Heavy metal content in propolis and propolis extracts

The aim of the study was to determine the content of heavy metals in native propolis and its extracts: alcoholic extracts (5%, 20%, and concentrated 70%) and aqueous extracts of propolis prepared via different methods, in order to optimize production technology and minimize the transfer of toxic metals into the final product. The concentrations of three toxic metals (Cr, Cd, Pb) were determined in native propolis samples from the Ryazan region and in the indicated extracts. The content of these pollutants was assessed by atomic absorption spectrophotometry. The results showed the presence of all analyzed metals in native propolis samples. The concentrations of elements ranged from 0 to 0.92 mg/kg for Pb, from 0 to 0.2 mg/kg for Cd, and from 0 to 1.54 mg/kg for Cr. Native propolis can be considered an indicator of toxic metals in the environment. For all analyzed metals, a significant decrease in their concentration was observed upon transfer into ethanolic and aqueous propolis extracts, making the product safe for consumption. The presence of toxic heavy metals necessitates quality control of bee products before their use as food additives. Given that bee products are highly heterogeneous and vary in elemental content depending on environmental factors, standards should be developed to regulate permissible levels of inorganic pollutants.