What are the essential ingredients used in the production of beer?

Barley malt, of course, and other grains and special sugars that combine to make a sweet extract known as wort.

Then hops, the salt and pepper of the process, add piny, resiny, spicy and fruit aromas and flavours. And there is water, not any common-or-garden tap water, but pure liquor, often drawn from deep underground wells or bursting from the ground from natural springs. Even when water does come from the public supply it is purified several times before it is deemed fit for purpose.

But if a brewer makes a hopped wort from these three ingredients, we still would not have beer. It takes something special, almost magical, to turn malt, hops and water into a pleasurable and life-enhancing form of alcohol. That something special is yeast. Unknown to the ancients in the Old World of Babylon, Egypt and Mesopotamia, it was wild yeast spores in the air that turned a sweet liquid derived from the bread-making process into a drink that encouraged a Sumerian poet around 3000 BC to write, “I feel wonderful, drinking beer/in a blissful mood/with joy in my heart and a happy liver.”

The role and behaviour of yeast was not understood until modern times. In medieval England, brewers called the froth on wort that produced ale “God-is-good” as it seemed to be manna from heaven.

It was not until the 18th and 19th centuries when first the Dutch scientist Anton van Leeuwenhoek and then the French micro-biologist Louis Pasteur analysed yeast that its role in brewing was finally grasped.

With the aid of a microscope, Pasteur was able to demonstrate that the production of alcohol was not a miracle but a natural chemical reaction in which yeast cells multiplied as they turned sugars into alcohol and carbon dioxide. Thanks to Pasteur’s microscope, the next stage in our understanding of brewer’s yeast came in the Carlsberg laboratory where a pure strain, free from harmful bacteria, was isolated by the brewing scientist Emil Hansen.

Article continues in Issue 9 of Beers of the World Magazine