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

26 Section I: Bioactive Components in Milk
A number of in vitro studies have demonstrated
that fermentation of milk with starter cultures or
enzymes derived from such cultures prior to or after
treatment with digestive enzymes can enhance the
release and alter the profi le of bioactive peptides
produced. It can be speculated that such events may
happen also under in vivo conditions in the gastrointestinal
tract. S ü tas et al. (1996) found that successive
hydrolysis of casein fractions with pepsin and
trypsin, respectively, produced both immunostimulatory
and immunosuppressive peptides as measured
in vitro with human blood lymphocytes. When the
caseins were hydrolyzed by enzymes isolated from
a probiotic strain of Lactobacillus GG var. casei
prior to pepsin - trypsin treatment, the hydrolysate
became primarily immunosuppressive, suggesting
that the bacterial proteinases had modifi ed the
immunomodulatory profi le of caseins. These results
imply that it may be possible to reduce allergenic
properties of milk proteins by a double enzymatic
treatment as described above. Pihlanto - Lepp ä l ä
et al. (1998) studied the potential formation of
ACE - inhibitory peptides from cheese whey and
caseins during fermentation with various commercial
dairy starters used in the manufacture of yogurt,
ropy milk, and sour milk. No ACE - inhibitory activity
was observed in these hydrolysates. However,
additional successive digestion of the hydrolysates
with pepsin and trypsin resulted in the release of
several strong ACE - inhibitory peptides derived primarily
from α s1 - casein and β - casein. In a recent
study Lorenzen and Meisel (2005) demonstrated
that trypsin treatment of yogurt milk prior to fermentation
with yogurt cultures resulted in a release
of phosphopeptide - rich fractions. In particular,
the release of the CPP sequences β - CN(1 – 25) - 4P
and α s1 – CN(43 – 79) - 7P during trypsin treatment
was pronounced, whereas the proteolysis caused
by peptidases of the yogurt cultures was not
signifi cant.
Bioactive Peptides in Dairy Products
and Novel Applications
A great variety of naturally formed bioactive peptides
have been found in fermented traditional dairy
products, such as yogurt, sour milk, dahi (an Indian
fermented milk), quark, and different types of cheese
(FitzGerald and Murray 2006 ). The occurrence, specifi
c activity, and amount of bioactive peptides in
fermented dairy products depend on many factors,
such as type of starters used, type of product, time
of fermentation, and storage conditions (Korhonen
and Pihlanto 2006 ; Ard ö et al. 2007 ). Ong et al.
(2007) have studied the release of ACE - inhibitory
peptides in cheddar cheese made with starter lactococci
and commercial probiotic lactobacilli. The
results demonstrated that ACE inhibition in cheese
was dependent on proteolysis to a certain extent.
The addition of probiotic strains increased the ACE -
inhibitory activity in cheese during ripening at
4 ° C.
Table 2.2 gives examples of bioactive peptides
found in different fermented dairy products. It is
noteworthy that in these products peptides with different
bioactivities, e.g., calcium - binding, antihypertensive,
antioxidative, immunomodulatory, and
antimicrobial, can be found at the same time. The
formation of peptides can be regulated to some
extent by starter cultures used, but the stability of
desired peptides during storage seems diffi cult to
control (Ryh ä nen et al. 2001 ; B ü tikofer et al. 2007 ).
The potential health benefi ts attributable to bioactive
peptides formed in traditional dairy products warrant
extensive research. In a recent study, Ashar and
Chand (2004) demonstrated that administration of
dahi reduced blood pressure in middle - aged hypertensive
male subjects. Two fermented milk products
are on the market, and they have been developed
with the aim to provide clinically effective amounts
of antihypertensive peptides, that can be consumed
on a daily basis as part of a regular diet. These commercial
products are the Japanese fermented milk
product Calpis or Ameal S and the Finnish fermented
milk product Evolus; both contain the same
ACE - inhibitory peptides Ile - Pro - Pro and Val - Pro -
Pro. The blood pressure – reducing effects of both
products have been established in many animal -
model and human studies (FitzGerald et al. 2004 ;
Hartmann and Meisel 2007 ; Korhonen and Pihlanto
2007b ).
An increasing number of ingredients containing
specifi c bioactive peptides derived from milk protein
hydrolysates have been launched on the market
within the past few years or are currently under
development. Such peptides possess, e.g., anticariogenic,
antihypertensive, mineral - binding, and stress -
relieving properties. Examples of these commercial
ingredients and their applications are listed in
Table 2.3 .