Until the early 1990s, Manuka honey was just a really nice honey produced from flowering native New Zealand trees. That’s when Dr. Peter Molan of the Waikato University in New Zealand, through his research, discovered a very unique and special property of Manuka honey. Dr. Molan was studying the health properties of honeys. Normally these properties are attributed to a natural mild hydrogen peroxide formed by the enzyme glucose oxidase that bees add to nectar as they digest it and turn it into honey.
However, this "peroxide activity" is easily destroyed by exposure to fluids, heat and sunlight. Dr. Molan discovered that Manuka honey had a different property, what he termed a "non-peroxide activity" (NPA), which was more potent and stable, opening up the possibility of a wide range of uses. The term "Unique Manuka Factor," or UMF was coined (and trademarked) to describe this property which was originally based on its NPA test result.
Later, Professor Thomas Henle at the Technical University of Dresden in Germany set out to isolate what in Manuka honey was producing this more potent and stable antibacterial effect. The compound, methylglyoxal (MG/MGO), was isolated as having a direct correlation to the NPA or UMF rating of Manuka honey. NPA or UMF can be directly measured by observing the inhibition of growth of bacteria within honey samples.* As a practical matter, this test is seldom used today. Instead, MG/MGO is directly measured, and then the NPA or UMF value is correlated to the MG levels. In the case of the UMF grading system, there is also a verification that a threshold level of Leptosperin is present, and maximum level of Hydroxymethylfurfural (HMF) is not exceeded.
MG/MGO is directly measured in ppm or parts per million, typical Manuka honey sold at retail will have a MG concentration of 100 to 600ppm. NPA or UMF ratings typically range from 5+ to 15+.
For labeling purposes, MGO is trademarked by Manuka Health New Zealand Ltd. The abbreviation MG is also used to represent methylglyoxal. UMF is registered and controlled by the UMF Honey Association (UMFHA).
For a more in-depth look at the unique characteristics of Manuka honey, you can read this article by Steve Howse, Analytica Laboratories, published in The “New Zealand Beekeeper.” DHA and MGO: The Most Common Testing in Manuka Honey.
*In this video from 2014, the late Professor Peter Molan takes the viewer into his laboratory to show the special non-peroxide antibacterial activity of Manuka honey versus other honey. Why you need the right sort of activity in Manuka honey