Influence of the harvesting procedure and extracting process on the antioxidant capacity of ethanolic propolis extracts

Under article 1339 of the Argentine Food Code, food containing propolis is considered dietary. Propolis is a complex mixture of over 200 compounds, mainly polyphenols, which are classified as bioactive, and have important biological effects. Its composition depends on the origin of the sample, and therefore the relationship between flavonoids and biological effects is of interest to assess those constituents. Propolis may be suitable for use in the formulation of functional foods or potentiate the biological effects of other food constituents, combining and acting together. Propolis samples were obtained by scraping and trapping. Extractions were also carried out with dissolutions in 70, 80, and 85% ethanol at room temperature, by mixing and stirring; and by the Soxhlet method. The concentration of the resulting extracts was achieved at 30 and 40 °C. In all cases the antioxidant capacity was measured by the Trolox method, the efficiency of the extraction and the concentration of the total flavonoids and phenols were calculated. We found that the temperature which is used to concentrate them has influence on their antioxidant power, the latter being lower at lower temperature. Soxhlet extraction decreases antioxidant capacity as well as content of flavonoids and phenolic compounds. The resulting extracts showed good antioxidant capacity and didn’t show direct relationship with ethanol concentration.