Posted on September 29, 2015
The significance of DHA, MGO, HMF and Leptosperin in Manuka
Methylglyoxyl (MGO) is found predominantly in Manuka honey and is the main chemical responsible for the unique non-peroxide antibacterial activity of the honey.
Dihydroxyacetone (DHA), a precursor chemical of MGO, is found in the nectar of Leptospermum scoparium (Manuka) in New Zealand. The DHA levels are often still relatively high in freshly harvested honey. Over a period of time, the DHA will convert to MGO in the honey, through a natural chemical process. The conversion process takes between 3 to 4 years to complete, based on maintaining the temperature of the honey at about 22 degrees Celsius. Although most beekeepers prefer to sell their honey 12 to 18 months after harvest. The conversion process can be fast tracked at higher temperatures, but this can result in the development of unwanted compounds, in particular Hydroxymethylfurfural (HMF). As a general rule of thumb, the higher the level of DHA in the freshly harvested honey, the higher the level of MGO in the honey after 12 to 18 months of storage. Therefore, we can conclude that the higher the DHA levels in the nectar, should result in higher levels of MGO in the honey.
Recently, a chemical called Leptosperin was discovered by Professor Kato from Japan. UMF Honey Association (UMFHA) analysis has found it to be uniquely at high concentrations in Manuka nectar and honey. The chemical’s biological properties are yet to be discovered, but the UMFHA Manuka ID project has identified it as a good chemical marker for determining the authenticity of Manuka honey.
Classification of honey floral type
The combination of DHA, MGO, HMF and Leptosperin in honey can now be used to classify honey floral type. In collaboration with Sagito Ltd, the UMFHA has developed a ‘classifier program’ that takes the laboratory test results of the four chemicals and produces a report classifying the honey as either ‘Manuka honey’, ‘Manuka blend honey’ or ‘Non Manuka honey’. The standardisation of honey type based on new chemical marker testing technology and contemporary data interpretation software will help provide assurance of the quality and authenticity of New Zealand Manuka honey.
As the Manuka honey industry develops, high MGO/high purity Manuka honey will likely remain in strong demand from the nutraceutical and medicinal sector of the market. Manuka blend and Mixed floral honeys are likely to level out in value as volumes increase.
A new Manuka plantation is a long term investment. If the goal of the Manuka forester is to target high value honey, then it is prudent to plant larger areas with a predominance of high DHA Manuka selections. Any additional plant cost for higher DHA selections is quickly recovered in the premium value of the honey.
By Andrew Wearmouth