Protein profile of honeys (Apis mellifera) of different plant origin

The flowers nectars collected by the bees are transformed by physicochemical processes originating the honey, which is one of the most commercialized hive products. The honey composition is modifyed in accordance with the nectar produced by each plant. Honey contains proteins in minute quantities with an average content of 0.7%. The protein analysis has been used to detect the authenticity of honey. In this way, the aim of this study was to investigate different methods to prepare honey samples and to analyze its protein profile by SDS-PAGE comparing with honeys of different flowerage. Honeys samples from flowers of Eucalyptus sp, Citrus sp, aroeira (Myracrodruon sp), cipo (Paullinia sp) and copaiba (Copaifera sp) were provide by local Apiary. At the laboratory each sample was diluted and mixed in water. To concentrate honey proteins, the samples had been submitted to trichloroacetic acid (TCA) precipitation or lyophilization. In the first one, the honey samples were incubated with TCA 50% and centrifuged; in the second, after centrifugation, the supernatant fraction was dialyzed against water and subsequently lyophilized. All samples were processed by electrophoresis in gradient (5-16%) gel. The results showed different resolution of protein separation in the gels upon the method. The lyophilized samples presented protein profiles with better definition of each band, showing polypeptides not visible when samples were submitted to TCA precipitation. Comparing the protein profile among samples we observed that some bands migrated with similar relative molecular mass. Furthermore, cipo honey has specific polypeptides bands of 40 and 42 kDa and the samples of aroeira and copaiba have only the polypeptides bands of 79, 58, 49, 33 and 19 kDa, which are common for all honeys beyond other polypeptides of 25 and 16 kDa. We concluded that the protocols to prepare honey samples of different plants origin are important factors to exhibit a protein profile that allows a characterization of honey upon its flowerage. In this way, we suggest that analysis of honey samples by its protein profile can be a useful tool to indicate the floral origin of the honey. Futures studies will probe the honey samples with the antibody against apalbumin-1 to verify the presence of this protein of royal jelly in the honey.