Boiling the Wort

Boiling the WortOnce the first runnings of wort are collected and then combined with sparged wort it’s time to start the boil. There are a couple of reasons why the boil is vitally important to making beer, firstly the wort needs to be sanitised and free from bacteria. There may be bacteria present in the malted grain in the mash and boiling will eradicate all of these beer spoiling bacteria. In the not too distant past, beer was considerably safer to drink than many sources of water simply because of the fact it was boiled and drinking water sources were full of bacteria.

A really important reason for boiling is to do with the taste. Bitterness is key to the way beer tastes and the way we get bitterness into the beer is by boiling hops to isomerize the acids within them. The process of isomerization takes time and this is the reason why most beers will be boiled for 60 minutes or more. Hops added at the beginning of the boil contribute the most to bitterness as the rate of isomerization grows the longer the hops are boiled. After around 60 minutes isomerization slows as all of the alpha acids are used.

As well as these two factors there are a couple of other reasons a good vigourous boil is desirable, firstly the hot break. 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 (rapid cooling), will help to ensure the beer doesn’t have any haze when bottled or packaged. The next factor is to clean up some unwanted flavours in the beer. 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 out of the wort.

Home Brew Boiler or Kettle

The boiler, along with the mash tun are the two basic bits of kit you will need to invest in to progress into all grain brewing, what may seem like a big expense at first soon recoups its value after brewing a few times.

When we brew all grain we ideally want to boil the whole batch of beer, unlike brewing with extract, where you perform a partial boil and then top up the wort to the desired level at the end. Taking the time to mash and extract all the flavour and sugars from grain provides a better quality wort than if you extract only a partial amount and then dilute down with water. This means we need a vessel big enough to accommodate more liquid than the intended batch size.

What Kind Of Home Brew Boiler?

There are various options available to the home brewer and one of the first places to check will be your nearest home brew shop. There are various commercial varieties of boiler available and all will do an admirable job for our purposes. The boilers available are usually around 25 – 30 litres or more which are large enough for a 21 litre or 5 gallon batch. Many of the commercial examples available in the UK are electric boilers with elements in which plug directly into the mains. These boilers will easily achieve a vigorous rolling boil in a short time and often have hop filters in the bottom which allow you to run off a clear wort.

Home Brew Boiler



Alternatively if you can get your hands on a large enough catering stock pot you can modify this to your needs. If you are brewing with malt extract or brewing smaller batches you can get by with a stock pot to boil the whole or just part of the batch of beer. At the end of the boil you will be able to top up the wort to the required level. A 12 – 15 litre stock pot is ideal for this kind of brewing. These stock pots are great because they can be placed on the hob in the kitchen which means making beer is as easy as cooking.

Beer Boiler

If you want to boil bigger batches and brew all grain though you will need a 25 litre pot. To heat this size boiler you will need a burner and gas bottle which means you will need to brew outside but they are a great option which are easily available. Some modifications may be necessary such as making a hole for an outlet tap at the bottom and some brewers even go as far as completely overhauling the pot to add electric elements and sight glasses to measure wort levels. If you do not have these means however there are plenty of brewers who just use a jug to move wort from pot to fermenter so do not worry too much.



Cooling The Wort

Cooling the WortDuring the brewing process after the boil has finished it is a good idea to think about trying to cool the wort down as quickly as possible. There are a couple of reasons to do this, one is that oxidation can occur when cooled over a long period as well as allowing possibilities of bacteria contaminating the wort. Also as the beer cools slowly it also produces a sulfur compound that won’t be boiled off but remain in the finished beer creating off-flavours.

This effect of rapid cooling is called the “Cold Break” just as bringing the wort to the boil is called the “Hot Break”. This cold break causes proteins to precipitate out of the wort. If the proteins remain in the beer which will occur if the beer is cooled slowly you will notice the finished beer will have a haze when put in the fridge. This is purely cosmetic however and won’t effect the taste.

What we are going to look at now are some of the most common ways to chill the beer quickly. First off I will look at the easiest way for the first time brewer, it requires no excess equipment and is what I used to do.

Types of Wort Chiller

So here are the basic options you can go for to get the wort from boiling to cool enough to add yeast as quickly as possible:

Cooling the Wort in a Water Bath

This really is as easy as it sounds. Obviously if you boil your wort in a metal pot then it will cool a lot quicker due to conduction. If you boil your wort in an electric boiler you will need to syphon off to the fermentation vessel before cooling.

So you sit your vessel in a bath of ice cold water. You can of course throw a load of ice into the water bath to speed up cooling and you will notice after 5 minutes or so the water bath will be noticeably warm. Its a good idea to stir this water to even out the temperature. Also you may find you will need several changes of water to get it to around room temperature.

Immersion Chillers

Immersion coolers are a relatively cost effective solution to cooling your wort rapidly. They are basically a long length of copper pipe coiled many times with a couple of hoses on each end of the pipe. All you need to do is attach one end of the coil to a cold water tap and put the other end in a bucket or in the drain to get rid of the water, turn the tap on low and let it do its thing. You will surprised at the heat transfer.

I must say this is what I use and they cool my batch of 21 litres in around 20 minutes to pitching temperature. It has shortened my brew day by a fair amount.

You can find immersion chillers at your home brew shop and a number of people have made their own just by coiling a length of copper pipe. If you have the means to do it then I thoroughly recommend it.

Counter-flow Chillers

Counter-flow chillers work with the same principle as immersion chillers but in this case the wort is run through a copper pipe that is being cooled from the outside. A common setup is to run a copper pipe through a garden hose. The wort is then run through the pipe whilst cold water is run in the opposite direction through the hose.

Counter-flow chillers have greater cooling effect and the wort can usually be run straight from the boiler to the fermenter and be cool enough to pitch straight away. They are particularly effective when you’re brewing larger batches.