After grain (usually barley) used for brewing has been harvested, it is allowed to start germinating by soaking it in water, and then it is quickly dried. The manner in which the malt is dried has a profound effect on the colour of the beer.

Drying malt on coke (smokeless coal) brought about pale ale in the seventeenth century – it was the smoke from traditional coal drying that gave normal dark ale its depth of colour.

Drying stops the germination in its tracks, but not before various enzymes have started to develop. The resulting product is malt. Those enzymes become useful in the next stage, mashing, where the malt is boiled in water, often with other grains to add flavour. The enzymes break down the starches and convert them into sugars, most importantly maltose and maltotriose.

Along with the sugars already present in the malt, you get a sugary mixture called wort, which is perfect for the yeast to gorge on. The grain husks are filtered off, leaving the liquid wort on its own – a concoction of sugary water which is ready for stage 2 of the brewing process.

Hops are the flowers of the imaginatively named hop plant, which is a cousin of cannabis – although it should be noted that the hops themselves have no psychoactive effect in beer.

They have been used as a key ingredient in beer for around a thousand years, and replaced the myriad herbal ingredients like dandelions, ivy and heather that came before. Within a few hundred years of the first beers being made with hops, it became the runaway favourite.

It is hops that bring the flavour, complexity and bitterness to beer, and balance out the sweetness of malt. Hops are added at different stages of the brewing process to garner different results. Adding the hops early helps to boost the bitterness, while adding later on will offer bigger and brighter aromas. But hops also have antibacterial properties that affect the action of microorganisms and increase beer’s shelf life, which was perhaps one of the reasons it was popularised in medieval times.

There are thousands of varieties of yeast, but breweries all have their favourite strains, which are cultivated to maintain consistency of the brew. The job of yeast is to convert those sugars in the wort into alcohol. It’s a natural biological process, and it’s where the alcohol in beer comes from.

Different yeasts can have profound effects on the means of production and the end product itself. For example “Saccharomyces pastorianus” is the variety that ferments at the bottom of the vessel in cooler conditions, and is used to make lager.

Meanwhile “Saccharomyces cerevisiae” ferments at the top of the liquid in warmer conditions, and is used to make ale. Different yeasts can also give the beer its distinct flavour. Another yeast, Brettanomyces, is what puts the acid in sour beers, for example.

The amount of fermentation a yeast is allowed to do directly affects several properties of the beer. The most obvious is alcohol content, which affects a beer’s strength and also its bitterness (alcohol is bitter to taste).
But yeast also produces CO₂, which determines how gassy it is, as well as the size of the head. Finally, yeast produces other chemicals like esters and phenols, which affect the aroma and the taste.

Beer is, of course, a liquid, and that means the vast majority of it must be water. Without water, the dry malt and yeast wouldn’t get to work, so it’s not only integral to the taste, it’s also part of the process.

Water might be just H₂O, but waters from around the world all have their own unique blends of suspended minerals, and they all have an effect on the flavours of the beers that come from there. Burton-on-trent is particularly famous for its soft water which makes great Bitters and Pale Ales. While if we take a trip back in time to London around a century ago, the notoriously hard water was better for making stouts and porters, which because popular with the city dwellers around this time.

When you consider that beer is 90–95% water, you might get more of an appreciation of how important it is.