Abstract: By taking advantage of the controlled release capacity of sodium alginate (SA) and the reversible assembly characteristics of under extremely acidic conditions, horse spleen apoferritin (HSF) and SA were used as nano-carriers for encapsulation of an angiotensin converting enzyme (ACE) inhibitory peptide, alanine-histidine-leucine-leucine (Ala-His-Leu-Leu, AHLL), aiming to improve the absorption of AHLL in the digestive system. The results showed that the optimal conditions for the preparation of nanoparticles that provided maximum encapsulation efficiency were determined as follows: HSF concentration 1–2 μmol/L, sodium alginate concentration 10 mg/L, and final concentration of AHLL 100–200 μg/mL. The as-prepared nanoparticle system was stable. Preliminary structural representation of HSF-AHLL and HSF-SA-AHLL was performed with transmission electron microscopy, which indicated that a uniform nano-system has been formed. The particle size and potential of the nanoparticles demonstrated the stability of the encapsulation system. Furthermore, AHLL in the nano-system could be well absorbed by the digestive system as revealed by the in vitro transport test uisng Caco-2 cell monolayer model. These results support that HSF-SA could be applied as a nanocarrier for maintaining the homeostasis of bioactive peptides and provide an effective way to improve the absorption of bioactive nutrients.

Key words: horse spleen apoferritin, angiotensin converting enzyme inhibitory peptide, sodium alginate, encapsulation, nanoparticle, absorption