3. Results and discussion
3.1. Effect of cooling rate on cell viability
Many authors have highlighted the importance of cooling rate in
the freeze-drying process (Berny & Hennebert, 1991; Abadias et al.,
2001). In this vein, the first experiments were carried out in order
to evaluate the effect of cooling rate on viability of L. casei cells.
More specifically, free L. casei cells were subjected to freeze-drying
using three different cooling rates (1, 3 or 5 C/min) and their effect
on cell viability after freeze-drying and storage for 15 days at 4 C
was evaluated. The results are summarized in Fig. 1 and showed
that as the cooling rate increased, higher values of viability were
observed. This trend was more obvious after 15 days of storage, as
the cooling rate of 5 C/min resulted in significantly higher (P