Effect of low molecular weight dextrins on gelatinization and retrogradation of starch

alpha -Amylases, usually added to bread recipes as anti-firming agents, are known to produce low molecular weight dextrins by starch hydrolysis. The i nfluence of these compounds on the gelatinization and retrogradation of sta rch was studied by differential scanning calorimetry. Adding oligosaccharid es to starch caused a delay in gelatinization, although its extent was not quantified. However, oligosaccharides of degrees of polymerization (DP) 3-5 reduced the enthalpy of the retrogradation endotherm, shown as the staling endotherm. The addition of gluten to starch and starch/oligosaccharide mix tures had no effect on the gelatinization and retrogradation of starch. The retrogradation of starch in dough samples was also analysed, after 'baking ' in the calorimeter, to obtain additional information about starch retrogr adation during storage. Oligosaccharides of DP 3-5 also reduced the enthalp y of the retrogradation endotherm. This work provides evidence that oligosa ccharides influence starch changes during the baking and storage of bread. These effects could be considered as the mechanism by which the bacterial a lpha -amylase reduces starch retrogradation and acts as an anti-firming age nt.