The article provides a mathematical solution to the problem of choosing the dosages of ingredients in regulating the baking properties of wheat flour with the use of soy protein isolate, which allows not only adjusting the process but also improving the biological value of bakery products. The chosen main factors that influenced bread quality were the following: x1 – the dosage of soybean isolate, %; and x2 – dough moisture, %. These factors were compatible and uncorrelated. The central-composite rotatable design was chosen. The research program was laid out in the experiments planning matrix. The order of experiments was randomized using the table of random numbers, which excluded the influence of uncontrollable parameters on the results of the experiment. For statistical processing of the experiment results, the following statistical criteria were used: the significance of regression equations coefficients – Student's t-test, adequacy of equations – Fisher's variance ratio. As a result of the experimental data statistical processing according to the known methods, regression equations that adequately describe at the significance level of 5 % the dependence of the specific volume of bread and dimensional stability on the studied factors were obtained.