Evaluation of alginate-whey protein microcapsules for intestinal delivery of lipophilic compounds in pigs

BACKGROUND: In animal care and management, there is an increasing demand for convenient methods of oral delivery of bioactive compounds to specific segments of an animal's gastrointestinal tract. The objective of this study was to test the suitability of microcapsules made with alginate and whey proteins of two different sizes (250 and 800μm; containing 72 and 76 g kg-1 of carvacrol respectively) for intestinal delivery of carvacrol in pigs. RESULTS: Encapsulated carvacrol was completely released from the microcapsules after 5h incubation in simulated intestinal fluids or 6h in (ex vivo) ileal digesta, whereas release in simulated gastric fluid was minimal. Tests with growing pigs showed over 95% of unencapsulated carvacrol was absorbed or metabolized in the stomach and the duodenum. Encapsulation effectively minimized carvacrol absorption in the stomach (P < 0.05), and increased carvacrol recovery in the small intestine (P < 0.05). Encapsulated carvacrol was completely released from both small and large size capsules within the gastrointestinal tract of pigs. Larger size microcapsules showed a slower in vitro release and greater in vivo recovery of carvacrol in the small intestine (P < 0.05) than the smaller ones. CONCLUSION: This study indicates alginate-whey protein microencapsulation is a feasible approach for targeted oral delivery of hydrophobic compounds to pig intestines; increasing capsule size increased delivery of carvacrol to the end of the small intestine.