Abstract
Aims
Evaluate the effect of varying the droplet size of microspheres charged with thyme essential 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-gastrointestinal 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.
Acknowledgements
The authors would like to thank the Anatomy, Histology and Pathology Department of Universidad Austral de Chile where some experiments were carried out, and Joscelyn Diaz, PhD., for her editorial advice.
Disclosure statement
No potential conflict of interest was reported by the author(s).