The analytical panel behind a Medical Grade specification.
A Medical Grade honey is only as credible as the lab data behind it. These are the tests an accredited honey laboratory will routinely run, why each one matters, and which are non-negotiable before any honey enters a sterilisation and CE-mark pathway.
Why testing matters
From food-grade jar to medical-device input.
Honey purchased at retail is tested only against food standards. A honey destined for medical use — wound dressing, oral gel, ENT rinse, surgical adjunct — must clear a much wider analytical net before it is sterilised, because gamma irradiation does nothing to remove residues, adulterants or mislabelled botanical origin.
The panel below is the working short-list. It maps directly onto the regulatory expectations of the New Zealand MPI mānuka definition, the EU honey directive, and the residue requirements of the major export markets. It is the same panel an independent laboratory would run for a manufacturer building a Medical Grade dossier.
The panel
Eight tests that should sit behind every Medical Grade batch.
01
LC-MS for chemistry, qPCR for DNA
Manuka 5 Attributes (NZ MPI)
WhatThe four chemical markers (2′-methoxyacetophenone, 2-methoxybenzoic acid, 3-phenyllactic acid, 4-hydroxyphenyllactic acid) plus one DNA marker from Leptospermum scoparium pollen.
Why it mattersMandatory under New Zealand law for any honey labelled or exported as ‘mānuka’. Distinguishes monofloral from multifloral and from non-mānuka entirely. The single most important authenticity test for a Manuka-derived Medical Grade specification.
02
UPLC, single analysis
MGO + DHA by UPLC
WhatMethylglyoxal (the antibacterial) and dihydroxyacetone (its nectar precursor) measured in a single ultra-performance liquid chromatography run.
Why it mattersMGO is the dose; DHA tells you whether the honey will still be gaining MGO during storage. A Medical Grade spec should declare both, with a stability curve over shelf life rather than a single release number.
03
UPLC-MS
Leptosperin
WhatA glycoside unique to Leptospermum nectar, measured in mg/kg.
Why it mattersCannot be added or formed by adulteration. The strongest single chemical marker of true mānuka provenance and a key authenticity check alongside MGO and DHA.
04
LC-MS
Tutin
WhatA neurotoxic compound that can transfer into honey when bees forage on honeydew from vines infesting tutu plants.
Why it mattersRegulated under a New Zealand MPI standard with a 0.7 mg/kg limit. Non-negotiable safety screen for any honey of NZ origin destined for medical use.
05
Spore culture / PCR
American Foulbrood (AFB)
WhatDetection of Paenibacillus larvae spores — the spore-forming bacterium that causes the fatal honey-bee brood disease.
Why it mattersSpores survive normal processing and can persist in finished honey. Screening protects hive supply, supports export documentation and is part of an auditable traceability chain back to the apiary.
06
AOAC 998.12 (EA-IRMS)
C4 sugar (AOAC and screening)
WhatStable-carbon isotope ratio testing for added cane or corn syrup (C4 plants) in a honey that should be C3-derived from nectar.
Why it mattersThe standard test for sugar adulteration. Required for export to several markets and a baseline integrity check before any honey enters a Medical Grade process.
07
LC-MS/MS
Glyphosate residues
WhatQuantification of the herbicide glyphosate and AMPA in honey.
Why it mattersMandatory for export to Japan and the EU. Residue exceedances at food level make a batch ineligible for medical use regardless of activity level.
08
Refractometry
Moisture
WhatFree water content, by refractive index.
Why it mattersMedical Grade specifications target moisture under 20% to ensure osmotic activity, microbial stability and predictable rheology in a dressing or single-use applicator.
Operational notes
What good looks like in practice.
Accreditation
Use a laboratory accredited to ISO/IEC 17025 (in New Zealand, by IANZ) for the specific method, not just the lab as a whole. Scope of accreditation should be checked test-by-test.
Turnaround
Routine honey panels typically return in five to ten working days; urgent service can return MGO, DHA and leptosperin in 24–48 hours. Build that lead time into batch release planning.
Sample chain
Sampling kit, sealed transfer and a documented chain-of-custody from drum to lab are part of the audit trail under . Results without traceable sampling are not usable evidence.
Need help interpreting a Certificate of Analysis?
We routinely review honey CoAs for manufacturers, regulators and clinical teams — checking method scope, limits of quantitation, stability claims and the gap between what the lab measured and what the label says.
Why free acidity and HMF aren't useful Medical Grade markers.
Free acidity
Free acidity (meq/kg, by titration to pH 8.3) is a useful food authenticity and fermentation indicator under the EU Honey Directive — the regulatory ceiling is 50 meq/kg. For a Medical Grade honey it has very little discriminating power. Acidity rises predictably as gluconic acid forms from residual glucose oxidase activity and as the honey is exposed to heat during gamma irradiation (typically 25 kGy), aseptic processing, filling into single-use applicators, and — critically — accelerated-ageing studies at 40 °C / 75% RH used to support shelf-life claims under and ISO 11607.
A Medical Grade batch released at 25 meq/kg can drift well past 40 meq/kg by the end of its validated shelf life without any change to its antibacterial performance, sterility, or clinical suitability. Treating free acidity as a release-or-reject specification therefore generates false fails on perfectly safe dressings. We keep it on the CoA as a trending parameter, not as an acceptance criterion.
HMF, by analogy
Hydroxymethylfurfural (HMF) is the textbook example of the same problem. It's a Maillard-reaction product that accumulates with heat and storage; the EU food ceiling is 40 mg/kg (80 mg/kg for tropical-origin honey). Gamma irradiation, terminal heat steps in aseptic processing, and accelerated ageing all push HMF upward in a fully sterile, fully potent medical honey. No published wound- care study links HMF in a sterilised honey dressing to a clinical outcome.
The Medical Grade spec we recommend therefore treats HMF and free acidity the same way: monitor for trend, report on the CoA, but do not gate batch release on a number borrowed from a food standard that never anticipated gamma sterilisation or a 40 °C ageing chamber. The acceptance criteria that actually matter are MGO stability over shelf life, authenticity markers (leptosperin, Manuka 5), residue screens, and sterility.