Effects of process parameters on quality changes of shrimp during drying in a jet-spouted bed dryer

The objective of the present study was to investigate the effects of various parameters, that is, concentration of salt solution (2%, 3%, 4%[w/v]), boiling time (3, 5, 7 min), drying air temperature (80, 100, 120 degrees C), and size of shrimp, on the kinetics of drying and various quality attributes of shrimp, namely, shrinkage, rehydration ability, texture, colors, and microstructure, during drying in a jet-spouted bed dryer. In addition, the effects of these processing parameters on the sensory attributes of dried shrimp were also investigated. Small shrimp (350 to 360 shrimp/kg) and large shrimp (150 to 160 shrimp/kg) were boiled and then dried until their moisture content was around 25% (d.b.). It was found that the degree of color changes, toughness, and shrinkage of shrimp increased while the rehydration ability decreased with an increase in the concentration of salt solution and boiling time. Size of shrimp and drying temperature significantly affected all quality attributes of dried shrimp. The conditions that gave the highest hedonic scores of sensory evaluation for small dried shrimp are the concentration of salt solution of 2% (w/v), boiling time of 7 min, and drying air temperature of 120 degrees C. On the other hand, the conditions that gave the highest hedonic scores of sensory evaluation for large dried shrimp are the concentration of salt solution of 4% (w/v), boiling time of 7 min, and drying air temperature of 100 degrees C. The quality attributes of dried shrimp measured by instruments correlated well with the sensory attributes, especially the color of dried shrimp.