Post-Fermentation Flashcards
What is the only action that the brewer is legally required to do prior to packing
Filtration
What is Jōzō alcohol?
A distilled alcohol
If used, when is Jōzō alcohol added?
After the end of the fermentation and before filtration.
What is the only thing that can be added to a sake after filtration?
Water
What are sakes that are made with jōzō alcohol sometimes referred to as?
Aruten
What can sakes made without jōzō alcohol labelled as?
Junmai
What strength is most jōzō alcohol distilled to and what strength is it stored at?
It is typically distilled to 95% abv and stored at between 30-40%abc
What are the advantages of jōzō alcohol distilled to 95%?
This type of spirit does not add any unwanted aromas or textures to a sake
Why might a brewer use a jōzō alcohol distilled to a lower strength?
The brewer wants to use the jōzō alcohol to contribute its character to their sake
What are the main effects on the style of a sake caused by adding jōzō alcohol?
Many of the characteristics of the sake (sweetness, acidity, umami, dextrins) are diluted but the additional liquid. However, the increase in alcohol helps to extract aroma compounds that are more soluble in alcohol (especially ginjō aromas) from the rice solids. The overall effect is a lighter, leaner, purer sake.
Does the use of jōzō alcohol result in a permanent increase in the abv of the sake?
No. The rise in alcohol is reversed by the final water addition prior to packaging.
What can be used to offset the dilution caused by the use of jōzō alcohol and the final addition of water?
The fourth addition. The sugars and dextrins in this addition are sued to manage the texture and final sweetness of a sake
At what point are brewers no longer permitted to make additions other than jōzō alcohol and water to futsū-shu?
After filtration
What features of a futsū-shu can be adjusted post fermentation?
Sweetness, acidity and umami.
What are the three main method used to separate the sake liquid from the solids?
Yabuta-shibori, Funa-shibori or fune-shibori, fukuro-zuri or shizuku-dori
Describe yabuta-shibori
The freshly made sake is pumped into vertical pockets in the filtering machine. Between each of these pockets is a bag that can be inflated with air. Once the machine has been fully loaded, the air bags are inflated and this squeezes the pockets containing the sake. The pockets allow the liquid to flow out and hold back the rice solids.
Describe funa-shibori/fune-shibori.
The freshly made sake is placed into cloth bags which are stacked up in a large rectangular tub called a fune. The bags are squeezed by a mechanical device applying pressure from above. This forces the liquid out of the bags which holds back the rice solids.
Describe fukuro-zuri/shizuku-dori.
The freshly made sake is placed into cloth bags that are then hung up. The liquid drips out of the bags which hold the rice solids back. No pressure is applied on the bags. Separation is achieved relying on gravity alone.
List the three filtration fractions in the order in which they come off. Which one produces the highest quality sake?
- Arabashiri
- Naka-dori/naka-gumi (this middle fraction produces the highest quality sake)
- Seme
What is sake-kasu?
It is the rice and other solids that are held back in the filter and separated from the sake liquid.
What are the four main processes after the initial filtration that brewers can choose from?
Sedimentation, protein fining, activated charcoal fining/earth filtration and other methods of filtration
What is the problem that relates to the sediment that forms during sedimentation. How does a brewer overcome this?
The sediment is not compact and contains a lot of sake. In order to avoid losing this sake it can be removed using a filter
How does fining work?
A substance (fining agent) is added to the sake. This forms clumps with small particles the brewer cannot otherwise remove. These large clumps can then be removed using sedimentation or filtration
What fining agents are used to remove proteins?
Gelatin and persimmon tannins
Why do brewers use protein fining?
Protein fining is used to prevent a haziness from developing in a sake
What characteristics of a sake can be changed using activated charcoal fining?
Colour, aromas/flavours, texture
What are the potential disadvantages of activated charcoal fining?
Activated charcoal is not selective. It can remove undesirable qualities, but it can also result in a thin sake with little character
What is the labelling term for a sake that has not been charcoal fined?
muroka
What can micron filters remove from a sake which other filters cannot?
