If you eat honey, you probably eat fake honey too. A report from the European Commission in 2023 found that almost half of commercialized honey was diluted with sugary syrups. Because not all honey is the same (depending on the nectar it was made from), it’s hard to figure out which honey is counterfeit, especially without opening the jar. Authentication methods are typically costly and time consuming.

However, a new study from a team of UK researchers has developed a DNA barcoding method that offers a more sensitive and reliable means of identifying such adulteration.

Authenticating Adulterated Honey

The most common form of honey adulteration involves the addition of various sugar syrups, which are cheaper and easily available. These syrups mimic the sweetness and appearance of honey, making detection difficult. To make matters even worse, some syrups derive from plants with similar biochemical profiles to honey. Sources like rice and sugar beet make it even more challenging to spot the fake honey.

This is where DNA barcoding comes in. The technique works by analyzing short, standardized regions of DNA that are unique to different species (markers), allowing for precise identification of the species present in a sample. In the context of food authentication, such as honey, DNA from the product is extracted and specific genetic markers are amplified and compared against a reference database. By detecting the presence or absence of these markers, DNA barcoding can identify whether the product contains unauthorized ingredients, such as sugar syrups, and thus confirm its authenticity.

DNA barcoding has already emerged as a powerful tool in food authentication, capable of identifying the specific plant species present in food products. In the case of honey, DNA barcoding can detect plant DNA from the floral sources bees forage on, as well as any residual DNA from sugar syrups used as adulterants.

The research project was led by Dr Maria Anastasiadi, Lecturer in Bioinformatics at Cranfield University, with the Food Standards Agency and the UK’s Science and Technology Facilities Council (STFC). The team collected 17 honey samples from UK beekeepers, representing different seasons and floral sources. Additionally, they purchased commercially available honey samples and 16 sugar syrup samples derived from corn, rice, and sugar beet. The honeys were then spiked with varying concentrations of sugar syrup (ranging from 1% to 30%) to simulate adulteration.

The researchers used novel DNA markers to identify corn, rice, and sugar beet syrups, even when present at levels as low as 1% — all without opening the jar.

Money and Honey

“Honey is expensive, and in demand — and can be targeted by fraudsters which leaves genuine suppliers out of pocket and undermines consumers’ trust. This method is an effective, quick tool to identify suspicious samples of honey, helping the industry to protect consumers and verify supply chains,” Anastasiadi says.

Moreover, the method was effective across different types of honey, regardless of their natural variations in sugar composition. This is particularly important, as honey’s composition can vary widely depending on the botanical origin of the nectar and the region where the honey is produced. Traditional methods often struggle with this variability, leading to false negatives or inconclusive results. The new DNA barcoding method, however, demonstrated robustness across these different variables.

“To date, DNA methods haven’t been widely used to examine honey authenticity,” commented Dr Anastasiadi. “But our study showed that this is a sensitive, reliable and robust way to detect adulteration and confirm the origins of syrups added to the honey.

While the study’s findings are promising, there are still challenges to overcome. One of the key issues is the variability in DNA content among different sugar syrups. For example, the study found that some sugar beet syrups did not amplify as expected, possibly due to the degradation of DNA during processing. This highlights the need for further refinement of the method to ensure consistent results across all types of syrups.

“It is vital to have samples of known origin and purity to validate the methods, so we want to extend our thanks to the Bee Farmers Association who we work closely with in our projects,” concludes Sophie Dodd, who is completing her PhD on the topic of honey authentication at Cranfield University

The paper Detection of sugar syrup adulteration in UK honey using DNA barcoding was published in Food Control, vol. 167.