Publication . Martins, Isabel M.; Rodrigues, Sofia Nogueira; Barreiro, M.F.; Rodrigues, Alírio
The objective of this work is to prepare microcapsules of polylactide-containing thyme oil by coacervation
using a variety of nonionic surfactants with different hydrophilic-lipophilic balance (HLB) values and evaluate
the encapsulation efficiency of polar and apolar compounds of oil. Thus, Tween 20, Tween 80, Tergitol
15-S-9, and a combination of Tergitol 15-S-9 with Span 85 have been used. The HLB value was comprised
between 11 and 16.5. For all the studied cases, microcapsules are spherical in shape and have bimodal particle
size distribution with mean size between 30 and 40 μm. The amount of encapsulated thyme oil reaches a
maximum of 65% for Tergitol 15-S-9, a polyglycol ether surfactant with a HLB value of 13.3. The results
confirm the dependence of the encapsulation efficiency as result of the hydrophobic properties of the surfactants.
Moreover, it was confirmed a preferential encapsulation of apolar compounds of thyme oil in detriment of
polar ones.