Yeast and bacteria
What can a molecular sieve remove which a micron filters cannot?
Enzymes. A sake that is passed through a molecular sieve is fully stable and does not need to be pasteurised. The use of molecular sieves is rare.
What does pasteurisation do?
Pasteurisation uses heat to destroy yeast, bacteria, and kōji enzymes which could spoil a sake.
What is the name of the most problematic bacteria and how does it affect a sake?
Hi-ochi kin. It can cause a sake to go cloudy, oxidise and develop unpleasant aromas.
What can kōji enzymes do to a sake?
They can contribute breaking down starch fragments, increasing the sweetness, and accelerating the rate at which a sake oxidises and loses its freshness.
If a brewer does not have a molecular sieve and chooses not to pasteurise their sake how can kōji enzymes be kept under control.
the sake needs to be stored at very cold temperatures in order to slow the enzyme activity
For how long and to what temperature is sake heated during pasteurisation?
60–65°C (140–149°F) for half an hour.
What are the two main methods used for pasteurising sake?
Bulk and bottle
Bulk pasteurisation uses heat exchange. Describe how a heat exchanger work to heat up a sake
The sake is passed through a heat exchanger. Hot water, that does not come into contact heats up the cold sake
How are modern heat exchangers different from the older style of heat exchangers called ja-kan?
The modern heat exchangers cool the sake once it has been heated for long enough to be pasteurised. Therefore it is only hot for as long as is necessary. Sake heated using a ja-kan had to cool down over a period of days in a tank and this extended period of warmth damages ginjō aromas
How are bottled sakes pasteurised?
The bottled sakes are heated. This can either be done by immersing the bottles in hot water or passing them on a conveyor belt through a machine where they are showered with hot water. The bottles are then rapidly cooled either by using a cold water shower or by relying on the cold ambient temperatures in a brewery.
What is the main advantage and the main disadvantage of bottle pasteurisation?
This method expose sake to the least heat for the shortest amount of time time and only one pasteurisation is required. Therefore, delicate aromas are less likely to be damaged. It is more labour intense than bulk pasteurisation and less well suited for dealing with high volumes of sake as it takes more space to store sake in bottles before shipping, so brewers need to install larger temperature controlled warehouse.
How many times are most sakes pasteurised?
Most sakes are pasteurised twice. Once after filtration and prior to storage and once after storage and prior to packaging.
What does nama-chozō mean and is it legally defined?
The sake is pasteurised once after storage. It is legally defined as
What does nama-zume mean and is it legally defined?
Typically, this refers to a sake that is pasteurised after filtration but not prior to packaging. It is not a term that is legally defined.
What does the term ‘once pasteurised’ typically refer to?
This is typically used to refer to a sake that is bottled, then pasteurised and then stored.
Why is sake typically stored prior to release?
Pasteurised sake have an unrefined taste and freshly filtered sakes can have a rough texture. A period of storage allows textures and flavours to become balanced.
For how long and at what temperature is sake typically stored?
Most sakes are stored for between six months to a year at cool and steady temperatures (10-20°C, 50-68°F). Sake storage temperatures do range from freezing to ambient temperatures which includes the summer highs and winter lows
After filtration what is the only thing that can be added to a sake?
Water
What is the labelling term used to identify a sake that has not been diluted with water?
Genshu
Genshu sakes are often higher in alcohol. Is this always the case?
No. Some genshu sakes are bottled at 15-16% abv. This is achieved through careful management of the fermentation
What does blending enable sake brewers to do?
The ability to achieve a consistency and complexity that is hard to achieve in individual batches.
List different kinds of blending components a brewer could use
- Sakes made from rice with different polishing ratios (the component with the highest polishing ratio determine the sake’s grade)
- Sakes made using different types of kōji
- Sakes made using different types of rice
- Sakes made using different strains of yeast
- Different press fractions
- Sakes that have been stored/matured for different lengths of time
- Sakes with different levels of cloudiness (for nigori-zake only)
