Benavides, SergioMariotti-Celis, María SaloméParedes, Maria Jose CarolinaParada, Javier A.Franco, Wendy V.2021-12-142021-12-142020-10-13Journal of Microencapsulation, Vol. 38, N° 1 (2021) p. 11-211464-5246http://hdl.handle.net/20.500.12254/2094Aims: Evaluate the effect of varying the droplet size of microspheres charged with thyme essen tial oil (TEO-MS) on their swelling (Sw), release rate (%RR) and in vitro antifungal activity against Saprolegnia sp. Methods: TEO-MS obtained by ionic gelation were characterised through SEM microscopy and X-ray microtomography. Their Sw and RR% were evaluated at simulated fish-astrointestinal conditions using gravimetric and spectrophotometric techniques. Results: For all evaluated droplet sizes (p 0.05), TEO was heterogeneously distributed inside of the MS and TEO-MS experimented agglomeration and sphericity loss after the drying process. Under gastric conditions, the acid pH (2.9) limited the Sw (50–100%) of TEO-MS, generating a low RR% (14–18%). Contrary, the slightly alkaline intestinal pH (8.1) favoured the Sw ( 3.2 to 3.8 times) and therefore the RR% (42–63%). Conclusions: TEO-MS (5–100 mg/mL) presented antifungal capacity onto Saprolegnia sp. after the simulated fish digestion, being the small droplet size once the most effective.enAtribución-NoComercial-CompartirIgual 3.0 Chile (CC BY-NC-SA 3.0 CL)MicrospheresEssential oilMicrostructureAntifungal capacityArtículohttps://orcid.org/0000-0003-1357-812Xhttps://doi.org/10.1080/02652048.2020.1836055