The official AOAC method for the detection of C4 derived exogenous sugars, such as cane sugar or high fructose corn syrup, in honey is based on stable-isotope ratio mass spectrometry analysis of δ13C value of honey versus δ13C of honey protein. However, this method gives false positives with certain Australian honeys, especially those from the Leptospermum species such as Manuka honey. Australian researchers have improved the method, which not only determines the isotopic values of “proteins” precipitated using the standard AOAC method, but also “proteins” precipitated after incorporation of a further modification step, which removes insoluble material (including pollen) from the honey before precipitation. The modified method includes the analysis of different isotopes of the precipitated protein, sugar profiles and Manuka markers. This new method will detect residual sugar feeding of bees, as well as the adulteration of honey with C4 sugar.
Read the abstract here