How shochu is made, step by step

English

The process in one sentence

Honkaku shochu is made by growing koji on steamed grain, fermenting it with water and yeast, adding the steamed main ingredient for a second fermentation, distilling once in a pot still, then resting and diluting the spirit before bottling.

The six steps

1. Koji making (製麹, seikiku) — Steamed rice, barley or sweet potato is dusted with koji spores and kept warm for about two days. The mold spreads, producing enzymes that break starch into sugar, and citric acid that protects the mash.

2. Primary mash (一次仕込み, ichiji-jikomi) — Koji, water and yeast are combined. For about a week the yeast multiplies in this acidic, protected environment.

3. Secondary mash (二次仕込み, niji-jikomi) — The steamed main ingredient (sweet potato, barley, rice…) is added. Fermentation runs for roughly two weeks. Some makers still ferment in buried clay pots, kame.

4. Distillation (蒸留, jōryū) — The mash is distilled once in a pot still. Atmospheric distillation keeps rich, heavy aromas; vacuum distillation boils at a lower temperature for a lighter spirit. The raw spirit (genshu) comes off at around 37–44%.

5. Rest and aging (貯蔵, chozō) — The spirit is filtered and rested in tanks, clay pots or casks — from a few months to many years — so that oils settle and the taste rounds out.

6. Dilution and bottling (割水, warimizu) — Water is added to bring it to bottling strength, most often 25% in Kagoshima and 20–25% elsewhere, and the shochu is bottled.

Why two mashes?

Yeast cannot eat starch. Koji's enzymes must first make sugar, and koji's citric acid keeps unwanted bacteria away in warm southern Japan. Building a healthy yeast culture before adding the main ingredient is the wisdom of a hot climate.

Seasons

Sweet potatoes bruise and spoil quickly, so imo shochu is made mostly from late summer to winter, when the harvest is fresh. Freshly distilled autumn shochu is sometimes released as shinshu (新焼酎), new shochu.

Read next: Koji: the unseen hand · Atmospheric or vacuum · What is shochu?

日本語

ひとことで

本格焼酎は、蒸した穀類に麹を育て、水と酵母で一次仕込み、主原料を加えて二次仕込みし、単式蒸留機で一度だけ蒸留して、寝かせ、割水してから瓶に詰めます。

六つの工程

1. 製麹 —— 蒸した米・麦・芋に種麹をまき、約2日かけて麹を育てる。麹はデンプンを糖に変える酵素と、もろみを守るクエン酸をつくる。

2. 一次仕込み —— 麹・水・酵母を合わせ、約1週間。酸に守られた環境で酵母を増やす。

3. 二次仕込み —— 蒸した主原料（芋・麦・米など）を加え、約2週間発酵させる。土に埋めた甕で仕込む蔵もある。

4. 蒸留 —— 単式蒸留機で一度だけ。常圧は香り豊かに、減圧は軽やかに。取れたての原酒はおよそ37〜44度。

5. 貯蔵・熟成 —— ろ過してタンク・甕・樽で寝かせる。数か月から数年。油分が落ち着き、味が丸くなる。

6. 割水・瓶詰め —— 水で度数を整える。鹿児島は25度、ほかは20〜25度が多い。

なぜ二度仕込むのか

酵母はデンプンを食べられません。まず麹が糖をつくり、麹のクエン酸が雑菌を防ぐ。暖かい南九州で、主原料を入れる前に元気な酵母を育てておく —— 気候が生んだ知恵です。

季節

芋は傷みやすいため、芋焼酎の仕込みは収穫期の晩夏から冬に集中します。秋に蒸留したての焼酎は「新焼酎」として出回ることもあります。

次に読む：見えない手仕事 —— 黒麹・白麹・黄麹・常圧と減圧・焼酎とは？

Sources / 出典: National Tax Agency, "酒のしおり" production flow; Government of Japan, Highlighting Japan (March 2025) ／ 国税庁「酒のしおり」製造工程、政府広報「Highlighting Japan」2025年3月号

For adults of legal drinking age. Enjoy responsibly. ／ 飲酒は20歳になってから。適量を楽しみましょう。