Tomatoes sold in supermarkets can be made to taste better by dunking them in hot water before they ripen, a study has found.

The research could result in tomatoes bought from stores being as flavoursome as those straight off the vine.

Typically tomatoes destined for supermarkets are picked while still green and coaxed to ripen while they are stored and transported at low temperatures.

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The problem is that chilling degrades their flavour, making supermarket tomatoes relatively tasteless compared with those sold on farms.

But scientists from the US Department of Agriculture found that a simple treatment process can dramatically boost the flavour of transported tomatoes.

Dr Jinhe Bai said: "Ideally, tomatoes should be picked ripe and then sold immediately, as they are at farm stands.

"To produce a better tasting tomato, we added a hot water pre-treatment step to the usual protocol that growers follow. We found that this pre-treatment step prevents flavour loss due to chilling."

In the tests, Florida-grown green tomatoes were dipped in water heated to about 51.6C for five minutes and allowed to cool at room temperature.

Only then were the fruit chilled to the temperatures normally used for shipping.

Heating before chilling led to higher levels of flavour compounds, the scientists found.

Dr Bai, whose research was presented at an American Chemical Society meeting in Boston, US, said: "Chilling suppresses production of oxygen, nitrogen and sulphur-containing heterocyclic compounds, ketones, alcohols and aldehydes, including 13 important aroma components of tomato flavour. But hot water-treated fruit actually produced higher concentrations of these important aroma contributors, even with subsequent chilling."

Another technique that involved treating half-ripened tomatoes with a plant growth regulator chemical also prevented flavour loss, said the scientists.