Biomedical Engineering Reference
In-Depth Information
Intensive degradation of prolamin of wheat and rye has also opened new possibilities
to use these cereals even as part of gluten-free diets [
23,
40,
41
] . Controlled proteolysis
in wheat and rye doughs was suggested to reduce gluten levels to such an extent that the
products were tolerated by celiac patients [
42
]. While such sourdoughs with extended
fermentation time are not suitable for bread production as such, they can be incorporated
as baking improvers into gluten-free recipes. It was shown in a 60-day clinical trial that
biscuits and cakes produced using a hydrolysed wheat product made using sourdough
lactobacilli and fungal proteases were not toxic to patients with celiac disease [
43
] .
The quality of gluten-free bread is often inferior when compared to conventional
(wheat) products [
2
]. However, by degrading prolamins of wheat or rye with a pro-
teolysis-intensive sourdough process, it is possible to produce good quality gluten-
free bread with sourdough technology [
40,
42
]. The concept of complete elimination
of gluten, however, is controversial. Gluten is considered essential for wheat baking
and the complete elimination of gluten from wheat and rye, albeit possible, is tech-
nically challenging in industrial baking operations. The use of germinated rye in
sourdoughs may avoid, in part, such controversy because the water binding as well
as gas retention in rye doughs are mediated by pentosans which remain unaffected
by proteolysis [
30
] . De Angelis et al. [
23
] demonstrated that fermentation by selected
sourdough lactic acid bacteria to decrease celiac intolerance to rye flour [
44,
45
]
used flour from germinated wheat and rye grains to enhance the proteolysis and
efficient degradation of wheat and rye prolamins.
Recently, it has been demonstrated that sourdough fermentation can promote
the formation of bioactive peptides [
46-
48
] . Bioactive peptides are de fi ned as
specific protein fragments that have positive effects on body functions or condi-
tions and that may influence human health. Usually, bioactive peptides correspond
to specific sequences from native proteins, which are released through hydrolysis
by digestive, microbial, and plant proteolytic enzymes, and their levels generally
increase during food fermentation. Coda et al. [
46
] summarised that bioactive
peptides, on the basis of in vitro and in vivo studies, have demonstrated a large
spectrum of biological functions, such as opioid-like, mineral-binding, immuno-
modulatory, antimicrobial, antioxidative, antithrombotic, hypocholesterolemic,
and antihypertensive activities. The ability of selected lactic acid bacteria to
produce antioxidant peptides during sourdough fermentation by using various
cereal flours as substrates was demonstrated [
46
] . The radical-scavenging activity
of water/salt-soluble extracts (WSE) from sourdoughs was shown to be significantly
(
P
< 0.05) higher than that of chemically acidified doughs. Twenty-five peptides of
8-57 amino acid residues were identified in their study and nearly all sequences
shared compositional features that are typical of antioxidant peptides. All of the
purified fractions showed ex vivo antioxidant activity on mouse fibroblasts
artificially subjected to oxidative stress. Recently, interest in antioxidant peptides
derived from food proteins has increased, and evidence that bioactive peptides pre-
vent oxidative stresses associated with numerous degenerative aging diseases (e.g.
cancer and arteriosclerosis) is accumulating [
49
] .
Rizzello et al. [
47
] exploited the potential of sourdough lactic acid bacteria to
release lunasin, an anticarcinogenic peptide, during fermentation of cereal and
