title: Quantitation using a stable isotope dilution assay (SIDA) and thresholds of taste-active pyroglutamyl decapeptide ethyl esters (PGDPEs) in sake.
abstract: A stable isotope dilution assay (SIDA) for two taste-active pyroglutamyl decapeptide ethyl esters (PGDPE1; (pGlu)LFGPNVNPWCOOC2H5, PGDPE2; (pGlu)LFNPSTNPWCOOC2H5) in sake was developed using deuterated isotopes and high-resolution mass spectrometry. Recognition thresholds of PGDPEs in sake were estimated as 3.8 μg/L for PGDPE1 and 8.1 μg/L for PGDPE2, evaluated using 11 student panelists aged in their twenties. Quantitated concentrations in 18 commercial sake samples ranged from 0 to 27 μg/L for PGDPE1 and from 0 to 202 μg/L for PGDPE2. The maximum levels of PGDPE1 and PGDPE2 in the sake samples were approximately 8 and 25 times higher than the estimated recognition thresholds, respectively. The results indicated that PGDPEs may play significant sensory roles in the sake. The level of PGDPEs in unpasteurized sake samples decreased during storage for 50 days at 6 °C, suggesting PGDPEs may be enzymatically decomposed.
authors.affiliation: a Department of Biological Resource Sciences , Akita Prefectural University , Akita , Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Hashizume
authors.affiliation: a Department of Biological Resource Sciences , Akita Prefectural University , Akita , Japan.
authors.forename: Toshiko
authors.initials: T
authors.lastname: Ito
authors.affiliation: a Department of Biological Resource Sciences , Akita Prefectural University , Akita , Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Igarashi
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis*; D003903:Deuterium; D005504:Food Analysis / Q000379:methods*; D006801:Humans; D007201:Indicator Dilution Techniques; D010455:Peptides / Q000032:analysis*; D015203:Reproducibility of Results; D013652:Taste Threshold
chemical_list: D010455:Peptides; D003903:Deuterium
keywords: SIDA; peptide; sake; taste; threshold