Brewing
& ingredients

Sake is brewed from rice. Koji supplies enzymes that turn rice starch into sugar, and yeast turns that sugar into alcohol.

Those two jobs overlap in the main fermentation tank. After fermentation, the brewer separates the liquid from the rice solids and decides how to finish it for the bottle. Sake is fermented, rather than distilled.

Overview: JSS: How sake is made. Expanded from WhatSake’s original brewing article.

You’ll often hear “rice, water, koji and yeast”. Think of these as the brewing team: each has a different job.

References: JSS: Ingredients and their roles · JSS: Rice and brewing alcohol.

Follow the numbered stops. Open a little more detail wherever you’re curious.

This is an overview of the journey. Some jobs happen alongside each other, and finishing choices vary by brewery.

1. 01

   

   STEP 01

   Polish the rice

   Polishing removes some of the outer grain, where more protein and fat are found. It gives the brewer a different starting point for the flavour they want.

   60% polishing ratio = 60% of the original weight remains. A smaller number means more has been removed.

   Explore the polishing ratio+

   REMAINS60%

   REMOVED40%

   From 100 g of brown rice, a 60% polishing ratio leaves 60 g for brewing and removes 40 g. This bar shows weight, not the shape or diameter of a grain.

   More polished ≠ better

   Polishing is one clue about production, rather than a score for quality. Rice variety, koji, yeast and the brewer’s decisions also shape the result.

   Reference: JSS: Polishing and quality.

2. 02

   

   STEP 02

   Wash the rice

   The polished rice is washed to remove the powder left on its surface.

   It looks familiar, but this is preparation for brewing: the condition of the rice matters for the steps that follow.

   Reference: NRIB: Washing rice.

3. 03

   

   STEP 03

   Soak the rice

   The washed rice absorbs water. The brewer controls this absorption so the rice is ready to steam.

   The aim is the right moisture, rather than simply a long soak.

   Why separate washing from soaking?+

   Washing removes the powder. Soaking controls water absorption. They happen close together, but they have different jobs.

   Reference: NRIB: Rice preparation.

4. 04

   

   STEP 04

   Steam the rice

   The rice is steamed, then cooled for its next job. Steaming prepares it for koji making and the fermentation mash.

   From here, the rice takes different paths: some becomes koji, while other portions feed the starter and main mash.

   To kojiTo the starterTo the main mash

   Reference: NRIB: Steaming.

5. 05

   

   STEP 05

   Make koji

   Brewers cultivate Aspergillus oryzae on a portion of the steamed rice in a controlled room, usually over about two days.

   Koji supplies enzymes that turn starch into sugar. Think of it as preparing food for the yeast.

   See how koji and yeast work together+

   Rice starchThe starting material

   Koji enzymes→

   SugarFood for the yeast

   Yeast→

   Alcohol + CO₂The products of fermentation

   In the main mash, starch breakdown and alcoholic fermentation overlap. This is multiple parallel fermentation: sugar is being made while yeast uses it.

   Reference: NRIB: Koji making.

6. 06

   

   STEP 06

   Build the yeast starter

   The shubo, also called moto, establishes a healthy yeast population before the main fermentation.

   An acidic environment helps protect this small starter from unwanted microbes.

   Compare Sokujo, Kimoto and Yamahai+

   Sokujo

   Lactic acid added

   The brewer adds lactic acid to create the acidic environment for the starter.

   Kimoto & Yamahai

   Acidity develops through bacteria

   These methods use lactic acid bacteria. Yamahai omits the traditional rice-mashing step used in Kimoto.

   These are starter methods. They can give you clues on a label, but they don’t promise a fixed flavour.

   Reference: NRIB: Starter methods.

7. 07

   

   STEP 07

   Ferment the main mash

   The main mash, or moromi, brings the ingredients together in a larger tank. Koji enzymes release sugar while yeast converts it into alcohol and carbon dioxide.

   Temperature, time and yeast choice help shape the result. The brewer watches the fermentation develop, rather than relying on one timer.

   See the three additions across four days+

   A common method, sandan-jikomi, builds the mash gradually.

   1. DAY 1

      First addition

      Begin building the main mash.

   2. DAY 2

      A pause

      Give the yeast population time to grow.

   3. DAY 3

      Second addition

      Increase the mash gradually.

   4. DAY 4

      Third addition

      Complete the staged additions.

   Four days isn’t the whole fermentation

   This is the schedule for building the mash. Fermentation continues afterwards.

   Reference: JSS: Moromi and Sandan-jikomi.

8. 08

   

   STEP 08

   Separate the sake from the solids

   The fermented mash still contains rice solids. Pressing or straining separates liquid sake from the remaining lees, called sake kasu.

   Breweries may use machines, bags or slow dripping. The illustration shows one of these methods.

   Liquid sake

   The liquid continues towards settling, finishing and bottling.

   Sake kasu

   The separated solids are a brewing by-product used in foods and cooking.

   So why is Nigori cloudy?+

   Nigori passes through a coarser separation that allows some rice solids into the liquid. The amount varies. Cloudiness doesn’t tell you whether it is sweet or whether it has been pasteurised.

   Reference: JSS: Pressing methods and sake kasu.

9. 09

   

   STEP 09

   Choose the finishing steps

   After pressing, the brewer decides how to finish the sake. The order and combination of these treatments vary.

   These are possible branches, rather than four compulsory steps.

   CLARITY & FLAVOUR

   Settle or filter

   Further treatment can refine the liquid. Muroka describes sake without secondary filtration, often referring to charcoal treatment; it has still been separated from the mash.

   Label clue · Muroka

   STABILITY

   Pasteurise

   Heating, called hi-ire, helps stabilise sake and deactivate enzymes. Namazake skips pasteurisation. Follow its storage instructions and keep it refrigerated.

   Label clue · Nama

   ALCOHOL STRENGTH

   Adjust with water

   Water is often added to bring the sake to the intended strength. Genshu indicates sake without this dilution; check the ABV rather than assuming one strength.

   Label clue · Genshu

   TIME & DEVELOPMENT

   Rest or mature

   Some sake rests before release; other sake is deliberately aged. Koshu is an aged-sake clue. Use the bottle’s tasting notes to learn what its maturation has produced.

   Label clue · Koshu

   Read “Muroka Nama Genshu” as three decisions+

   Muroka concerns secondary filtration, Nama concerns pasteurisation, and Genshu concerns dilution. These words can appear together because they describe different choices.

   Explore the types and styles guide for a full comparison.

   Reference: JSS: Production and label terms.

10. 10

    

    STEP 10

    Bottle the sake

    The finished sake is bottled for release. Its label, alcohol strength and storage advice help you understand what the brewer has made.

    The toji and brewery team have guided the journey—from rice preparation through fermentation to the finished sake.

    Read one detail. Notice one thing.

    Pick a brewing clue on your next bottle and connect it to your tasting note: its aroma, texture or finish.

    Reference: JSS: Toji and brewing terms.

Further reading: JSS: Sake questions · JSS: Brewing vocabulary.