| dc.description.abstract | The aims of this work were to optimize the spray drying and fluidized bed drying processes in order to obtain a dehydrated product with desirable properties at a lower energy consumption and production cost. The optimization was made by using response surface methodology. A rotatable central composite design was used to establish optimum drying conditions. For the spray drying process, the independent variables
investigated were the inlet air temperature (180 to 220 °C), outlet air temperature (80 to 100 °C) and silica and maltodextrina (DE-10) as wall material at 2 and 5%, respectively. For the fluidized bed drying the
factors investigated were the drying time (60, 90 and 120 min), drying air temperature (50, 60 and 70 °C), and particle size (0.5, 2 and 3.5 cm). By superimposing the contour plots was obtained the feasible region. The optimun spray drying conditions were the inlet air temperature of 180 °C, outlet air temperature of 84.91 °C and 2.91 % of wall material. Under these conditions, 0.1008 kg/h of dried product was obtained, with a moisture content of 2.85% and water activity of 0.2390, and the product cost was $ 19.7095 kg with an energy consumption of 2.1274 kW·h/kg of dry product. The best fluidized bed drying conditions were the particle size of 1.7 cm, drying temperature of 55 °C and drying time of 72 min. The results obtained for the optimum conditions were close to the predicted values obtained from the optimization. 0.047 kg/h of dried product was obtained, with a moisture content of 0.77% and water activity of 0.36, and the count of lactobacilli was 6.66 log CFU with protein and sodium chloride content of 30.79 and 2.46, respectively. | es |
