Understanding Honey Quality: Moisture Content, Enzymes and HMF

Honey contains over 200 different compounds -- sugars, enzymes, amino acids, vitamins and aromatic substances. But not all honey is equally good. Quality depends on factors that you as a beekeeper can actively influence.

In this lesson you will learn about the three most important quality parameters: moisture content, enzyme activity and HMF value. You will discover how to measure them, what legal limits apply and how to produce top-quality honey.

Why Quality Matters

Honey quality has direct economic consequences:

• Selling price: DIB honey (German Beekeepers Association standard) fetches 8-12 EUR per 500g jar, while discount honey sells for 3-5 EUR
• Shelf life: Honey with low moisture content keeps practically indefinitely; honey that is too moist can ferment
• Customer loyalty: Poor-quality honey means lost customers
• Legal compliance: The German Honey Ordinance (HonigV) sets binding minimum standards

Honey quality begins at the colony and ends with the consumer. The beekeeper decides whether the honey remains a premium natural product or loses value through mistakes.

Moisture Content: Quality Criterion No. 1

Moisture content determines shelf life, consistency and marketability. Honey is a supersaturated sugar solution -- the bees reduce the water content of nectar (40-80 %) through fanning and enzymatic breakdown to 15-20 %.

If the moisture content is too high, fermentation threatens: osmophilic yeasts become active at around 18-20 % and ferment sugars into alcohol and CO2. The honey tastes sour and is no longer sellable.

Legal Limits

Measuring Moisture Content: The Refractometer

1. Calibrate

   Before measuring, calibrate the refractometer with distilled water or calibration solution. Place 2-3 drops on the prism, close the flap, adjust the calibration screw.

2. Prepare the sample

   Take a representative sample and stir briefly. The sample should be at room temperature (20 degrees C).

3. Apply and read

   Place 1-2 drops of honey on the prism, close the flap (no air bubbles!). Hold against a light source and read the boundary line on the scale.

4. Evaluate

   Under 18 % -- excellent, extract immediately. 18-20 % -- acceptable under the Honey Ordinance. Over 20 % -- do NOT extract, return frames to the hive!

Honey Refractometer

Pflichtausstattung

25-80 EUR

Analogue refractometer with ATC (automatic temperature compensation), measuring range 12-27 % water. Look for a model with a honey scale, not just a Brix scale.

Reducing Moisture Content

At the hive: Only extract frames when at least 2/3 are capped. Use smaller supers. Improve ventilation.

In the extraction room: Use a dehumidifier (below 50 % humidity), store frames for 24-48 hours. Maximum 30 degrees, no direct sunlight.

Enzyme Activity: The Sign of Naturalness

Enzymes originate from the honey bee's glands and are a direct measure of gentle processing.

Invertase Number

The invertase? is the most heat-sensitive enzyme in honey. Degradation begins above 40 degrees Celsius.

• Over 150: Excellent -- fresh quality honey
• 64-150: Very good -- DIB top quality
• Under 15: Poor -- probably heated or very old

Diastase Number

The diastase? is the legally required parameter: at least 8 DN according to Schade. Exception: for honey that is naturally low in enzymes (e.g. acacia), DN 3 is sufficient if HMF is below 15 mg/kg.

Protecting Enzymes

The HMF Value: Ageing and Heating Indicator

HMF? (Hydroxymethylfurfural) is formed during the breakdown of fructose under the influence of acid and heat. Fresh honey has only 1-10 mg/kg, but the value rises rapidly through heating or prolonged storage.

Influencing factors: Temperature (most important factor), acidity, fructose content, storage time, light exposure.

You cannot measure HMF yourself -- the determination is carried out in a laboratory (HPLC or photometrically according to Winkler).

Where to have it tested?

• Bee institutes: State bee research institutes (in Germany: Hohenheim, Celle, Mayen, Veitshochheim) offer analyses partly free or at reduced rates for association members
• Accredited laboratories: QSI Bremen, Intertek, Eurofins -- costs approx. 30-80 EUR per sample
• DIB quality control: In cases of complaints, samples are automatically analysed

The German Honey Ordinance (HonigV): Overview

The German Honey Ordinance of 16 January 2004 (last amended 2025) transposes the EU Honey Directive into German law. It defines what may be sold as "honey."

DIB vs. Honey Ordinance: The Quality Comparison

Varietal Honey vs. Mixed Blossom Honey

A honey may carry a varietal designation if it predominantly originates from that forage source. Verification is carried out through pollen analysis, sensory testing and physico-chemical parameters (conductivity, sugar spectrum).

Storage: Preserving Quality

Quality Workflow

1. Before Harvesting

   Check capping level (min. 2/3), shake test, refractometer measurement. Only extract if below 18 % (DIB).

2. During Harvesting

   Clean, dry room, 20-25 degrees. No sunlight. Stainless steel or food-grade containers.

3. After Extracting

   Double sieve, document moisture content, create batch record.

4. Ripening and Bottling

   Let rest for 48-72 hours, skim foam. For fast-crystallising varieties, begin stirring immediately (Lesson 4). Fill cleanly, apply label (Lesson 5).

5. Storage

   Cool, dark, dry. Check sensory quality regularly. Observe best-before date (typically 2 years).

Knowledge Check

In the next lesson, we follow the honey from hive to jar: the perfect harvest workflow with all steps and tools.