The Role of Sialic Acid in the Functional Properties of Ovomucin

The importance of sialic acid to the foaming and emulsifying properties of ovomucin was investigated using asialoovomucin prepared by a neuraminidase treatment, which selectively cleaved the terminal sialic acid. The intrinsic viscosity of soluble ovomucin was decreased by the neuraminidase treatment, while that of reduced ovomucin was not similarly affected, suggesting the involvement of sialic acid in intermolecular interaction only for the regular conformation of ovomucin. The emulsifying properties of ovomucin were markedly decreased by the neuraminidase treatment, suggesting the importance of the repulsive force of sialic acid polyanions in the emulsion. On the other hand, the foaming properties of ovomucin were increased by the neuraminidase treatment. These results suggest that the electrostatic repulsive force of terminal sialic acids affects the emulsifying and foaming properties of ovomucin.