Different reasons exist in explaining this worrying and widespread
lack of compliance with the guidelines. One of the problems, we
hypothesized, was the use of dried microbial species near their expiry
date or the use of microbial species injured during the drying because
of the inadequate processing. The presence of extracellular polysaccharides
or teichoic acids is disadvantageous for long-term survival
(Miyamoto-Shinohara et al., 2008); especially, with Lactobacillus spp.,
after freeze-drying non-trehalose-fermenting species have shown
better survival rates than fermenting species. Those species with
teichoic acid in the cell wall have lower survival rates during storage
than species with teichoic acid in the cell membrane (Miyamoto-
Shinohara et al., 2008). For Bifidobacteria, as their strict anaerobic
requirements were not respected, this may have affected their
survival during processing and storage. Furthermore, the severity of
the processing conditions adopted to guarantee the higher level of drying of the cultures could have contributed to a reduction in the
viability of the dried cultures (Morgan et al., 2006). It is therefore
necessary to select with care the appropriate microbial species and
the type of drying processing used (Morgan et al., 2006).