title: A novel method for determining vitamin B1 in a wide variety of foodstuffs with or without polyphenols.
abstract: Certain foodstuffs exhibit matrix interference effects on the vitamin B(1) analysis prescribed in the official methods of the European Union, AOAC International, and Japan. In this study, we demonstrated that one of the problematic polyphenols in green tea or cocoa was tannin. For these matrices, thiamine was found to interact with tannin in the extraction step and was thus removed by filtration as a residue. To resolve the matrix interference, we proposed lowering the pH of the extraction solution by adding hydrochloric acid after the enzyme reaction. High precision (2-3% RSDr) and good recovery (98.3-103%) were obtained with reference materials using the proposed method. We also confirmed the equivalence of the obtained data from the proposed method and the Japanese official method for nutritional labeling. From these results, the method was found to be effective for vitamin B(1) analysis regardless of the presence of interference matrices.
authors.affiliation: Japan Food Research Laboratories, 3-1 Toyotsu-cho, Suita-shi, Osaka 564-0051, Japan. yosidami@jfrl.or.jp
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Yoshida
authors.forename: Takashi
authors.initials: T
authors.lastname: Hishiyama
authors.forename: Masako
authors.initials: M
authors.lastname: Ogawara
authors.forename: Koji
authors.initials: K
authors.lastname: Fuse
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Mori
authors.forename: Tomoji
authors.initials: T
authors.lastname: Igarashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Taniguchi
mesh_terms: D002099:Cacao / Q000737:chemistry; D005504:Food Analysis / Q000379:methods*; D059808:Polyphenols / Q000032:analysis*; D013662:Tea / Q000737:chemistry; D013831:Thiamine / Q000032:analysis*
chemical_list: D059808:Polyphenols; D013662:Tea; D013831:Thiamine