Effect of storage temperature on starch retrogradation of bread staling

Abstract The objective of the present work was to study the effect of bread storage temperature on starch retrogradation, using water activity measurement and X‐ray diffractometry technique to analyse the changes produced in the crumb firmness such as recrystallization. When storing bread with crust, the crust tends to trap moisture from the crumb, resulting in a dehydration of the crumb with faster staling. For storage temperatures of 25 and 4°C, water activity decreases as a function of storage time whereas at −18°C it is maintained at an almost constant level for 23 days. During storage, the starch molecules are reassociated and generate a new crystalline order which has a typical XRD pattern: the B‐type structure. The peak at 17.4° is indicative of this structure and is related to bread aging. As observed with the recrystallization kinetics, at −18°C only crystal growth may occur, whereas at 25 and 4°C there would be not only growth but also formation of new crystals. At 4°C the rate of starch retrogradation is the highest for the studied conditions.