Influence of alpha-amylases on bread staling and on retrogradation of wheat starch models

The influence of two commercial a-amylase preparations on starch gelation w as studied in breads and starch gels. Amylopectin retrogradation, crumb fir ming, amylose-lipid complexes, and macromolecular degradation were analyzed in bread samples supplemented with two bacterial enzyme mixtures. The exte nt of amylopectin retrogradation, as measured by the enthalpy change at 45 degrees C, was reduced by the use of the enzyme mixtures. The firming rate was also strongly related to the extent of amylopepctin retrogradation for breads supplemented with the enzyme preparations. These changes are believe d to be related to the depolymerization of starch molecules, which occurs t hroughout storage, and demonstrates that the amylases in bread were not com pletely denaturated by baking. Changes of starch gels throughout storage de monstrated that crystallinity and firmness are not correlated.