Influence of Process Conditions on Drying by Atomization Pulp Umbu

Abstract

The present study evaluated the influence of variables involved in the drying process by atomization on the physico-chemical properties of umbu powder. The process was carried out using a laboratory scale atomizer with DE 15 maltodextrin as the carrier agent. Seventeen assays were performed according to a central composite rotational design. The independent variables were drying air temperature, mass feeding flow, and carrier agent concentration. The analyzed responses were water activity, moisture, hygroscopicity, process yield, and retention of phenolic compounds (RPC) in the final product. Drying air temperature negatively affected water activity and moisture content, i.e., higher applied temperatures led to lower water activity and moisture content in atomized umbu. However, the effects of the linear, quadratic, and interaction factors were not statistically significant over hygroscopicity and process yield at 95% level of statistical significance; therefore, it was not possible to generate a model. The RPC was influenced by the mass feeding flow and carrier agent concentration; the use of faster flows and higher concentrations of maltodextrin presented a final product with higher RPC. Based on the analysis of response surface graphs, an assay was selected and physically characterized: apparent density of 0.61 g/mL and percentage of solubility of 80.28%. Atomized umbu particles showed uniform size and formed numerous small pellets with spherical shape and predominantly rough surface.