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NEW ZEALAND BEEKEEPER, JUNE 2017
HOW DO LABS CONDUCT THE MPI MANUKA TESTS? RESEARCH Steve Howse, Dr Gary Depree, and Dr Maria Tourna Analytica Laboratories In April 2017, MPI announced a proposed new definition for mānuka honey, which includes some new requirements for laboratory testing. This article gives an overview of how the testing is carried out by laboratories, and some thoughts about how to understand the results. The testing uses well-established techniques, and prices are in the range of $180–$200 + GST per sample if all five tests are requested for a honey sample.
MPI’s proposed mānuka definition was announced on 11 April 2017 A great deal of useful information is available on MPI’s website (www.mpi.govt.nz) about the proposed definition of mānuka honey. The proposed definition includes testing for a combination of five attributes (four chemicals and one DNA marker from mānuka pollen) to distinguish mānuka honey from other honey types, and to identify monofloral and multifloral mānuka honey. A summary of these tests and required results is given in Table 1. All four chemical markers can be analysed in a single test carried out by the laboratory. The DNA pollen test is a separate test using entirely different equipment and testing procedures. Take care if your test results are close to the required levels If a honey sample is tested a number of times, you will not get exactly the same result each time. Because there is variability in both a sample and in the testing process, results will naturally vary across a range. Laboratories measure this when setting up a test, and refer to it as Uncertainty of Measurement (UoM). Many readers will have experienced this when asking for re-tests of samples in the past. UoM is very important to take into account when comparing your test results against required levels such as those in the proposed MPI mānuka honey definition. If a result for a sample is quite close to the threshold, there is a chance it will produce a result on the other side of the threshold if re-tested (by you or by someone else). For example: • Assume that a method has a UoM of plus or minus 10%, and you are aiming for a minimum of 400 mg/kg.
Required levels for multifloral mānuka honey
Required levels for monofloral mānuka honey
Chemical markers 3-phenyllactic acid
Greater than or equal to 20 mg/ kg and less than 400 mg/kg
Greater than or equal to 400 mg/kg
2’-methoxyacetophenone 2-methoxybenzoic acid 4-hydroxyphenyllactic acid
Greater than or equal to 1 mg/kg Greater than or equal to 1 mg/kg Greater than or equal to 1 mg/kg
DNA pollen Cq value of less than 36* Table 1. Summary of tests and required results. * The results of an MPI manuka pollen DNA test are reported as a ‘Cq’ value, and for a sample to meet MPI’s standard for manuka honey, the Cq value needs to be less than 36.
If you have test results close to an important threshold, we suggest that you talk with your laboratory about their UoM for that testing method. In general, most methods would have a UoM of at least plus or minus 10%, and it can easily be higher.
• You submit a sample, and get an actual result of 420 mg/kg, which is above the threshold. • However, it falls within the UoM range of 360–440 mg/kg for the method compared with the threshold level of 400, and there is a reasonable chance that your sample could give a result below 400 mg/kg if re-tested.
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