5-Hydroxymethylfurfural (CHEBI:412516), commonly abbreviated to 5-HMF, was one of the compounds that was studied by Louis-Camille Maillard (1878–1936) during his investigations into the browning reaction that now bears his name [1] (although the first coherent scheme to explain the various products did not appear for another 40 years [2]). The Maillard reaction occurs during the heating of substances containing reducing_sugars, such as D-glucopyranose, and free amino groups (of amino acids or, in proteins, mainly the ε-amino group of L-lysine, but also the α-amino groups of terminal amino acids). It is of particular importance in the food industry, as its products play an important part in the aroma, taste and colour of foods prepared by baking, roasting or toasting.