Boiling the Wort

There are a number of reasons to boil the wort:

• extracts flavour & bitterness from the hops
• sterilises the wort to prevent infection
• clears protein debris from the wort (the 'hot break')

The last of these is worth further mention. The wort from the sparger is full of all sorts of bits and pieces of protein matter extracted from the grains or produced by reactions in the mash tun. If these were left in the beer, they would cause hazes and off-flavours.

Boiling causes these particles to clump together (coagulate) and sink to the bottom of the boiler during the 'stand'. During the run off they are left behind in the boiler as so-called 'hot trub'.

Hot trub left in the boiler after the 'run off'

To successfully 'coagulate' the proteins and extract bittering acids from the hops takes around 1 - 1½ hrs of vigorous boiling.

My Old Boiler

I use a Thorne boiler with the thermostat removed and the element supplied from a variac, so that the heat can be adjusted to get a perfect boil:

My boiling schedule is as follows: