الفهرس 
Chapter I : IntroductionOnly 14 pages are availabe for public view
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Abstract
Milk and dairy products provide a rich source of valuable proteins, minerals
and vitamins. The nutritional significance of proteins includes macronutrient as well as
physiological and functional aspects. Besides bioactive proteins, dairy products may
also provide antibacterial peptides. These are formed by enzymatic hydrolysis of intact
proteins, which themselves are not necessarily bioactive.
Antibacterial peptides from food protein deserve attention due to their
mechanism of activity, which makes microbial resistance improbable and for increasing
the functional values of food. The current study demonstrated several key points. First
and in related to lactoferrin hydrolysate (LFH), rennet LFH contains several
antibacterial peptides. One of them is previously reported as the first 11-residues of Lfcin
B. Another peptide (KLLSKAQEKFGKNKSRSFQL) has not only antibacterial
activities in broth, but also, in milk. Other two peptide(APRKNVRWCTISQPEWFKCR
and TRVVWCAVG) showed antibacterial activity in broth only.
The commercially available casein hydrolysate contains two peptides with high
levels of homology to well-known antibacterial peptides. These peptides have not only
antibacterial activities, but also have some biological activities as immuno-stimulant
and ACE-inhibiting activity in the basic autofocusing fractions.
In the sight of these results, we conclude that rennet LFH and casein hydrolysate
may be used as new nutrapreservatives to fulfill consumer’s demand for natural
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preservation of food. Moreover, the rennet LFH can be used for Islamic communities
that can’t used food products of porcine origin. In addition, the autofocusing can
increase the antibacterial activity of the peptides, so this technique could be used for the
preparation of peptide-based food preservatives to suppress microbial growth, as this
technique doesn’t require expensive and harmful solvents.
The antibacterial activity of the peptides identified in the present study from
LFH and casein hydrloysate was confirmed by using synthetic peptides in liquid media
and milk. So, further studies for the application of hydrolysates and their autofocusing
fractions in various food systems are required to give insight into what may happen in
food system.