Effect of proteolysis on the sialic acid content and bifidogenic activity of ovomucin hydrolysates.

Ovomucin, accounting for ∼3.5% of egg white proteins, contains 2.6-7.4% of sialic acid; sialic acid is suggested to play important roles in host-recognition, cognition and memory development. However, ovomucin's limited water solubility might restrict its future applications. The objective of the study was to examine the effect of proteolysis of ovomucin on the sialic acid content and bifidogenic activity of ovomucin hydrolysates. Ovomucin extract was hydrolyzed by 14 proteases with yields and DHs ranging from 42.6% (flavourzyme) to 97.4% (protease N), and 2.4% (flavourzyme) to 46.3% (pronase), respectively. Ovomucin hydrolyzed by pronase and protex 26L showed molecular weight (Mw) distributions less than 40kDa while others larger than 200kDa. Allergenicity of ovomucin hydrolysates was significantly reduced (P<0.05) in comparison to ovomucin extract. The content of sialic acid in hydrolysates ranged from 0.1% (protex 26L) to 3.7% (pronase). Ovomucin hydrolysates did not generally support growth of Bifidobacterium spp. in vitro.