Sake Filtration & Fining

Question 1

What are the objectives of the brewer at when considering the addition of jōzō alcohol and the filtration process?

Answer 1

• stop the fermentation at the required level of alcohol and sugar
• ensure desirable components get into the sake
• ensure undesirable components stay behind
• extract as much sake as is appropriate for the style being produced

Question 2

What are the additions that can be made to a sake after filtration?

Answer 2

Only water.

All other additions must be made before filtration.

Question 3

What is jōzō alcohol made from?

Answer 3

It can be made from rice and locally made, but is often made from molasses and grains, and imported from Brazil.

Question 4

At what abv is the jōzō added to the sake?

Answer 4

30-40% abv

It’s purchased at 95% and watered back

Question 5

How much jōzō can be added to premium sake?

Answer 5

No more than 10% of the volume

Question 6

How much jōzō can be added to futsū-shu?

Answer 6

No more than 50% of the volume (including any other additions)

Question 7

Why would a brewer decide to add jōzō to his premium sake?

Answer 7

• better extraction of aromas and flavours which are more soluble in alcohol than water and don’t remain in the rice solids
• lighter palate profile - lower sugar, umami, acidity, body
• shorter more cleansing, crisp kire finish

Question 8

What is the ‘fourth addition’?

Answer 8

A method to adjust the sweetness of a sake.
Kōji is added to steamed rice and water. The enzymes convert starch to sugar without fermentation occurring and the liquid is added to the sake to create the desired balance.

Question 9

What are the three main methods of filtration?

Answer 9

• Yabuta-shibori or Assakuki (mechanised modern system)
• Funa-shibori (traditional press, sake in cloth bags)
• Fukuro-shibori (drip separation)

Question 10

Is filtration used for all sake?

Answer 10

Yes - a legal requirement

Question 11

Is filtration used for nigori sake?

Answer 11

Yes - a legal requirement

Question 12

What are the benefits of yabuta-shibori?

Answer 12

• efficient extraction of large amounts of liquid
• short filtration time - just a few hours
• pressure can be adjusted for different types of sake so suited to both futsū-shu and daiginjō.
• minimise oxidisation

Question 13

How long does funa-shibori take?

Answer 13

2 days

Question 14

What are the benefits and disadvantages of funa-shibori?

Answer 14

• slow and gentle pressing gives fine texture
• small scale allows for precise separation of fractions
• takes 2 days
• risk of oxidisation

Question 15

What are the benefits and disadvantages of fukuro-shibori?

Answer 15

• even gentler and finer than funa-shibori
• suited to the ultra-premium and competition sake
• slowest method and can only be done on a small scale
• highly labour intensive and time consuming
• very inefficient - the remaining kasu is usually refiltered in a yabuta.

Question 16

What are the three filtration fractions?

Answer 16

• arabashiri
• naka-gumi
• seme

Question 17

What is arabashiri?

Answer 17

The free-run liquid from the sake filter.

Lively, with dissolved CO2 and can be cloudy and rough-textured

Question 18

What is naka-gumi?

Answer 18

The best fraction of the filtration.

Silky texture and pure aromas

Question 19

What is seme?

Answer 19

The final fraction of the filtration.
Coarsely textured with less aromatic freshness. Possible astringency and bitterness.
Usually blended away in less expensive sake

Question 20

What are the factors that influence the kasu-buai?

Answer 20

• fermentation technique (higher temperature is more efficient with more dissolved rice so lower kasu-buai, lower temperatures are less efficient)
• filtration techniques (yabuta-shibori more efficient than funa- or fukuro-shibori)

Question 21

What is the typical kasu-buai of a daiginjō?

Answer 21

40-60%

Question 22

What is the typical kasu-buai of a futsū-shu?

Answer 22

below 30%

Question 23

What types of fining can be done to a sake?

Answer 23

• sedimentation (natural settling)
• protein fining (to prevent protein haze)
• charcoal fining (to remove colour and undesirable aromas)
• final filtration (to remove yeast and bacteria)

Question 24

What are the advantages and disadvantages of charcoal fining?

Answer 24

• remove colour
• remove undesirable aromas
• slows the ageing of the sake
• can make the sake thin and characterless
• in extreme cases the carbon can be tasted

Question 25

What is hi-ire?

Answer 25

Pasteurisation

Question 26

Why isn’t sulphur dioxide used as a sake preservative?

Answer 26

• SO2 depends on acidity to be affective (sake much lower in acidity than wine)
• sake cannot legally have preservatives added

Question 27

What is the most problematic spoilage bacteria?

Answer 27

Hi-ochi kin

Question 28

What is hi-ochi kin?

Answer 28

Lactic acid spoilage bacteria.
Produces off-aromas, cloudiness and oxidisation
Can be prevented by ultra-fine filtration but usually pasteurisation

Question 29

At what temperature is the sake heated to during pasteurisation?

Answer 29

60-65°C

Question 30

When can the sake be pasteurised?

Answer 30

• in bulk, after filtration but before bulk storage
• in bottle (a gentle technique used for ginjō)
• both!

Question 31

What is nama-chozō?

Answer 31

A sake pasteurised once, after storage in bulk.

Question 32

What is nama-zume?

Answer 32

A sake pasteurised once, before storage in bulk and bottled without a second pasteurisation

Question 33

What is ‘once-pasteurised’?

Answer 33

A sake pasteurised just once, after bottling.

Question 34

How long is sake stored for before release? Why?

Answer 34

Six to twelve months

After pasteurisation, the sake can have an unrefined taste.

Question 35

What type of blending is used for sake?

Answer 35

• different polishing rates
• different rice types
• different yeast types
• different press fractions
• different ages or storage methods
• higher and lower amounts of sake lees for nigori