Barley has been around for about 20,000 years when it was bred from its ancestor into its more recogisable form in ancient Egypt.   It belongs to the grass family and produces grains containing a tiny dormant embryo and a large starchy food source to fuel the growth of the new plant until it can photosynthesise its own food.   This starch is wanted by the brewer so it can be converted into sugars that yeast can in turn into alcohol.

From the Field to the Maltster

When the barley is harvested, it contains a moisture content of around 10-15%.   The maltster tricks the barley into germinating by steeping it in water until the moisture content reaches around 45% and then taking it out of the water and keeping it warm.   The embryo generates hormones that prompt enzyme production.   These enzymes break open the starch containing cells to allow moisture in.   Other enzymes break down the protein matrix that keeps the starch stable into amino acids.   These in turn can be used to build other proteins that will become the new growth tissue of the embryo.   At this point the maltster stops germination by drying the malt until its moisture content falls low enough to make the embryo inside the grain dormant again.

The grain is then kilned to dry it.   The length of time it is kilned for makes the grain different colours.   Just like bread in a toaster, the longer it is roasted, the darker the grain becomes.   Also the flavours of the grain change, from sulphury flavours in very pale malts, through nutty, caramel through to chocolate, burnt and bitter flavours in darker malts.   The more a grain is kilned, the less sugars can be derived from the starches inside as they caramelise.   This provides body to a finished beer.

To the brewer

The brewer crushes the grain in a mill to expose the starchy insides, allowing access for water to penetrate better later.   The brewer puts the grain into hot water at around 65^oC.   This promotes the enzymic reaction that was earlier laid dormant by the drying process to continue.   Proteins are broken down further which would otherwise cause a haze in the finished beer.   The starch is now broken down into maltose sugar which is dissolved into the hot brewing water.   This is called the mash.   After about an hour the enzymes should have finshed converting the last of the starch to sugar and removed much of the protein.

The resulting sugary water is called wort.   It can now has hops added and goes on to the boil stage which extracts the hops flavours, which will be writen about in another section.

Other Malted Grains

Wheat is used in many beers in tiny amounts to promote head retention in the finished beer.   Wheat beers contain more to give a grainy, fuller flavour and the characteristic haze of witbier & weissbier.   Rye is used in only very specialised products, giving a brown beer with a distinctive taste.

Unmalted Grains

Unmalted grains will not have the enzymes present to convert their starch store to fermentable sugars.   Oats are used in some beers, particularly stouts as they give a sweeter, full bodied mouthfeel.   Unmalted wheat, corn or rice can be used in the mash as the enzymes in the malted products will break down the starches present given time although the temperature of the mash may need adjusting to acheive the perfect transformation.   Non malted ingredients that provide sources of fermentable sugars are called adjuncts.   Unmalted roast barley is intensely black and bitter tasting and contains no fermentables.   It gives a full bodied bitter, burnt flavour to stouts.   Used very sparingly.

A list of malts (palest to darkest):

Lagerⁱ malt - the palest of the pale.   Contains the most enzymes, so can be used with unmalted ingredients for a good starch conversion.

Wheat malt - used for its head retention properties and characteristic haze in more continental style beers.

Pale malt - most common malt used in British beers.

Rye malt - speciality malt used for its characteritic flavour.

Vienna malt - produces a reddish-brown beer traditionally produced in Austria.

Munich malt - similar to Vienna malt giving an orange-brown beer.

Crystal malt - the starches are converted to sugar and then it is kilned to a high degree to caramalise them, making them much less fermentable.   Produces a sweeter, caramel flavour and adds body to a beer.

Brown malt - smoked over a wood fire for a very distinctive taste in a Rauchbier for example.

Chocolate malt - dark malt that a brewer can produce chocolate flavours from in darker beers.

Black malt - intensely flavoured malt with a burnt, bitter flavour.