Application of heat-cooling treatment of white sweet potato flour for gluten-free bread

Heating-cooling treatment (HCT), also known as heat-moisture treatment (HMT), is a physical treatment to alter starch's physicochemical properties without destroying its granular structure. Heat-treated flour can be used in many food processing applications, such as preparing a cake, bread, and noodles. This research evaluated the characteristics of gluten-free bread prepared from the heating-cooling treatment sweet potato flour (HCT-SPF). Sweet potato flour (SPF) was treated by heating-cooling treatment (HCT). The sweet potato flour was adjusted to 30% (wet basis) moisture content and heated for six h at 85°C, 95°C, and 105°C. The physicochemical properties included moisture, ash, protein, fat, dietary fibre, specific volume, color, and texture of gluten-free bread made from HCT-SPF were then evaluated. The results showed that the solubility and swelling power of SPF decreased, and the baking expansion of SPF increased gradually as the heating temperature of HCT was increased. In addition, gluten-free bread made from HCT-SPF showed higher specific volume and lowered lightness and hardness values than those prepared from native SPF. However, the use of HCT-SPF did not influence the proximate composition, springiness, and cohesiveness of the gluten-free bread. Furthermore, the gluten-free bread made from HCT-SPF at a higher temperature (105°C) showed a high bread volume and softer texture.