Scientists in New Zealand have developed a way to distinguish between Manuka honey and lower-quality substitutes.
Using fluorescence spectroscopy, the team were able to detect genuine Manuka (Leptospermum scoparium) honey thanks to a marker compound - called leptosperin - that is only found in trace quantities in other honey types.
Real New Zealand Manuka honey is traded at a premium because it has been attributed with health and nutritional benefits that outperform common-or-garden honey varieties. As a result, Manuka honey has become a notorious target for food fraud, with consumers duped into paying well over the odds for mislabelled regular honey.
Genuine Manuka can cost up to ten times the price of regular honey and is hard to distinguish by taste alone. Add in a rapid increase in demand, and all the ingredients are in place for fraudsters to try to make an illicit profit. Figures from 2014 have suggested that total production of Manuka was 1,700 tonnes, with total sales in that year estimated at 10,000 tonnes worldwide.
Scientists are already using a number of chemical marker compounds (e.g. DHA and MGO) to try to differentiate between Manuka and other honeys, but this is a challenge as many of the best candidates have their levels dramatically altered when the honey is processed and stored. Moreover, in some cases the markets are available commercially, so can be added to honey to disguise the adulteration.
Leptosperin concentrations stay fairly constant - changing little when the honey was stored at 37 degrees C over a 444-day storage period - and could be used to distinguish between New Zealand Manuka honey and products made from nectar from other *Leptospermum *species, as well as fully artificial products.
"Fluorescence spectroscopy could potentially offer a rapid and high-throughput screening method for identification of *Leptospermum *honeys," write the authors.
The research is published in the journal Food Chemistry (1 January 2017).