Structural and functional characterization of red kidney bean (Phaseolus vulgaris) proteins and enzymatic protein hydrolysates

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dc.contributor.supervisor Rotimi, Aluko (Human Nutritional Sciences) en_US
dc.contributor.author Mundi, Sule
dc.date.accessioned 2012-08-09T20:47:05Z
dc.date.available 2012-08-09T20:47:05Z
dc.date.issued 2012-08-09
dc.identifier.uri http://hdl.handle.net/1993/8154
dc.description.abstract Kidney bean proteins and peptides can be developed to serve as an important ingredient for the formulation of high quality foods or therapeutic products that may positively impact on body function and human health. The main goal of this thesis was to determine the in vitro structural and functional characteristics of major proteins and enzymatic protein hydrolysate of red kidney bean (Phaseolus vulgaris). Selective aammonium sulfate precipitation of the kidney bean proteins yielded 88% globulin and 7% albumin.The globulin and albumin are glycoproteins that contained ~4% and 45% carbohydrate contents, respectively. Physicochemical and functional characteristics of the globulin fraction, such as, gelation concentration, foam stability, emulsion capacity, and emulsion stability were superior to those of albumin. Reducing SDS-PAGE revealed vicilin with molecular weight of ~45 kDa as the major globulin in kidney beans. Circular dichroism spectroscopy of the purified vicilin showed reductions in α-helix, and β-pleated sheet conformations upon addition of NaCl or changes in pH. Likewise, the tertiary structures as observed from the near-UV CD spectra were also changed by shifts in pH conditions and NaCl addition. Far UV-CD showed increased β-sheet content up till 60oC from room temperature, but a steady loss in the tertiary structure as temperature was further increased; however, β-sheet structure was still detectable at 80oC. Differential scanning calorimetry thermograms showed a prominent endothermic peak with denaturation temperature at around 90oC, attributed to thermal denaturation of vicilin. Alcalase hydrolysis of kidney bean globulin produced multifunctional peptides that showed potential antihypertensive properties because of the in vitro inhibition of activities of renin and angiotensin I converting enzyme as well as the antioxidant properties. The <1 and 5-10 kDa peptide fractions exhibited highest (p<0.05) renin inhibition and the ability to scavenge 2, 2-Diphenyl-1-picrylhydrazyl free radical, inhibit peroxidation of linoleic acid and reduce Fe3+ to Fe2+. Based on this study, incorporation of kidney bean globulin as an ingredient may be useful for the manufacture of high quality food products. Likewise, the kidney bean protein hydrolysates, especially the <1 kDa fraction represent a potential source of bioactive peptides for the formulation of functional foods and nutraceuticals. en_US
dc.subject Kidney beans en_US
dc.subject Physicochemical properties en_US
dc.subject Functional properties en_US
dc.subject Vicilin en_US
dc.subject Circular dichroism en_US
dc.subject Fluorescence intensity en_US
dc.subject peptides en_US
dc.subject Ultrafiltration en_US
dc.subject Globulin en_US
dc.subject Antihypertensive en_US
dc.subject Alcalase hydrolysis en_US
dc.subject Antioxidant en_US
dc.title Structural and functional characterization of red kidney bean (Phaseolus vulgaris) proteins and enzymatic protein hydrolysates en_US
dc.degree.discipline Food and Nutritional Sciences en_US
dc.contributor.examiningcommittee Michael, Eskin (Human Nutritional Sciences) Prashen, Chelikani (Oral Biology)Boye, Joyce (Agriculture and Agri-Food Canada) en_US
dc.degree.level Doctor of Philosophy (Ph.D.) en_US
dc.description.note October 2012 en_US

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