Résumé
Traditional Iranian flat breads have been widely produced and consumed all over the country and still play a major part in nutrition of the people. Starch gelatinization, retrogradation and staling of flat breads are topics of considerable interest to cereal chemists and baking technologists. This study aimed to investigate the processes of gelatinization, retrogradation, and staling of two types of Iranian flat breads, namely, Lavash and Taftoon. Three different flours with protein contents of 12.56%, 11.52%, 11.28% and extraction rates of 90%, 86% and 58%, respectively, were selected and, after chemical and rheological testing, used to bake Taftoon and Lavash breads. Starch gelatinization and retrogradation of the breads were quantified using Differential Scanning Calorimetry [DSC] after 1 and 3 days of storage. In the endothermic curves, the area under the curve, temperature at the start, and crystallization peak were used as the main criteria. Bread staling was determined using the shear test by Texture Profile Analyzer on days 1, 3, 5, and 7 of storage. Enthalpy, temperature at the start, and the crystallization peak were lower in Lavash bread, which is an indication of a slower rate of gelatinization and retrogradation in this type of bread due to the shorter time of the baking process. The data also show that Lavash bread is softer than Taftoon, but the staling rate [which shows the rate of firming during storage] is lower in Taftoon. Although the temperature in baking Lavash bread is higher, starch gelatinization cannot be completed due to the shorter time of the baking process and, consequently, its rate of crystallization is lower than in Taftoon. Therefore, retrogradation rate is lower in Lavash than in Taftoon. In addition, Lavash bread is thinner and softer than Taftoon and, therefore, it loses moisture faster and stales and dries more quickly