Changes in mango foam morphology and its effects on texture and selected phenolics during foam mat drying

Abstract

Foam mat drying can yield various foam morphologies, influencing product quality and texture. This study investigated the effects of foam density (0.3, 0.5 and 0.8 g/cm3), drying temperature (60, 70 and 80 °C) and final moisture content (12 and 4% d.b.) on drying characteristics and product quality. Lowering foam density increased porosity, enhancing the second falling drying rate and minimizing differences in drying time to achieve moisture contents of 12 and 4% (d.b.). Lower-density mango foams exhibited superior retention of total phenolics content (TPC) and antioxidant activity compared to higher-density foams. TPC losses and reduced antioxidant activities were not significantly different for 12% and 4% (d.b.) mango foams. However, a shorter drying time with increased drying temperature resulted in higher TPC losses and reduced antioxidant activities, while maintaining higher levels of gallic acid and chlorogenic acid. The drying temperature had no discernible impact on shrinkage and texture. Lower-density foam structures exhibited reduced hardness, crispness and toughness. Mango foam mats with an initial density of 0.3 g/cm3, dried at 60 °C, showed minimal shrinkage (1–2%), TPC loss (7%), and reduced antioxidant activity (11–17%). However, panelists preferred a commercial snack due to the sponginess and less crispiness of 4% dried mango foam mats with initial densities of 0.3 and 0.5 g/cm3. Compared to commercial mango leather, the 12% dried mango foam mat with an initial density of 0.8 g/cm3 had similar toughness, but was harder, resulting in a preference for commercial mango leather.