الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 147 |  |  |
| | | from | 147 | | |
Abstract
Milk proteins considered to be precursors of many important bio-active components i.e peptides, these bio-active peptides have a hormone-like effect, for example, immunodulatory, antihypertensive …etc.
The bio-active peptides could be liberated by, A) hydrolysis of milk proteins by gastrointestinal enzymes, B) fermentation of milk and C) hydrolysis of milk proteins by proteolytic enzymes from animals, plants or microorganisms, and sometimes a combination between two of these methods to liberate bio-active peptides with specific function.
The Renin-Angiotensin-Aldosterone system considered to be responsible for the regulation of blood pressure, the angiotensin converting enzyme (ACE) converts angiotensin І to angiotensin ІІ, the later compound causes hypertension. The inhibition of ACE is the main idea of treating hypertension.
Hypertension drugs have a bad side effects on kidneys and this affects the other functions of the body system, in the past two decades, the researchers were trying to find out new drugs from natural resources and have a good effect against the ACE.
According to the World Health Organization (WHO) reports, there are a billion person in the world suffering from hypertension and this causes 9.4 million death each year.
So, the importance of this study is to discover a new bio-active peptides with ACE-inhibitory activity, also, magnification
of some dairy products, such as, yoghurt to contain ACE-inhibitors besides its nutritional value.
This study was divided into two parts
Part 1:
3- Liberation of new bio-active peptides that inhibit angiotensin-converting enzyme during the fermentation of milk by different lactic acid bacteria and kombucha liquor (fermented green tea) cultures.
UHT milk was fermented by different microorganisms i.e: Lb. casei ATCC 7469, Lb. delbreuckii subsp. bulgaricus, Lb. acidophilus, Lb. helveticus, Lc. lactis subsp. lactis ATCC 11454, Pediococcus acidilactici PO2 ATCC 643, Leuconostoc mesenteroides ATCC 14935, Lb. paracasei 6A and kombucha liquor. The fermentation process time was 72 h at 37°C. The crude extracts of the fermented milks were ultrafilterd using 3 and 10 KDa filters, the obtained filtrates were, A) crude extraxts, B) 3-KDa filtrate and 10-KDa filtrate.
The different treatments of UHT milk were as follows:
- Control non-inoculated UHT milk
- T1 UHT milk fermented with Lb. casei ATCC 7469
- T2 UHT milk fermented with Lb. delbreuckii subsp. bulgaricus
- T3 UHT milk fermented with Lb. acidophilus
- T4 UHT milk fermented with Lb. helveticus
- T5 UHT milk fermented with Lc. lactis subsp. lactis ATCC 11454
- T6 UHT milk fermented with Pediococcus acidilactici PO2
- T7 UHT milk fermented with Leuconostoc mesenteroides
ATCC 14935
- T8 UHT milk fermented with Lb. paracasei 6A
- T9 UHT milk fermented with kombucha liquor
The kombucha liquor microorganisms were isolated then identified using 16s rDNA gene for bacterial isolates and 26s rDNA gene for yeast isolates. The 16s rDNA sequences for six bacterial isolates from kombucha liquor showed that the isolated bacteria are Gluconobacter oxydans with different cods at a rate of 95 to 98%. The 26s rDNA sequences for the yeast isolates from kombucha liquor showed that the isolated yeasts are Dekkera anomala (at 100 % of the probability).
from the obtained results it was clear that:
The higher ACE-inhibitory activity were from the 10 KDa filtrates in all treatments through all interval times of fermentation.
T1, T8 and T9 10-KDa filtrates after 72 h of fermentation found to have high ACE-inhibitory activity, as they were 81.98, 68.34 and 91.90%, respectively.
The 10-KDa filtrates of T1 and T9 were chosen to be purified at two stages of RP-HPLC, then identification of the peptides using LC-MS/MS.
The identified peptides of T1 (Lb. casei ATCC 7469) 10-KDa filtrate were:
1) Leu-Val-Glu-Ser-Pro-Pro-Glu-Leu-Asn-Thr-Val-Gln
2) Leu-Thr-Gln-Pro-Leu-Ala-Pro-Lys
3) Val-Leu-Glu-Ser-Pro-Pro-Glu-Leu-Asn
4) His-Ser-Ala-Phe-Glu-Val-Val-Lys-Thr
5) Trp-Gly-Tyr-Leu-Ala-Tyr-Gly-Leu-Asn
6) Trp-Gly-Tyr-Leu-Ala-Tyr-Gly-Leu-Asp