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STUDIES ON BIOACTIVE PEPTIDES OF BUFFALO’S MILK AND ITS PRODUCTS
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Abstract: Proteins and peptides play important roles in living body systems by controlling, directing and/or coordinating inter- and intra-cellular communications and cellular function. From a nutritional perspective, peptides are more bioavailable than proteins even compare to free amino acids. These peptides with low molecular weight have been known to be less allergenic than their native proteins.
Bioactive peptides (BPs) have been defined as specific protein fragments that have a positive impact on body functions or conditions and may influence health.
Functional properties of such peptides are released only after degradation of the native protein by enzymatic hydrolysis, fermentation of milk conducted by the starter cultures or non-starter cultures of proteolytic bacteria and other processes used in dairy production, storage and milk digestion by digestive enzymes.
Milk and dairy products are the greatest sources of bioactive proteins and peptides. Although, bovine, goat, sheep and camel milks have received much interest and study concerning the presence of bioactive peptides, little researches have been conducted on buffalo’s milk and buffalo’s yogurt while no studies were carried out on Domiatti cheese as a source of bioactive peptides, therefore this thesis aimed to:
1-Through light on the effect of some proteolytic enzymes on the functionality of buffalo’s casein and whey hydrolysates.
2-Study the effect of starter culture on the functionalities of water soluble extract of buffalo’s yoghurt during cold storage.
3-Study the functionalities of water soluble extract of Domiatti cheese (as affected by addition of neutrase) during ripening.
4-Identification of the bioactive peptides in WSPE of both of the resultant yoghurt and Domiatti cheese.
a: Functionalities of buffalo’s casein and whey hydrolysates
Both of buffalo’s casein and whey were hydrolysed by: neutrase, thermolysin and pepsin for 4h at 37 and 42 ?C. The hydrolysates were examined for: degree of hydrolysis (DH), antioxidant, ACE- inhibitory activities, antibacterial and antifungal activity and anticancer effects. The obtained results can be illustrated as follows:
1-As for casein hydrolysate, the DH increased gradually in all samples during hydrolysis and the highest value was obtained in case of thermolysin (84.27%) followed by neutrase (63.18%) and lastely by pepsin (58.44%). The DH values of whey hydrlysate also increased gradually during hydrolysis time (4h) with significant differences between treatments. The highest value was recorded for neutrase (48.32%) followed by thermolysin and pepsin treatments (34.03 & 30.08%).
2-As for the radical scavenging activity (%) of casein hydrolysate using the DPPH methods, it is obvious that it ranged from 55.50 to 63.85% (after 4h), while in case of ABTS, the highest value was recorded in casein hydrolysed by thermolysin being 51.65% followed by neutrase (47.04%) and lastly pepsin (33.74%).
The radical scavenging activity (%) of whey hydrolysate (using DPPH assay) was the highest in case of thermolysin being 62.03 followed by pepsin (57.64%) and lastly by neutrase (46.59%), while whey hydrolysate with neutrase had the highest radical scavenging activity % (40.54%) followed by thermolysin (36.91%) and lastly pepsin (30.13%), using the ABTS assay.
3- It is clear that almost all casein and whey hydrolysates had antibacterial effect against the tested strains. Also, it is noticeable that the antibacterial activity of both of casein and whey hydrolysates by pepsin was the highest against most of the tested strains. As for the MIC of both of casein and whey hydrolysates, it ranged from 60 to 80 mg powder/ ml for all the tested strains. All hydrolysates had antifungal activity against most of the tested fungal strains. The pepsin whey hydrolysate had no effect on A. niger and Ca. albicans while casein hydrolysate with pepsin had non antifungal effect against P. expansum. The MIC ranged from 60 to 100 mg powder/ml.
4- The ACE inhibitory activity (%) increased as the concentration of protein content increased. The ACE inhibitory activity of casein hydrolysate was the highest with neutrase being 72.87 % (IC50 15.11 mg/ml) followed by thermolysin being 66.11 % (IC50 1.83 mg/ml) and lastly hydrolysate with pepsin being 27.23% (IC50 41.58mg/ml) with significant difference between treatments.
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| Publication year |
2018
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| Organization Name |
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| Country |
Egypt
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| Publisher |
Name:
Faculty of Agriculture Cairo University
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| Author(s) from ARC |
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| Publication Type |
PhD Thesis
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