The Dulce de Leche and condensed milk molecule.
 
Supplied at 10% in TEC or neat.
 
I’ve been brooding over how to release this one for far too long, so here it is.
 
5-Hydroxymethylfurfural (5-HMF) is relatively abundant -- not in raw foods, but in those that have undergone some culinary transformation: heating, cooking, fermenting, roasting etc. The main pathway is via caramelisation or the Maillard reaction (the source of many of the tastiest things)
 
Example 1: To make the famous Latin American confection Dulce de Leche, milk and sugar are heated to >100C for several hours: the mixture thickens and darkens, the heat causing a cascade of chemistry which settles with familiar molecules like sugar lactone, furaneol and acetyl furan but also 5-HMF. This browning process imparts a warm, caramelised note with a butterscotch aspect. Also known as Confiture de Lait (literally milk jam), Kajmak, shushchene moloko and Manjar
 
Example 2: In wines, particularly sweet and dessert varieties, 5-HMF levels increase during aging and are often considered a marker of quality. The same is true for dried fruits like dates, prunes and apricots. 
 
5HMF is found in the strangest places -- from cured vanilla beans to roasted barley and from coffee to cloudberry. A bit like Green tea ketone and Methoxyvinyl Phenol, it is one of nature's biochemical cul-de-sacs; a biproduct produced so frequently that its absence would be more surprising than its presence in most flavours. And yet absent it remans from most accords and organs..!