Orange flavour

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Orange flavour

The typical flavour of oranges stands out between the other citrus fruits. But long was unknown what causes that specific flavour. Now American researchers identified that a combination of 26 flavour compounds that give oranges their unique orange flavour.

Flavour compounds are often volatile substances that we perceive with our nose. Think alcohols, terpenes, and esters. But which of these was giving oranges their flavour was not well studied. The researchers decided to change that. They analysed and compared the flavour compounds of 198 species of oranges, mandarins and other citrus species.

In total the researchers identified 60 flavour compounds. After studying these in more detail, they discovered that oranges and mandarins have unique flavour compound profiles. With 26 flavour compounds contributing to orange flavour. One type of flavour compounds stood out specifically, the esters. It was the first time that these flavour compounds were connected with orange flavour.

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One day breeders may predict the flavour of the fruits of their orange trees before they set fruit

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To find out which enzyme(s) are responsible for the production of those esters, the researchers studied the genes that were turned on in oranges and mandarins. This resulted in a group of 93 genes that were turned on in ripening oranges but not in ripening mandarins. In between these genes the researchers found one gene, AAS1, that codes for an enzyme that is involved in the production of esters.

To confirm that this gene indeed codes for an enzyme involved in the production of orange flavour esters, the researchers turned this gene on in ripening mandarins. Resulting in the presence of 5 of the 7 orange flavour esters in mandarins. Suggesting that there are probably more genes that regulate the production of orange flavour esters.

Now it is known which flavour compounds contribute to the orange flavour researchers can start with identifying those genes involved in the production of these flavour compounds. When these are known then breeders no longer have to wait till an orange tree produces its first oranges to know if these oranges indeed will have an orange flavour.

Literature

Zhen Fan et al., (202) Chemical and genetic basis of orange flavor. Sci. Adv.10, eadk2051 DOI:10.1126/sciadv.adk2051   

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