Effect of microwave power on foam-mat drying of tomato pulp

Abstract

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.

Keywords: foam-mat drying, tomato, microwave drying, tomato powder