Researchers may be able to turn regular oranges into healthier blood oranges by manipulating their genes.
The red pigments in blood oranges are flavonoids, which are believed to have health benefits including fighting obesity and heart disease.
A recent study, published in the journal The Plant Cell found that drinking blood orange juice with a full English breakfast could reduce the harmful effects of the fry-up.
But the red pigmentation requires exposure to a period of cold weather while they ripen, meaning the oranges can only be commercially grown in the Sicilian area of Italy around Mount Etna, which is why they are sold at a premium.
Scientists have identified 'ruby', the gene responsible for the pigmentation in blood oranges. They discovered that it is controlled by mobile genetic elements that are activated by the stress of cold.
It is hoped the findings will enable them to activate it in regular orange varieties.
Professor Cathie Martin, who led the research team from the John Innes Centre in Norwich, said: "Blood oranges contain naturally occurring pigments associated with improved cardiovascular health, controlling diabetes and reducing obesity.
"Our improved understanding of this trait could offer relatively straightforward solutions to growing blood oranges reliably in warmer climates through genetic engineering."
The gene has been implanted in a test batch of orange plants in Valencia, Spain, which are hoped to produce the genetically modified fruit by the end of the year.
Speaking at a press conference in London, Professor Martin said: "Hopefully in the near future, seven years down the line, we will have blood orange varieties which can be grown in the major orange growing areas like Brazil and Florida. So blood orange juice will become more available worldwide and the healthy properties enjoyed by more and more people."
