Modification of ovalbumin with oligogalacturonic acids through the Maillard reaction

Abstract

First, to examine the effect of the chain length of oligosaccharides on the advanced stage of the Maillard reaction, ovalbumin (OVA) was incubated at the dry-state with glucose or maltooligosaccharides from maltose to maltohexaose in the same molar ratio. The browning and polymerization of OVA were suppressed with an increase in the chain length of oligosaccharides. Secondly, OVA was incubated with oligogalacturonic acids prepared by hydrolysis of pectin and pectic acid with pectinase. After 3 days of incubation, 20–25 and 31% of amino groups in OVA were modified with oligogalacturonic-acids and galacturonic acid, respectively. The browning and polymerization of OVA modified with oligogalacturonic acids were markedly lower than those of OVA modified with galacturonic acid. Only small amount of precipitate was formed even when OVA modified with oligogalacturonic acid was heated at 95°C. These results suggest that the heat stability of OVA can be improved without its marked browning and polymerization by conjugation with oligogalacturonic acids through the Maillard reaction.