title: Content of free D-Ala and D-Glu in traditional Asian fermented seasonings.
abstract: Free D-amino acids have increasingly attracted attention due to their physiological roles and pathological effects on animals, including humans. In this study, using a chiral high-performance liquid chromatography system, we determined free D-amino acids, particularly D-Ala and D-Glu, in traditional seasonings of four soy sauces, three misos, and four fish sauces that are commonly used in Asian cuisine. Examination of the average contents of the free D-amino acids in all the samples revealed that the content of D-Ala was 3.6 times higher than that of free D-Glu, while the average content of free L-Ala was lower (0.8 times) than that of free L-Glu. The average content of free L-Ala was significantly higher in the soy sauces (53 µmol/g sample) and fish sauces (53 µmol/g sample) than in the misos (14 µmol/g sample), whereas the average content of free D-Ala was almost equal among the soy sauces, misos, and fish sauces (0.25, 0.29, and 0.23 µmol/g sample, respectively). Taken together, neither free D-Ala nor D-Glu content showed a correlation with its free L-form in the samples, suggesting that the D-enantiomers are not necessarily produced by the same factors as those for the L-enantiomers, which originate from raw materials. Thus, factors specific to the production process of the fermented seasonings appear to play a significant role in their enantiomer content.
authors.affiliation: The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Mori
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagasawa
mesh_terms: D000409:Alanine / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis; D001208:Asia; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D005421:Flavoring Agents / Q000737:chemistry*; D018698:Glutamic Acid / Q000032:analysis*; D017747:Seafood / Q000032:analysis*; D045730:Soy Foods / Q000032:analysis*; D013025:Glycine max / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D005421:Flavoring Agents; D018698:Glutamic Acid; D000409:Alanine