Process optimization for drying of Shrimp (Metapenaeus dobsoni) under hot air-assisted microwave drying technology using response surface methodology

The study was carried out to optimize the drying conditions of shrimp in the hot airassisted microwave drying system using response surface methodology. The drying experiments were performed using a Box-Behnken design with air temperature (50-70 degrees C), air velocity (.5-1.5 m/s), and microwave power level (600-1000 W) as independent variables and drying time, water activity, and rehydration ratio as independent variables. The obtained response variables were fitted into the various regression equations to predict a suitable model. The methodology of desired function was applied to indicate 61.74 degrees C air temperature, 922.61 W microwave power, and 1.0 m/s air velocity which offered a reduced drying time of 2.8 h, the water activity of .424 and improved rehydration ratio of 2.51, respectively with a desirability value of .949. The moisture content, drying efficiency, shrinkage, and total color change were determined for the samples obtained under optimized conditions and were observed as 16.5% (w.b), 35.71%, 14.14%, and 16.95 +/- 2.14, respectively. Scanning electron microscopy analysis of dried shrimp showed the formation of pores of diameters ranging from 3.17 to 10.6 mu m. The process parameters optimized under the study for hot air-assisted microwave drying can be used for the production of good-quality dried shrimps.