The effects of drying methods and leucine addition on properties of propolis powder: Towards the development of a new formulation

Abstract

Propolis, a valuable resin from beehives has many potential health benefits. In this study, we examine the effects of addition of L-Leucine (LL) on the properties of propolis powder produced by spray and freeze drying. Gum Arabic (GA) with LL at different ratios were used as wall materials. Adding LL increases the yield of spray dried (SD) propolis powders, while hygroscopicity, flowability and reconstitution characteristics were affected by both drying method and LL concentration. Freeze dried (FD) powders were more porous as evident by the scanning electron micrographs and showed release of >90 % of compounds within 15 min in both gastric and intestinal media. SD powders were spherical and showed a sustained release of compounds in both media. The best powders were produced with a GA to LL ratio of 8:2 dried by spray drying at 120 °C or 150 °C and by freeze drying. These three optimized formulations showed greater yields (> 50 %), lower hygroscopicity (< 10 %) and moderate antioxidant and antibacterial activities. The formulations remained stable for up to 6 months at ambient temperature, but instability was observed at 40 °C. In conclusion, leucine addition facilitates the formation of SD and FD propolis powders with good properties.

Keywords

• Propolis
• Drying
• Spray-drying
• Freeze-drying
• Leucine