Chemical Characterization of Beer Aging Products Derived from Hard Resin Components in Hops (Humulus lupulus L.).
The bitter taste of beer originates from resins in hops (Humulus lupulus L.), which are classified into two subtypes (soft and hard). Whereas the nature and reactivity of soft-resin-derived compounds, such as α-, β-, and iso-α-acids, are well studied, there is only a little information on the compounds in hard resin. For this work, hard resin was prepared from stored hops and investigated for its compositional changes in an experimental model of beer aging. The hard resin contained a series of α-acid oxides. Among them, 4'-hydroxyallohumulinones were unstable under beer storage conditions, and their transformation induced primary compositional changes of the hard resin during beer aging. The chemical structures of the products, including novel polycyclic compounds scorpiohumulinols A and B and dicyclohumulinols A and B, were determined by HRMS and NMR analyses. These compounds were proposed to be produced via proton-catalyzed cyclization reactions of 4'-hydroxyallohumulinones. Furthermore, they were more stable than their precursor 4'-hydroxyallohumulinones during prolonged storage periods.
Central Laboratories for Key Technologies, Research & Development Division, KIRIN Company, Ltd. , 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa 236-0004, Japan.
Yoshimasa
Y
Taniguchi
Central Laboratories for Key Technologies, Research & Development Division, KIRIN Company, Ltd. , 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa 236-0004, Japan.
Makiko
M
Yamada
Central Laboratories for Key Technologies, Research & Development Division, KIRIN Company, Ltd. , 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa 236-0004, Japan.
Harumi
H
Taniguchi
Central Laboratories for Key Technologies, Research & Development Division, KIRIN Company, Ltd. , 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa 236-0004, Japan.
Yasuko
Y
Matsukura
Department of Food and Nutrition, Japan Women's University , 2-8-1 Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan.
Kazutoshi
K
Shindo
D001515:Beer / Q000032:analysis*; D003510:Cyclohexanes / Q000032:analysis / Q000737:chemistry; D053138:Cyclohexenes / Q000737:chemistry; D005511:Food Handling / Q000379:methods; D027582:Humulus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012116:Resins, Plant / Q000737:chemistry*; D013729:Terpenes / Q000032:analysis / Q000737:chemistry
D003510:Cyclohexanes; D053138:Cyclohexenes; D012116:Resins, Plant; D013729:Terpenes; C007966:humulon
4′-hydroxyallohumulinone; Humulus lupulus L.; beer aging; dicyclohumulinol; hard resin; hop; scorpiohumulinol