In 1487, the German duchy of Munich adopted a law that insisted the only permissible ingredients for making beer were water, barley and hops. The law was introduced to the rest of Bavaria in 1516 and then embraced later still by greater Germany.
It is called the Reinheitsgebot and has been regarded as a credo by fundamentalist brewers around the world ever since.
Now, however, a team of scientists led by bioscientist Jay Keasling from the University of California, Berkeley, in the US, is suggesting that the Reinheitsgebot might actually be a bit too complicated and the interests of good beer might be best served by dropping the hops altogether.
This news, of course, will send a collective cry of “mein Gott!” around the globe, but Keasling and co base their argument on the one crucial ingredient on which the German code is silent – yeast.
There is a very good reason for the absence of the world’s most useful fungus from the Reinheitsgebot. At the time, no one knew of it, much less of its crucial role. As every ale aficionado today knows, brewer’s yeast (Saccharomyces cerevisiae) gobbles up simple sugars such as glucose and maltose and produces carbon dioxide and alcohol.
In a paper published in the journal Nature Communications, Keasling and his colleagues show that with a little tweaking it can also produce the bitterness and flavour long associated with hops.
In beer-making, the word “hops” denotes the flowers of a herbaceous perennial plant called Humulus lupulus. There are scores of different varieties, bred obsessively by brewers to impart specific blends of bitterness and flavour to what might be otherwise rather bland drinks.
Hops, however, are energy and water intensive to grow. They are also notoriously troublesome, in that they do not breed “true” – that is, a seed from a plant will not produce an identical offspring, meaning that commercial crops must be effectively cloned from cuttings.
Keasling’s team has found a way to avoid all these problems by ditching them completely and instead engineering the genome of the yeast to produce hoppy characteristics. They do so by altering commercial S. cerevisiae DNA, adding snippets derived from other yeasts and herbs such as mint and basil.
Doing so, they report, involves a “unique challenge” and requires “state-of-the-art engineering techniques”.
The result, however, is a yeast that is able to biosynthesis aromatic molecules that impart hoppy flavours – and does so better than hops.
“Beers produced using these strains are perceived as hoppier than traditionally hopped beers by a sensory panel in a double-blind tasting,” they conclude.
Originally published by Cosmos as The pursuit of hoppiness
Andrew Masterson is a former editor of Cosmos.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.