ИССЛЕДОВАНИЕ СПОСОБОВ ТЕПЛОВОЙ ОБРАБОТКИ РЫБЫ ПРИ АВТОМАТИЧЕСКОМ УПРАВЛЕНИИ ПРОЦЕССАМИ ЕЕ НАГРЕВА И ОБЕЗВОЖИВАНИЯ

Abstract

The article deals with the small-size drying plant built in Murmansk State Technical University and used to study advantages and disadvantages of traditional methods of fish thermal processing: convective and infrared. In the course of study the temperature values corresponded to those in technological processes of drying, curing and smoking fish (20-120°C). Poutassou carcasses were taken as raw material (specific surface - 0.2 m2/kg, average weight - 280 g). There are presented the processing parameters: starting weight and end weight, weight loss, processing length, average speed of dehydration, average power supply, energy costs at 30, 50, 80°C. At convective type of processing temperature of fish skin didn’t reach 50°С. Experiment lasted 6.5 hours, average speed of dehydration made 37.8 %/h, energy costs - 6.6 kWt∙h. During infrared type of processing the desired temperature was kept both on the fish skin and in the heat chamber during one hour, after which temperature in the chamber decreased due to fish warming-up and decreasing power supply to infrared lamps. Experiment lasted 5 hours, average speed of dehydration made 51 %/h, energy costs made 5.6 kWt∙h. The results obtained served as a basis for developing energy efficient combined method of thermal processing which has a two-circuit automatic control system: the first circuit controls temperature in the heat chamber and regulates power in pipe electric heater; the second circuit controls the temperature of the fish and regulates power of the infrared radiation. This method is characterized by higher speed of dehydration (51 %/h), less duration of the process (more than 4 hours) and lower energy costs (4.86 kWt.h). The higher temperature of raw material processing, the less energy intensive the combined method.