A fungus that bursts from the bark of birch trees can produce a volatile molecule with the sweet smell of pineapple—an aroma usually formed by a mixture of many compounds (J. Agric. Food Chem. 2019, DOI: 10.1021/acs.jafc.9b06105). The smell of the new molecule “is able to duplicate hundreds of compounds which are present in real pineapple flavor,” says Ralf G. Berger, a food chemist at Gottfried Wilhelm Leibniz University who led the team that discovered the molecule.
Berger, Miriam Grosse, and their colleagues discovered this flavor compound when they were testing out substrates for cultivating Fomitopsis betulina, an edible fungus commonly called the birch polypore. When they grew the fungus, they got a strong waft of a pineapple-and-honey-like aroma.
To find its source, they concentrated the volatiles from the fungus, purified them, and then analyzed the components with gas chromatography/mass spectrometry and nuclear magnetic resonance spectroscopy.
The researchers identified two stereoisomers of a molecule—(5E,7E,9)-decatrien-2-one and (5Z,7E,9)-decatrien-2-one—that had a strong pineapple aroma. The 5Z isomer could be perceived at a lower concentration, but the 5E isomer was much more abundant, they found.