Characterization of Canadian propolis fractions obtained from two-step sequential extraction

- Propolis fractions were produced by sequential extraction with water and ethanol.
- Composition varied according to solvent and sequence of extraction steps.
- Ethanol fractions showed higher polyphenol and flavonoid concentrations.
- The sensory detection threshold concentration was higher in water fractions.

The antioxidant capacity, as well as the concentration threshold for sensorial detection of Canadian propolis fractions in milk were determined. Propolis fractions were obtained using two-step sequential extraction with ethanol and water. Two processing pathways were carried out by interchanging ethanol and water extraction steps. Total polyphenol and flavonoid contents were quantified and ESI-MS fingerprints in negative mode were collected to determine the chemical composition of the propolis and propolis extracts. The ferric-reducing power assay and DPPH· methods were performed to determine antioxidant capacity. For both extraction pathways, the ethanolic extract showed higher polyphenol and flavonoid concentrations and higher antioxidant capacity as compared to commercial propolis and water extracts. The polyphenol composition of the extracts varied according to both, the extraction solvent and the extraction pathway as revealed by ESI-MS fingerprints. The sensory detection threshold concentration in milk was significantly higher in water extracts than in ethanol extracts. It was further increased when ethanol extraction was carried out as the first step and water extraction as the second step. The results of this study suggest that sequential extraction process can be used to produce propolis fractions with different polyphenol composition, antioxidant and sensory properties.