PREDICTION OF WORT COLD BREAK PERFORMANCE OF MALT AND ITS APPLICATIONS

A new test for wort cold break performance of malt was developed. base d on laboratory mashing and boiling. followed by adding a range of con centrations of copper finings at different wort pH values. The test pr edicted successfully brewery wort cold break performance. with malts b eing ranked on the basis of production of wort cold break which requir ed a low concentration of copper finings for precipitation and floccul ation. A relationship between wort pH and the concentration of copper finings required to give an acceptable cold break was established with both brewery and laboratory worts. A strong correlation (r = 0.922, p much less than 0.01) was found between copper finings concentration a nd the two variables wort pH and the amount of cold break protein. Dif ferences in brewery cold, break performance were explained largely by a difference in wort pH. although other as yet unidentified factors ap peared to be involved. Cold break performance of malts was affected by both crop year and protein modification, but not total nitrogen or to tal soluble nitrogen. A brewing trial is described in which wort pH is increased at the end of boiling. leading to significant improvements in both cold break and isinglass finings performance.