Secondary Fermentation
Bottle-Conditioned Beers
The practice of using priming sugars for bottle-conditioning is frequently applied to top-fermented beers in Britain and is still followed by some craft brewers as well as a few larger British brewers. Belgian brewers are also known for using this method to add unique flavors. Bottle-conditioning usually involves a short time in the conditioning tanks to improve overall stability and flavor before adding priming sugars.
Yeast
Although yeast for bottle conditioning can be derived from different sources, it is generally accepted that the most common inoculum is yeast which has been cropped from a primary fermentation. Such yeast is typically variable in terms of its quality, as the physiological condition of yeast can be negatively affected by fermentation and exacerbated during serial repitching. If yeast slurry is used, it should be harvested within a week of the beginning of fermentation.
Bottling
After a brief maturation period, the beer may be filtered before being sent to tanks with stirring agitators, where the priming sugar (e.g., glucose, dextrose, or invert sugar) is added. It is important that yeast and extract are thoroughly blended with the finished beer to insure uniform carbonation. The ideal is to have bottling tanks equipped with agitators. Yeast slurry and extract (or fermenting wort) are pumped or forced with carbon dioxide into bottling tanks and mixed.
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