Watermelon and 2,6-Dimethyl-5-heptenal (FEMA#2389)
Sweet flavor components are the esters found in many fruits: ethyl
butyrate, ethyl acetate, ethyl isobutyrate and the crystals used in most
fruit flavors: vanillin and maltol. A light sweet floral note is needed
to balance the harshness of the aldehyde: geranyl acetate, octyl
butyrate, and methyl heptanoate. The ketone, anisyl acetone, can add the
fruity, seedy note found in watermelon. Aldehyes, like octanal
and 2,5-dimethyl-5-heptenal add that subtle sharp rind note, but be
careful.

http://flavorscientist.com/2016/05/28/watermelon-and-26-dimethyl-5-heptenal-fema2389/

http://flavorscientist.com/2016/05/28/watermelon-and-26-dimethyl-5-heptenal-fema2389/