pH Meters for Honey

A honey pH meter is a device that measures the acidity (pH) of honey diluted with water using an electrode; the pH of blossom honeys is mostly between 3.5 and 4.5, and higher in honeydew honeys such as pine honey. pH on its own is not a quality limit; the criterion in the regulations is free acidity. A properly calibrated pH meter gives a useful clue about the origin and consistency of a honey but does not replace laboratory analysis.

What is the pH of honey, and why is honey acidic?

pH is a measure of acidity in a solution: 7 is neutral, below 7 is acidic and above 7 is basic. The scale is logarithmic; a solution at pH 3.5 is about ten times more acidic than one at pH 4.5.

Honey is acidic even though it is sweet. The main source of acidity is gluconic acid: the enzyme glucose oxidase, secreted by the bees, converts part of the glucose into gluconic acid and hydrogen peroxide during ripening. Small amounts of other organic acids are also present.

Low pH and high sugar are among the reasons honey resists microbes. However, the factor that really determines spoilage is moisture content; even if the pH is low enough, honey with high moisture can ferment.

What is the pH of blossom honey and honeydew honey?

These ranges are general, not strict limits. To distinguish honeydew honeys from blossom honeys legally, it is not pH but electrical conductivity, measured in the laboratory, that is used.

What is the difference between pH and free acidity?

The two concepts are often confused:

• pH: Shows the "strength" of the acidity. Because minerals in honey buffer the acids, even a honey containing a lot of acid can show a moderate pH.
• Free acidity: Shows the "amount" of acid in the honey. It is found by titrating the honey solution with a base to a set pH and is given in milliequivalents per kilogram (meq/kg).

The Turkish Food Codex Honey Communiqué (in Türkiye) and European regulations use free acidity as a quality criterion; the general upper limit is 50 meq/kg. There is no legal limit for pH. A rise in free acidity is often a sign of fermentation, because yeasts turn sugar into alcohol and bacteria turn alcohol into acetic acid.

What does a pH reading tell the beekeeper — and what doesn't it?

What it tells you

• A clue to origin: A markedly high pH suggests that the share of honeydew honey may be high.
• Consistency: Batches taken from the same area in the same period should have similar pH values. An outlying value raises the suspicion of mixing or a problem.
• Your own records: Knowing the pH range of your own honeys over the years provides a reference for sales and quality monitoring.

What it does not tell you

• Whether the honey is adulterated: added syrup cannot be reliably detected with pH; isotope and similar laboratory analyses are needed.
• The level of HMF and the diastase activity, which indicate heat treatment and freshness.
• Drug and pesticide residues.
• Bee health: there is no such practice as "adjusting the acidity" of the hive interior or of the bees.

Types of pH meter

• Pocket (pen) pH meter: Portable and cheap; a resolution of 0.1 pH is usually enough. Choose a model with a replaceable electrode.
• Benchtop pH meter: More precise, with temperature compensation and multi-point calibration; for operations and laboratories that measure regularly.
• Test strips: The colour of the honey interferes with the reading and sensitivity is low; not recommended for honey.

Smearing honey directly on the electrode does not give a correct result and fouls the electrode; the measurement is always made in a diluted solution.

How do you measure the pH of honey? (step by step)

1. Representative sample: Mix the batch thoroughly and take a sample. Crystallised honey is gently liquefied in a closed container in a warm water bath.
2. Weighing: In laboratory methods 10 g of honey is commonly dissolved in 75 mL of distilled water. The water should be boiled beforehand and cooled so that it contains no carbon dioxide.
3. Mixing: Stir until the honey is completely dissolved; the solution should be at room temperature.
4. Measurement: Immerse the calibrated electrode in the solution, wait until the value stabilises and read it.
5. Record: Note the value, temperature, date and batch number.
6. Rinsing: Rinse the electrode with distilled water and put it back in its storage cap.

If you always use the same ratio and the same water, your results will be comparable with one another.

Calibration and electrode care

• Two-point calibration: Because honey is acidic, pH 7 and pH 4 buffer solutions are used. Calibrate first with pH 7, then with pH 4.
• Frequency: Every day you take measurements, and always after a long break.
• Buffer solutions: Do not use buffer that is out of date or that has been used and poured back into the bottle.
• Storage: The electrode must be kept wet; store it in the solution recommended by the manufacturer (usually potassium chloride). Leaving it in distilled water for long periods or letting it dry out damages the electrode.
• Cleaning: Honey and wax residues coat the glass membrane of the electrode; rinse it with warm distilled water after each measurement.
• Service life: Electrodes slow down over time depending on use and care; if the value settles slowly during calibration or the deviation grows, it is time for a replacement.

Common mistakes

• Interpreting the pH value as if it were a legal quality limit; the criterion in the regulations is free acidity.
• Measuring acidic honey without calibrating, or after a one-point calibration (pH 7 only).
• Trying to measure honey without diluting it.
• Using a different honey-to-water ratio each time.
• Storing the electrode dry.
• Believing that adulterated honey can be detected with pH.