Correction, October 2026: we removed or corrected claims and figures on this page that our sources did not support. How we handle corrections
Honey Enzyme Activity
Three enzymes. Three biological functions. One regulatory standard. Diastase tells you how much heat the honey has seen. Invertase tells you whether the bees finished the job. Glucose oxidase is where the antibacterial activity actually comes from — unless you’re buying Manuka, in which case it doesn’t come from that at all.
Diastase: honey’s heat thermometer
Diastase is the enzyme EU law uses to flag heated or old honey: Directive 2001/110/EC requires at least 8 Schade units, or 3 for honeys declared low in enzymes with HMF no more than 15 mg/kg.
Diastase (amylase) is the enzyme the EU chose as honey’s official quality marker. Not because it does much biologically in the jar — honey isn’t digesting starch when you eat it — but because it degrades predictably with heat, making it an indirect proxy for processing temperature.
Diastase activity by variety (Schade units)
Approximate values for raw, unheated honey. EU minimum: 8 Schade (3 for low-enzyme honeys with HMF ≤ 15 mg/kg*). Sources: White (1992), Bogdanov et al. (1999), Schade et al. (1958).
Diastase originates from the bees’ hypopharyngeal glands. The amount added per unit of honey depends on bee colony size, nectar flow rate, and ripening time. Fast-flowing nectars (acacia) get less processing per litre than slow-flowing ones (buckwheat, heather), resulting in systematically lower enzyme counts for high-yield light honeys.
Acacia, citrus-blossom, and some manuka honeys naturally produce low diastase regardless of heat history. The EU directive permits these varieties to be sold with a minimum of just 3 Schade — but the label must declare “honey with a low enzyme content.” Without that declaration, the 8 Schade floor applies.
HMF (5-hydroxymethylfurfural) accumulates with heat; diastase degrades with heat. Using both creates a two-sided quality check: high HMF + low diastase = double flag for overprocessing. High HMF alone could be old honey (not heated). Low diastase alone could be a naturally low-enzyme variety. Together, they are harder to fake. See the HMF & Diastase Guide.
Invertase: the ripeness enzyme
Invertase is the bee enzyme that converts nectar’s sucrose into fructose and glucose during ripening. Properly ripened honey has high invertase activity; prematurely harvested honey and honey cut with syrup show low activity.
Nectar is mostly sucrose. Honey is mostly fructose and glucose. Invertase is what does the conversion — bees add it to nectar in the hive, and it works through the ripening period as moisture drops from ~80% (nectar) to ~17% (sealed honey). A properly ripened honey has high invertase activity; prematurely harvested or synthetic honey does not.
| Variety | Diastase (Schade) | Invertase (relative) | GOx (relative) |
|---|---|---|---|
| Buckwheat | 58 | 88 | 78 |
| Heather | 52 | 72 | 52 |
| Chestnut | 47 | 68 | 46 |
| Linden | 40 | 74 | 58 |
| Wildflower | 35 | 76 | 64 |
| Thyme | 32 | 65 | 55 |
| Lavender | 28 | 62 | 50 |
| Clover | 27 | 80 | 82 |
| Tupelo | 24 | 66 | 62 |
| Sunflower | 23 | 58 | 44 |
| Manuka(low-enzyme) | 22* | 48 | 14 |
| Orange Blossom(low-enzyme) | 15* | 55 | 60 |
| Acacia(low-enzyme) | 10* | 50 | 84 |
GOx (glucose oxidase) relative activity 0–100. Manuka shown in purple — low GOx is a feature, not a defect (see Glucose Oxidase section). Invertase and GOx are relative scales; diastase in Schade units. Sources: White (1992), Molan (1992), Allen et al. (1991), Bogdanov et al. (1999).
High-fructose corn syrup (HFCS) and inverted sugar syrups already contain fructose and glucose — they were converted chemically or enzymatically before blending. A honey adulterated with HFCS will show normal sugar ratios (F/G) but abnormally low invertase, because the industrial conversion process didn’t add bee-derived enzyme. Authenticity testing for commercial honey typically combines invertase, diastase, and C4 sugar carbon-isotope analysis (AOAC 998.12 δ¹³C) as a three-marker suite.
Glucose oxidase: where the antibacterial activity lives
Glucose oxidase is the honey enzyme that produces hydrogen peroxide once honey is diluted with water. The National Honey Board identifies that peroxide as the source of most of the antibacterial activity measured in honey in the lab.
The most practically important of honey’s three enzymes is also the least tested commercially. Glucose oxidase (GOx) produces hydrogen peroxide, which the National Honey Board identifies as the source of most of the antibacterial activity measured in honey in the lab. The output is dilution-dependent: H₂O₂ builds up when honey is diluted with water. In the jar, GOx is suppressed by the concentrated sugar environment. These are lab measurements, not health claims.
How GOx creates antibacterial activity
- 1.Bees secrete glucose oxidase from hypopharyngeal glands into nectar during ripening.
- 2.In the concentrated jar, enzyme activity is suppressed (water activity ≈ 0.6).
- 3.When honey is diluted with water, GOx activates: β-D-glucose + O₂ → gluconolactone + H₂O₂.
- 4.Peroxide levels in diluted honey vary widely between honeys (Bang et al. 2003 measured them in the lab).
The Manuka paradox
Manuka honey has low glucose oxidase activity, yet it measures high for antibacterial activity in lab tests. How?
Leptospermum scoparium nectar contains dihydroxyacetone (DHA), which converts slowly to methylglyoxal (MGO) during ripening. MGO is a non-peroxide compound, so its lab antibacterial activity does not depend on hydrogen peroxide.
