Compac CG is the semi-refined, granulated form of the seaweed species Eucheuma cottonii. The species Eucheuma 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.