| dc.description.abstract | Background:
In recent years bioactive peptides in foods and their role in improving consumer
health have attracted the attention of food industries. Due to the various biological
effects of these peptides, they are known as bioactive compounds and have a high
potential to extract and isolate from food sources and applied in the production of
new products. The present study was carried out to evaluate the antioxidant and
antimicrobial activity of peptide fractions extracted from water soluble extract of
Koopeh cheese. Also, peptides were separated into three fractions according to
their molecular weight by using ultrafiltration and the best sample was subjected
to reverse phase HPLC.
Material and Method:
In this research, traditional Koopeh cheeses of western Azerbaijan wich prepared
from cow's milk, were randomly sampled and physicochemical properties
(acidity-salt-fat-total protein-moisture content -ash -PH ) and bacterial (Total
counting of bacteria on Plate Count Agar medium) and molds / yeasts (on YGC
medium) determined for all samples according to Iranian national standards.
Water-soluble extract of all sample were converted to a powder by liofiliser.
Electrophoresis analysis was performed to determine the accuracy of separation of
peptides and removal of proteins in water-soluble extract after centrifuging and
filtration. The peptides concentration in the powder was determined by buret
method with the standard curve of bovin serum albumin, and then the antioxidant
and anti-microbial activity of peptides was determined in 200 μl of samples with
the same concentrations. Activity of peptides on inhibiting free radicals of ABTS,
2 and 2 Azinobis-Ethylbenzothiazolin-6 sulfonic acid and DPPH 2,2-Diphenyl-1-
Pyridine Hydrazyl as well as Metal Scalping were studied. Also the antimicrobialactivity of peptides in preventing the growth of E.coli, Bacillus cereus,
Staphylococcus aureus, Listeria monocytogenes, Pseudomonas aeruginosa and
Salmonella typhi-murium was investigated by Minimal inhibitory concentration
metod (MIC).
Result:
According to the results of the experiments, cheeses produced in different regions
differed in physicochemical characteristics, (acidity (0.24-4.2%), protein (12.8-
20.8%),fat (12-35%), ash (2.2-5.9%), salt (2.2-8.04%), moisture (33-51%), pH
(4.2-4.9)) which directly affected the process of ripening, proteolysis and
formation of peptides. After extraction of water soluble peptides, antioxidant and
antimicrobial activity of the extracts were investigated. Also, after examining the
antimicrobial properties against the six bacteria, some extracts, especially extracts
No. 4 and 5, showed antimicrobial effects against all bacteria especially
Pseudomonas and Bacillus. After selecting the extracts No. 4 and 6, according to
the total bioactivity characteristics, three fractions (below 2), (between 2 and 10)
and (above 10) kDa were prepared by ultrafiltration and re-evaluated by
antioxidant methods. Also, after examining MIC fractions on Pseudomonas
bacteria, peptides above 10 kDa showed the best performance compared to other
fractions.
Conclusion:
This study found that Koopeh cheese contains bioactive peptides that produced
during its unique ripping period (under the soil) with antioxidant and
antimicrobial activity. The high antioxidant properties of Koopeh cheese can be
the basis for further studies to purify and larg scale production of selected
peptides. | en_US |
