Chemical name for an aldehyde and furan compound formed during the thermal decomposition of sugar or carbohydrates. HMF can be detected in many heat treated foods including milk, fruit juice, alcoholic beverages, honey, etc. The formation of hydroxymethylfurfural has been observed in the course of caramelisation of hexoses (e.g. fructose, glucose, maltose), among others. It can be formed in wine during any pasteurisation process and is the cause of the boiling clay.