INFLUENCE OF TECHNOLOGICAL PARAMETERS ON THE TEMPERATURE-TIME MODES OF VACUUM FREEZE-DRYING OF THE PRODUCT

The process of sublimation drying of berries provided, this is the drying method along the berry the humidity is reduced to 2-5%. The dryer is conditional consists of two blocks - refrigeration and sublimation unit. At room temperature the product is placed in the drying chamber. Equipment after connection, vacuum pump in the chamber reduces the pressure to 10-30 Pa. When a vacuum is created and free product due to evaporation of moisture leads to freezing. Most of the moisture is converted into ice crystals, and then the sublimation process begins. This equipment uses 404 a freon. Temperature to register 8 channel OVEN TRM138 RS-485 temperature meter was used. Of the product to measure weight every 30 minutes removed from the chamber Vibra HT 224RCE was weighed on an analytical balance. The experiment was performed with three types of berries: strawberries; currants and raspberries. Experience during the temperatures on the surface of the berries, inside the chamber and the mass of the product were measured. Duration of drying as a criterion of effective mode, energy expenses and quality indicators of dried berries were determined. The effective sublimation time was 4.5 hours. Inside the chamber at a pressure of (20 ± 5) Pa, at a temperature of (-42 ± 2) 0С, general freezing and sublimation time not more than 5 hours, the total drying time is 8 hours. The initial weight of strawberries decreased by 36%, currants by 28% and raspberries by 27.4%. Drying should be stopped when the chamber temperature reaches 40 ° C.