Are there coffee plants that naturally contain no caffeine?

Back in the old days of 2004, there was a lot of press announcing the news coffee-loving insomniacs the world over have been waiting for - a naturally caffeine-free coffee plant.

Brazilian agronomists studied 3,000 coffee plants from Ethiopia and found three that had almost no caffeine. The plants, labelled AC1, AC2 and AC3, appeared to lack an enzyme needed to make caffeine.

The scientists promised a future of decaf that was as good as caffeinated thanks to an Ethiopian variety of Coffea Arabica that they had successfully crossed with a caffeine-free variety to produce a natural caffeine free commercial crop within five years as part of a genetic coffee breeding programme.

One of the researchers wrote: "Given that C arabica has a narrow genetic diversity and that even accessions from Ethiopia and Arabia (now Yemen), as well as old varieties, all produce high-quality coffee, it is likely that AC plants will produce a good beverage."

That was fifteen years ago and yet this much heralded naturally decaffeinated coffee is still nowhere to be seen. What happened? We decided to investigate…

Researchers have long sought a better bean, harvested directly from the plant caffeine-free to preserve coffee's complex flavour and give growers a high-end slice of the decaf market.

However, developing such a bean through conventional breeding or even genetic modification has proved more difficult than anyone anticipated.

Coffee plants take five years to begin producing mature beans and they need to ripen synchronously and be of a size and shape that can be harvested easily by hand or by machines.

Back in the 1980s, there was an attempt to produce caffeine-free coffee in the 1980s by American scientists based DNA Plant Technology in New Jersey, but only produced a string of high-profile papers and not a drop of marketable coffee.

Meanwhile, in Brazil, also in the 1980s, the Agronomical Institute of Campinas (IAC) near São Paulo set out to study the genetics and physiology of caffeine biosynthesis, which now number 70,000 wild strains, breeding lines, hybrids, mutants and cultivated varieties.

They used a variety of methods to measure caffeine in plants back then such as using a spectrophotometer to measure caffeine content one sample at a time or a high-performance liquid chromatography machine allowing them to process samples more efficiently.

By 2000, the Brazilians has teamed up with a coffee association and shifted their focus on a group of arabica plants originally collected during a 1964 United Nations expedition to Eritrea and Ethiopia. Seed samples were then divided up and grown in several countries, including Costa Rica. It was in 2003 that two caffeine free strains were discovered. These particular plants were defective in the final step of the chemical pathway that turns theobromine into caffeine.

As with most scientific research, it’s all about the funding and this scheme was no different. The Brazilian government offered the research group a $1.2-million grant along with an order to keep the location of the precious plants secret. It was announced that the new naturally decaffeinated variety could be planted in less than five years…

Meanwhile, in Hawaii in the USA, in the 1990s, scientists were taking another tack at addressing this caffeine question by splicing the right genes into the right beans through genetic engineering, but it turns out coffee is resistant to genetic engineering. They then tried to get a gene inserted into the plant to reduce production of a target protein in the caffeine-producing pathway, but this too was unsuccessful despite some close calls to success. Indeed, by 1999, the scientist told the Walls Street Journal they expected commercial trials in three years.

But, failure beckoned once more. In growing trials, as the coffee plants grew, their caffeine levels went back up, frustrating the scientists. By 2008, the trials had ended and we find ourselves on another cold trail.

Showing how international this story is, in 2001, we meanwhile hear about a research program in Japan targeting an enzyme in the caffeine pathway that had recently been identified in tea using an efficient gene-silencing technology called RNA interference. Once again, coffee rejected engineered DNA, but the good news was much as 70% less caffeine than in the control plants.

Apparently this research is still ongoing, but being kept tightly under wraps. The main issue, though, continues to be the female part of the flowers, called the pistil, which matures and deteriorates a week before the pollen is ready.

This leads us back to Brazil and the more old fashioned method of discovering new strains in the field. Breeding the trait into a commercially viable cultivar, however, has taken longer than much longer than the agronomist researchers have anticipated, but they are still continuing to fight the good fight. Apparently, the naturally decaffeinated beans taste good, but the plants tend to be bushy and don't flower uniformly, so they are working on breeding plants that have the low-caffeine trait but not the low-productivity one.

But, even if they do find a commercially viable naturally decaffeinated coffee, there are two big dangers…

The biggest challenge of all in removing caffeine from living plants is that it is there for a reason. Caffeine is a natural insecticide, which explains why wild coffee plants that lack caffeine tend to contain other bitter compounds — to deter pests. So, how do you protect the coffee plant from insects when it’s natural defence, caffeine, has been removed?

As with all things in nature, any successful caffeine free coffee strain is susceptible to cross pollination, which could then reinstate caffeine production into the beans.

In short, the search for naturally caffeine free coffee goes on and we might be in for a wait.