Roller Dryer for Drying Milk in Low-Tonnage Conditions

Introduction. Milk has a high nutritional value and is a vital component of human diet. Today, the dairy market is one of the largest and actively developing food markets. However, this industry is characterized by such problems as seasonality and poor transportability of raw materials. These problems particularly affect small farms. Deep processing of dairy raw materials to obtain dry powders is the most effective way to solve these problems. The research objective was to develop a low-tonnage dryer for producing milk powder on small farms and to select the optimal drying temperature. Study objects and methods. The research featured whole milk of the ‘Svoya Ferma' brand, mass fraction of fat = 3.4–4.5%. The research was performed on the premises of Kemerovo State University (Kemerovo, Russia). The milk was dried on a pilot sample of the roller dryer developed by the research team. The dryer consisted of a vessel, heating drums, and a microcontroller, which was connected to the temperature sensor and the control circuit of the power part, which had a powerful rectifier and pulse regulator. Results and discussion. When the drying temperature exceeded 98°C, the characteristics of the milk powder deteriorated, and the milk failed to meet the State Standard. The optimal drying temperature was 92–95°C, since at this temperature all the characteristics, except for the solubility index, corresponded to the State Standard. The sensory and physical properties of the milk powder were improved by reducing the drying time and the distance between the knife and the drum. Conclusion. Further experiments have to be performed to determine the optimal rotation speed of the drums and the distance between the knife and the drum.