Carrageenan is well established in the brewing industry as an important processing aid. Originally, unprocessed seaweed of the species Chondrus crispus (Irish Moss) was used to good effect. As interest in the food industry for high kappa isomer species such as Euchema cottonii increased, so did availability and quality. Today most carrageenan used in brewing is this species. Its role as the most cost effective method of wort clarification is undisputed.
When added to the 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.