60
The initial temperature will likely be above 20°C/68°F and we
recommend fermenting at 15°C/59°F so it will take a few hours
after pitching the yeast for the temperature of the vessel to
reach target.
Lager yeast ferment slower than ales and at a lower temperature,
so the start to a lager fermentation takes longer. After 1 day, the
pressure will start to build and a pressure of 1.5 bar should be
reached before Day 2.
After 3 days fermentation, you need to change the temperature
setting to 18°C/65°F. This increase in temperature is to speed
up the reduction of a flavour that the yeast has produced, called
Diacetyl. This chemical has a sweet butterscotch flavour and is
normally seen as an off-flavour in lager. The exception is Pilsner
Urquell from the Czech Republic, whose brewmasters like a
little bit of Diacetyl in their famous pilsner. This temperature
increase is called a Diacetyl Rest or Ruh or The Narziss
Fermentation after the famous German Brewing scientist.
The SG for a 1.045 lager should be at 1.008 by Day 5 and we
give one day more extra warm maturation.
So on Day 6, you can put the cooling on for our lager yeast for
1.045 SG beers. If you would like to take SG samples to check
each day or on Day 6 you can do this by taking a sample out of
the tap (See Appendix 3 for details).
However as a rule, WilliamsWarn Standard Kits should reach the
final SG’s each time and you can check fermentation is finished
by looking into the sediment bottle and confirming you have a
decent amount of settled yeast and almost no bubbles rising
anymore.
This 6 day rule will be true probably up to about 1.055 initial
SG made with these 2 lager yeast. However it is a good policy to
take a sample on Day 6 to ensure a higher alcohol fermentation
has finished before you put the cooling on.
Lagers at higher initial SG’s will likely need an extra day or two
depending on how high you go. For lagers at above 8% you
may need an extra packet of yeast pitched at the beginning of
fermentation.
NOTE: As mentioned in the note for ales, the sharp drops in
pressure in the chart on Day 6.5 and Day 7.5 are indicative of
the Clarification Process when we create a pressure differential
of 0.25-0.5 bar between the vessel and the gas cylinder in order
to force clarification agent into the beverage. This is described
in Appendices 5 and 8.
WHEN TO COOL THE CIDER
The cider should be at 1.010 by Day 4 and we recommend
putting the cooling on then. Alternatively, you can wait a few
more days for it to get to 1.007. Once the cider is cold the yeast
should have stopped and the cider should be clear and ready to
consume.
However, we recommend you determine when to put the cooling
on by the actual S.G. measurement rather than the day. If you
ferment the cider all the way to 1.007 or lower, you may find
the cider to be too thin, dry and tart (sour), which is why we
suggest to put the cooling on before it is fermented right out.
The yeast will settle and leave a clear cider, so do not add any
clarification agent as this is not required.
In reality S-04 will struggle to ferment lower than 1.007
anyway as most of the yeast has flocculated by then. We like
this ale yeast to be used as our cider yeast as it doesn't need
clarification and our clarification agent doesn't work well in
apple juice.
COOLING AND BEVERAGE CLARITY
To a certain extent, the cooling helps some of the remaining
yeast in the beverage to settle down into the sediment bottle,
but the yeast mostly flocculates when it has finished consuming
the sugars that it can consume.
However you should notice the layer above the sedimented yeast
to be a bit more settled after cooling compared to before the
cooling is put on.
The cold temperatures also assists the clarification agent to
combine not only with yeast to clear beer, but also with haze
proteins from the barley that make beers hazy. The colder the
beer the more of a reaction there will be between these proteins
and the clarification agent, which helps make a brighter beer.
This is why we recommend cooling any beer to 1°C/34°F for
clarification with our clarification agent.
The dispense temperature can be increased on the controller
once clarification is complete if you would prefer to drink the
beverage at a warmer temperature.
