ABSTRACT
A protein is a large polymer of amino acids (AAs) linked via the peptide bond. The susceptibility of foodstuff proteins to heat damage during processing is increased in the presence of carbohydrates, owing to the Maillard reaction, which involves a condensation between the carbonyl group of a reducing sugar with the free amino group of an AA residue. Four of the reactions, conjugation, deamination, transamination, and oxymethylation, are briefly discussed here because of their biological relevance and use in the analysis of AAs and their metabolites. The amino or carboxyl group of the side chain of a-AAs ca. take part in certain chemical reactions. Since a-AAs contain both amino and carboxyl groups that are chemically active, they participate in some unique reactions, including chelation, cyclization, racemization, formation of N-carboxy anhydride, and oxidative deamination. These reactions yield AA chelates, azlactone, diketopiperazine, N-carboxy AA anhydride, peptide bonds, and aldehyde.
