Abstract
Fluidized bed granulation is widely used to improve flowability and solubility of various kinds of powdered food products. Aqueous solution is usually sprayed to the powder to grow the granules in the process, however, increase in the moisture content of granules often spoils the product quality and elongates successive drying period. This study investigated effects of binder spraying rate (10～40 g/min) and binder atomizing air pressure (0.05～0.25 MPa) on the moisture balance of the fluidized bed and the granule growth to determine the preferable binder spraying condition for mixed powder of maize starch (800 g) and dextrin (200 g). Although the amount of binder that evaporated without binding the particles increased as the binder spraying rate increased, the ratio of the evaporated binder to the amount of totally sprayed binder decreased from approximately 60% to 30%. The pressure of binder atomizing air had no effect on the powder moisture content. The amount of binder required for the granulation decreased at faster binder spraying rate and lower atomizing air pressure, however, coarse particles were produced in these conditions. At lower binder spraying rate, spherical and uniform size granules were produced.
