Compac CG is the semi-refined form of the seaweed species Euchema cottonii, used for wort clarification and available in granular or tablet form.
The species Euchema cottonii is rich in the kappa isomer of carrageenan. When added to boiling wort, kappa carrageenan reacts strongly with soluble proteins, notably the proline rich haze precursor fraction. When the wort is cooled the carrageenan protein complex becomes unstable and precipitates out of solution. The clear wort that results produces a beer with enhanced processing characteristics.