Manuka honey is a premium export product from New Zealand that has been under scrutiny due to claims of fraud, adulteration and mislabelling. Although there are several industry approaches for defining manuka honey, there is currently no scientifically robust definition suitable for use in a regulatory setting. As such, ensuring the authenticity of manuka honey is challenging.
Here we present the results of a three year science programme which developed scientifically robust definitions for monofloral and multifloral manuka honey produced in New Zealand. The programme involved: selecting appropriate markers to identify honey sourced from Leptospermum scoparium (manuka), establishing plant and honey reference collections, developing test methods to determine the levels of the markers and analysing the data generated to develop the definitions.
The suitability of 16 markers (chemical and DNA-based) were evaluated for use in a regulatory definition for manuka honey. Plant samples were collected from two flowering seasons representing both manuka and non-manuka species from both New Zealand and Australia. Honey samples, also representing manuka and non-manuka floral types, were sourced from seven New Zealand production seasons. Additionally, honey samples were sourced from another 12 countries to enable comparison. All samples were tested for the markers being evaluated using the developed test methods.
The method of CART (Classification and Regression Trees) was used to develop the monofloral and multifloral manuka honey definitions. The CART outputs were further processed using a simulation approach to determine the sensitivity and the robustness of the definitions. The definitions use a combination of 5 markers (4 chemical and 1 DNA) at set thresholds to classify a sample as manuka honey or otherwise. We discuss the practicalities of using the science-based definitions within a regulatory context.