HMF – Silent enemy in honey and bee food
When we think that we know a lot from beekeeping point, again and again we are surprised when the development of science goes further and reveals interesting details.
Such innovations also include measurement of HMF, which was in the last century, and in some cases still unknown for beekeepers. Let’s look at why it is necessary to monitor the content of HMF in honey and in bee food.
What is HMF?
The compound hydroxymethylfurfural (HMF) or 5 – Hydroxymethylfurfural is an organic compound that is produced by acid-catalyzed dehydration of sugars, primarily fructose and it is crucial to evaluate the conformity of honey for daily use according to the government legislation. Elevated concentrations of HMF in honey provide an indication of overheating, stored in poor conditions or higher age of the honey.
The maximum value of HMF ‘s honey
In the fresh honey HMF practically doesn’t exist. Codex Alimentarius Commission (Alinorm 01/25, 2000) and the European Union (Directive 110/2001) established that its concentration in the honey usually should not exceed 80 or 40 mg/kg.
In some researches (White, 1992) state that is toxic to the human by consuming 2.4 mg of HMF per kg of body weight.
Kandolf (2007) states that the analysis of honey stored for one year at a temperature of 20 degrees Celsius (+ / – 5 degrees), show an increase in HMF content of 16 mg / kg of honey per year, or 1 to 2 mg / kg per month.
Differences between types of honey
HMF is slowly formed in a honey with a high pH value. Because the pH of honeys of forest origin is higher in comparison with floral honeys, that kind of honeys has a longer date of use.
The levels of the HMF in bee food
It is because of high levels of HMF risk of feeding families with invert sugars and syrups that contain a high proportion of fructose is bigger (LeBlanc, 2009 Brodschneider and Crailsheim, 2010). HMF in the honey and sugar meant to feed bees is formed at high temperatures and in long term storage.
According to the literature, researchers have in many cases proved that the HMF is toxic to bees. They found that higher concentrations of HMF in food for bees in experiments in cages increased bee mortality compared with lower concentrations (Jachimowicz and El Sherbiny, 1975 Prandin et al., 2001 Le Blanc 2009, Ruiz- Matute, 2010), but more precise data on the exact value of the content of HMF that is toxic to bees and what the content of these compounds adversely affect the colony, yet is not known. Jachimowicz and El Sherbiny (1975) on the basis of the results of their research conclude that the food (syrups) for bees is acceptable if it contains up to 30 mg / kg HMF, if this value is exceeded, the health of bees can be compromised. Since the effects of HMF on honey bees have not yet been sufficiently explored, it is necessary to be careful.
By using a sugar beet feed or syrup sugar there is important to analyze levels of HMF, however there is a risk to the health and survival of honeybee colonies.
For this reason before purchase, for example sugar cakes, there is required to check HMF levels, but when this information is unknown or is a value greater than 40 mg / kg of honey, the purchase of that sugar cake is not advisable. It was in 2013, on the Slovenian market that emerged Greek sugar cake, which exceeded the permitted values. The results of the analysis of internal controls conducted by the laboratory Slovenian Beekeepers’ Association and the Agricultural Institute of Slovenia, the levels of HMF was from 1 to 700 mg HMF / kg of cake. Some beekeepers had because of that devastating result.
Proper storage of honey
As we know that it often happens that before selling honey stays in storage for one year, so before it gets to the consumer is more important that the conditions in the warehouse are appropriate.
According to the findings of the thesis in 2012 with title »Influence of storage conditions on the HMF content in Honey«, light has minimal impact on the levels of HMF in honey ‘s, so more important is the temperature in the warehouse, which for a longer usefulness of honey should not exceed 22 degrees Celsius, and the time storage, on which sometimes we do not have much impact. The research of fresh honey samples included in this case, the analysis of the content of water, ash, free acids, proline and HMF. During the time of honey storage the content of HMF and honey was evaluated every six months.
Because quality is essential for customers every beekeeper should ask himself how good warehouse conditions for honey are.
Source: czs.si, sl.wikipedia.org, www.digitalna-knjiznica.bf.uni-lj.si