RACEMIZATION OF AMINO-ACID RESIDUES IN CASEIN ROASTED WITH GLUCOSE AND-OR METHYL LINOLEATE

As model systems of foods, casein mixed with glucose and/or methyl linoleate were heated in an electric roaster at 120-230°C for 20 min under air or nitrogen and racemization of amino acid residues in these roasted materials was investigated by capillary column gas chromatography. On roasting the food model systems as well as in the case of pure protein, racemization in the amino acid residues occurred, and aspartic acid, glutamic acid and alanine residues were remarkably racemized. Correlation between the remaining ratio and the degree of racemization of amino acids is observed. It has been found that some components of food model systems, such as reducing sugar and lipid, promote the decomposition and racemization of amino acid residues. © 1979 Taylor & Francis Group, LLC.