L. Izadi Najafabadi - Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, P. O. Box: ۸۴۱۵۶-۸۳۱۱۱, Isfahan, Islamic Republic of Iran.
N. Hamdami - Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, P. O. Box: ۸۴۱۵۶-۸۳۱۱۱, Isfahan, Islamic Republic of Iran.
A. Le-Bail - CNRS, Nantes, F-۴۴۳۰۷, France.
J. Y. Monteau - CNRS, Nantes, F-۴۴۳۰۷, France.
J. Keramat - Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, P. O. Box: ۸۴۱۵۶-۸۳۱۱۱, Isfahan, Islamic Republic of Iran.

The mode of heat and mass transfer during baking of bakery products is an important factor determining the quality of the final product. The heating rate could alter the starch properties during gelatinization and affect the quality of products after baking and during aging. Sangak is a kind of Iranian flat bread baked on the hot pebble gravels. The aim of this study was to evaluate the impacts of baking beds (gravel and metal beds) and baking temperatures (۲۸۰, ۳۱۰ and ۳۴۰°C) on staling of Sangak bread during storage at ۲۰°C. The mean value of the measured heating rate of bread baked on gravel bed was higher than that in bread baked on metal bed. In the case of baking on gravel bed, unlike baking on the metal bed, the increase of baking temperature had no significant effect on all quality parameters (moisture content, firmness and freezable water of breads, etc). Recrystallization of amylopectin seemed not to be related to the baking condition. During aging, the firmness of bread baked on gravel bed was significantly lower than that for bread baked on the metal bed and baking at higher temperature and shorter time resulted in the increment of moisture content and the decrease of firmness. As a consequence, baking on gravels and higher baking temperature increased the heating rate, which led to reduction of the staling kinetic of Sangak bread.

Amylopectin retrogradation, Bread Firmness, Freezable water, Heating rate, Unfreezable water