Improvement of the vacuum evaporator for the production of paste-like semi-finished products with a high degree of readiness

Abstract

The object of this study is the process of cooking blended pureed mass based on apple, Jerusalem artichoke, cranberry, and hawthorn in an improved vacuum evaporation apparatus with a unified stirrer for the production of paste-like semi-finished products with a high degree of readiness. Conventional devices for cooking are associated with intermediate heat carriers, significant energy and metal consumption, the difficulty of stabilizing the temperature field under the conditions of a significant duration of the process, which prevents ensuring mobility, resource efficiency, and reducing the quality of resulting products. This led to the improvement of the vacuum evaporator by replacing the steam jacket with a film-like resistive electric heater of the radiating type, with the simultaneous use of a unified stirrer to increase the useful heat exchange surface by 0.6 m2. This was achieved by heating the internal space of the stirrer with the heater mentioned above, thereby forming the total area of heat exchange up to 2.8 m2, which is 28 % more than the area of the prototype (2.2 m)2. The rheological parameters of the resulting fruit and vegetable paste at a boiling temperature of 50...55 °C at a shear rate of 0.8...2.0 s-1 were determined, while the effective viscosity was in the range of 5.0...18.0 Pa·s. At the same time, the character of boiling kinetics in the improved vacuum-evaporating apparatus was 30 % lower than the indicator for the basic design MZ-2S-241a. The improved vacuum-evaporator with a unified stirrer is characterized by reduced specific heat consumption for heating the loaded pureed semi-finished product by 13.8 %. By increasing the heating surface by 28 % and reducing the duration of the temperature load on the product according to experimental data in the device by 29.6 %