Enhancing mass transfer and preserving heat-sensitive quality of mango through foam mat drying

Mango puree was foamed using hydroxypropyl methylcellulose to achieve foam densities ranging from 0.3 to 0.8 g/cm3. Subsequently, these mango foams were dried at temperatures ranging from 60 to 80 °C. The experimental results showed that mango foam drying was in the falling rate period. The effective moisture diffusivity (Deff) was well described by the Arrhenius equation, with the pre-exponential factor (D0) and activation energy (Ea) closely related to the void area fraction in mango foam. This relationship led to higher Deff and shorter drying times at higher void area fractions. The minimum loss of total phenolics content (TPC) was observed in mango foams with an initial foam density of 0.3 g/cm3 dried at 60ºC, with only a 7% loss. Increasing drying temperatures to reduce drying time did not mitigate TPC loss. Similarly, the minimum reductions in antioxidant activities, as measured by both the 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid and ferric reducing antioxidant power assays, were observed in mango foams with an initial foam density of 0.3 g/cm3 dried at 60 °C, with values of 14% and 18%, respectively. Dried mango foams with lower densities exhibited more pronounced color changes due to the presence of more sponge-like voids. However, the drying temperature did not significantly affect the product color. In addition, dried mango foams with lower initial foam densities displayed a more brittle and spongy texture.