Quercus crispula Blume syn.Quercus mongolica var. crispula - Fagaceae - mizunara, 水楢 (Jap.), water oak, Mizunara
Deciduous tree, up to 30m tall, native to Northeast Asia (Japan, Korea, China); leaves obovate, dull green, sharply serrated; flowers up to 5cm long.
„Mizunara is most widely known outside Japan for its use in barrels to age Japanese and Scotch whisky. It has received international acclaim as a material that can brew a delicate flavor completely different from oak barrels… They have also become popular since the 20th century for the cultivation of shiitake mushrooms.“ wikipedia
Japanese oak wood powders (Mizu-Nara, Ishi-Nara, and Kashiwa-Nara) contained organoleptic important amounts of free and bound cis/trans β-methyl-γ-octalactone (oak lactone).
[Otsuka, Ken-ichi, et al. „Presence and significance of two diastereomers of β-methyl-γ-octalactone in aged distilled liquors.“ Agricultural and Biological Chemistry 38.3 (1974): 485-490]
Especially for Japanese oak whisky, more than 20 years are needed to develope a unique flavor, described as ‘Incense’ and ‘Coconut’. Focused on the coconut aroma compound, cis/trans β-methyl-γ-octalactone (oak lactone or whisky lactone), Japanese whiskies showed higher levels of trans-lactone.
[Noguchi, Yushi. The influence of wood species of casks on matured whisky aroma: identification of unique character imparted to whisky by casks constructed of Japanese oak. Diss. Heriot-Watt University, 2017]
Main components found in hexane extracts of Japanese oak wood were pentadecanoic acid (30.1%), tetradecanoic acid (1.2%), and 3-methyl-4-octanolide (oak lactone; 1.0%).
[Hasegawa, Toshio, et al. „Characteristic Aromas of Quercus crispula (Japanese Oak).“ Natural Product Communications 13.4 (2018): 1934578×1801300424.]