Rachok V. Scientific and technical aspects of effective kneading of the yeast dough in dough machines of continuous action

The dissertation is devoted to the study of the process of mixing the yeast dough and to the study of the influence of the constructive parameters of working elements on the process of kneading in the dough machines of continuous action. The effect of mechanical treatment on the dough during its kneading accelerates the rate of flow of physical, colloidal and biochemical processes and is one of the main ways of regulating the physical properties of yeast dough and the quality of finished products in general. Тhe duration of each stage was determined in the three-stage model of the kneading of the yeast dough at different rates of rotation. With the increase of the frequency of the rotation of working element, the duration of kneading the yeast dough decreases. At the first stage, the moisture content of the dough is also affected. With the humidity increase, the duration of mixing of the components decreases by the linear dependence. The second stage, in particular, the batch, requires intensive machining. At this stage, the humidity within the established limits does not actually affect. The reducing of the duration of mixing is achieved by increasing the frequency of rotation of the working element. Increasing the frequency of rotation reduces the duration of kneading. With the increase of the frequency of the rotation of working element, the duration of the formation of the dough decreases. Excessive mechanical impact leads to the destruction of the gluten-free frame formed during the kneading. The experimental setup equipped by screw, cam and finger working elements was developed. Studies have been conducted based on the duration of mixing stages. It has been established that with the increase of the frequency of the rotation of working element, the duration of the yeast dough mixing decreases. The process of the kneading of yeast dough in a dough machine of continuous action with the use of screw, cam and finger working elements was investigated. It is established that the intensity of the influence of cam working elements on the processes of kneading of wheat dough has the highest value (U = 32 W/g). It is accelerated the formation and maturation of the dough under the obtained values. The equability of distribution of dough components after kneading has been investigated, porosity parameters of the finished product were compared, after mixing the yeast dough by the working elements of various configurations. Distribution coefficient after kneading by cam operating elements is 84%, it is observed an equable distribution of components in the structure of yeast dough. A mathematical model was formulated and simulation parametric modeling of the process of mixing the yeast dough with cam operating elements was carried out. The influence of changing the distance between the cams and the frequency of rotation of the working body was investigated. At the stage of the formation of the task the conditions of the contact interaction of the material with working elements and kneading tube, and also values of structural-mechanical characteristics of the dough are specified. After all parameters are entered to the software complex, it begins the process of calculation and visualization of the process of kneading the dough. Based on the results and after the parametrical modeling of the process of kneading the dough by cam working elements a linear dependence of the speed of transferring in the working dough tube is obtained. It was established that with increasing the frequency of rotation of the working element, the pressure in the kneading tube increases. The distance between cam working elements also affects, the shorter distance, the greater pressure in the tube. The highest value of indicators of the pressure in the kneading tube arises in the zone of the contact of cam working elements and the wall of the kneading tube and in the zone of the contact of two cam working elements. The results of the modeling confirmed the nature of the dough is pseudo plastic, which is explained by the variables of the numerical data of the viscosity of the dough in the kneading tube. It has been established that the distance between the cam working elements in the range from 2 to 10 mm does not significantly affect the process of mixing the yeast dough. Based on the obtained results, it is proposed specific structures of working elements for kneading the yeast dough in dough machines of continuous action. It is rationally to use the space between working elements and the wall of kneading tube for cam working elements. This will help to compensate acceptable manufacturing defects and inequalities. This will also compensate an unequal heat distribution and will reduce overpressure on the semi-finished product. The mixing-fermentation-molding unit and dough machines of continuous action with the use of cam operating elements have been developed.