Functional properties of 'native' and modified wheat germ protein isolates and fractions

Osborne-type protein fractions and alkaline wheat germ protein isolate were produced and the latter was modified by urea-treatment, reduction and re-oxidation. The effects of modification on the protein subunit structure and on functional properties were investigated. Emulsifying activity, emulsion stability, solubility and aromatic surface hydrophobicity of 'native' and modified products were determined. Usually, the functional properties of the wheat germ protein isolate and the fractions were lower compared to casein. The comparison of Osborne-fractions, showed that albumins and glutelins have better functional properties than those of alkaline isolation and the globulin fraction. The results of the modification processes used in this work show, that only the elimination of hydrogen bonds have significant effects on solubility, emulsifying stability and surface hydrophobicity. These results indicate that hydrogen bonds play a main role in the formation of wheat germ protein structure.