Wort meets yeast
In this stage, the prepared wort finally meets the yeast to begin the fermentation process.
The yeast breaks down the sugars in the wort, producing alcohol and carbon dioxide bubbles. It is with the addition of yeast that the wort begins its dramatic transformation into beer.
The boiled wort is quickly cooled to a temperature range where the yeast can begin its work, then transferred to a fermentation tank.
When the temperature of the wort decreases, it must be cooled extremely rapidly and prevented from coming into contact with outside air. This keeps contaminants (bacteria other than the yeast) from being introduced into the mixture. If bacteria do get in, it can cause the beer to develop a “skunked” taste that is sour or foul smelling.
Through the Middle Ages until the modern era, when scientific knowledge was still in its infancy, wort was cooked in shallow copper cooking tanks that looked like pools and allowed to sit overnight. Today, heat exchanges are used to quickly cool the mixture before it is stored in a fermentation tanks.
There are many different types of yeast, but they can all be categorized into two major groups: top fermenting and bottom fermenting.
Top-fermenting yeasts prefer a room temperature between 15 and 25ºC. They are known for bringing out rich flavors in the beers they produce, which are known as ales. Bottom-fermenting yeast prefer cooler temperatures of between 5 and 10ºC. The beers they produce have a cleaner, more balanced taste and less richness of flavor. These beers are known as lagers.
The enduring power of yeast
Once the fermentation process is complete, bottom-fermenting yeasts gradually settle to the bottom of the maturation tank, while the top-fermenting yeasts float to the surface of the liquid mixture.
At this stage, our artisans swiftly scoop out the spent yeast and add in a new batch of wort.
The collected yeast is not simply thrown away, but expertly measured by our craft brewers and continually recycled as long as it still retains the power to ferment and brew beer.
It is the job of craft beer artisans to create the perfect conditions for yeast to do its job.
This means making sure that the sugar content, temperature, ph values, and so on are just right; observing the yeast under a microscope; and using valves to release excess carbon dioxide—all the while analyzing the progress of the fermentation based on the aromas wafting around the brewery.
Every aspect of the fermentation environment must be held in a delicate balance in order to brew the finest quality beer.
During the first stage of fermentation, which lasts about a week, yeasts break down about 90% of the sugars in the wort. By the end of this stage, alcohol and carbon dioxide have already formed in the fermentation tank, creating what is called “young beer”.
However, the flavors in young beer have not yet had a chance to mingle, and the taste remains disjointed. In addition, primary fermentation always produces an “off” flavor that must be released into the air along with the carbonation.
In order to turn young beer in to fine Coedo beer, we must allow it to age for an extended period of time.
Secondary fermentation (Extending the fermentation process by having yeast continue to break down the remaining sugars as the beer ages)
In this stage, the tank is tightly sealed so that the carbon dioxide produced by the yeast is dissolved in the beer as fine bubbles. At Coedo, we never add anything artificial to our beers, so the carbonation is exclusively the result of yeast action.
Allowing the beer to mature in the tank for one to three months allows the disparate flavors to come together into a harmonized, balanced whole. The delicious clear liquid is finally complete.