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Title: Development of an integrative process for the production of angiotensin converting enzyme inhibitory peptides from whey using proteolytic mixtures
Author: Welderufael, Fisseha Tesfay
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2011
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Abstract:
In recent years, nutraceuticals and functional foods have attracted considerable interest as potential alternative therapies for treatment of hypertension, especially for pre-hypertensive patients. Researches to date on a new technology suitable for production of hydrolysate have gained in importance. Currently, most hydrolysates are produced in a batch reactor followed by , subsequent purification technologies. Here, we present the findings of an integrative process that contains anion exchange adsorber in a stirred tank reactor fitted with micro filtration membrane for the production of ACE inhibitory hydrolysates. The adsorption kinetics and capacity were first elucidated using a standard solution of β- lactoglobulin. Higher binding capacity with short adsorption time was achieved because of strong electrostatic and hydrophobic interactions. In the case of β-lactoglobulin from whey, the adsorption capacity decreased because of the presence of ions and other whey proteins. However, a higher recovery of β-lactoglobulin (98%) and casein derived peptides (CDP) (76%) was achieved while only 21 % for α-lactalbumin. The hydrolysis of the proteins while bound could result in two different hydrolysates enriched in ACE inhibitory peptides; one from CDP at 2 h (IC50=288 μg/ml) and the other one from β-lactoglobulin after removing the 2 h hydrolysate. The eluted hydrolysate fraction also had antioxidant activity; this could lead for the production of hydrolysates with different functionality in a single production process. The 2h hydrolysate contained the well-known and widely studied potent antihypertensive tri- peptide IPP and several other novel peptides. Ten major peptides from the β-lactoglobulin hydrolysate were also identified. Two of the peptides lIAE and KPTPEGDLEILL were the most abundant and have structural similarity with other ACE inhibitory peptides. Particularly, the C- terminal sequence of the tetrapeptide lIAE has structural similarity with that of micro algae derived tripeptide lAB (IC50=34.7μM). This peptide could be the main contributor for the bioactive potency of this hydrolysate. Furthermore, the simulated gastrointestinal digestibility study demonstrated the bioactivity of the hydrolysates did not change. The in-silico digestibility study of individual pep tides indicated most of the peptides were stable or cleaved only partially without affecting their C-terminal sequences. This is an interesting outcome and further investigation was conducted after scaling-up the process. These scale-up hydrolysate products were then spray dried to study the sensory attributes and the impact of processing in bioactivity. No significant changes were observed in both studies. Furthermore, the same bioactivity was achieved comparing the scale-up and lab scale hydrolysates. In conclusion, this process was successfully investigated and proved to have several benefits. In this context, the results of this study provided several interesting evidence giving some new insights about various different aspects: (i) produce two different ACEi hydrolysates; (ii) the non-hydrolyzed substrate, less active ACEi and bitter causing peptides remain adsorbed on the resin and resulted partial fractionation; (iii) high stability of residual enzyme activity; (iv) the adsorbed hydrolysate fraction (elute) showed antioxidant activity that might be very effective to promote the production of both ACE inhibitory and antioxidant hydrolysates in a single production process; (vi) the in-vitro simulated digestibility study demonstrated the stability of the bioactivity after digestion.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.559250  DOI: Not available
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