Boiling the Wort – Why You Need To Boil
I want to talk about boiling your wort, why we are doing it and some common ways people go about doing it.
When I first started home brewing I read a few books and it said boil the wort for 90 minutes then cool. This was fine and I went along with it and only later did I read further and find out why so here we have a list of reasons why you have to boil the wort for certain lengths of time.
Why Boil the Wort
To ensure the wort to free from bacteria. Plain and simple by boiling the bacteria that can cause your beer to go off will be killed. You are in effect sanitising the wort.
Primarily the boil length will be dictated by the amount of bitterness you want to extract from the hops. As the alpha acids in the hops are not very soluble they require boiling for around an hour to utilize a desirable amount of the bitterness.
The hot break occurs during the early stages of the boil. You will notice when the wort is close to boiling large amounts of foam on top and small clumps forming in the wort. This is caused by proteins coagulating together. This together with the cold break, will help to ensure the beer doesn’t have any haze when bottled.
Di-methyl Sulfide is present in the wort and evaporates during the boiling process. This is a sulfur compound and will add a vegetal aroma to the beer if present in large enough amounts. It also occurs if the wort is cooled slowly. Although in some lagers it is desirable you can avoid this off-taste occurring by having a good rolling boil with the boiler uncovered so it can evaporate.
When boiling anything be careful. When boiling wort because of the foaming action it is all to easy for a boilover to happen. This is of course very dangerous and very difficult to clean because the sugary wort will soon dry and turn rock hard.
The easiest way to stop boil overs occurring is to make sure your boiler is big enough and not full to the top and to watch it like a hawk when it is approaching the boil. You can also spray the surface with cold water but this shouldn’t be necessary if you are careful about things.
How to Boil the Wort
Boil then Dilute
If you have read and tried the introduction brewing techniques posted here you may of used the following method. Boiling only a partial amount of the finished batch size then diluting with water. A lot of beginners use this method, because it can be done on the stove using ordinary stock pots, no extra equipment is required. It is also a lot easier to handle a smaller amount of boiling hot wort, whilst be quicker and easier to cool.
The only shortcomings of this method is there is a finite amount of bitterness that can be extracted from the hops and of course in essence you are making a concentrated beer then watering it down, like you would with fruit cordial.
So quite self explanatory is a full boil in which you boil the final brew volume. This is how commercial breweries work and if you brew all-grain you will need to do this also. The only shortcoming with this method is the need for a vessel big enough to boil the finished brew size. You can have a look at some example boilers here.