Feel the flavour Ami Vitale/PanosCredit

It gets you up in the morning and helps you power through the day. Now coffee aficionados have been armed with a new tool in their quest for the perfect cup – the coffee genome.

Scientists have sequenced the genome of Coffea canephora, better known as robusta, uncovering many of the genes involved in making caffeine and aromas. Armed with this knowledge, growers and blenders could make higher quality, tastier varieties of coffee, and help to protect the plants against climate change and disease.

“It’s like somebody turned on the lights,” says Tim Schilling, executive director of World Coffee Research, a scientific collaboration formed by the coffee industry and based at Texas A&M University. He says coffee lovers could see the impacts of this scientific feat in around five years.


Save our coffee

Coffee faces many threats, and knowing its genome will help us protect it. Traditional methods for breeding new varieties of coffee can take more than 12 years to reach farmers.

Climate change is a big problem for coffee farmers. High-quality Coffea arabica, a hybrid of robusta and another coffee species, can only grow within a certain temperature range. So as temperatures rise, arabica farming is being pushed up the mountains, and the total area suitable for coffee is shrinking. “We have seen the average temperature increase,” says Alejandro Martinez, who owns a coffee farm in El Salvador. In his area, the rainy season has started about a month later for the past three years.

“Ideally, [the genome] will accelerate the development of varieties that can sustain the dramatic impact of climate change on the crop,” says Martinez.

Coffee is also threatened by diseases such as the coffee rust fungus. Now coffee breeders will be able to use the genome to quickly breed resistance into the coffee crop.

Caffeine highs

Then there is the caffeine level. Coffee scientists have been hunting for years for a low-caffeine coffee that tastes as good as high-caffeine varieties, and the genome could help make one.

The robusta genome includes a cluster of genes likely to be involved in making caffeine. The expression of these genes, which code for enzymes called N-methyltransferases, could in theory be tweaked to alter the caffeine content of the coffee, says Philippe Lashermes of the Institute of Research for Development in Montpellier, France, and a leader of the sequencing project.

The genome will speed up research, says Paulo Mazzafera at the University of Campinas in São Paulo, Brazil. He studies proteins called transcription factors that, among other things, regulate caffeine production by switching other genes on or off. “This coffee genome will give us more information on [how] the transcription factor genes we have selected work,” he says.

Chase the taste

Tweaking the caffeine content could also lead to better-tasting cheap coffees, says Christopher Hendon of the University of Bath, UK, who experiments on coffee in his spare time.

When you buy low-quality coffee on the high street, it is usually a mix of arabica, for flavour, and robusta, which doesn’t taste as good but gives regular coffee the high caffeine kick that customers have come to expect. Hendon suggests boosting the caffeine content of the robusta bean. “You could substitute less robusta into the same blend, and get the same amount of caffeine,” says Hendon. Non-speciality coffee could then include more arabica, and would taste better, without losing its punch.

Beyond that, Hendon says the robusta genome could also be useful in making new flavours of speciality coffee. For instance, around 5 per cent of a coffee bean is chlorogenic acid, which doesn’t taste very nice. So he proposes getting rid of it.

“That would be a very powerful tool,” says Hendon. He thinks the resulting coffee would be “incredibly sweet and very floral”, because the acid would be converted into substances like sugar and citric acid. “That would be cool!”

The genome could unlock new flavours in coffee, says speciality coffee roaster James Hoffmann of Square Mile Coffee Roasters in London. He says the genome also offers the opportunity to improve coffee yields and pest resistance without compromising on quality.

Journal reference: Science, DOI: 10.1126/science.1255274

It’s not just coffee genes The coffee genome might help create new coffee flavours, but genetics are not the only factor affecting how your coffee tastes. “I have tasted coffees that come from the same varietal but taste different depending on where they are grown, so taste is not only about genetics,” says coffee farmer Alejandro Martinez in El Salvador. A crucial determinant of coffee flavour is how the bean is roasted. Speciality coffee roaster James Hoffmann of Square Mile Coffee Roasters in London collects swathes of data on roasting. “We’re looking for as much data as possible to help improve quality and also increase consistency,” he says. His company tracks bean moisture content, roast temperature and the colours of their ground coffee carefully, and tracks how they affect the final flavour. This is being taken a step further by former roast master Morten Münchow of the University of Copenhagen in Denmark, who teaches at the London School of Coffee. Münchow is trying to precisely determine the effects of roast temperature and time on the flavour of speciality coffees. “I’m trying to map out the parameter space of speciality coffee, so that people can more quickly navigate inside this parameter space, and avoid defects,” he says. The water used to make coffee also makes a difference, says Christopher Hendon of the University of Bath, UK, who spends his weekends studying coffee chemistry with the 2014 UK barista champion Maxwell Colonna-Dashwood. Earlier this year they found that the relative levels of magnesium, calcium and bicarbonate ions in the water has a dramatic effect on the flavour. Magnesium and calcium ions bring out the flavour of coffee, while bicarbonate kills it (Journal of Agricultural and Food Chemistry, doi.org/vhq).