Beeswax and resin are the main components of propolis, both of which are hydrophobic. The use of emulsifiers helps to improve the extraction of active propolis compounds and makes them more widely used. In this study, we investigated the optimal parameters for the emulsification of Taiwanese green propolis (TGP) using different polysorbates (polysorbate-20, polysorbate-60, and polysorbate-80) and evaluated the effects on the immunomodulatory response in broilers. The results showed that 4 mg/mL of TGP in combination with 2% polysorbate-60 at 60 °C for 60 min significantly decreased the undissolved particle size of ethanol extract of TGP during the emulsification. The bioactive compounds of TGP, the propolins (C, D, F, G, and H), were also detected after emulsification. Supplementation of emulsified TGP (eTGP) in the drinking water of broilers before and after vaccination significantly enhanced the antibody titer response to infectious bronchitis virus at 28 days of age. In the lipopolysaccharide-challenged model, supplementation of eTGP in the drinking water of broilers decreased pro-inflammatory gene expression and increased anti-inflammatory gene expression. These results together suggested that the polysorbate-60 could effectively emulsify the ethanol extract of TGP. Moreover, eTGP could be used as a vaccine adjuvant and an immunomodulator to improve the immune response of broilers.
Keywords: Taiwanese green propolis; broilers; emulsification; immunomodulation; polysorbate.