Drying characteristics and quality of banana foam mat

The combination of foaming and drying is an alternative method to produce crisp banana chips. The influences of whipping time and egg albumen concentration on the foam density were studied. The influences of foam density, drying temperature and egg albumen concentration on the drying characteristics and qualities of the final products in terms of shrinkage, texture and microstructure were subsequently evaluated. Banana puree with egg albumen, which was used as the foaming agent, was foamed to the densities of 0.3, 0.5 and 0.7 g/cm3. Banana foam mats with 5 mm thickness were then dried to the moisture content of 0.03 kg/kg db at 60, 70 and 80 °C and superficial air velocity of 0.5 m/s. The experimental results showed that the extensive porous structure of foams with lower densities resulted in higher drying rates, moisture diffusivities and shrinkage. Dried banana foams with lower foam densities also had lower hardness and crispness values. The drying temperature and the egg albumen concentration did not influence the textural properties of the final products, however. To produce banana chips, the initial foam density of 0.5 g/cm3 and drying temperature of 80 °C were recommended.