Unlocking the secrets of mānuka honey

Work is underway at the University of Waikato, led by Associate Professor Merilyn Manley-Harris, to try to understand why some mānuka trees produce high levels of the precursor of bioactivity in mānuka honey, and the optimal conditions for converting it to the active component as the honey matures.

It has been established that the precursor for the active antibacterial agent methylglyoxal (MGO) comes from the nectar of mānuka trees; but there is currently little information about what factors govern the conversion of dihydroxyacetone (DHA) into MGO during the maturation process so prediction of MGO yield is still strictly empirical.

There is also no published information that accounts for the variation of DHA content of nectar observed in small scale studies of the trees and which may give rise to observed variation in the honey.

A range of doctoral and postgraduate research is developing scientific models for finding answers to these questions.

Doctoral student Megan Grainger is working to develop the theoretical basis for a computer program to forecast the effect of storage conditions on MGO formation and coincidentally the formation of hydroxymethylfurfural (HMF), an unwanted substance formed in any maturing honey, especially if it is heated. The program, once developed, will be available to beekeepers.

A study of dihydroxyacetone in the nectar of mānuka trees around the North Island has been completed and the results submitted for publication.

Master of Science student Yinying Jie is working on the development of a rapid assay for use in the field to identify suitable mānuka trees for possible breeding. This technology may be of use to landowners looking to improve their tree stocks.

Another doctoral student Maria Revell is investigating the origin of DHA production in the tree; once this is established it will provide a scientific basis for potential manipulation of DHA content of the nectar.