Initial Fermentation

We do two brews in one day. This makes twenty two barrels of beer. There are 31 gallons in a barrel (bbl). Our fermenters are 24 barrel tanks, so they have a small head room for foam created during the bubbly fermentation.

Fermentation begins within 12 to 24 hours after the yeast is pitched into the fermenter. This initial lag phase is when the yeast grow and divide. Each yeast cell will produce two to three new cells. Once all of the oxygen is used up, they stop dividing, and start to ferment. This starts slow, as small bubbles in the bucket next to the fermenter. In a few hours, though, it really starts going.

Lager yeast like to ferment at about 55 degrees F. Initial fermentation will last 3-5 days. We let our brews sit in the fermenter for a full seven days to be sure that fermentation is complete. Then we cool the beer to help the yeast settle down to the bottom of the tank.

Lagering

When the beer has been under active cooling for several days, we transfer the beer into a tank in our cold Lagering Cellar. This room is kept at 39 F all year round. This beer is called Green Beer because it still needs to mature. The fermentation by the yeast was hasty, and they have left many undesirable byproducts behind, such as sulfur. Many yeast are still in suspension, and they continue to mature the beer. We prefer to leave the beer in this phase for atleast two weeks, though beer can stay in the lager stage nearly indefinately.

Yeast Harvesting

After the beer has been transfered to the the Cellar, the yeast are harvested from the fermenter. Yeast flocculate to the bottom of the fermenter when all of the sugars have been eaten and turned into alcohol. I need to harvest this yeast, and check its viability, for use in the making the next batch of beer. We re-use our lager yeast many times. We typically will re-proprogate it back up from the master stock once a year.

To harvest I simply reach inside with plastic scoop and transfer the yeast into cornelius kegs. The yeast is then kept in an ice bath until it is needed. When we brew, we will wash the yeast with acid to clean them up and get them ready for doing their job, fermenting!

Filtration

Filtration is an important step in the beer making process. It removes yeast and and chill-haze forming protiens that could leave the beer cloudy and unappetizing. Furthermore, many of these same haze forming compounds can lead to off-flavors if not removed (such as yeast-autolysis flavors). However, not all beers are meant to be filtered, and we don't filter every beer. We rarely filter our seasonal beers, because they are drank so quickly. Other beers are intentionally hazy, such as Wit beers and Hefewiess, and it would be difficult to filter them even if we tried.

We used a Diametacious earth, or D.E. filter. It passes the beer under pressure through a layer of this fine stuff. D.E. is continously dosed inline to keep the bed evenly porous, this allows a longer filter run than with a conventional pad filter. What comes out the other side of the filter is beer that is clear enough that a flash light will be bright if shined though it. We call this Bright Beer, and the tanks we put this beer into are called Bright Beer Tanks. After the filter, the beer passes over a carbonating stone. This injects C02 into the beer, carbonating it. We check our carbonation carefully with a carbonation tester, to make sure the beer is not flat or over-carbonated.

The beer is now finished, and can be packaged in either bottles or kegs.