Análise dos méis de abelhas do gênero Melipona (abelhas sem ferrão) através de LC-SPE/NMR, LC-BPSU/NMR e RMN aliada à quimiometria.

Abstract

In Brazil, there are approximately 200 species of stingless bees, especially in the Amazon region. The Melipona seminigra and the M. interrupta are species that stand out in Central Amazon, since they are abundant and have great honey potential; however, little is known about the chemical constituents of the honey varietals produced by these species. Therefore, the objective of this work was to study the honey varietals produced by the aforementioned species through LC-SPE/NMR and LC-BPSU/NMR techniques in order to identify the minor constituents. The 1H NMR technique combined with chemometrics and with the determination of the isotopic 2H/1H (SNIF-NMR) ratio was also used in order to evaluate the authenticity of commercial honey varietals. The varietals considered authentic were acquired from the apiary of the Instituto Nacional de Pesquisas da Amazônia (INPA) and the commercial varietals were bought at different stores in the north region. The SNIF analysis showed that all evaluated types of honey come from the C3 biosynthetic cycle and, thus, through isotopic analysis, it was possible to infer that there was no adulteration to the varietals when it comes to addition of sugar directly to the honey or to the feeding of bees and it was also possible to observe that the bees did not prefer plants of different cycles. Nonetheless, the chemometrics clearly showed another type of fraud performed in the commercialization of stingless bee honey. It was possible to observe the difference between authentic and commercial honey varietals, especially due to the presence of 5-hydroxy-methyl-furfural (HMF) and citric acid only in the commercial varietals. Only two of the ten commercial honey varietals analyzed grouped together with the authentic ones. In order to determine the origin of these commercial types, some samples of honey produced by bees with stings (Apis melifera) were also analyzed. The results showed the grouping of commercial honey varietals bought as being from stingless bees together with the honey types from Apis melifera. From the chemometrics analyses, the presence of phenylalanine and threonine was clear only in the authentic honey varietals, which helped in the separation of the commercial varietals. Through the LC-SPE and LC-BPSU techniques, it was possible to identify 5 substances in the honey varietals from M. seminigra, and 19 in the varietals from M. interrupta, of which 11 had never been reported in honey.