title: Elucidating the formation pathway of the off-flavor compound 6-propylbenzofuran-7-ol.
abstract: In a previous work, we identified 6-propylbenzofuran-7-ol as an off-flavor compound formed from ascorbic acid and (E)-hex-2-enal in a test apple beverage. In this study, we elucidate the pathway by which 6-propylbenzofuran-7-ol formed. Isotope labeling studies revealed that the propyl group of 6-propylbenzofuran-7-ol derives from (E)-hex-2-enal and that 6-propylbenzofuran-7-ol contains carbons 2-6 of ascorbic acid. Two compounds, namely, 2,3-dihydro-6-propylbenzofuran-3,7-diol and 3-(2-furoyl)hexanal, were identified as byproducts of a model reaction of ascorbic acid and (E)-hex-2-enal. Each of these compounds was dissolved in an aqueous solution of citric acid and stored at 60 °C for 1 week. After storage, 6-propylbenzofuran-7-ol was detected from a solution of 2,3-dihydro-6-propylbenzofuran-3,7-diol, but not from 3-(2-furoyl)hexanal. 6-Propylbenzofuran-7-ol was formed by isolating tricyclic hemiacetal lactone derived from the Michael addition of ascorbic acid to (E)-hex-2-enal, mixing the tricyclic hemiacetal lactone with the aqueous solution of citric acid, and applying heat. This confirmed that 6-propylbenzofuran-7-ol was formed via the Michael adduct.
authors.affiliation: Technical Research Institute R&D Center, T. Hasegawa Co., Ltd. , 29-7, Kariyado, Nakahara-ku, Kawasaki-shi, 211-0022, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sakamaki
authors.forename: Susumu
authors.initials: S
authors.lastname: Ishizaki
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Ohkubo
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Tateno
authors.forename: Akira
authors.initials: A
authors.lastname: Nakanishi
authors.forename: Akira
authors.initials: A
authors.lastname: Fujita
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D001205:Ascorbic Acid / Q000737:chemistry*; D001572:Benzofurans / Q000032:analysis / Q000138:chemical synthesis*; D001628:Beverages / Q000032:analysis; D005638:Fruit; D008401:Gas Chromatography-Mass Spectrometry; D006358:Hot Temperature; D027845:Malus; D012996:Solutions; D013649:Taste
chemical_list: D000447:Aldehydes; D001572:Benzofurans; D012996:Solutions; C051750:2-hexenal; D001205:Ascorbic Acid