What's all this stuff in my pint? Well it's not yeast this time and it's not even beer yet! The pint glass shows the 'cold break', from the rapidly cooled copper wort sample, dropping slowly as the flocs or little lumps of protein gather together or coagulate and fall to the bottom of the glass.These proteins precipitate from the brilliantly clear hot wort as it is cooled and if we get a clear cold wort with what we call a 'good cold break' at the bottom of the glass like in the picture above, there is much rejoicing in the brewhouse, for it means that we shall have clarity in the beer. Without a good cold break, that is, one which does not settle out well and remains as a murky, cloudy wort, then there will be wailing and gnashing of teeth as this certainly means clarification issues ahead.
What the cold break tells us is that the wort has been boiled vigorously and strongly and for long enough (60 - 90 minutes) so that the ultra-microscopic protein particles are flung together at their iso-electric point, the pH at which the numbers of positive and negative particles are equal, and stick together to form large flocs - the 'hot break', which separates out leaving crystal clear wort in the copper. If the boil is not vigorous the wort will generally remain turbid - a bad word in a brewery!
However the cold break is a lovely sight to a brewer and is more proof that beer is a protein drink!
Slainte, Ken
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