Cucumbers are complex in their flavour.
The flavour of this fruit is characterised by just 30 volatile compounds.
All these volatiles are either six-carbon or nine-carbon and come from fatty acids which are generated through the lipoxygenase (LOX) pathway. Lipoxygenases are enzymes catalysing the production of a range of compounds but one of their most important are these flavours.
There are two nine-carbon aldehydes that appear to contribute most to flavour and are present in the highest concentration. They are:
- (E,Z)-2,6-nonadienal (NDE)
- (E) -2-nonenal (NE)
NDE as it is often abbreviated to has the characteristic cucumber-like flavour and is found in any squash or curcubit with pretensions to be ‘cucumber’ like. The nonenal has a green and tallowy odour note.
The concentration of NDE is actually five times higher than NE. However, the odour threshold of NDE is 10 times lower than NE. The presence of NE at different levels heavily influences the perception of the cucumber note. On top of this are many other 6-carbon volatiles which contribute green and grassy flavours and have a significant presence. These are hexanol, hexanal, (Z)-3 hexenal, (E)2-hexenal and so on.
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