STUDIES ON THE MECHANISM OF ACTION OF COPPER FINING AGENTS (KAPPA-CARRAGEENAN)

Carrageenan mediated clarification of brewers' wort comprises two reac tions: interaction between carrageenan and soluble wort polypeptides a nd flocculation of particulate material. The dose/response characteris tics of interaction between carrageenan and soluble polypeptide materi al suggested that carrageenan exhibits selectivity with respect to spe cific polypeptide fractions. Size exclusion chromatography of worts de monstrated that carrageenan treatment resulted in reductions in fracti ons of relative molecular mass Mr 70 000, 40 000 and 12 000. Fining tr ials demonstrated that the reactivity towards soluble polypeptides is independent of the presence of insoluble particulate material. Further more, both interaction with soluble polypeptides and flocculation of p articulate material occurred in systems fined under high (80 degrees C ) and low (20-25 degrees C) initial temperatures and this suggested th at the presence of carrageenan in a helical conformation is essential to fining action rather than conformational transitions in polysacchar ide structure, Additionally, carrageenan has no effect on the levels o f low molecular mass wort solutes such as nucleic acid derivatives, ar omatic and heterocyclic amino acids.