Effect of microencapsulation conditions on phenolic compounds and antioxidant activity of propolis using double emulsion solvent evaporation approach

The aim of this work was to microencapsulate propolis phenolic compounds using polycaprolactone as wall material by double emulsion solvent evaporation (w(1)/o/w(2)). Microencapsulation experiments were carried out by investigating the effect of sample/solvent ratio (10-100 mg mL(-1)), poly(epsilon-caprolactone) (PCL) concentrations (200-1,000 mg mL(-1)), poly(vinyl alcohol) (PVA) concentrations (0.5-2.5 g mL(-1)), and stirring speed (200-1,000 r.p.m.) on the microencapsulation efficiency of total phenolic content (TPC%) and antioxidant activity of propolis. The best microencapsulation conditions were selected according to the total phenolic amount and their antioxidant activity. Experimental results showed that all microencapsulation conditions had significant effects (P < 0.05) on total phenolic content and antioxidant activities. The best conditions were: 30 mg mL(-1), 600 mg mL(-1), 2 g mL(-1), and 400 r.p.m. for sample/solvent ratio, PCL concentrations, PVA concentrations, and stirring speed, respectively, with values of 86.98 +/- 0.03% for phenolic encapsulation efficiency, 53.81 +/- 0.50% for free radical scavenging activity (DPPH), and 45,480 Trolox equivalent, mg TE/100 g dry weight for ferric reducing antioxidant power (FRAP). Under all encapsulation conditions, a significant positive correlation was observed between ferric reducing antioxidant power, free radical scavenging activity, and phenolic content.