Foam-mat drying of shrimp: characterization and drying kinetics of foam

Abstract

The effects of water: shrimp ratio and xanthan gum (XG) concentration on characteristics of shrimp foam were investigated.  Foams were prepared from shrimp puree by adding several xanthan gum concentrations (0.1, 0.2, 0.3 % w/w), water: shrimp ratios (2:1, 3.5:1, 5:1 w/w) and whipped for five minutes.  Incorporation of 0.2% w/w XG with 3.5:1 w/w water: shrimp ratio was selected because of having better characteristics of produced foams and then dried at 50, 60 and 70°C.  Results showed that stability and density of foam increased with increasing xanthan gum concentration.  However, increasing water : shrimp ratio caused to decrease in stability and density of foam.  As the temperature increased from 50 to 70°C, the drying time decreased to 55 minutes.  Only the falling rate period could be observed during the drying process.  The average values of effective diffusivities of dried samples at mentioned temperature range were estimated to be between 3.24–6.49×10^-9 m² s^-1.  The Arrhenius equation with the activation energy value of 32.16 kJ mol^-1 described the influence of temperature on the diffusion coefficient.  Seven thin-layer drying models were fitted to the experimental data.  Among all the drying models, the Midilli–Kucuk model was found to give better prediction than the others.

Keywords: activation energy, effective diffusivity, foam-mat drying, foam characteristics, modeling, Shrimp