Impact of biopolymer-surfactant interactions on the particle aggregation inhibition of β-carotene in high loaded microcapsules: Spontaneous dispersibility and in vitro digestion

The particle aggregation of β-carotene has been a challenge for the development of powdery microcapsules with a high loading. Herein, solvent-free β-carotene high loaded microcapsules based on the wet-milling technique were fabricated by using a complex stabilizer composed of octenyl succinic anhydride modified starch (OSA-starch) and tea saponin (TS). The influence of biopolymer-surfactant interactions on the particle aggregation inhibition of β-carotene in the microcapsules was investigated. The particle size distribution, micromorphology, redispersibility and in vitro digestion of the microcapsules were altered by regulating the addition sequence and the mass ratio of both stabilizers. The optimized β-carotene microcapsule presented a small particle size after rehydration (275.1 nm) with the high encapsulation efficiency and loading capacity (99.04% and 18.87%, respectively). As analyzed by FTIR and XRD, the hydrogen bonding and hydrophobic interactions between β-carotene and wall materials were involved in the amorphization of β-carotene. SEM and CLSM images jointly verified that the biopolymer-surfactant complex retarded the expansion of the microcapsules, and the dents on the surface of microcapsules facilitated the moisture infiltration during rehydration. Moreover, the wall material composition of microcapsules further affected the bioaccessibility of β-carotene during the simulated digestion, and the bioaccessibility of β-carotene was increased from 2.73% to 15.97% due to the enhanced micellization and transport capacity of β-carotene.