title: D-amino acid formation in sterilized alkali-treated olives.
abstract: The occurrence of d-amino acids in commercial ripe olives, a well-known sterilized alkali-treated product, was investigated by high-performance liquid chromatography (HPLC) with precolumn automatic derivatization. Absolute amounts of D-amino acids were in total 18.6-38.2 mg/100 g edible portion. The major D-amino acids were D-aspartic acid, D-glutamic acid, D-serine, and D-leucine. Furthermore, to evaluate the effects of sterilization time and olive pH on amino acid racemization, a simulated processing of green ripe olives was carried out. Serine (both free and bound form) was the most-racemized amino acid after heat treatment. Sterilization (15-35 min at 121 degrees C) increased the racemization values of both free and protein-bound amino acids, although in case of protein-bound phenylalanine the increase was not statistically significant. With an increase of pH from 8 to 10 units, the racemization values of all amino acids increased significantly, except for free forms of aspartic and glutamic acids. In general, the effects of the sterilization time and olive pH on total concentration (L + D enantiomers) of each amino acid were also significant.
authors.affiliation: Instituto de la Grasa (C.S.I.C.), Apartado 1078, 41012 Seville, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Casado
authors.forename: Antonio Higinio
authors.initials: AH
authors.lastname: Sánchez
authors.forename: Luis
authors.initials: L
authors.lastname: Rejano
authors.forename: Alfredo
authors.initials: A
authors.lastname: Montaño
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D026603:D-Aspartic Acid / Q000032:analysis; D018698:Glutamic Acid / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D007930:Leucine / Q000032:analysis; D031658:Olea / Q000737:chemistry*; D012694:Serine / Q000032:analysis; D013242:Sterilization
chemical_list: D000596:Amino Acids; D018698:Glutamic Acid; D012694:Serine; D026603:D-Aspartic Acid; D007930:Leucine