The moisture plasticizing effect on enzyme-catalyzed reactions in model and real systems in view of legume ageing and their hard to cook development

This study aims to understand the role of storage conditions (temperature, T and moisture content) in reactions involved cation-pectin-phytate hypothesis, postulated cause Hard-to-cook (HTC) defect beans as influenced by plasticizing effect (glass transition (Tg) concept). The enzyme catalysed reactions, demethylesterification pectin hydrolysis phytic acid, were monitored respectively simplified acid/protein model systems. In addition, both studied a real system, red kidney bean cotyledon during at 35 °C different relative humidity (6%, 54%, 66%, 72% 82%) for 15 weeks. Tg-moisture relation systems established Dynamic Mechanical Thermal Analysis (DMTA). Tg-line, fitted using Gordon-Taylor equation, was combined with sorption isotherm create stability diagram. diagram obtained can be used ascertain biochemical post-harvest ageing beans. Results displayed that there significant acid system when stored above their glass values. On other hand, degree methylesterifcation (DM) did not significantly change storage. significant, although small, changes DM noted T-Tg > 20 °C. An examination lines revealed moisture.