Hydrogen bond density and glass-transition temperature govern gelatinization and gel rheology in cereal and tuber starches

The gelatinization behaviour, pasting properties, and rheology of potato, cassava, rice, wheat, and waxy corn starches were studied. Gelatinization behaviour was examined at different starch-to-water ratios using differential scanning calorimetry to construct state diagrams of melting. The obtained onset, peak, and end temperatures of gelatinization were described using the Flory-Huggins theory for biopolymer melting. The validity of the obtained diagrams was tested against literature data, including gelatinization in different sugar solutions for all starches. Water-sugar mixtures were treated as a single solvent by considering the volumetric density of hydrogen bonds in the sugar solutions ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>Φ</mml:mi> <mml:mrow><mml:mi>w</mml:mi> <mml:mo>,</mml:mo> <mml:mi>e</mml:mi> <mml:mi>f</mml:mi> <mml:mi>f</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> ). All literature data collapsed into the melting diagrams, except for T_onset at high sugar concentrations, due to phase separation between starch-rich and sugar-rich phases. The pasting properties and the rheology of freshly prepared starch gels were analyzed at three concentrations (5, 8, and 11 % w/w) in water, revealing differences among the starches as a function of concentration. However, G' and G″ values obtained from frequency sweeps scaled with the computed <i>T</i> _<i>g</i> <i>/T</i>, based on amylose concentrations. Cereal and tuber starches exhibited distinct relationships with <i>T</i> _<i>g</i> <i>/T</i>. Notably, literature data collected under similar experimental conditions aligned with the scaling observed in this study, despite differences in ingredient sourcing. Overall, this study provides insights into the physicochemical principles governing gelatinization and rheological behaviour in starches from diverse botanical sources. The findings offer a universally applicable understanding that can aid in designing cereal- and starch-based food formulations.