Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 9/14/2006
Publication Date: 9/14/2006
Citation: Mohamed, A., Singh, M., Hojillaevangelist, M.P. 2006. Functional properties of crosslinked and acetylated barley protein isolate [abstract]. American Association of Cereal Chemists Meetings. p. 187-198.
Technical Abstract: Barley protein isolate (BPI) was prepared using defatted barley flour. BPI was extracted in 0.05 N NaOH in a 10:1 ratio solvent:flour, was precipitated by adjusting the pH to 4.5 and freeze-dried. Portion of the BPI sample was crosslinked using Transglutaminase and acetylated using acetic anhydride. The surface hydrophobicity of the modified BPI was determined by a method based on that of Kato and Nakai. BPI (200 mg) was dispersed in 15 mL of 0.01M phosphate buffer (pH 8.0) and stirred for 3 hr at 35°C where the first scan was used for excitation wavelength. The initial emission wavelength was 484 nm, and the instrument was set to scan from 200-470 nm. The surface hydrophobicity of the acetylated BPI exhibited the highest value relative to the control or the BPI samples. The crosslinked BPI and the defatted barley flour showed the lowest surface hydrophobicity values. The barley protein isolates had similar values for foaming capacity, emulsifying capacity (EAI) and emulsion stability. Acetylated-BPI produced markedly less stable foam than did the acid-precipitated (AP), and was in fact the least stable foam among those produced by the flours and isolates tested. Foaming capacities of both barley protein isolates were ~ 12% less than that of AP soy protein isolate. Foams produced by the AP and acetylated barley protein isolates were also considerably less stable than foam produced by AP soy protein-isolate (30 and 60% less foam left after standing 15 min, respectively). Their EAI values were almost 50% greater than that of AP soy protein isolate.