The war of words between two rival brands of manuka honey testing is set to continue after a new study backed the effectiveness of the newer testing method.

The Active Manuka Honey Association (AMHA) and Manuka Health New Zealand (MHNZ) have been embroiled in a long-running stoush over their different methods of testing for the antibacterial properties manuka honey is famous for.

AMHA licenses the use of the UMF test, which rates manuka honey’s bacteria-killing activity in comparison to the laboratory disinfectant phenol.

In contrast, MHNZ’s testing process MGO ™ examines the level of the chemical methylglyoxal present in the honey.

MHNZ says beekeepers call the UMF test “prone to error” and say it has problems with “repeatability”, while earlier this week AMHA general manager John Rawliffe said the MGO ™ system doesn’t fully measure antibacterial activity and is therefore misleading.

But new research conducted at the Institute of Food Chemistry at the Technical University of Dresden has backed MGO ™ as an accurate measure of manuka honey’s antibacterial properties.

In a peer-reviewed paper published this month in the Czech Journal of Food Sciences, the German researchers show a “perfect linear correlation” between methylglyoxal levels in 61 manuka honey samples and their antibacterial ratings in equivalent phenol concentration.

The research checked whether it was possible to back-reference from methylglyoxal content to the antibacterial properties of a honey sample. The linear correlation showed this was the case.

“This clearly underlines that methylglyoxal is the dominant bioactive compound in manuka honey and above concentrations of around 150 mg/kg is directly responsible for the characteristic antibacterial properties of manuka honey,” the paper says.

“Methyglyoxal can be a suitable tool for labelling the unique bioactivity of manuka honey.”

The researchers said their results were in perfect agreement with a 2008 University of Waikato study which reported methylglyoxal levels and antibacterial results for 49 samples.

MHNZ chief executive Kerry Paul says the research has finally settled the issue of whether MGO™ Manuka Honey is valid for commercial labelling purposes.

He says critics have claimed for years that the antibacterial activity in manuka honey depends on other substances in addition to methylglyoxal.

The UMF test can vary more than 25% in re-tests, he says.

“Some in the manuka honey industry want to stick with an inaccurate and unreliable test from which even the original developer has dissociated himself.