Drying of Baker's yeast by a new method: Dehydration by Successive Pressure Drops (DDS). Effect on cell survival and enzymatic activities

Dehydration by Successive Pressure Drops (DDS) is a new unit operation, bas ed on a repetition of compression/decompression cycles. In this work, we pr esent the application of this drying process to baker's yeast. Drying rate, cycle efficiency, cell survival and the activities of four enzymes were ev aluated. The effects of two parameters of DDS (P1 and Dvp) on drying kineti cs and product quality were studied, using the surface responses methodolog y. The results were also compared to those obtained with freeze-drying. P1 had a positive effect on drying rate. Both P1 and Dvp had an effect on cycl e efficiency, particularly Dvp. Cell survival were much higher than that ob tained with freeze-drying, with no significant impact of the parameters. Th e enzymatic activities were higher or close to the corresponding activities of freeze-dried sample, except the glucose-6-phosphate activity. The effec ts of P1 and Dvp varied according to the enzyme.