Qualifying Mānuka Honey

Written by Andrea Strang

Mānuka Honey is made exclusively by bees harvesting nectar from New Zealand’s indigenous Mānuka flower (Leptospermum scoparium). New Zealand Mānuka Honey is world-renowned for its healing properties and ranks as the most researched therapeutic honey in the world.

Since the discovery of Mānuka Honey’s therapeutic properties in 1981 by Peter Molan, MBE of Waikato University, regulatory testing and labelling of Mānuka Honey has continuously evolved to ensure its authenticity and antibacterial efficacy.

Is it Mānuka Honey?

To qualify for export, honey is assigned an MPI Manuka Classification. Honey is categorized as non-manuka, multi-floral Mānuka or mono-floral Mānuka Honey according to the combined results of five attribute tests; the concentration of four unique manuka compounds and a manuka DNA marker. Testing is carried out on a honey sample that typically represents a 300kg drum of honey or all honey simultaneously harvested from a single apiary.

How pure and potent is the Mānuka Honey?

Once MPI Manuka classification is determined, multi- and mono-floral Mānuka Honeys are tested for potency of manuka-derived antibacterial compounds. Whilst all types of honey convey some antibacterial activity by virtue of their hydrogen peroxide content, it is only active Mānuka Honey that provides additional antibacterial Non-Peroxide Activity (NPA). Not all Mānuka Honey carries this additional antibacterial activity.

To determine NPA potency the following compounds are tested:

  1. Methylglyoxyl (MG) – MG is a rare healing compound found at high levels in Mānuka Honey. Generally, the higher the concentration of MG, the stronger the healing properties. The MG content of Mānuka Honey varies according to the amount of DHA present in the manuka nectar and pollen that bees forage. Manuka flower DHA concentration varies according to geographical region. DHA converts to MG in the hive.

Active Mānuka Honey is rated according to the concentration of MG present in honey at the time of testing. As MG concentration increases over time honey may be tested again immediately prior to sale or packaging and labelling to capitalize on the increased value gained as a result of increased MG. 

  1. Dihydroxy Acetone (DHA) – the MGO content of active Mānuka Honey increases over time when stored at appropriate room temperatures as DHA converts to MGO. Therefore, DHA content at the time of testing can be used to calculate a forecast of potency over time
  1. NPA (non-peroxide activity) – is a direct measure of antibacterial potency and is reported as antibacterial performance compared with phenol equivalent solution (a common disinfectant) i.e. NPA 5 is the equivalent of a 5% phenol solution. NPA grading measures the distance over which Mānuka Honey (or phenol) kills bacteria on a cultured petri dish, a larger distance of bactericide activity indicates a honey of higher NPA. A direct correlation exists between MGO concentration and Non-Peroxide Activity.
  1. Hydroxymethylfurfural (HMF) – is a breakdown product of fructose, one of the main sugars in honey. HMF increases slowly over time and rapidly when heated. Freshly harvested raw honey usually contains less than 10 mg/kg HMF, whilst international food standards require HMF less than 40 mg/kg. Honey exposed to excessive temperature during extraction or blending incurs a quality reduction.

To qualify for export as active Mānuka Honey, each rigorously tested sample must include the above compounds in appropriate concentrations to ensure its authenticity, purity and antibacterial efficacy.

The Mānuka Honey market has occasionally suffered undermining by fraudulent incidents of counterfeit Mānuka Honey, honey diluted with sugar or corn syrup and artificially enhanced MG concentration. Therefore, overseas buyers often request many other honey compounds to be tested to provide further evidence of Mānuka Honey purity and potency.

UMF or MG/MGO rating?

Export honey labels must display the MPI classification; multi- or mono- floral Mānuka Honey. However, antibacterial activity may be reported according to either of two trusted grading systems.

Methylglyoxyl concentration i.e. MG mg/kg or MGO mg/kg (MGO is a registered trademark of Manuka Health Limited).

MG grading is applicable to both multi-and mono-floral Mānuka Honey, the testing regime for MG or MGO is described above. A direct correlation exists between MG concentration and Non-Peroxide Activity.

The UMF (Unique Manuka Factor): active mono-floral Mānuka Honey may be UMF rated. The UMF grading system was developed and is licensed by The UMF Honey Association. Honey manufacturers that meet UMF standards may label honey with the UMF trademark and appropriate ranking. As well as MG, DHA, HMF and NPA, the UMF grading system measures Leptosperin; a unique Manuka-specific chemical marker so an additional measure of Mānuka Honey authenticity.

How the ratings compare:


MG (mg/kg)









In the interest of protecting our valuable Mānuka Honey Industry, New Zealand honey producers and MPI work collaboratively to evolve honey grading standards and labeling requirements to ensure the authenticity, purity and potency of export quality Mānuka Honey.