title: Quantitation of selected terpenoids and mercaptans in the dual-purpose hop varieties Amarillo, Citra, Hallertau Blanc, Mosaic, and Sorachi Ace.
abstract: Free terpenoids and both free and bound polyfunctional thiols were investigated in five selected dual-purpose hop cultivars. Surprisingly, the dual-purpose Sorachi Ace variety was found to contain higher amounts of farnesene (2101 mg/kg) than aromatic hops such as Saaz but only traces of 3-methylbutylisobutyrate, a compound that usually distinguishes all bitter varieties. All five cultivars investigated here showed an exceptional citrus-like potential explained by either monoterpenic alcohols or polyfunctional thiols. Among the monoterpenic alcohols, β-citronellol at concentrations above 7 mg/kg distinguished Amarillo, Citra, Hallertau Blanc, Mosaic, and Sorachi Ace from Nelson Sauvin and Tomahawk, two previously investigated dual-purpose hops, while linalool (312 mg/kg) and geraniol (211 mg/kg) remained good discriminating compounds for Nelson Sauvin and Tomahawk, respectively. Regarding polyfunctional thiols, higher amounts of 3-sulfanylhexyl acetate (27 μg/kg) characterized the Citra variety. Free 4-sulfanyl-4-methylpentan-2-one proved discriminant for Sorachi Ace, while the bound form is predominant in Nelson Sauvin. On the other hand, an S-conjugate of 3-sulfanylhexan-1-ol was found in Sorachi Ace at levels not far from those previously reported for Cascade, although the free form was undetected here. Both free and bound grapefruit-like 3-sulfanyl-4-methylpentan-1-ol (never evidenced before the present work) emerged as discriminating compounds for the Hallertau Blanc variety. The apotryptophanase assay also allowed us to evidence for the first time an S-conjugate of 2-sulfanylethan-1-ol.
authors.affiliation: Unité de Brasserie et des Industries Alimentaires, Earth and Life Institute (ELIM), Université Catholique de Louvain, Croix du Sud 2, Box L7.05.07, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Marie-Lucie Kankolongo
authors.initials: ML
authors.lastname: Cibaka
authors.affiliation: Unité de Brasserie et des Industries Alimentaires, Earth and Life Institute (ELIM), Université Catholique de Louvain, Croix du Sud 2, Box L7.05.07, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Jacques
authors.initials: J
authors.lastname: Gros
authors.affiliation: Unité de Brasserie et des Industries Alimentaires, Earth and Life Institute (ELIM), Université Catholique de Louvain, Croix du Sud 2, Box L7.05.07, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Nizet
authors.affiliation: Unité de Brasserie et des Industries Alimentaires, Earth and Life Institute (ELIM), Université Catholique de Louvain, Croix du Sud 2, Box L7.05.07, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Sonia
authors.initials: S
authors.lastname: Collin
mesh_terms: D027582:Humulus / Q000737:chemistry* / Q000145:classification; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D013438:Sulfhydryl Compounds / Q000737:chemistry* / Q000302:isolation & purification; D013729:Terpenes / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D010936:Plant Extracts; D013438:Sulfhydryl Compounds; D013729:Terpenes
keywords: cysteine-S-conjugates; felinine; flavor; hop (Humulus lupulus L.); polyfunctional thiols; terpenic alcohols