In recent years, dissatisfaction of people about the quality of Iranian traditional breads has increased. In order to improve the quality of Sangak bread, three types of improver, Ascorbic acid in three levels (30, 60 and 90 ppm), Sodium stearoyl lactylate in three levels (0.25, 0.5 and 0.75 percent) and Xylanase in three levels (20,40 and 60 mg per kg of flour) were used. Design expert software and fractional Box-behnken design were used to select the best combination of the improvers. To evaluate the models and choose an optimal formula, eight replies that had included moisture content of bread 1 and 72 hours after baking, color of bread 72 hours after baking, shear strenght 1 and 72 hours after baking and back extrusion test of dough after 90 minutes of fermentation had measured. Software had chosen t he best amount of each improver by analyzing the results of replies. The best formula of improvers had included 70 ppm Ascorbic acid, 0.6 percent Sodium stearoyl lactylate and 36 mg Xylanase per kg of flour. Then two types of dough, the one had included improvers (A formula) and another without improvers (B formula), had made. farinograph , back extrusion, moisture content, shear stress tests and sensory evaluation had carried out. The rate of water absorption, dough stability and dough development time in A formula had increased 11, 43 and 32 percent respectively. In back extrusion test, the resistance of dough had increased 20 percent in dough with A formula. The shear stress measurement had shown 48 and 43 percent increase in bread with A formula. The result of color determination had shown that improvers had caused to increase the bread lightness, decrease the intensity of red color and the intensity of yellow color. The results of the bread's tests had showed 27 and 24 percent increase in moisture content of bread with A formula respectively 1 and 72 hours after baking. Also organoleptic quality of the breads was evaluated by panelists, and the results show that bread with A formula had higher scores than the bread with B formula. Although the amount of stocked sand to the bread decreased in bread with A formula. Key words: Sangak bread, Ascorbic acid, Sodium stearoyl lactylate, Xylanase
