Friday, December 2, 2022

Wood *ethanol* from Japan

Distilled spirits from... wood?
Credit: Japan Times, Alex K.T. Martin
Via the Japan Times, this fascinating story: 

To begin with, harvested wood is crushed into 2-by-2-centimeter pieces using a chipper, and then processed using a hammer mill with a 0.7-millimeter screen. This powdered wood is then slowly inserted into a rapidly rotating mill with circulating spring water and heavy beads made of zirconia-reinforced alumina to create wood slurry. The resulting gooey, pinkish substance is then sterilized and put in a fermenter. An enzyme solution that breaks down the cellulose into glucose is added and enzymatic saccharification and alcohol fermentation is performed to brew doburoku, the Japanese term for an unrefined alcoholic liquid. This unfiltered solution then undergoes solid-liquid separation and, voila, the base product is made.

“Here it is,” Otsuka says, as he pulls out labeled glass bottles filled with liquids of varying colors produced from a range of trees: cedar, birch, the Somei-Yoshino and yamazakura varieties of cherry trees, mizunara oak and kuromoji, a deciduous tree endemic to Japan. “But at this stage, the alcohol content is very low, at around 2.5% or even 1% when we’re using hardwood,” he says.

“To raise the strength to around 30% to 40% alcohol by volume while retaining the aroma, we double-distill these,” Otsuka continues, proceeding to fish out smaller bottles filled with clear liquids. “All in all, it takes around two weeks to make wood alcohol. Now, take a whiff.”

The alcohol made from cedar lets off that familiar, refreshing woody aroma, while the mizunara oak is mellower, reminiscent of whisky, perhaps because the tree is often made into barrels that are used to age the liquor in. From the birch spirit wafts a fruity smell, akin to brandy, while the cherry trees have a softer but bright, sweet presence, similar to white wine. The scents, in any case, are surprisingly strong, clear and distinct from tree to tree.

How do they taste? Besides the pleasant fragrance, Otsuka says the spirits are quite smooth, without any of the burning sensation associated with downing high-proof liquor.

“I’ve finished one of these smaller bottles on my own one night and didn’t have the slightest hangover,” he says.

I would definitely be interested to try this, but I'm guessing that those who don't like peaty/smoky Scotches won't like this... 

1 comment:

  1. There's a distillery in Durham, NC called Durham Distillery that "distills" their spirits by a 20 L Buchi rotovap. I guess by distilling under vacuum, the distillate helps keep a lot of the VOCs from botanicals and other subtleties. I wonder if these people also distill under vacuum, whether by rotovap or not...


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