Fermentation is one of the most delicate steps of brewing and it happens in the fermentation kegs not in the machine. During fermentation, yeast converts the carbohydrates contained in the wort to alcohol, carbon dioxide, and various aromas (esters). Different yeast species work optimally at different temperatures, but generally, higher than optimal temperature results faster fermentation and more esters, while cooler than optimal temperature results slower fermentation. Creating and maintaining the temperature during fermentation is essential to form the characteristics of each type of beer.
Hygiene is the most important aspect; as unintended microorganisms may infect the wort and cause a change in the taste or spoil brew.
The state of fermentation can be observed by taking a look at the airlock. If carbon dioxide is still leaving through the airlock, fermentation has not finished yet. If there is no movement in the airlock, it’s practical to measure the Final Gravity (FG) of the beer with a hydrometer. If the FG is around 1.010, and this does not change for 2 days, and its taste is not sweet or fizzy, you can start bottling. If the FG value changes, wait 2 more days with bottling, and check again. After reaching this point, fermentation can be considered finished, but this value is recipe dependent. If Original Gravity (OG) was measured at the start of the fermentation, alcohol by volume (ABV) can be estimated from the difference of the two.
After draining the wort into the fermentation vessel, add the yeast. Attempt to cover as much of the wort’s surface as you can. Air-seal the fermentation tank and place the airlock. Ensure the required constant fermentation temperature for your container.
You can measure the Original Gravity (OG) at this point to check the efficiency of brewing.
PRIMARY FERMENTATION
Primary fermentation generally takes 7-10 days depending on the recipe. Alcohol and carbon dioxide forms during this critical phase. Also, during the main fermentation, foam is formed, which consists of approximately 20% of the full amount of the beer – for this, a „foamspace” might be let empty. You can notice the end of the main fermentation phase, when the fermentation lock stops clucking, and the beer does not taste sweet or fizzy.
Equipment fit for fermentation: Fermentation bucket or tank
SECONDARY FERMENTATION
Conditioning usually happens in bottles or kegs. In this phase carbon dioxide still forms, but the taste starts to clear out. Although there is already alcohol and carbon dioxide in the beer, its taste is still not whole, so it pays off to wait out this phase. Depending on the beertype, it might last 2-8 weeks, but even more in some cases.
The amount of sugar is usually between 5-10 g/ l – use only 5 g/l for bottles and 10 g/l for kegging.
Equipment fit for conditioning: Bottles, Party keg, Cornelius
