Heat‐Moisture‐Additive Treatment Enhanced the Functional, Rheological, and Breadmaking Properties of White Sorghum Flour

Hydrothermal‐chemical modification methods have the potential of enhancing synergy between gluten‐free flours and wheat gluten in producing acceptable leavened composite flour bread. In this study, response surface methodology was utilized in determining optimal heat‐moisture treatment (HMT) conditions (26% moisture, 108°C for 33 min), which enhanced thermomechanical stability and decreased retrogradation tendency (80% and 20% decreases in breakdown and setback viscosities) of white sorghum flour. The optimization study revealed that temperature had the largest effect on the pasting responses, followed by treatment time and moisture. Furthermore, chemical and biological leavening agents, namely baking powder or dry baker′s yeast at 1%, 3%, and 5% were combined with white sorghum flour and then treated with the optimal HMT conditions. The yeast was inactivated under the optimal HMT conditions and therefore acted as a functional additive rather than a leavening agent. The heat‐moisture‐additive treatments further increased thermomechanical stability and decreased retrogradation tendency and swelling properties of the flour. Notably, heat‐moisture‐1% baking powder treatment led to a 100% decrease in breakdown viscosity, whereas heat‐moisture‐1% yeast treatment led to a 61% decrease in setback viscosity. Furthermore, the treated flours were combined with wheat flour at 15% w/w substitution level and were compared with their untreated counterparts and 100% wheat flour in terms of rheological properties, bread volume, and bread sensory properties. All the treatments had contrasting effects on dough rheological properties of the wheat‐white sorghum flour, while increasing loaf volume properties. Notably, composite flour containing heat‐moisture‐3% yeast‐treated white sorghum flour had 6% and 17% higher dough extensibilities than composite flour with untreated and optimal heat‐moisture treated flours, respectively. It also had 20% and 9% higher dough energies than that of untreated flour and 100% wheat flour, and had a 218%, 166%, and 60% higher loaf volumes than composite flour bread containing untreated flour and optimal heat‐moisture treated flour, and 100% wheat bread. It also had comparable exterior bread properties with wheat flour when subjected to sensory analysis. This study is of relevance to the flour mills and baking industries.