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After conducting exhaustive taste tests of 100 tomato varieties and sequencing the genomes of nearly 400 varieties, researchers have found the 13 volatile compounds that give a tomato its inherent flavour.

By comparing traditional tomatoes with their modern descendants, the teams uncovered the properties that have been lost in the quest for improved size, yields and resistance.

Antonio Granell, a research professor at the Spanish National Research Council who co-authored the report, said the aim was simple. “This study came out of the general complaint that modern tomato varieties — the kind that you find in supermarkets — have lost that typical tomato taste,” he said. “We decided to look at the basis for this loss of flavour in modern commercial varieties; you can still find that flavour in traditional varieties that are grown on a small scale locally.”

The first task was establishing precisely which components of a tomato interact with the tasting apparatus in our mouths and noses. Granell’s colleagues in the US assembled a 100-person tasting panel to sample about 100 tomato varieties and describe the flavours and aromas.

“Over various years and sessions, we managed to identify which molecules and components were involved. We did chemical and biochemical analysis of all the sugars, organic acids and volatile compounds. There are around 400 organic compounds that interact with our saliva, but not all of them contribute to flavour.”

The researchers then isolated the 13 volatile compounds responsible for flavour and found they were present at good levels in tomatoes judged favourably by the panel.

The compounds’ absence from modern varieties suggests flavour was inadvertently sacrificed as the industry sought to maximise yields and resistance to pests and disease. The team also found the 100 genes necessary to ensuring the high levels of the taste compounds that occur in traditional tomato varieties.

“We were trying to see what had happened in programmes to ‘improve’ tomatoes,” said Granell. “After the Second World War, seed companies started to worry about producing more to feed people. The principal aim was to increase production, and it’s very difficult to control flavour character in an ‘improvement’ programme.

“The flavour got lost because people didn’t know what the molecular and genetic bases were, so they couldn’t apply them. It was because they focused on quantity, productivity and resistance. We discovered that they basically lost these volatile compounds that we’ve identified in this study.”

But thanks to the study, which is published in the journal Science, producers have the genetic information they need to reintroduce the missing flavours. “This study is a tool — a genetic marker — that has revealed these 100 genes and shows where the best version of those genes can be found among traditional varieties,” said Granell.

But he added that flavour was unlikely to be the only concern for growers: “We need to cross these traditional varieties with modern ones that have resistance and productivity genes.”

- Guardian News & Media Ltd

The absence of 13 volatile compounds from modern varieties suggests flavour was inadvertently sacrificed as the industry sought to maximise yields and resistance to pests and disease, say researchers.