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IV. Resultados y discusión. Capítulo II 221
simulated human gastrointestinal digestion (SGID) and GG survivals are
shown in Table 3. In all the samples tested, more than half (60 - 65%) of the
initial bacteria survived to SGID, which was higher than that those values
(20 - 40%) reported by other authors (Bezkorovainy, 2001). Generally, GG
bacteria are seen to be highly resistant to acid and bile and have high
adhesion ability in in vitro enterocytes (Deepika et al., 2011; Hekmat et al.,
2009), although survival in acidic conditions might occur as long as easily
metabolisable sugars were present within the matrix (Corcoran et al., 2005).
The results obtained point to the fact that GG might be able to colonise
the human colon and, thus, exert health benefits, such as competing with
non-desirable microbiota to obtain nutrients; this last assumption is believed
to be one of the probiotics’ mechanisms of action (Buddington, 2009; Saad
et al., 2013). Nevertheless, this should be reinforced with in vitro and in
vivo assays.
As concerns proteolytic action, the OPA-based spectrophotometric
assay detects -amino groups released from peptides. Hence, information
regarding starter proteolysis can be measured by obtaining the differences
between the absorbance values of non-fermented and fermented hazelnut
milks. Proteolysis has a great influence on the final flavour of the fermented
product (Tamime and Robinson, 2000). Nevertheless, the obtained results
(Table 3) showed that the absorbance of the pasteurised milk was higher
than that of fermented products. This suggests that hazelnut milk processing
might have already hydrolysed the small amount of peptides present and
generated free amino acids that were directly consumed by the starter
bacteria to obtain the necessary nitrogen (Heller, 2001). Therefore, the heat