Additionally, Manuka contains catalase-like activity that degrades H₂O₂ as it forms — meaning even the small amount of GOx present produces little net peroxide. The low GOx reading is not a defect; the lab activity comes from MGO instead. UMF and MGO grading systems measure DHA/MGO content precisely because of this distinction.
Glucose oxidase is destroyed by UV exposure. Honey stored in clear jars on windowsills loses GOx activity significantly — one reason some producers use amber glass or opaque packaging. Dark storage preserves both GOx and diastase better than bright-light exposure.
Clover and acacia score lowest for diastase but highest for glucose oxidase — a clean example of why the two enzyme systems are independent. Acacia’s low diastase reflects slow nectar processing; its high GOx reflects strong enzyme secretion from bees working the particular floral source. GOx and diastase are not correlated.
GOx assays are more expensive and technically demanding than diastase testing. The EU directive and the Codex quality annex set limits for diastase and HMF only, and the US sets neither; no GOx floor exists commercially, and standard honey grading ignores GOx entirely.
How temperature destroys enzyme activity
Heat speeds diastase loss sharply: in a 2022 University of Waikato storage study of mānuka honey, diastase lost half its activity in about 1,340 days at 20 °C and in about 160 days at 34 °C (Bell 2022).
Diastase loss in stored honey follows first-order kinetics. A 2022 University of Waikato study of manuka honey measured a half-life of 1,340 days at 20 °C and 160 days at 34 °C; the curves below fit those two points and show % activity remaining over one year of storage.
Diastase activity remaining over time at different temperatures
Starting from a typical raw honey at ~30 Schade. Dashed red line = EU 8 Schade minimum (≈ 27% of 30 Schade starting activity). Curves from first-order Arrhenius kinetics fitted to the two measured half-lives: k(T) = (ln 2 / 32,160 h) · exp(113,646/8.314 · (1/293.15 − 1/T)) hr⁻¹. The 27 °C and 40 °C lines are model values, not measurements.
| Temperature | Half-life | Time to EU limit | Context |
|---|---|---|---|
| 20 °C | ~1,340 days (measured) | ~7 years | Cool pantry storage |
| 27 °C | ~450 days (model) | ~2.4 years | Warm room; a separate 27 °C control in the same study measured 590 days |
| 34 °C | ~160 days (measured) | ~10 months | Hot warehouse or summer storage |
| 40 °C | ~68 days (model) | ~4 months | Extrapolation above the measured range |
"Time to EU limit" assumes starting at 30 Schade — a typical commercial raw honey. Varieties starting higher (buckwheat at 58) have more buffer; varieties starting lower (acacia at 10) may already be near the threshold before any heating. Calculations from the two-point fit to Bell (2022), Ea ≈ 114 kJ/mol. Processing temperatures (60 °C and above, held for minutes) are outside this storage study, so the table stops at 40 °C. Before October 20, 2026 this table used a model that put the 20 °C half-life at ~34 days, about 40 times too short.
Raw vs. processed: what enzyme testing tells you
Raw honey typically tests at 10–60+ Schade diastase with 1–15 mg/kg HMF, while pasteurised or ultra-filtered honey typically tests at 3–12 Schade with 20–80+ mg/kg HMF. A jar labelled “raw” with no third-party testing can still be heat-treated.
Raw honey profile
- Diastase: variety-typical range (10–60+ Schade)
- Invertase: high (90%+ of native activity)
- GOx: fully active on dilution
- HMF: 1–15 mg/kg (EU max: 40 mg/kg)
- Pollen count intact (supports provenance tracing)
Pasteurised / ultra-filtered profile
- Diastase: 3–12 Schade (60–90% degraded)
- Invertase: low (extensive denaturation)
- GOx: mostly inactive
- HMF: 20–80+ mg/kg depending on temperature
- Pollen: removed (origin tracing impossible)
Practical buying tip: A jar labelled “raw” with no third-party testing can still be heat-treated. Look for diastase activity ≥20 Schade (for clover/wildflower varieties), or purchase from producers who publish third-party enzyme test results. The combination of diastase ≥8, HMF ≤40 mg/kg, and pollen-count-verified provenance is the EU’s three-signal quality suite — and the closest proxy for “actually raw” without going to the hive.
Frequently asked questions
What enzymes are found in honey?
What is the diastase number in honey and why does it matter?
What is the EU minimum diastase requirement for honey?
How does temperature destroy honey enzymes?
What is glucose oxidase in honey and what does it do?
Why does Manuka honey have low glucose oxidase activity?
Do raw and pasteurised honey differ significantly in enzyme activity?
Which honey has the highest enzyme activity?
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Sources and Updates
Updated : Replaced the diastase heat model: it gave a 20 °C half-life of ~34 days, but a 2022 University of Waikato storage study measured 1,340 days at 20 °C and 160 days at 34 °C. The chart and table now fit those measurements and stop at 40 °C. Corrected the EU low-enzyme rule (3 Schade if HMF is at most 15 mg/kg; no labeling condition), the USDA grade factors, and an unsupported claim that 63 °C for 30 minutes is a US/EU pasteurisation standard; removed wound and antioxidant-ranking wording.
- Bell A. (2022), An investigation of low diastase activity in mānuka honey, MSc thesis, University of Waikato
- Council Directive 2001/110/EC relating to honey, Annex II (consolidated text, legislation.gov.uk)
- National Honey Board, Honey: A Reference Guide to Nature's Sweetener (enzymes, heat treatment, antimicrobial properties)
- USDA AMS, United States Standards for Grades of Extracted Honey (effective May 23, 1985)
Edited by Sam French · Raw Honey Guide Editorial Team
Source reviewed against primary literature and official guidance where available. Health content is educational, not medical advice, and does not replace a licensed clinician.