Vacuum drying for the production of dried starter cultures

6 Vacuum drying for the production of dried starter cultures 

The survival rate after vacuum drying can be increased by the use of an appropriate drying medium. As the most suitable protectants are dependent on the drying process, and the protective mechanisms are not yet fully understood, the most appropriate protectants must be found in elaborative experiments. For vacuum drying, the following protectants were shown to be effective sorbitol (Foerst, Reitmaier, Kulozik, 2006 Santivarangkna, Kulozik, Foerst, 2006), trehalose and sucrose (Tymczyszyn et al., 2007), and skim milk powder (King, Lin, Liu, 1998). 

For optimization of the vacuum drying process it is important to know the concentration and temperature-dependent inactivation kinetics and to link them to the drying 

As the microwave drying process can be controlled by the absorbed energy in the sample and the energy inpnt is more uniform than for contact drying (lower temperature gradients within the sample), the dynamic adaptation of process parameters seems to be possible. This process is subject of actual research of our group. 

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