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The experiments were conducted to study the effect of microwave power on drying characteristics vis-à-vis on quality attributes of foamed tomato pulp-egg albumin mixture in a microwave assisted foam-mat drying system. Samples were prepared using tomato pulp by incorporating 10% egg albumin as foaming agent and whipping for 5 min. 10 mm thick layer of foamed tomato pulp was spread on a tray and dried in the dryer at different microwave power levels (0, 480 W, 640 W and 800 W) at an inlet air temperature of 45oC. The increase of microwave power accelerated the dehydration of the foam and it was observed that the drying time reduced about 15-16 times in case of microwave assisted foam-mat drying as compared to simple foam-mat drying. There was no adverse effect on colour, titrable acidity and pH of the product, and the retention of ascorbic acid, in samples dried in microwave assisted foam-mat drying, was also better as compared to that in samples dried in air convection foam-mat dried system. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]