This study aims to optimize the parameters of the foam-mat drying to produce banana powder. Input parameters of the foam drying such as foaming agent (egg albumin) concentration used from 5 to 15%, the foam stabilizer (maltodextrin) used from 1 to 3% and the drying temperature varied between 60 and 80^oC. Factors with 3 levels are arranged according to the Box-Behnken design, which further modelled by RSM (response surface methodology) and ANN (artificial neural network), and optimized. The drying rate and total polyphenol content (TPC) of banana powder under the studied conditions were determined as the target output. The moisture, color, total polyphenol, antioxidant activity and some physical parameters of final fine powder were analyzed. Increasing temperature has increased the drying rate. In addition, increasing the concentrations of egg albumin and maltodextrin maintained the highest TPC and maximum drying rate. ANN model showed the higher forecasting capacity than that of RSM. Moreover, simultaneous optimization of two responses (TPC and drying rate) was selected to maximize the desired value at the concentration of albumin, maltodextrin and drying temperature of 11.86%, 1.92%, 74.94^oC, respectively, corresponding to the highest TPC value and drying rate of 1.31 mgGAE/ g DW and 2.48 g water/g dry matter/min. At this condition, the drying time was recorded as 103 min. Validation of the optimal ratios showed that the experimental values of TPC and drying rate were in good agreement with the model predicted data. The moisture content and water activity of product were found to be 5.87±0.07% and 0.37±0.01. The product had bright colors with L*, a* and b* values were measured as 86.4±0.5, 1.75±0.08 and 15.2±0.3, respectively. The high DPPH radical scavenging activity was detected (53.5 %) with the water solubility index and water absorption index of banana powder was determined at value of 56.98% and 5.17 g/g, respectively. Foam mat dried banana powder was well preserved in paper packaging with aluminum foil.

Keywords: Banana, foam-mat drying, polyphenol, drying rate, modeling, optimization