Industry infighting over how biologically active manuka honey should be measured and ranked are far from being resolved, with the tiff likely to get even more sticky.

Ratings of the unique manuka factor (UMF) underpin domestic and export manuka honey markets worth more than NZ$100 million a year, but have been caught up in a series of disputes.

UMF ratings are based on measurement of the antibacterial activity of samples of honey to indicate how well it fights a wide range of very resistant bacteria.

Manuka honey has proven effective against major wound-infecting bacteria and the bacteria which causes stomach ulcers.

One company, Manuka Health NZ Ltd, has said objective measurement of the active ingredient methylglyoxal might be the best way to measure anti-bacterial strength.

Now the industry’s leading researcher, Dr Peter Molan – who has said methylglyoxal is not a reliable indicator of anti-microbial activity – has cut his ties to the body which holds the trademark for UMF ratings.

Molan last Thursday told honey companies in a personal email that he will no longer have anything to do with the Active Manuka Honey Association (AMHA).

The association has 48 members, with 32 licensed to use its trademarked UMF ratings.

“I hold the executive of AMHA responsible for my reaching this personal decision,” Molan said.

AMHA chairwoman Moira Haddrell said she could not comment for legal reasons. Her chief executive John Rawcliffe also said he could not comment.

Molan, who has spent decades on the research underpinning the industry’s sale of high-value biologically-active manuka honey to combat infections, said his employer Waikato University did not want to get involved in litigation, so he could only make personal comments.

“Regrettably, I cannot specify why I am unhappy with the executive of AMHA,” said Molan.

The AMHA was created only after Molan was asked by Government trade officials to help set up an industry group for producers of active manuka honey.

And the UMF testing on which it relies uses a method described by Molan and other honey researchers at Waikato University in 1991.

Molan said in the NZ Beekeeper magazine in August that though researchers had developed further improvements to increase the reliability of the method , AMHA had not adopted these.

“Since that article in the NZ Beekeeper was published, further developments have come from our research which will allow greatly improved reliability in the assay of the UMF and a much faster turn-around time in getting assays done,” he said today.

Research done at the honey research unit into the nature of the antibacterial substances has revealed why testing of some manuka honey gives only partial inhibition of bacteria.

Scientists are now able to reliably assay such honeys in a way which will show the true full antibacterial activity.

The intellectual property involved in these advances was controlled by Waikato University, he said.

Manuka Health this year claimed UMF test variations had led to conflict between beekeepers and honey producers, by causing differences in payment of up to NZ$2000 for a 300kg drum of honey.