Fragrance release profile from sonochemically prepared protein microsphere containers

Protein microspheres have been prepared by sonicating a mixture of pure fragrant oil (amyl acetate (AA)) with an aqueous protein (bovine serum albumin) solution. The prepared protein spheres are nano- to micrometer sized with an encapsulation efficiency of approx. 97% for the AA present on the surface and inside the BSA capsule. Containers were found stable for more than 6 months when stored sealed at 4 °C and 20 °C. For the release profile measurements, we used a simple, automated and direct method. We continuously weighed the encapsulated microspheres and measured the evaporation rates. The release profiles at 15 °C and 25 °C display two different evaporation rates. The higher rate is the sum of a few evaporation rates, including water molecules, while the slower rate is due to the evaporation of pure AA. The changes in the evaporation rates occur upon the collapse of the container. This event coincides with the full evaporation of water. For morphological characterization we dyed the AA with Nile red, and used SEM, ESEM, Cryo-SEM, light microscopy, and confocal laser scanning microscopy measurements.