Craft beers have become wildly successful over the last few years and one reason consumers are so crazy about them is that key ingredient – hops. Hops are a plant added during the beer making process to impart a bitter flavour to balance out sweetness, and add unique tropical or citrus aromas or flavours. But all those darn hipsters and their hoppy beer means the global supply of hops can’t meet the demand, making them very expensive. On top of that, they require a lot of water and natural resources to grow. Furthermore, the actual content of the essential oils within the hops can vary wildly, so it’s hard to achieve a consistent hoppy taste in beer. Researchers at the University of California – Berkeley have genetically engineered a strain of brewer’s yeast that means you can make hoppy beer without the hops.
First they identified two particular chemical compounds that give hoppy beer its special taste and smell, and then they found enzymes (biological catalysts) that can make these compounds from precursors already produced naturally by the yeast. They used CRISPR/Cas9 gene editing technology (you know, those molecular scissors I talked about in a previous post?) to genetically engineer yeast to produce high levels of these flavour molecules. This is a pretty impressive achievement because firstly, brewer’s yeast, unlike domesticated wine yeast, is pretty wild and has lots of crazy things going on with its chromosomes, making it notoriously difficult to genetically manipulate. Secondly, making sure those genetic manipulations stick so that the population is stable is pretty challenging. The researchers then used these new strains of yeast to ferment beers and checked that the levels of the flavour molecules were consistent. They showed much less variation than traditional dry-hopped beers, which will help brewers ensure a consistent taste. But, as they always say, the proof of the beer is in the drinking. A panel of taste testers consistently rated the beers as having a hoppy flavour and aroma. Of course, the complex flavour of hops cannot be completely encapsulated by just two molecules, but these methodologies provide a foundation to build more complex yeast strains that produce a wider variety of flavours and aromas. Ultimately, this technology means not only can you brew hoppy beer without the hops, but it paves the way for further improvements in brewer’s yeast and advancements in environmental sustainability.
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Emi Schutz Archives
March 2018
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