Bottling is an important part of creating a home brew beer and one which can have a dramatic effect on the outcome of the beer depending on the care taken and timing of the bottling process.
Additional sugar is added during bottling, which is then fermented by the remaining yeast into CO2 to carbonate the beer. The amount of sugar added will dictate how fizzy the final product is, so lagers tend to have more sugar added than ales, for example.
Another easy option is purchasing carbonation drops which are effectively a fixed amount of sugar so that all bottles have the same amount of sugar added and can help with consistency but are typically several times more expensive than using sugar.
As mentioned in the Primary and Secondary fermentation posts you must be extremely vigilant to not bottle before fermentation has finished. The risk of bottling early is that an uncontrolled amount of sugar will be converted to CO2 in the bottle, causing the pressure inside to rise to unsafe levels. This can cause anything from slight extra carbonation to so-called bottle bombs where the pressure is high enough to shatter the bottles.
Warm storage in bottles is basically a ‘Primary Fermentation’ in the bottle to aid the yeast is converting the additional sugar to CO2 and is typically done at a temperature where the yeast is happiest. This normally takes between 1-2 weeks, its worth tasting at least one of your beers at this stage to make sure you are happy with the carbonation or if you think they may benefit from additional time at a warm temperature.
Cold storage is similar to secondary fermentation although is arguably not optional. This stage will help clarify the beer and cause sediment to settle to the bottom of the bottle, also it will chill the beer for drinking. Alongside this it also helps to mature the flavour of the beer as the yeast runs out of sugar to eat and will turn to other items, meaning the longer you store your beer the better it should get.
Other Posts in the Home Brew “Lager” Series