With the resurgence of the understanding of the value of honey in treating wounds and as a dietary supplement, sections of the industry are becoming increasingly competitive.
This is creating a flurry of number measuring systems. Created purely for commercial purposes and do not communicate any new or additional benefit.
The downside of this is confusion in the market place.
The phenol comparison test (Phenol being one of the strongest antibacterial compounds known) is used by independent laboratories worldwide, to measure and compare all sorts of antiseptic agents.
The test is relatively simple and highly reliable, simply explained, two dishes are placed side by side containing bacteria, in one the honey being tested, in the other a percentage of Phenol in water (%w/v).
For example, if you tested a honey sample against a 5% solution of Phenol in water and the kill rate was the same, then you would have a 5+NPA, if the honey outperformed the Phenol, then the percentage of Phenol is increased in increments until a exact match is obtained. So 10% Phenol in water = 10+NPA, 15% = 15+NPA and so on.
The confusion in the market place is understandable when you have trademark systems, for example the new MGO rating where, 10 MGO =1.4+NPA, 15 MGO = 1.8+NPA, 20 MGO = 2.1+NPA, 30 MGO = 2.7+NPA and so on, a 12+NPA converts to 353 MGO. Vallentines 32.8+NPA honey equals 1884 MGO, according to the conversion chart on the official web site, UMF.org.nz.