Modeling the gelatinization-melting transition of the starch-water system in pulses (lentil, bean and chickpea)

Cooking-induced conversion of starch, the major carbohydrate in pulses, is crucial for the digestibility of the seed. The gelatinization-melting transition of lentil, bean and chickpea starches was studied using Differential Scanning Calorimetry at different temperatures (T values ranged from 20 to 160 °C) and water contents (X from 0.2 to 3 kg kg^-1 db). Gelatinization and melting endotherms were successfully modeled as two desummed Gaussian functions. This modeling enabled to generate the degree of starch conversion for any T and X conditions, a valuable indicator that could be used in predictive cooking models. As previously reported for melting, the temperature of gelatinization was found to depend on moisture in a way that can be modeled using the Flory-Huggins equation. The results suggest that starch undergoes melting transition irrespective of water content. The similar starch conversion diagram for the three pulses suggest that starches have similar thermal behavior.