Mash

The sugar and some of the flavour come from the malted barley.

Malted barley is barley grains which have been encouraged to germinate by soaking them in water. The germination is then halted by drying the grains in warm air. This process develops enzymes in the grains which will, under the right conditions, convert the starch in the endosperm to sugar. After drying these grains are crushed so that the starch is exposed. This is all done at the maltings; you buy the barley ready malted and crushed.

In the mashing process the crushed malted barley is soaked in hot (65°C) water for around an hour and three quarters in a mash tun.These are the conditions which activate the enzyme, which malting developed, to convert the starch in the endosperm of the barley to sugar. At the end of this stage you get a sweet malty sloppy porridge of barley.

The liquid in this porridge is called wort and is drained into another vessel

Sparge

After draining, the barley in the mash tun will still contain useful sugar (and flavours for that matter) which must now be rinsed out to join the rest of the wort. The rinsing process is called sparging.

This has to be done very gently because we want the sugar but not some of the other parts of the grains and other products of the mash process. So hot water is sprinkled very gently over the grain and allowed to soak through to join the wort. The water should be just hot enough to dissolve the syrupy sugar solution, but not too hot because that would increase the amount of the other stuff which gets through. The actual temperature is the subject of debate but it should be somewhere around 75°C. The water can be heated in a Hot Liquor Tun (HLT). The temperature in the HLT should be higher than 75°C to allow for cooling as the liquor (water) travels to the mash. I heat this water to 80°C.

Boil

The wort should now be boiled with the bittering hops tumbling around freely for around an hour and a half. This length of time is needed for two reasons:

1. It takes of the order of an hour and a half to extract a useful amount of the acid in the hops to create the bitterness and, for that matter, preservative.
2. There are proteins in the wort which are produced during mashing and, if left, they would make the beer cloudy and could affect the flavour. Boiling for a long time causes these proteins to coagulate and subsequently drop to the bottom to form trub which is like a sludge. This makes it easier to avoid transfering these proteins to the fermenting vessel.

Hops also contain oil which can provide a pleasing aroma in the finished beer. However, these oils are quite volatile so although they are absorbed by the wort during the boil they will mainly evaporate. So, adding some more hops near the end of the boil will allow some more oil to be absorbed which will not have enough time to evaporate.

Chilling

The yeast cannot be introduced to the wort until it has cooled to 25°C or below otherwise it would be destroyed. You could just leave the wort to cool down at this stage which would take many hours, probably over-night. However, if the cooling is rapid enough more proteins which are still dissolved in the wort will come out of solution and will fall to the bottom during fermentation and so will be left behind with all of the dead yeast. There are several methods for rapid chilling. I have a coil of copper pipe which is immersed in the wort and through which I run cold water.

Fermenting 

The wort is now transfered to the sterilised and rinsed fermenting vessel (FV) and the yeast is introduced. The yeast needs plenty of oxygen dissolved in the wort at this stage so you need to run it into the FV from a great height and give it a really good whisking with a long handled sterilised plastic spoon. You need to cover it loosly to stop bacteria getting in while allowing CO₂ to escape and then you leave it for about a week at around 20°C. It can be worthwhile giving the FV another good stirring up early the next morning after your brewday. Yeast needs oxygen to grow happily. Later on in the fermentation process and when it is finished you must be carefull not to introduce more oxygen as this can cause flavour problems

It is quite astonishing how much CO₂ the yeast produces while it is consuming the sugar and producing alcohol. If you brew 23 litres (40 pints) of 5% beer you'll get nearly 900 grams of CO₂. You don't need to worry about your "carbon footprint" though because all that CO₂ was in the atmosphere last year being absorbed by the barley as it grew.

Adding a few grams of hops to the fermenting vessel will allow more of the hop oils to be absorbed into the wort to enhance the beer's aroma. You don't have to worry about sterilising these hops because of their preservative properties.

To start with, the yeast will be very active (we hope) but as time goes on it will slow down. When you think it might be stopping you need to check the specific gravity every day until you see no change from one day to the next; hopefully the specific gravity -1000 will be around 1/4 of the original gravity -1000 e.g. 1040 to 1010 or 1050 to 1012. At this stage the yeast is mostly replete and there's not much sugar left and it's time to transfer the beer to the pressure barrel.

NOTE. don't forget to sterilise the hydrometer and the measuring cylinder if you want to put the beer back in the fermenting vessel each day.

Racking

The beer will have a few bits of yeast floating around in it which are still hungry; we use these to produce some more CO₂ in the pressure barrel to give the beer its liveliness. To do this for 23 litres, boil 200ml of water with 50g of sugar to sterilise it and dissolve the sugar. When it's cool put it in the sterilised barrel.

I have been frustrated on a few occassions by leaks so I always check that the lid's "O" ring is in good condition and smeared with petroleum jelly vegetable oil.and that the tap is securely fitted that it is all in good working order before I commit the hard won beer to it.

Unlike when the wort was transfered to the fermenting vessel with the yeast it is now very important NOT to introduce any air. So, sterilise a plastic tube and place it over the tap of the FV with the other end on the bottom of the pressure barrel and let the beer run in very gently. Then put it in a cool place, ideally around 10°C to 12°C, and wait for around 2 to 4 weeks (depending on thirst)..