BioEd Online

Naturally caffeine-free coffee has been found growing on trees. Its discoverers hope it will yield a cheap, flavoursome alternative to the artificially decaffeinated coffee already on the market.

Brazilian researchers bred 3,000 Ethiopian coffee plants as part of a programme to produce low-caffeine strains. They found three bushes, all derived from the same plant, that were virtually caffeine free, containing 15 times less stimulant than commercial strains. The discovery is reported in this week's Nature¹

Caffeine-free coffee plants have been found before, growing wild in Madagascar. But they yield inferior beans unsuited for coffee production. The Brazilian shrubs belong to the species Coffea arabica, the most cultivated and consumed coffee in the world.

"This is the first time anyone has found a decaffeinated version of Coffea arabica," says Paulo Mazzafera from the State University of Campinas, who co-discovered the plants. They are thought to lack the gene for an enzyme that is required to make caffeine.

Full of beans

Over 10% of coffee consumed worldwide is decaffeinated, so demand for a tasty, low-caffeine blend is high. Currently caffeine is stripped from coffee using costly industrial processes. Organic solvents and carbon dioxide are used to purge the caffeine from the beans, but they strip away key flavour compounds at the same time. An alternative that does not destroy so much of the taste is to sift out the caffeine with a carbon filter, but this is even more expensive.

Mazzafera, who prefers a full-strength fix, hopes his discovery will help those who find it physically difficult to tolerate caffeine. The chemical can raise blood pressure, trigger palpitations and disrupt sleep.

The researchers do not yet know how their plants would fare as a commercial crop. They have not been able to taste any coffee made from the plants as these will take several years to mature. Their bushes also grow around 30% more slowly than standard arabica plants, so the team hopes to crossbreed them with their caffeine-rich relatives to produce a fast-growing, caffeine-free variety.

But selective breeding like this can take ten years or more, giving competitors a chance to edge in on the market. For example, a genetically modified low-caffeine coffee plant is just a few years from maturity.

"The genetically modified route may well be more successful," says plant scientist Alan Crozier of the University of Glasgow's Institute of Biomedical and Life Sciences "It should be possible to produce a plant that is completely caffeine free," he explains. Naturally bred species can still contain trace amounts of the chemical. But those opposed to genetically modified foods may find the Brazilian approach worth the wait.