The process of fortification of wheaten bread with calcium salts was studied. The effect of interaction between phytic acid, containing in flour and calcium salts, introduced into the samples for fortification, on the amount of bioavailability calcium in the final product was analyzed. Calcium salts form insoluble complexes with phytic acid, which are not disposable for gastrointestinal digestion. During the fermentation process phytic acid is being dephosphorilazed under the action of phytaza and lowers its ability to form insoluble complexes with calcium. So, calcium introduced into the dough during the second phase of fermentation process becomes bioavaliable. Phytazic activity correlates directly with intensification of fermentation process and the main factor showing calcium bioavailability is the total contains of ethyl alcohol. The amount of supplied calcium influences significantly on the evolution of dough fermentation. At high concentrations of supplement suppression of fermentation process takes place, what affects the quality of final product. There is a strict correlation between intensity of dough fermentation process, degree of calcium bioavailability, the amount of introduced supplement and the moment of its introduction.