Decarbonation

In the modern beverage plant dissolved gas levels often need to be adjusted. If ales or stouts, which frequently have relatively low carbon dioxide specifications, are fermented in large cylindroconical vessels then the hydrostatic pressure towards the base can cause higher levels of carbon dioxide than required and decarbonation is necessary. Conversely high carbonation small-pack and draught beers may require extra carbonation. Some products are pressurized with a mixture of carbon dioxide and nitrogen. The result is a product with sufficient top-pressure of gas but a lower carbon dioxide loading. Nitrogen is found to have benefits in terms of foam quality and "mouthfeel" (Kennedy, 1994 and Taylor et al, 1992).

The fact that the TLE was colourless and the residue was brown after decarbonation, indicates that the pigment responsible for the pink colour bands is part of the kerogen fraction.