ABSTRACT
Introduction ........................................................................................................ 463
Materials and Methods ..................................................................................... 464
Dehydration Procedure............................................................................. 464
Results.................................................................................................................. 465
Effect of Growth at Low Water Activities in the Presence
of Sugars .................................................................................................. 465
Growth at Low Water Activities in the Absence of Sugars ................ 466
Conclusion .......................................................................................................... 467
References ........................................................................................................... 468
The cell membrane is the main target for damage during stress processes
(i.e., freeze-thawing and lyophilization) (Texeira et al., 1997). Cytoplasmic
membrane (together with nucleic acid and ribosomes) has been considered
as the cellular thermosensor. Preservation procedures imply a stress for the
cell. Therefore, the recovery of biological properties after these procedures is
one of the issues in preservation. Freeze-thaw and lyophilization are widely
used to preserve starter cultures in the dairy industry, but these techniques
imply a high cost. These reasons encouraged us to investigate the use of
dehydration as an alternative method to preserve lactic acid bacteria. From
the biotechnological point of view, the spray drying process may be highly
convenient and economical when large volumes of cultures are dehydrated.
Spray drying is a methodology that implies a thermal dehydration (Teixeira
et al., 1994, 1995a). However, starter cultures of lactic acid bacteria prepared
by spray drying cannot be used for direct inoculation of milk for dairy
fermentation due to the increase in the lag phase before growth onset.
Injured cells have extended lag periods before they start to grow. This means
that injured cells will take longer to start their desirable activities in food
fermentations (Busta, 1976; Texeira et al., 1997).
