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