreover, the study provides new insights into the formulation of gluten-free breads and demonstrates the value-added potential of a local crop as a sustainable, functional ingredient for gluten-free food systems.