Unit 5: Maturation and Clarification Flashcards
What is warm maturation?
-1st step after fermentation
-9 degrees C (roughly the same as fermentation)
-Dry hop phase
-**Yeast turns unwanted flavours and aromas into good (or unnoticeable) flavours
Why is warm maturation necessary?
It allows time for the yeast to remove any unwanted flavours or aromas produced during fermentation and add good ones.
**the warm temperature helps with this
How is beer dry hopped?
-Its tricky because the vessel is carbonated and the addition of hops will make it fizz more. Also whole hop cones float.
-hops are in a tank (hop dosing machine) and the beer gets filtered through the hope tank then back to its vessel (like a coffee filter)
*Most brewers use hop pellets because theyre easier to mix with the beer and have an intense aroma profile.
How is beer transferred to cold storage?
IF its not being done in the fermentation vessel the beer will be transferred to a new cold maturation vessel and will pass through a centrifuge first.
The centrifuge spins the beer quickly to remove any solids fater
What is cold maturation?
-2nd step of the maturation process
-below 0 degrees C
-3 days to 3 months length (can be reduced if a centrifuge is used to spin the beer and remove solids)
-Happens in either the fermentation vessel, warm maturation vessel or transferred to its own cold maturation vessel
What changes occur during cold maturation?
-Beer gets clarified
-Unwanted flavours and aromas are removed
-Any un fermented sugar gets fermented slowly
*(more alcohol means more CO2 which is good for the carbonation level)
What conditions are required for cold maturation?
-below 0 degrees C
Where do the bad flavours and aromas come from at the end of fermentation?
Unhealthy yeast.
But in warm maturation the healthy yeast works to get rid of those flavours.
**temperature up, acetaldehyde/diacetyl down
What does the diacetyl compound smell like?
Honey and butterscotch
What does acetaldehyde compound smell like?
Green apple
What is the main reason for cold maturation?
-To allow yeast and other materials to settle out of the beer
Why do we clarify beer?
If beer is clear there is a much lesser chance that it has been contaminated by bacteria.
*that being said people like hazy beers and just because its hazy doesn’t mean its contaminated
How does beer get clarified?
A sheet filter will remove the smallest particles
What is “Bright” beer?
Beer that has been filtered and you can see through it
What are some beers that are meant to be cloudy?
Wheat beers
New England IPA’s
Why are wheat beers cloudy?
The wheat makes them cloudy
*the proteins in wheat don’t easily settle out like barley
Why are New England IPA’s (and other IPA’s) cloudy?
They have a large amount of dry hops added during warm maturation that cause the cloudiness.
They usually don’t get filtered because that would change the flavour profile.
Why are stouts and British cask beers not filtered?
Stouts are so dark you cant even tell if its cloudy so why bother
The yeast in British cask beers matures over time so you dont want to filter it out.
Now that maturation and clarification are done the beer is ready to get packaged. What specifications are analyzed to make sure the beer is up to par?
- Alcohol level
- Flavour by tasting
- Bitterness
- Haze (for clear beers)
- pH
- CO2
- Colour
- Dissolved O2
- Residual solids content (measured by what brewers call “gravity” or “extract”)
CLARIFICATION. Tell me about the sheet filter?
Fine fiber sheet surrounded by metal frame. Beer passes through and any solids get trapped by the filter.
Cons. If too many solids the filter gets blocked and needs to be replaced. This can cause beer loss and risk of contamination. It also costs more money
CLARIFICATION. Tell me about the depth filter?
Like a sheet filter but particles also get trapped in channels within the filter.
Filter powder is added to create a filter bed.
Clarification. Tell me about the the depth filter (plate and frame filter)
Like the sheet filter but with many plates of filters that act like sieves to collect the filter powder.
CLARIFICATION. Tell me about the depth filter (Candle filter)
Hollow porous rods (candles) inside a tank.
Bed of filter powder forms around the candles. The beer flows up the candles and the large particles get stuck on the filter beds while the bright beer gets pushed up the candles into the “outflow outlet”.
*unfiltered beer enters the bottom of the tank, Filtered beer exits the top of the tank
CLARIFICATION. Tell me about Crossflow filters.
Tubes made of a type of plastic with small pores.
Unfiltered beer flows through the tubes and the bright beer passes through the pores
*instead of pouring beer head on to the filter the beer is pushed sideways and gets filtered that way
How is alcohol measured in beer?
NIR machine. (Near infra-red).
Machine passes infra-red light at the sample and measures how much light is absorbed.
*the more absorbance the higher the alcohol content.
How is “Gravity” measured in beer?
Gravity = the amount of stuff dissolved in the solution
Hydrometer (looks like a thermometer but acts as a fishing float)
Degrees Plato (P)
How far it sinks represents the amount of gravity.
*the further it sinks the lower the gravity.
** a machine with a vibrating U tube will detect the gravity as well. The lower the gravity the higher the vibrations. The higher the gravity the lower the vibrations.
How is beer colour measured?
In units of EBC (European Brewing Congress)
Measured using a spectrophotometer
5-10 for light beers
up to and over 50 for dark beers
**SAME AS SRM but doubled (2srm = 4 ebc)
How is bitterness measured?
Extracting the bitter compounds and measuring their concentration.
Measured in IBUs (international bitterness units)
10-15 for light beers like lagers
over 40 for IPAs
How is CO2 levels measured in beer?
Measuring the pressure that CO2 creates when it is pushed out of beer.
Measured in g/L (2-9)
How are O2 levels in beer measured?
Using ug/L and should be below 100
How is haze measured in beer?
EBC.
same as colour
Why would you add water to beer after it has been filtered?
Reduce the level of alcohol
