EFFECTS OF SOLUTES ON RETROGRADATION OF STORED STARCHES AND AMYLOPECTINS - A CALORIMETRIC STUDY

Starch and amylopectins from different sources were studied to know their calorimetric behavior when mixed with sucrose, glucose and sodium chloride to different concentrations, and stored to different times. It was found that for control samples of amaranth, waxy and normal corn starches slight changes in enthalpy values were observed. The three starches presented retrogradation endotherms, in the presence of sugars, after 2 storage weeks with low enthalpy values; these values tended to be higher by decreasing sugar concentration. The effect of sodium chloride on starch retrogadation was different to that of sugars; waxy corn starch did not show enthalpy values at all experimental conditions. Theories on retarding effect of sugars have been proposed but the effect of salt on retrogradation until now is difficult to explain. Amylopectin in the presence of sucrose showed retrogradation endotherms after 3 storage weeks and with glucose after 4 weeks, except potato amylopectin which did not exhibit this trend at any tested condition. With sodium chloride all amylopectins presented retrogradation endotherms after 4 weeks. The different behavior of amylopectins with solutes could be explained by the different chain distribution in such macromolecules.