Hydroxymethylfurfural (HMF): What it indicates about quality

When talking about the quality of honey, one value almost always appears in the analysis reports and in discussions between experts: the’hydroxymethylfurfural, abbreviated to HMF. It's one of those acronyms that seem reserved for chemists, but which actually tells something very concrete to those who buy and eat honey: how fresh it is, how it has been stored, and whether it has undergone incorrect treatments.

In this article, we'll take a simple look at what HMF is, why it's so important, what limitations you should be aware of, and how to interpret it when looking at a label or analysis report.

What is HMF?

Hydroxymethylfurfural is an organic compound that forms naturally in sugar-rich foods when they are exposed to heat or age over time. It arises from the transformation of simple sugars, particularly fructose, through reactions accelerated by heat.

In freshly extracted and properly stored honey, HMF is present in quantities very low or almost non-existent. As the months pass, and even more so if the product is heated, its concentration progressively increases. For this reason, HMF is considered a real indicator of freshness and correct processing: the lower the value, the more carefully the honey has been treated.

It must be said immediately, to avoid alarmism: HMF is present in honey it's not dangerous for health at the concentrations we're talking about. It's not a contaminant or a toxic substance in this context. It's simply a "signal" of quality.

Why HMF increases

Understanding what drives the HMF rise helps us understand why it's such a reliable indicator. There are three main factors.

The heat. This is the number one cause. Heated honey, whether to pasteurize it, to liquefy it after crystallization, or during careless industrial processing, sees HMF increase rapidly. This is where a honey extraction done according to the rules of the art It makes a difference: extracting honey cold, without thermal forcing, is the first step to keeping the value low. The higher the temperature and the longer the heating, the higher the value.

Time. Even without heating, honey ages. Stored at room temperature, month after month, the HMF slowly increases naturally. A high value may therefore simply indicate an older product, perhaps one that has been stored for a long time.

Conservation. Honey stored in a warm environment, near heat sources, in a non-air-conditioned warehouse in the summer, or exposed to the sun, ages much faster. Storage temperature makes a huge difference: this is why it's worth knowing a few things. trick to best preserve honey even at home.

Then there is a fourth, more technical element: the’acidity of honey. More acidic honeys tend to develop HMF more easily, which is why some varieties start with slightly different values.

Legal limits: the numbers you need to know

Here we come to the practical part, the one needed to read an analysis. European legislation sets maximum HMF limits, expressed in milligrams per kilogram (mg/kg).

• For most honeys, the limit is 40 mg/kg.
• For honeys of declared origin from tropical climate regions, the limit rises to 80 mg/kg, because high temperatures naturally increase the value.

These are the limits legalHoney that exceeds these standards cannot be sold as such. But to truly understand quality, it's important to think beyond the simple "within or outside the norm.".

A honey freshly picked and well processed has values typically lower than 10 mg/kg, often close to zero. This is the sign of a fresh, cold-treated product, like that of a careful beekeeper. Values between 10 to 40 mg/kg They may indicate older or less than ideally stored honey, even if it remains perfectly within the norm. A value approaching or exceeding the limit, however, indicates a product that has aged or been excessively heated.

In summary, a small indicative scale:

• Below 10 mg/kg → fresh honey, cold processed, excellent quality.
• 10-40 mg/kg → compliant, but probably not very recent or not optimally preserved.
• Over 40 mg/kg → outside the legal limits for common honeys: old, poorly stored or heated product.

How to read HMF on a label or analysis

And here we come to the point that most interests the consumer. The question is: where do I find this value, and how do I use it?

On the label, almost never. It's important to know: HMF it is not mandatory information On labels and in practice, it's almost never listed on jars at the supermarket. Don't expect to find it listed next to the ingredients. This doesn't mean the honey isn't good; it just means that this information isn't required for regular sales.

In laboratory tests, always. If you buy from a beekeeper, if you participate in honey competitions, or if you simply ask the manufacturer for a technical data sheet, HMF is one of the classic parameters. Many serious beekeepers have their honey analyzed And they're happy to show you the results. A manufacturer who spontaneously shows you an HMF level below 10 mg/kg is giving you concrete proof of freshness and care.

The practical advice, therefore, is twofold. If you buy at the supermarket, you won't see HMF, but you can use other clues (which we'll discuss shortly). If you buy directly from a beekeeper or a small business, ask if they have the testsThis is a legitimate and appreciated question, and the answer tells you a lot about the manufacturer's reliability.

Low HMF without analysis: the indirect clues

Don't have access to the exact number? There are, however, signs that indirectly link to a low HMF.

A honey crystallized This is often a good sign: it means that it has not been heated to keep it artificially liquid, and therefore that the HMF has not been made to rise. crystallization is a natural process and not a defect, on the contrary, testifies that the product has not undergone aggressive heat treatments.

Even the short supply chain It matters. Honey purchased close to its place of production, from the person who extracted it, generally has less time, fewer steps, and less heating behind it than a product that has passed through long commercial chains and warehouses.

Finally, be wary of honey that remains perfectly liquid and clear after many months: this constant clarity, in some cases, is achieved precisely thanks to heat, with the inevitable increase in HMF.

In conclusion

HMF is, in short, a "thermometer" of honey's freshness. It's not a substance to be feared, but a valuable indicator: low values indicate young honey, cold-processed and carefully stored; high values indicate aging, improper storage, or excessive heating.

For the consumer, the lesson is simple: this information won't appear on the jar at the supermarket, but when buying from a beekeeper, it's worth asking for it. A low HMF is one of the most concrete proofs that the honey you're about to enjoy has been treated with the respect it deserves.

From Save the Bees We promote this very culture of quality honey: a natural, cold-processed product, rooted in its local area. Understanding values like HMF is a small step toward becoming more informed consumers and rewarding those who practice beekeeping with integrity.

If you want to learn more, also take a look at the articles on the therapeutic properties of honey and on nutritional values of honey.