Optimization of Spray-Drying Process of Jerusalem artichoke Extract for Inulin Production

Jerusalem artichoke is an important natural matrix for inulin production. In this experiment, response surface methodology (RSM) was employed to optimize the spray-drying parameters in order to determine the maximal inulin yield. For this study, three independent variables (heating temperature (Tª, 110-120 °C), creep speed (V, 18-22 rpm) and pressure (P, 0.02-0.04 MPa)) were used in the experimental design. Using the Box-Behnken design, the optimal parameters obtained were: drying temperature 114.6 °C, creep speed 20.02 rpm, and pressure: 0.03 MPa. The inulin yield, water content and particle size of inulin obtained by spray-drying and freeze-drying were compared. In this regard, the spray-dried inulin consisted of a white powder having a fine particle size, and the freeze-dried inulin had a pale-yellow fluffy floc. On the other hand, the drying methods had a great influence on the appearance and internal structure of inulin powder, since the spray-dried inulin had a complete and uniform shape and size, whereas the freeze-dried inulin had a flocculated sheet structure. The analysis showed that the spray-drying led to a higher inulin yield, lower water content and better surface structure than freeze-drying.