Last updated March 23, 2018 at 12:23 pm
Beer without hops? It’s possible, thanks to a new engineered yeast that gives all the flavour – sans hops.
Hops give beer the zesty and bitter flavour that is part of the reason it’s so delicious. But hops aren’t easy to grow, they require a lot of water, and are really expensive.
So a team of scientists from the University of California Berkeley have tried to work out a way they can make beer without the vital flower, and they’ve ended up with a genetically modified yeast that creates the flavours, using none of the hops.
Creating hop flavours
The team, better known for developing sustainable fuels using compounds called terpenes, started working on the question when one of the researchers pointed out that some terpenes had a very similar taste to hops.
That researcher, a homebrewer himself, wanted to recreate the flavour profile of the Cascade hop, one of the most common hop varieties used in craft ales and Indian Pale Ale. To do this they needed to produce linalool and geraniol – two molecules found in essential oil, which are known to be the major flavour molecules in hops.
After trying several different plants they found the best candidate genes for producing these compounds came from mint and basil.
Using the CRISPR gene editing tool, the team inserted the mint and basil genes into the DNA of brewer’s yeast. The yeast, which normally converts sugar to alcohol, now also produced the hoppy oils.
However the success of the experiment would be decided in a taste test – could the hop-less beer compete with traditionally brewed ales?
It’s all about the taste
To find out the team handed over their yeast to a brewing expert at UC Davis to brew a beer from three of the most promising strains.
Recruiting 40 volunteers, the team carried out a double-blind taste test – and the beer produced by the new yeast strains came out on top.
The tasters found that the engineered strain produced beer with more hoppy flavour than regularly brewed beer. They also described “fruit-loops” and “orange blossom”, with no off flavours.
They didn’t manage to remove hops from the process entirely, however – it was still needed during the initial stage of brewing – the wort – to get the bitterness. However, the hop flavour isn’t developed at this early stage, meaning the hoppiness of the beer was created only by the new yeast strains later in the brewing process.
Less hops for better beer
Reducing or removing hops from the brewing process is something that could significantly improve the impact and sustainability, as well as quality, of beer.
The growing of hops uses a huge amount of water, not to mention fertilizer and energy to transport the crop, all of which could be avoided by using the new yeast strains.
In fact, a pint of craft beer can require 50 pints of water just to grow the hops.
“My hope is that if we can use the technology to make great beer that is produced with a more sustainable process, people will embrace that,” the lead researcher, Charles Denby said.
Using the engineered yeast will also mean more consistent and easier to brew beer. The flavourful components, or essential oils, in hops can change in concentration from year to year, and from farm to farm. Using a standardized yeast would allow more consistency in flavour.
Denby has now left UC Berkeley and created a start up company with some of his colleagues. Using what they learned in this study, they hope to market hoppy yeasts to brewers, and also create other strains that create unique flavours not usually found in beer brewed from the normal ingredients of water, barley, hops and yeast.
The research has been published in Nature Communications