changes in wheat starch crystallinity during staling of flat breads: effects of protein on retrogradation

abstract: the crystallinity of wheat starch in two types of flat breads was studied using differential scanning calorimetery. three types of flours with different proteins of 9.4, 11.6 and 13.5% were prepared and two different types of flat breads with thicknesses of 2 and 3 millimeters were baked from each flour. the crystallization enthalpy (∆h), peak temperature (tp) and onset point temperatures (to) of the dsc thermograms were analyzed on the first and 3rd days of storage in all types of breads. comparison of the results showed that the baking process and time influenced on the extent of starch crystallinity. in spite of the breads with 3mm thickness, the loss of crispiness in breads with 2 mm thickness proceeded over shorter times. in very thin flat breads (thickness of 2 mm), a temperature of about 100 c was rapidly riched, but due to the short time of baking process, starch was not fully gelatinized and the latter caused slower retrogradation upon the storage. the results indicated lower starch recrystallization enthalpy. under the experimental conditions, high protein breads showed lower extent of retrogradation.   keywords: flat bread, protein, retorgradation, starch crystallinity.