Foaming properties of custard apple pulp and mathematical modelling of foam mat drying.

Foaming of custard apple pulp was carried out using foaming agent and stabilizer for drying of pulp in thin layers. The effect of parameters was studied and optimization was performed using response surface methodology. The concentration of egg albumen (0-20%, w/w) as foaming agent with methyl cellulose (0.0-0.50%, w/w) as stabilizer were added for whipping time (5-25 min). The foam properties were influenced by concentration of foaming agent and whipping time. The desirable foaming properties (high foam expansion, lower foam density and high foam stability) was observed at 15% of egg albumen, 0.37% of methyl cellulose for a whipping time of 17.32 min. Dehydration of optimized foamed pulp was completed within 100-140 min for 60-75 °C temperatures at 2 mm thickness of pulp. Average effective diffusivities remained 2.01-9.67 × 10-08 m2/s and activation energy was 29.99 kJ/mol.