402 Chapter 16
enhancement. Scientifi c evidence suggests
a role of casein peptides in blood pressure
regulation. Conversion of angiotensin - I to
angiotensin - II is inhibited by certain hydroly-
zates of casein and whey proteins. Angiotensin -
II raises blood pressure by constricting blood
vessels; thus, its inhibition lowers blood pres-
sure. This ACE inhibitory activity therefore
makes dairy foods a natural functional food
for controlling hypertension. A commercial
ingredient derived by the hydrolysis of milk
protein has an anxiolytic bioactive peptide
with anti - stress effects. Psychometric tests
and measurement of specifi c hormonal
markers have displayed an anti - stress effect.
The glycomacropeptide released from κ -
casein as a result of proteolysis may be
involved in regulating digestion as well as
modulating platelet function and thrombosis
in a benefi cial way. It is reported to sup-
press appetite by stimulating the CCK hor-
mone. Consequently, it may be a signifi cant
ingredient of satiety diets designed for weight
reduction. Furthermore, this peptide may
inhibit binding of toxin in the gastrointesti-
nal tract.Bioactive peptides are generated during
digestive processes in the body and during
the fermentation processes used in fermented
dairy foods (Gobbetti et al., 2007 ). These
peptides are inactive in the native proteins
but assume activity after they are released
from them. They contain three to 64 amino
acids and display largely hydrophobic char-
acter and are resistant to hydrolysis in the
gastrointestinal tract. They can be absorbed
in intact form to exert various physiological
effects locally in the gut or they may have a
systemic effect after entry into the circulatory
system. Casomorphins derived from milk
caseins are known to be opioid agonists,
while casoxins act as opioid antagonists. The
opioids have analgesic properties similar to
opium. Casokinins are antihypertensive
(lower blood pressure), casoplatelins are
antithrombotic (reduce blood clotting), and
phosphopeptides are mineral carriers.
Casein phosphopeptides may aid in bio-
availability of calcium, phosphorus, and mag-
nesium for optimum bone health; may help
prevent dental caries, and may play a role in
secretion of entero - hormones and immune
Table 16.14. Physiological attributes of bioactive peptides derived from digestion of caseins and
whey proteins.
Peptide Origin Function
β - casomorphin - 4 β - casein Opioid agonist, induces muscular rigidity
β - casomorphin - 4amide β - casein Opioid agonist, most potent casomorphin
β - casomorphin - 5 β - casein Increases pain threshold, causes behavioral change
β - casomorphin - 7 β - casein Increases prolactin release (in rat)
β - casomorphin - 11 β - casein In vivo digestion product
Casoxin - A and B κ - casein Opioid anatagonistic
Casoxin - C κ - casein Opioid agonist, phagocyte - stimulating activityCasokinin - 5 and 6 α (^) s1 - casein ACE inhibitory, anti - hypertensive
Casoplatelins κ - casein Antithrombotic
Casocidin - 1 α - and β - caseins Antimicrobial
Immunopeptides α - and β - caseins Immunostimulants
Phosphopeptides α - and β - caseins Mineral carriers
Glycomacropeptide κ - casein Suppress appetite, anti - platelet, anticancer,
antihypertensive, prevent dental caries, gingivitis,
antiviral, antibacterial, bifi dogenic/probiotic
β - Lactorphin
α - lactorphin
β - lactoglobulin
α - lactalbumin
Opioid agonist, inhibition of
angiotensin - I - converting enzyme
Lactkinins β - lactoglobulin
α - lactalbumin
ACE inhibitory (antihypertensive)
Lactoferricin Lactoferrin Antimicrobial activity
Lactoferroxins Lactoferrin Opioid antagonist
Adapted from Aimutis (2004) , Boehm et al. (2007) , Harper (2000) , Pihlanto - Leppalo (2003) , Saxelin et al. (2003)