Protein oxidation affected the encapsulation properties of rice bran protein fibril-high internal phase pickering emulsions: Enhanced stability and bioaccessibility of β-carotene.

Rice bran protein fibril (RBPF)-high internal phase Pickering emulsions (HIPPEs) loaded with β-carotene (CE) were constructed to enhance stability and bioavailability of CE. Rice bran (RB) protein with varying oxidation degrees was extracted from RB with varying storage period (0-10 days) to prepare RBPF by acid-heating (90 °C, 2-12 h) to stabilize HIPPEs. The influence of protein oxidation on the encapsulation properties of RBPF-HIPPEs was studied. The results showed that CE-HIPPEs could be stably stored for 56 days at 25 °C. When RB storage time was the same, the average particle size, lipid hydroperoxide content, and malondialdehyde content of CE-HIPPEs and the CE degradation rate initially fell, and then grew as the acid-heating time prolonged, while the ζ-potential value, viscosity, viscoelasticity, free fatty acid (FFA) release rate, and bioaccessibility first rose, and subsequently fell. When acid-heating time of RBPF was the same, the average particle size, lipid hydroperoxide content, and malondialdehyde content of CE-HIPPEs initially fell, and subsequently increased with RB storage time extended, while the ζ-potential value, viscosity, viscoelasticity, FFA release rate, and bioaccessibility initially increased, and then decreased. Overall, Moderate oxidation and moderate acid-heating enhanced the stability as well as rheological properties of CE-HIPPEs, thus improving the stability and bioaccessibility of CE. This study offered a new insight into the delivery of bioactive substances by protein fibril aggregates-based HIPPEs.