Drying of immobilized yeast cells in spouted bed dryer with a moving draft tube

Brewery yeast cells immobilized in Ca-alginate were dried in a laboratory scale spouted bed with a draft tube The experiment was conducted under variable temperatures and air flow rates. Temperature and air velocity at the bottom of the column has been varied in the range from 30 to 60 oC and from 6 to 10 m/s in a duration of 60 minutes. The moisture of dryied particles was in the interval of 10.00 to 21.00 g/g , while the water activity was in the range of 0.40 to 0.45, what ensures preservation of immobilized yeast as a starter and provides the biological activity of dried particles. Rehidration process of dryied particles, proved that dried particles could restore completely their original shape and starting volume, while the mechanical resistance is somewhat reduced. The cells preserved in this way after rehidration completely restore their catalytical activity.