Enzymatic hydrolysis of ovomucin and effect on foaming properties

An ovomucin fraction was isolated from egg albumen by isoelectric precipitation, however, of low solubility. To improve solubility, the ovomucin was hydrolysed with four proteases (pronase E, alcalase, flavourzyme, neutrase) for 0-24 h. The hydrolysed ovomucin was analysed for degree of hydrolysis (DH), solubility, surface hydrophobicity (S-0), surface tension, and foaming properties: capacity and stability. The solubility of hydrolysed ovomucin increased logarithmically with DH. The pronase E exposed highest activity and neutrase the lowest, which correlated with the effect on ovomucin solubility. Hydrolysis with flavourzyme and neutrase increased the S-0, primarily during 0-6 h, but pronase E and alcalase hydrolysis reduced the S-0 compared with the unhydrolysed ovomucin. Foaming capacity reached an optimum at DH of 15-40%, and correlated highly with the initial surface tension drop. Enzymatic hydrolysis did no significantly affect the foam stability. (C) 2008 Elsevier Ltd. All rights reserved.