Bioactive Components in Milk and Dairy Products - Prof. Dr. Aulanni ...

24 Section I: Bioactive Components in Milk
this component in humans still remains to be established
in clinical studies. On the other hand, the
multiple physicochemical properties of GMP make
it a potential ingredient for many food applications
(Thom ä - Worringer et al. 2006 ).
Production and Functionality
of Bioactive Peptides
Bioactive peptides have been defi ned as specifi c
protein fragments that have a positive impact on
body functions or conditions and may ultimately
infl uence health (Kitts and Weiler 2003 ). The activity
of peptides is based on their inherent amino
acid composition and sequence. The size of active
sequences may vary from 2 – 20 amino acid residues,
and many peptides are known to reveal multifunctional
properties. Milk proteins are considered the
most important source of bioactive peptides. Over
the last decade a great number of peptide sequences
with different bioactivities have been identifi ed
in various milk proteins. The best characterized
sequences include antihypertensive, antithrombotic,
antimicrobial, antioxidative, immunomodulatory,
and opioid peptides (Korhonen and Pihlanto 2003 ).
These peptides have been found in enzymatic protein
hydrolysates and fermented dairy products, but they
Antihypertensive
Antioxidative
Antithrombotic
Hypocholesterolemic
Cardiovascular
system
Peptides from caseins or whey proteins
Opioid
–agonist
–antagonist
Nervous and
endocrine
system
Figure 2.2. Physiological functionality of milk - derived bioactive peptides.
can also be released during gastrointestinal digestion
of proteins, as reviewed in many articles (Meisel
1998 ; Clare and Swaisgood 2000 ; FitzGerald and
Meisel 2003 ; Kilara and Panyam 2003 ; Pihlanto and
Korhonen 2003 ; Meisel 2005 ; Korhonen and Pihlanto
2006 , 2007b ; Gobbetti et al. 2007 ; Hartmann
and Meisel 2007 ). Milk - derived bioactive peptides
may exert a number of physiological effects in vivo
on the gastrointestinal, cardiovascular, endocrine,
immune, central nervous, and other body systems,
as shown in Figure 2.2 .
Bioactive peptides are inactive within the sequence
of the parent protein molecule and can be released
from precursor proteins in the following ways: 1)
enzymatic hydrolysis by digestive enzymes, 2) fermentation
of milk with proteolytic starter cultures,
and 3) proteolysis by enzymes derived from microorganisms
or plants. In many studies a combination
of 1 and 2 or 1 and 3, respectively, has proven effective
in generating biofunctional peptides (Korhonen
and Pihlanto 2007a ). Examples of bioactive peptides
produced by the treatments above are described
below. A great number of studies have demonstrated
that hydrolysis of milk proteins by digestive enzymes
can produce biologically active peptides (Korhonen
and Pihlanto 2006 ). The most prominent enzymes
are pepsin, trypsin, and chymotrypsin, which have
Antimicrobial
MineralbindingSatietyinducing
Digestive
system
Antimicrobial
Cytomodulatory
Immunomodulatory
Immune
system