Characterization of Starch from Bread Aged at Different Temperatures

Abstract

A series of bread samples stored at various temperatures (4°, 25°, and 40°C) were analyzed by differential scanning calorimetry (DSC) to determine if retrogradation (quantified by DSC enthalpy values) and storage temperature were correlated. The increase in enthalpy values during storage time was dependent on storage temperature. However, the rate of recrystallization was not linear at any of the temperatures studied. The net result was that the enthalpy values tended to converge with time, irrespective of storage temperature. Another effect of the increased storage temperature was an increase in the peak temperature (T_p) of the amylopectin endotherm. This indicates either that storage temperature affects the type of crystal being formed as the starch recrystallizes, or that annealing of crystals occurs at the higher storage temperatures. X‐ray diffractometry of starch isolated from the crumb gave similar diffraction patterns indicating no difference in crystal type among the treatments. In addition, the DSC endotherm became sharper at the higher temperatures. Thus, the increase in T_p was apparently the result of annealing of the crystals at the higher storage temperatures.