[Formation of dehydroalanine, lanthionine and lysinoalanine during heat treatment of beta-lactoglobuline A (author's transl)].

Solutions of beta-lactoglobulin A were heated at 97.5 degrees C at pH 6.9 and 9.8 80 min. The formation of dehydroalanine, lanthionine and lysinoalanine as well as changes in the levels of cysteine, cystine and the basic amino acids were recorded. Lanthionine (equal amounts of the 1- and the mesoform) was formed only in small amounts, while the lysinoalanine levels were rather high. Beside this, lysine was converted to unknown compounds. The main sources for the formation of dehydroalanine are the cystine moieties of the protein. Cysteine residues are first oxidized to cystine before beta-elimination occurs.