Nonenzymatic deamidation of food proteins.

Many cereal proteins, such as wheat, corn, and oat proteins, have high levels of the amide-containing amino acids, glutamine and asparagine. These side chains are susceptible to hydrolysis of the amide bond, which leads to release of ammonia and transformation to acidic groups. The released ammonia has been implicated in the formation of aroma compounds and pigments because of its participation in the Maillard browning reaction. The conversion of the amide groups to acid groups may partially unfold the protein, resulting in an amphiphilic molecule that can be used as a surface active agent or emulsifier by food processors. This review provides general information on the factors that affect deamidation of proteins as well as the implications of deamidation for food processing.