Acylation of Egg White Proteins with Acetic Anhydride and Succinic Anhydride

Egg white was acylated with acetic anhydride and succinic anhydride. Addition of 5, 10, 15, 20, and 25 moles of acylating reagent per 50,000 g of egg white protein modified 10, 24, 40, 48, and 60% of the free amino groups, respectively. Functional group analyses indicated that the phenolic group of tyrosine and the hydroxyl groups of serine and threonine did not react with the anhydrides. Sulfhydryl groups were modified 1 to 6% at the 25 mole level of acetic and succinic anhydride, respectively. Conalbumin's ability to complex iron was impaired. Lysozyme was inactivated at levels of addition above 10 m of succinic anhydride and at levels of added acetic anhydride above 20 m. Polyacrylamide electrophoretograms indicated that considerable protein charge alteration occurred. Succinylated egg whit e exhibited improved heat stability and foaming ability, and there was no change in angel cake performance. Acetylation diminished heat stability, improved foaming ability, and at the 20 mole level diminished performance in angel cakes. These results show that chemical and functional properties of egg white protein can be significantly altered by relatively mild acylation reactions.