title: Identification of the medicinal off-flavor compound formed from ascorbic acid and (E)-hex-2-enal.
abstract: A test apple beverage made up of apple juice (20%), high-fructose corn syrup (11.5%), citric acid (0.43%), trisodium citrate (0.02%), apple-odor flavor (0.1%), and ascorbic acid (0.02%) was stored at 40 °C and then analyzed for the change of odor in the beverage. Although no thermoacidophilic bacteria (TAB) were detected, a medicinal off-flavor was perceived after the 8 weeks of storage. Model experiments on the ingredients of the test apple beverage revealed that the off-flavor compound had been formed by ascorbic acid and (E)-hex-2-enal. Synthesis and NMR (¹H, ¹³C, HMQC, and HMBC) analyses identified the compound as 6-propylbenzofuran-7-ol. The odor quality, retention index (RI), and mass spectrum of synthetic 6-propylbenzofuran-7-ol were identical with those of the medicinal odor compound from the test apple beverage. Sensory evaluation revealed the recognition thresholds for medicinal odor were 31.4 ppb in water and 24.0 ppb in apple beverage, and the detection thresholds were 19.6 ppb in water and 8.6 ppb in apple beverage, respectively. The quantified concentration of 6-propylbenzofuran-7-ol formed in test apple beverage was 90 ppb, approximately. This concentration was well above the odor threshold, so it was concluded that the compound was the source of the medicinal off-flavor.
authors.affiliation: Technical Research Institute R&D Center, T. Hasegawa Co., Ltd. , 29-7 Kariyado, Nakahara-ku, Kawasaki-shi 211-0022, Japan. kensuke_sakamaki @t-hasegawa.co.jp
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: Fujita
mesh_terms: D000447:Aldehydes / Q000032:analysis*; D001205:Ascorbic Acid / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D005421:Flavoring Agents / Q000032:analysis*; D006801:Humans; D027845:Malus / Q000737:chemistry; D013058:Mass Spectrometry; D009812:Odorants / Q000032:analysis; D013649:Taste
chemical_list: D000447:Aldehydes; D005421:Flavoring Agents; C051750:2-hexenal; D001205:Ascorbic Acid