Craft sake made with what?

After stepping down as tōji at the Wakaze Grand Paris brewery in the suburbs of the French capital, Shoya Imai returned to Japan and started on his quest to “liberate kōji“–which to him meant breaking away from the set sake-making process where yellow kōji (黄麹, ki-kōji) is cultured on polished white short-grain rice.

His crowdfunded craft sake venture LINNÉ is pushing that envelope by using every variety of kōji on a range of substrates including traditional rice, barley and buckwheat. But the company Instagram account has been posting pictures of kōji growing on… something that’s definitely not a grain.

The mysterious kōji substrate being used by ex-Wakaze Paris tōji Shoya Imai.

For anyone who doesn’t recognise the Japanese word kuri, these are steamed chestnuts! They will be used for kōji to make a limited run of 100 bottles of craft sake to be released at the end of May.

Sake can technically still be sake if it contains sake kasu (basically nigori), but in this same envelope-pushing spirit the haccoba craft sake brewery in Minamisoma, Fukushima Prefecture are turning their attention to other forms of kasu. The first product in the series was made with kasu from a sansho lemonade made in Tajima, Hyogo Prefecture in 2024, and this year they are brewing with pomace or marc (solid remains of grapes remaining after pressing) from the Ohno Field Blend made by Miyagi Prefecture winery Fattoria Al Fiore. Made from a blend of Merlot, Chardonnay, Muscat Bailey A and table grapes, the wine has a volatile acidity and astringency that is balanced by umami from the rice.

While haccoba have previously used various forms of kasu under their experimental haccoba_LAB label, they decided to make kasu a regular ingredient as it’s surprisingly easy to work with–low in oils and nutrients that are hard to handle in the brewing process while still being rich in flavour.
 
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LINNÉ Instagram account (Stories, 20 May 2025, Japanese)
日本酒の製造過程でワインの搾りかすを一緒に発酵させたお酒 “kasu [marc]”、4月25日より発売。酒蔵 haccobaの新定番シリーズ “kasu” の第2弾商品。 (PR Times 4 May 2025, Japanese)