The Science of Brewing Alcohol Addition

“Only junmai is real sake.” “Alcohol-added sake is inferior.”

You might hear opinions like these. But understanding the history and science of brewing alcohol addition (aruten) might change your perspective.

What is aruten? Why is it done? How does it affect flavor? Let’s examine this from a scientific viewpoint.

What Is Brewing Alcohol?

Definition

Brewing alcohol is ethyl alcohol produced by fermenting and distilling sugarcane, corn, or similar materials.

Characteristics

• High purity (95% or above)
• Nearly tasteless and odorless
• Approved as a food additive

Use in Sake

Adding brewing alcohol to sake is called “aruten” (alcohol addition).

Sake With Brewing Alcohol

• Honjozo
• Ginjo
• Daiginjo
• Futsu-shu (regular sake)

Sake Without Brewing Alcohol

• Junmai
• Junmai Ginjo
• Junmai Daiginjo

History of Alcohol Addition

Wartime Origins

Brewing alcohol addition became widespread during World War II.

Background

• Severe rice shortages
• Sake demand remained constant
• Need to produce more sake with limited rice

The Emergence of Triple-Diluted Sake

• Sake diluted to three times normal volume
• Sugar and acidifiers also added
• Called “sanzo-shu” (triple-increase sake)

The quality of aruten sake from this era was indeed poor. This impression still contributes to prejudice against alcohol addition today.

Postwar Changes

After the war, circumstances changed dramatically.

1950s onward

• Rice supply stabilized
• Efforts toward quality improvement
• Purpose of aruten shifted

2006

• Triple-diluted sake excluded from the legal definition of “sake”
• Transition to quality-focused era

Modern Aruten

Modern alcohol addition serves entirely different purposes than during wartime.

Modern Purposes

• Extracting aromas
• Adjusting flavor balance
• Expressing style

Why Add Brewing Alcohol?

Extracting Aromatic Compounds

This is the most important purpose of modern alcohol addition.

Mechanism

• During fermentation, yeast produces aromatic compounds (esters)
• These compounds dissolve more readily in alcohol than water
• Adding alcohol helps transfer aromas from the mash to the sake

Specific Effects

• Enhanced extraction of isoamyl acetate (banana aroma)
• Enhanced extraction of ethyl caproate (apple aroma)
• Results in more aromatic sake

This effect is particularly pronounced in ginjo and daiginjo, where alcohol is added to bring out the “ginjo aroma.”

Improved Crispness

Mechanism

• Brewing alcohol has no flavor
• Addition relatively reduces umami compound concentration
• Creates a cleaner finish

Effects

• Crisp sake profile
• Clean aftertaste
• Tends toward light, refined character

Improved Stability

Mechanism

• Alcohol content increases
• Suppresses bacterial growth
• Improves preservation

Effects

• Stable quality
• Extended shelf life

Cost and Production Volume

Honestly, there are cost benefits too.

For Regular Sake

• Can reduce rice usage
• Can increase production volume
• Can keep prices down

However, for ginjo and daiginjo, the amount added is small, and cost reduction isn’t the main purpose.

Regulations on Addition Amounts

Special Designation Sake Regulations

Addition amounts are strictly regulated by the Liquor Tax Act.

Honjozo

• Maximum 120 liters per ton of polished rice
• Equivalent to about 10% of raw rice

Ginjo and Daiginjo

• Same 120 liter maximum
• In practice, smaller amounts for aroma extraction

Regular Sake

Regulations for regular sake are more lenient.

