C. J. Langdon, M. A. Buchal-1998
Aquaculture Nutrition, 4: 275-284
Abstract:
Microparticles (< 40 microm diameter) composed of 600 mg per g tripalmitin/400 mg per g fish oil were used to encapsulate the low-molecular-weight (mol. wt 460) antibiotic oxytetracycline in the form of either oxytetracycline hydrochloride (OTC.HC1) or oxytetracycline hemicalcium salt (OTC.HEM). Dry, finely ground particles of core material were encapsulated in spray beads. Dissolved core material was encapsulated in lipid-walled microcapsules.
Oxytetracycline (OTC) was most efficiently delivered (+/- 46.5 mg/g lipid after 24 h suspension in seawater) as a hemicalcium salt in spray beads. Lipid-walled microcapsules were most efficient for delivering OTC (+/- 8.7 mg/g lipid) as OTC.HC1 dissolved in 0.2 M HC1 at a concentration of 300 mg/ml.
Spray beads containing OTC.HEM were very stable over 1 month in storage. Lipid-walled microcapsules containing aqueous OTC.HCI lost +/- 30% of their core material during storage. Freeze-drying of both microparticle types did not improve storage of spray beads, but showed promise for reducing leakage from lipid-walled microcapsules during storage and delivery to suspension feeders.
(Oregon State University/Coastal Oregon Marine Experiment Station, Newport, OR, USA, E-mail: mbuchal@ultraconnect.com)