Honey testing

Issues with adulteration of Australian honey

1. Honey testing: To bee or not to bee!

2. The Problem : Big honey companies are blending imported honey with local produce but the imported honey is adulterated – it contains sugars added from other sources. Testing to prove this has been either non-existent or inadequate.

3. FAIL! 12 out of 28 common supermarket brands tested failed.

4. Why adulterate honey? – to cut costs. Adding water will make each litre of honey go further, adding cheaper sugars saves money.

5. What is in honey? A range of sugars, organic acids and flavonoids. % Water is around 17%. Added water can be detected this way. Fructose:glucose is 38:31. Adulterated honey will have a different ratio.

6. Sugars: Carbohydrates Your textbook will tell you that glucose and fructose are examples of monosaccharides. Your textbook does not mention that there are hundreds of other important monosaccharides. They are classified by the number of carbon atoms in the backbone. Glucose is a hexose or C6 sugar. The molecule on the right is a tetrose , a C4 sugar.

7. Detecting adulterated honey is about detecting the presence of C4 and C3 monosaccharides. Added sugar cane syrup increases the level of C4s Added rice syrup increases the level of C3s

8. NMR: nuclear magnetic resonance Full NMR – each coloured line is a different sample of pure honey. Note the consistency in the shifts at which peaks appear.

9. The NMRs on the previous slide are so precise that they can be used to identify the country of origin of the honey. The composition varies with the climate, species of bee and species of plants the bees feed upon. The NMR stores the spectrum to use as a reference against future tests. The presence of C3 sugars adds peaks in unexpected shifts. The peak areas provide information about the likely concentrations of the sugars present –adulterated sugars will have different sugar ratios.

10. Specific shift regions are studied for a honey ‘fingerprint’. The sample below is for shifts between 3.2 and 5.3 corresponding to common monosaccharides.

11. High shift regions

12. Bottom line is this various honeys have distinctive NMR patterns. the presence of added sugars will produce peaks that should not be there or will enhance peaks that are present. heat treatment of honey will change the characteristic NMR spectra as the chemical composition of sugars can be changed by heat.

13. Adulteration is not limited to honey. Check out the two maple syrups below .

14. Conclusion Buy honey from your local farmers market or buy Beechworth honey – completely Australian produce.