Microencapsulation of thyme oil in PLA shell by coacervation
Microcapsules of polylactide-containing thyme oil are produced by coacervation using a variety of nonionic surfactants with different hydrophilic-lipophilic balance (HLB) values and the encapsulation efficiency of polar and apolar compounds of oil evaluated. 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.
Production of PLA microcapsules by coacervation
Particle size distribution of PLA microcapsules with Thyme oil
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