kobo yeast


Sake Basics

Sake rice

spring water

Rice polishing



koji mold

Sake rice

<Characteristics of Sake Rice>

  • - Larger and more expensive than food rice 

  • - White core, less protein and fat, easy to melt, high viscosity

  • - Absorbency, good environment for koji propagation

  • - More than 100 types of sake rice are grown in Japan

In sake brewing, we use the expression “polishing rice” instead of “scraping rice.”


The rice-polishing ratio shows how much of the rice surface is removed. For instance, when the ratio is 60%, 40% of the brown rice surface is polished away.


The reason for polishing has a significant connection to the composition of rice itself.

The core of the rice grain is rich in starch, while fats, vitamins and proteins are concentrated near the surface.


The fat and protein near the surface of normal rice for eating is nutritious, so the rice-polishing rate is around 90%.

On the other hand fat and protein have strong flavor profiles that, in excess, can adversely affect the flavors and aromas of sake, resulting in an unpleasant product. This is why rice-polishing is a vital step for making sake.


Sake made with unpolished rice has a comparatively deeper, thicker taste, giving the impression of a strongly flavored sake with a noticeable smell of rice.


But when sake is made using well-polished rice, the aroma is bright, with a flavor that leaves a light, clear impression.

This is the reason why many junmai ginjoshu and junmai daiginjoshu, with rice-polishing rates of 50-60%, have such a clear and brilliant taste.

Rice polishing



The 6 basic types of Sake are called premium Sake. Types of Sake are categorized by Rice Polishing Ratio and whether distilled alcohol is added.

​Rice Polishing Ratio

  • Less than 50%: Daiginjo, Junmai Daiginjo

  • Less than 60%: Ginjo, Junmai Daiginjo, Tokubetsu Junmai, Tokubetsu Honjozo

  • Less than 70%: Honjozo

  • Unspecified: Junmai

1. Distilled alcohol NOT added:

Junmai Shu (純米酒), Junmai Ginjo (純米吟醸), Junmai Daiginjo (純米大吟醸), Tokubetsu Junmai (特別純米).

Tends to have rich, savory, grainy, rice-like taste.

2. Distilled alcohol added:

Ginjo (吟醸), Daiginjo (大吟醸), Honjozo (本醸造), Tokubetsu Honjozo (特別本醸造).

Tends to have cleaner taste.

Please note that adding distilled alcohol is not necessarily bad. Many award-winning Sake have distilled alcohol in it.

   Sake is comprised of approx. 80% water. Thus, water quality greatly affects sake quality. The amount of water used in Sake making adds up to more than 50 times the total weight of rice. Water is used for almost all steps – washing & soaking rice, creating Moromi mash and dilute Sake to adjust flavor and alcohol content.

So what kind of water is suitable for Sake? Let’s take a look:

  • Beneficial Elements: Potassium, Phosphoric acid and magnesium

  • Detrimental Elements: Iron, Manganese

   Those beneficial elements are necessary to aid the propagation of yeasts and Koji mold. On the other hand, the detrimental ones will cause discoloration of Sake and ruin the Sake flavor and aroma. This is why many Sake breweries are located near exquisite, well-conserved water sources.

spring water

koji mold

kobo yeast


   Koji Mold is a type of mold. It’s a ‘mold’! Eww! But don’t step back; it’s harmless to human body and actually very nutritious.

Koji basically converts rice starch to sugar (glucose), which will be converted to alcohol by yeasts.

Many people confuse Koji Mold with Koji:

  • Koji Mold: Mold spores themselves (that will propagate on steamed rice).

  • Koji: Rice with propagated Koji mold (in case of Sake). So rice + koji mold. Also known as rice koji.

Koji can be called rice Koji, soy Koji, barley Koji, etc., depending on what Koji mold has propagated on.

Koji mold

Yeasts (Kobo) are used in the fermentation process, converting glucose (sugar) into alcohol. Yeasts play a crucial role in determining the aromas of Japanese sake. This is why the type of yeast used is often listed on the label of a Sake bottle. Most types of yeasts are stored and provided from Brewing Society of Japan.

Yeast type greatly affect Sake flavor and aroma. It can make Sake a savory Junmai-type, a fragrant Ginjo-type and others. 

kobo yeast

In fact, water comprises as much as 80% of the final product, so fine water and fine rice are natural prerequisites if one hopes to brew great sake. But beyond that, the technical skill needed to pull this all off lies with the toji (head brewers), the type of yeast they use, and the limitations entailed by local land and weather conditions. Please visit the links shown above for a detailed review of the crucial ingredients.


©2018 by Sake Clan PH.