Drying characteristics of heat pump dried shrimp (Pandalus borealis) and fish cake

The peeled, headed and whole shrimps (Pandalus borealis) as well as the fish cake of 50 mm (diameter) × (7-9) mm(thickness) and 50 mm × (14-18) mm were dried in a heat pump dryer at (-2-0)°C and 20°C. The results showed that the drying characteristics of shrimp and fish cake were significantly affected by the handling conditions (with shell or without shell, with head or without head) of shrimp and the thickness of fish cake. The peeled shrimp has the shortest drying time and the headed shrimp is dried faster than the whole shrimp both at the drying temperature of (-2-0)°C and 20°C, and the drying rate of thin fish cake is faster than thick fish cake especially at 20°C. The drying characteristics could be well described by diffusion model (MR = Aexp(-kt)). A series of empirical regression equations have been established and these models indicate that increasing the drying temperature from (-2-0)°C to 20°C significantly enhanced the drying rate and k-values, and the drying time decreased greatly.