Design of a Continuous Type Dryer for the Drying Kinetics Study of Foamed and Non-Foamed Mango Pulps

A continuous type dryer was designed for drying of foamed mango pulp at 0.30 kg/h w.b. over the 0.40-m2 surface area of the dryer belt. The pulp contained 10% egg albumen as a foaming agent and 0.5% methyl cellulose as a stabilizing agent. The dryer was operated with air heated to 60C and one mm foam thickness. Batch studies using similar conditions demonstrated that the foamed mango pulp could be dried to 5.07 % w.b. in 40 min when the foam was spread to a mat density of 0.52 kg/m2 w.b. Similarly, non-foamed pulp could be dried to 6.03% w.b. in 100 min when the pulp was spread to a mat density of 1.01 kg/m2. When the dryer was operated in continuous mode at a residence time of 35 min and a mat density of 0.52 kg/m2 w.b., the foamed mango pulp dried rapidly compared to the batch conditions, giving a final moisture content of 5.02% w.b. Biochemical changes were less for foamed drying compared to non-foamed drying.