Micro- and nano-encapsulation of β-carotene in zein protein: size-dependent release and absorption behavior.

β-Carotene is a lipophilic bioactive compound, providing significant health benefits. Formulation of β-carotene-enriched functional foods is a challenge, due to its poor stability, sensitivity towards light, temperature, oxygen, and its poor water solubility which leads to low bioaccessibility and bioavailability. Targeted delivery and controlled release of bioactive compounds directly depend on the encapsulating matrix and particle size. This work reports an effective encapsulation of β-carotene in zein matrix with glycerol as stabilizing agent. β-Carotene was encapsulated in zein protein matrix with different core-to-wall ratios (1 : 10, 1 : 50 and 1 : 100) at micro- and nano-level, through spray drying and electrospraying techniques, respectively. A comparative evaluation of processing technique, resulting particle size and its impact on powder flow properties, dissolution, release and absorption behaviour was conducted. Results showed that up to 81% of encapsulation efficiency was achieved for the nanoencapsulated form obtained through the electrospraying technique. Nanoencapsulates showed excellent dissolution behaviour compared to microencapsulates due to reduced particle size and larger surface area. Further, under simulated in vitro gastrointestinal conditions, nanoencapsulates showed faster release than microparticles. Among the three ratios tested, nanoencapsulates at 1 : 50 were found to be optimal with ∼73% encapsulation efficiency, exhibiting faster release giving more bioaccessibility, with 1.29- and 1.36-fold higher permeability than 1 : 10 and 1 : 100 formulations, respectively. Additionally, the 1 : 50 nanoencapsulates gave ∼1.7-fold increased permeability compared to microparticles at the end of 3 h using an ex vivo everted gut sac technique. This study proves the potential of zein nanoparticles for enhanced permeability and bioavailability of β-carotene.