The Fermentation Tank is the place where the real magic of brewing takes place. It is here that yeast changes the sugars in the wort into alcohol over a period days or weeks.
The process begins after the wort has passed through the chiller and enters the Fermentation Tank. At that time, we pitch the yeast, which is brewer talk for "put the yeast in the tank." The pitching has to happen when the wort is below 70 degrees F, in order to have the yeast start in healthy and hungry. Over the period of at least one week, every drop of wort will be passed through at least one yeast cell, having its sugars changed into alcohol, and a subtle flavor added.
Within a few hours, a fine, fluffy head will appear on the top of the
wort. This head will increase so much over the next few days,
that it will actually overflow the Fermentation Tank. For that
reason, we use a plastic hose attached to the top of the Fermentation
Tank that goes through a one-way airlock to keep out room air and contaminates,
and empties into a drain in the floor. The first few days of
the fermentation process, this hose is putting out a constant flow of
white fluffy foam as the little yeast cells do their magic, while reproducing
at a rate that would make rabbits jealous.
One of the important things happening during this process is called attenuation. This
is the reduction of the wort gravity or sugar density by the yeast. Many
times, when you read the description of beers written by brewers (usually
for brewers), you will see a starting gravity and an ending gravity. The
difference between these numbers can give you an idea of how much alcohol
has been produced by the fermentation process, and how dry the final taste
may be.
Usually, after about one week in a Fermentation Tank, we rack the
young beer over to another Fermentation Tank, leaving much of the flocculated
yeast in the bottom of the Fermentation Tank to be harvested, and used
on the next batch of fresh wort. After a second week in the
second Fermentation Tank, we keg the beer.
Check out our Brewery Tour pages for photos of this process.
