Principles of Home-Brewing

Without a doubt, making proper beer is the home craftsman’s toughest challenge. You can make beer from kits – and all good wine and beer making stores will stock a range of these. Quite often the process involves nothing more than dissolving the tin’s contents in water, adding the yeast, adding some sugar, fermenting it in a suitably sized container (5 gallon brewing bucket) – then bottling. The drinking bit is also fun!

Slightly more involved, is making the beer from a syrupy stuff called “malt extract”. Here, you need to dissolve the extract in boiling water (beer makers call this the wort) adding sugar and hops then continuing the boil for about an hour. After cooling to room temperature, you pitch the yeast into the wort (jargon for “adding” the yeast) and ferment out as above.

Boiling with hops is essential. The hop is a flower – and it provides flavour to the beer. Hops are also preservatives which help the beer to keep longer. The bitterness arises when a compound in the hop flower – called humulone isomerises to isohumulone. This isomerisation occurs at the temperature of boiling water. Isomerisation is a process in which a chemical substance changes its structure.  Isohumulone is more soluble than ordinary humulone and it is extracted efficiently into the boiling wort. If you want to see the chemistry of this process – simply follow the link:

It is fair to say that both kit beer and “extract” beer will give you a reasonable drink at a very good price per pint! However, these beers do possess a distinctive and fairly “amateurish” flavour.

Making truly delectable beer, comparable to any commercial product, involves another process. This is the art of “mashing”.  Here, the main ingredients are malted cereal grains. Which, most notably for beer is barley. However, other cereals can also be used: wheat, rye and oats.

In wine making, sugars from the fruit or added sugar are immediately fermentable by the yeast. The yeast “feeds” on sugar and produces alcohol.  In contrast, the brewer has to make fermentable sugar in the mashing process. When a cereal grain is “malted” it is first allowed to germinate. After a short while, the grain is heated up to dry it – which prevents any further growth. It is, in effect, killed off. What occurs is that the growing cereal grain produces a mixture of enzymes called “amylases”. Amylase breaks starch down into maltose. The art of malting is to allow the grain to produce enough amylase to convert the starch to fermentable sugar (maltose). But, and here’s the nifty bit, heating the grain kills it off! What malted grains, therefore, possess is a store of starch and a goodly dose of enzymes. Conversion of starch into maltose takes place at a future date – this is when the brewer “wakes the chemical reaction up”. In this process, the enzymes are re-activated and can get to work on the starch – this is the mashing process.

Crucially, mashing involves mixing the grain with hot water (65 Celsius), and maintaining this temperature, which allows the conversion to occur at a reasonable rate – generally, full conversion takes a couple of hours. Too high, and the enzymes are destroyed. Enzymes are proteins – and proteins can be denatured by excessive heating. When you cook an egg you deliberately denature the protein. This is when the runny albumin is converted into the more palatable solid egg-white. In beer making you must not denature the enzymes. Strict temperature control during mashing prevents this. The enzymes work best in a very narrow temperature range – around 65oC (150oF) plus or minus a couple of degrees – but no more.

The art of mashing

The malted grain is placed in a grain bag (obtained from any of the suppliers listed on the “Links” page) and immersed in 4.5 gallons (21L) of water at 70oC (158oF). This is the so-called “strike” temperature: the cold grain will ensure the mash temperature falls rapidly to 65oC. Maintain the temperature at 65oC until conversion is complete.

You will be using a 5 gallon vessel known as a “mash tun”. This is fitted with an electric heating element, and the temperature is controlled with a thermostat. However, get to know your own mash tun. In particular, experiment with plain water until you are confident that you’ve found a setting on your thermostat that will hold the temperature of 65oC (150oF) closely. Personally, and since 4 or 5 gallons of water cools very slowly, all I ever did was to turn the electricity off – then every half hour or so just give it a boost back to 65oC. However, recently I bought a conversion kit from Peco Services (see "Links"). This kit contains a digital temperature controller that holds any temperature to within plus or minus 1 degree! It is absolutely wonderful! All you have to do, to convert an old-style Electrim Mashing Bin, is to take the element out and then the old thermostat (a very easy operation). Drill a 20mm hole (full instructions supplied) above the element then fit the supplied sensor and refit the element. I have tried it - it's the "Rolls Royce" of temperature controllers. You can walk away and have a beer without worry! Utterly fantastic!

 Use the iodine test to check on the progress of the mash. Tincture of iodine – available from any pharmacist is used for this. Just add a drop to a little of the grain from your mash. It will turn intensely blue/black in the presence of starch. Note: it’s best to us a white saucer for this. If starch is still present – continue the mash. When conversion is complete, run the sweet wort into a 5 gallon vessel. Sparge the grain with a couple of kettles of boiling water. Sparging (an old-fashioned term) is where the grain in the bag is washed with boiling water. This frees it of any sweet wort that has been retained by the grain. Some people devise all sorts of sparging techniques – a favoured one being to use a shower head or a watering can head to direct the hot water in a steady stream. Personally, all I do is to pour on the water directly from the kettle. The grain acts as a sort of filter, the washings are collected and combined with the wort you collected earlier. Keep sparging until you have around 5 gallons of sweet wort.

Irish moss is used next. This is a coagulating agent which helps to clear the boiling wort. Add a couple of spoonfuls of Irish moss, then put hops into another grain bag and boil the wort with the hops for at least an hour (I like to use separate bags for hops and grain – hops tend to stain the fabric!). Run off the hopped wort into a 5 gallon vessel. Sparge the hops – try to get back to 5 gallons total. Allow it to cool to room temperature. A hydrometer reading should now be taken. This is called the “original gravity” of the beer. It is a rough measure of its potential strength. As a very rough and ready rule the last two digits can be interpreted as the % by volume of potential alcohol. So, an O.G. of 1060 should give you about 6% alcohol. This is a full strength beer. Many people prefer weaker beers for everyday drinking – those with an O.G of around 1035 – 1045. If that’s more to your taste – adjust the amount of malt in the mash.

Now pitch the yeast. Fermentation will be obvious in about 24 hours. After 2 or 3 days, the surface of the fermenting liquor becomes much less “troubled” and now is the time to siphon the beer into a 5 gallon demijohn fitted with an airlock. Here it stays for about 4 or 5 weeks. An optional step – and one which gives the finished beer a delightful aroma – is to add a handful of hops to the beer in the demijohn. This is called “dry hopping”. I “dry hop” most of my beers. During this time the beer clears and it is ready for bottling or putting into a pressure cask.

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24.01 | 23:08

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54-bottle wine rack, wood and galvanised steel construction
5 clear-glass dimijohns
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29.10 | 12:37

I have a Beer Sphere with gas and a number of Demi-Johns which I no longer need. If anyone is interested please contact me on 01892 832684 (Paddock Wood)

21.09 | 16:11

I am just starting wine making so could really use some Demijohns. I live close to S'oaks so easy collecting.

06.09 | 20:39

I have a black grape vine ( just turning black now) probably enough to fill a flexitub. I live in Blean Nr Canterbury if anyone is this way and would like them

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