Spray-dried propolis extract. I: physicochemical and antioxidant properties.

The effect of spray drying on the chemical and biological properties of alcoholic extract of green propolis was investigated. The total polyphenol and flavonoid contents in spray-dried propolis extract were determined by the Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. The antioxidant activity of the dry extract was assessed by the membrane lipid peroxidation inhibition method, using quercetin as reference. The polyphenol content was shown to depend on the drying air outlet temperature and its square at the 0.5% significance level, while the flavonoid content depended only on the square of the outlet temperature at the 5% significance level. Polyphenol and flavonoid recovery after spray-drying ranged from 45.1 to 54.9% and 30.6 to 40.8%, respectively. The antioxidant activity of the spray-dried propolis was shown to be affected by the extract feed rate and air outlet temperature at a significance level of 0.1%. The spray-dried propolis extract showed significant antioxidant activity, with 50% lipid peroxidation inhibition at concentrations ranging from 2.5 to 5.0 microg/ml.