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138 IV.Resultados y discusión. Capítulo II
decreased reaching a unit below the initial value. These changes were
expected considering that starters were viable over the entire storage time
and, therefore, they were still generating acidic compounds.
Although the viability of starter bacteria decreased during the storage
time, especially in L. reuteri, the minimum survival recommended (10 7
cfu/mL) was ensured in both strains until the end of the storage (Sanz and
Dalmau, 2008). Results show that both microorganisms are highly resistant
to an acidic environment and that the oat formulation contained sufficient
nutrients for starter growth during the whole storage time. Previous works
have also shown good fermentation results of L. reuteri by using oat as
culture media (Johansson et al., 1993; Mårtensson et al., 2002).
3.3.2. Sugar and -glucan contents
The concentration values of these components can provide interesting
information about bacterial activity during the product shelf life. Table 4
shows the values of each sugar identified in oat fermented product and their
changes throughout the storage time. In Figure 3, typical chromatograms,
with the sugar peaks obtained for both non-fermented milk and that
fermented for 28 days at 4 ºC, are shown.