Tea Tree Oil in Calcium Alginate Microparticles

The aim of this work was the characterisation of tea tree oil calcium-alginate microparticles prepared
using prilling vibration technology and drying according to three different methods (oven at 40°C,
dynamic drying under air-flow at 22°C and freeze-drying). Microparticles were characterized by
stereomicroscopy, scanning electron microscopy, thermogravimetric analysis and as regarding
essential oil content and in vitro release. After oven drying and air-flow drying processes,
microparticles were partially aggregated. They had a high oil content (more than 50% w/w) and were
able to release tea tree oil in about 3 hours. Freeze-drying gave microparticles well separated to each
other, characterized by the highest dimensions (about 500 μm), a good essential oil content and the
fastest release rate. For all systems, the oil content decreased during storage with a total loss, after 5
months, ranging from 10% (air-flow dried microparticles) to 24% (oven-dried microparticles).