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Keywords: Kneading Yeast, Dough Intensity Specific work PorosityIntroduction. There was investigated the influence of the geometric parameters of the main working elements on the intensity and quality of the kneading of the yeast dough.Materials and methods. There was researched the wheat yeast dough, which was mixed by a machine of continuous action using screw, cam and pin work elements. The structural and mechanical properties of the dough were determined by viscosimetry. The porosity of the finished product was determined by analyzing the look of the cut of the finished product and the ImageJ special software package.Results and discussion. With an increase of indicators of the rate of displacement from 0 to 100 s -1 , a prompt jump in the bias voltage from 2000 to 6800 Pa occurs, then slowly increases to 6950 Pa in the range of the shift rate from 100 to 800 s -1 . As the displacement rate increases from 0 to 800 s -1 , the viscosity decreases with degree dependence.Indicators of the cost of specific work during the kneading of the yeast dough by working elements of various configurations for the parameter of stabilizing grating 2,5%, reach 22-37 J/g. The intensity of kneading the dough depends on the design of the dough kneading machine, the rotational speed of the kneading element and its configuration. Screw working elements are very intense, intensity indicators range from 0.07 to 0.12 W/g.The porosity of the bread product after kneading by cam element is 72% and is a high indicator of the product.Conclusions. It is confirmed the positive effect of enhanced machine processing by cam and screw working elements during the process of kneading the yeast dough. Pin working elements can be used in combination with a screw element at the beginning of the shaft. A comparative analysis confirms the expediency of using cam-shaped working elements.

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Introduction. A mathematical model was developed and simulation modeling of the process of kneading the yeast dough by cam operating elements was carried out. Materials and methods. The conditions of the contact interaction of the material with the working elements and the chamber of kneading, as well as the value of the dough structuralmechanical characteristics were specified. During the simulation of the kneading process, the angular position of the cam element was changed from 90° to 585°. Results and discussion. The scheme of the mathematical modeling of the process of mixing of the yeast dough in a dough machine of continuous action is developed. Based on the results of simulation of the mixing process, cam operating elements, the distribution of strain of displacement and dissipation of yeast dough in the working chamber were obtained. As the angle of the position (90° to 360°) of the cam element increases on the shaft, there is an increase in the shear stress. The greatest indices of shear stress occur in the area of cam clamping elements and in the contact area of the cam with the walls of the case, numerical values reach within 7000-8000 Pa. For the rest of the camera, the displacement stress reaches 1000-3000 Pa. Distribution of dissipation shows that in parts of the working chamber there is the formation of heat in the area of flow. With the increase of the angle of the cam (from 180° to 585°) of the cam element, there is a gradual increase in temperature. At the site of mixing 12 pairs of cams, the temperature of the yeast dough increases by almost 5 °C. Taking into account that before the simulation, the initial temperature reached t=30 °C, and upon completion of the mixing process did not exceed 35 °С, the pastry preparation parameters were observed. The greatest heat release occurs in the area of the cam clamping elements. The results of mathematical modeling are confirmed by physical experiments on a test dough mixing machine of continuous action, an error within 5%. Conclusions. The proposed simulation scheme allows us to investigate the process of mixing the yeast dough according to various technological parameters. The obtained results give the initial data for the choice of rational parameters of the process of mixing the yeast dough by the cam working elements.

Corresponding author:Vitalii Rachok E-mail: RachokV3478@gmail.com DOI: 10.24263/2310-1008-2017-5-1-14 Introduction. It was considering consider the question of mixing the yeast dough with the variable speed of rotation of the working element and the different humidity of the dough.Materials and methods. The research was carried out by measuring the power and other parameters of kneading and recording the results in the form of pharynograms. Flour, water, salt and yeast blend was placed in a stirring chamber and recorded the torque and the corresponding technological parameters. The mixing of the yeast dough took place for 20 minutes for the rotational speed of the working element from 20 to 140 turns per minute and at different humidity levels of the dough in the range from 40,3% to 44,3%.Results and discussion. There have been stages of mixing the yeast dough investigated. The influence of reinforced mechanical processing on the yeast dough was studied. It has been established that with increasing the frequency of rotation, the time required for mixing the components decreases. At dampness of a dough 44,3% at any speed of a rotation, in a range from 20 to 140 rpm. After intensive mechanical treatment of the yeast dough with a rotational speed of 60 to 140 rpm, it is required on its own batch of dough at different humidity, ranging from 40 to 60 seconds. Time is required for the third stage of kneading (dough plasticization), for the dough humidity of 40,3-42,4% ranges from 160 to 180 seconds for the rotational speed of 60-80 revolutions per minute.The required, fine-grained and uniformly distributed porosity (the number of portions of 4500-4800 pieces) is observed in the intensive process of mixing the yeast dough for the rotational speed of the working body of 60 revolutions per minute. The highest porosity indices in the finished product for the parameters of the technological process of the rotational speed (n = 60 rpm), the moisture content of the yeast dough (H = 44,3%) under the given conditions, the porosity of the finished product (P = 70%) reaches the maximum values.Conclusions. The yeast dough mixing process should be carried out at relatively high turns of the working element 60-80 rpm, so the humidity in the specified ranges (40,3-44,3%) will not significantly affect the process, the gluten macromolecule under the influence of internal stresses, arising in the dough, are partially destroyed, but due to the internal restructuring of the structure are restored again, and the gluten turns out to be elastic.