HMF (hydroxymethylfurfural)

Definition

Formed from fructose in acidic conditions. Fresh honey contains very little; it accumulates with warm storage and jumps sharply with processing heat. Codex and EU standards generally set a limit of 40 mg/kg, with a higher allowance for honeys of declared tropical origin where ambient temperatures alone raise it.

Where the word gets used loosely

A high HMF figure indicates heat or age, not adulteration, and a low one does not certify that honey is unadulterated.

Question records that discuss this

• Is older honey better?No. Honey is stable for a very long time and it does not improve — it slowly loses aroma, darkens, and accumulates hydroxymethylfurfural. A jar five years old is safe to eat and will taste of measurably less than it did when fresh.
• Does heating honey destroy it?Heating does not make honey harmful, and it does degrade it. Volatile aroma compounds are driven off, enzyme activity falls and hydroxymethylfurfural rises — so a heated honey is duller rather than dangerous. The claim that heated honey becomes toxic comes from Ayurvedic tradition and is not supported by evidence.