Chapter 14: Finishing Flashcards
What are the 4 aims of filtration?
-Subtracting
-Pasteurisation
-Storage and maturation
-Additions
Explain subtracting
-Subtraction of proteins and undesirable colour
-Remove of alcohol not permitted
Why does haziness occur in sake?
Due to small particles of rice and yeast
What happens during sedimentation?
-The particles fall out due to gravity and then the layer of clear liquid can be separated from the layer of solids
-After filtering, brewers leave the sake for up to week to settle the remaining sediments
-When settled: clear sake pumped off the sediment
How can protein be removed from sake?
-Not by filtering, particles too small to be removed without removing desirable parts of the sake
-Fining agents used, suspended particles clump together -> can then be filtered out
Where is activated charcoal used for?
-A fining agent that reduces the amount of colour and remove undesirable aromas, flavours and textures
What is roka?
-Diatamaceous earth is added to avoid the charcoal blocking the filter
-The charcoal and earth are removed using a paper filter of cloth = roka
-Effects the way sake ages, slowing the development of the colour and the aged aromas
Name an advantage and disadvantage of charcoal fining
-Advantage: removes undesirable characteristics in the sake
-dis: also removes positive characteristics and can make sake too thin and characterless = shifting to muroka (uncharcoal fined) for a more natural style of sake with richer and less manipulated flavours
What is suroka?
Where producers don’t use charcoal but only diatomaceous earth filtration to only remove particles (and not colour)
What are micron filters and why would a brewer choose to use these?
-Because the pore size is measured in microns (small)
why: To produce a crystal clear sake + to remove yeast and bacteria in order to improve the stability of the sake
What is a disadvantage of micron filters? How can this be avoided?
- Because the pores are so small that it can get clogged easily
-How to avoid: first pass the sake through a coarser filter to remove cloudiness
What are 2 advantages of using cross flow filter?
-Can remove tiny particles
-Liquid flows parallel to the surface of the filter rather than directly, thus te flow of liquid unblocks any pores and tiny particles can be removed with the sake filtered once rather than twice
Where is molcular sieve used for?
-To remove enzymes, enabling the production of a stable sake without pasteurisation
Is sake a stable product after sedimentation/fining/filtration? Why (not)?
No
-Sake still has koji enzymes and starch fragments that can continue being broken down into sugars
-Sake still has remaining sugars, yeast and other microorganisms will feed on these sugars if the temp. of sake rises
-Preservatives such as SO2 cannot be added to sake
What is a problematic bacteria in sake, why?
-A strain of lactic bacteria called hi-ochi kin
-when hi-ochi kin is active, the sake becomes cloudy, oxidised and develops an unpleasant odour
What can koji enzymes produce when not removed from sake?
-Can increase the level of sweetness, accelerste oxidation leading to a loss of freshness
-when sake is stored very cold, this can slow down the enzyme activity but it can be activated again when temp. rises
How are koji enzymes sometimes removed, and often?
-Sometimes: by molecular filter without pasteurisation but costly
-Often: use heat to deactivate the koji enzyme and kill any yeasts and bacteria that may be present in a sake immediately after filtration
How many times is sake often pasteurised? Explain
-Twice
-Heated to temp of 60-65 degrees for half an hour (immediately after filtration)
-2nd time: before shipping out (after storage)
What are broadly speaking the 2 methods of pasteurisation?
-Bulk pasteurisation
-Bottle pasteurisation
Which pasteurisation method is more efficient?
Bulk pasteurisation