• Higher addition limits allowed
• Sugar addition also permitted (except triple-diluted)
• Different production approaches for different price points

The Science of Aruten and Flavor

Impact on Aroma

Aruten Sake

• Brilliant ginjo aroma
• Fruity ester notes
• Aroma-forward character

Junmai Sake

• Subdued aroma
• Rice-derived fragrance
• Flavor-focused character

Impact on Taste

Aruten Sake

• Good crispness
• Clean finish
• Tends toward light refinement

Junmai Sake

• Rich umami
• Full body
• Tends toward richness

Scientific Data

Research has revealed the following:

Amino Acid Content

• Junmai tends higher
• More umami compounds

Ester Concentration

• Aruten tends higher
• More aromatic compounds

Acidity

• No significant difference
• Greater influence from brewing method and yeast

Junmai vs. Aruten Sake

Junmai Characteristics

Advantages

• Easy to taste rice umami
• Rich body and depth
• Temperature-tolerant (good for warming)
• The story of “made only from rice”

Disadvantages

• Aroma tends to be subdued
• Can feel heavy
• Often higher priced

Aruten Sake Characteristics

Advantages

• Brilliant aroma
• Good crispness
• Clean taste
• Cost performance

Disadvantages

• Prejudice of “not junmai”
• May lack umami
• Generally not ideal for warming

Which Is Better?

The conclusion: both are excellent.

They serve different purposes.

• Want to enjoy aroma -> Aruten (ginjo, daiginjo)
• Want to enjoy umami -> Junmai
• Want to pair with food -> Both have suitable options
• Want to enjoy warm -> Junmai has an advantage

Dispelling Misconceptions

”Aruten Sake Causes Worse Hangovers”

Reality

• Hangover cause is alcohol quantity and drinking style
• Brewing alcohol isn’t particularly harmful
• High-purity alcohol is actually gentler on the body

”Aruten Sake Is Fake”

Reality

• “Hashira shochu” addition was practiced in the Edo period
• It’s a traditional technique
• Legally recognized as authentic sake

”Junmai Always Tastes Better”

Reality

• Taste preferences vary by individual
• Many excellent aruten sake exist
• Aruten sake also wins gold at the National New Sake Competition

Professional Perspectives

The Toji’s View

Many master brewers view alcohol addition as “one technique among many.”

A Toji’s Words “Aruten is like a painter’s palette. The quality of the work depends on how you use it.”

Brewery Choices

Attitudes toward aruten vary by brewery.

Junmai-Only Breweries

• Shinkame Shuzo: Brews only junmai
• Pursuing rice umami

Breweries Using Aruten

• Dassai: Uses aruten for daiginjo
• Emphasizes aroma extraction

Breweries Using Both

• Most breweries take this approach
• Select based on sake type

Enjoying Aruten Sake

Temperature

Chilled Recommended

• Aroma shines at 10-15°C
• Enjoy ginjo aroma
• Clean taste

Glassware

Wine Glass

• Allows aroma to open up
• Showcases ginjo sake’s appeal

Food Pairing

Good Matches

• Light sashimi
• White fish dishes
• Vegetable tempura
• Light appetizers

Selection Tips

Reading Labels

Junmai Types

• Junmai, Junmai Ginjo, Junmai Daiginjo
• No alcohol addition

Honjozo Types

• Honjozo, Ginjo, Daiginjo
• With alcohol addition

Regular Sake

• No special designation
• Addition amounts vary

Selection by Purpose

Want to Enjoy Aroma

• Daiginjo (with aruten) recommended
• Brilliant ginjo aroma

Want to Enjoy Umami

• Junmai recommended
• Rice body and depth

Want Balance

• Junmai Ginjo
• Both aroma and umami

Conclusion

Brewing alcohol addition today is completely different from wartime “dilution”—it’s a modern brewing technique.

The True Purpose of Aruten

• Extracting aromatic compounds
• Balancing flavor
• Expressing style

The idea that “only junmai is real” is too one-sided. Both junmai and aruten sake have their own appeal.

What matters is knowing your preferences. And trying various sake without prejudice.

Next time you choose sake, don’t decide based on “junmai” or “aruten”—consider what flavor profile that sake aims to achieve.

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For sake types, see Understanding Junmai, Ginjo, and Daiginjo.

For the brewing process, see How Sake Is Made.