The forced carbonation process can take several hours to days depending on the system being used. However, there is an alternative which is in-line carbonation using an available technology which is suitable for Microbreweries, SBT has done significant testing on this technology and it works. Beer can be in-line carbonated from the SURF to the tap or to the keg for filling.
While complete fermentation and conditioning can be completed in the non-pressure rated SURF with accurate control of temperature, there is one missing component in the beer which is the correct level of carbonation. The non-pressure rated SURF cannot be used for “forced” carbonation of beer with compressed CO2, this is only possible when the beer is enclosed in a pressure rated vessel and compressed CO2 is added to the cold beer. The majority of breweries transfer their beer from the fermenter to so called “Bright Beer” tanks for carbonation, storage prior to bottling or serving. During this transfer the beer may undergo filtration or centrifugation to remove the yeast. Most small microbreweries do not perform filtration/centrifugation and instead allow the majority of the yeast to settle out to the bottom of the fermenter.
An alternative approach to the carbonation issue would be to perform in-line carbonation using another existing technology. The conditioned beer can be brought up to the correct level of carbonation by pumping the beer from the SURF through a small in-line carbonator which is driven by air and supplied with CO2. For in-house brewpubs the beer can be pumped directly from the SURF via the in-line carbonator through a chiller (optional) and to the tap for serving. See sketch below for an overview of the set-up.
Equally the beer can be in carbonated in a similar manner using a larger in-line carbonation system if filling kegs, bottles or cans directly from the SURF, reference Moravek International. Leaving beer “sit” on the old yeast is not recommended as over time the yeast will autolyse (die) and release undesirable nasties which detrimentally impact taste and flavour of the beer. While the yeast will collect in the cone, it’s very difficult to push out all of this yeast using only the liquid head from the beer. The yeast slurry tends to “stick” to the cone wall and holds up a layer of the yeast down the length of the cone. The single skin SURF shell also offers an advantage in this regard. Tapping the outside of the SURF cone sends vibrations through the entire cone which causes the yeast to settle to the bottom where it can be removed by the liquid head from the beer.