β-Cyclodextrin encapsulates β-carotene on the basis of host–guest interactions to inhibit the photooxidative deterioration mediated by riboflavin in egg white

Liquid egg white protein (EWP) readily undergoes undesirable photooxidation triggered by endogenous photosensitizers such as riboflavin during routine shipping and ambient storage, which deteriorates the functional quality of liquid egg products. This study employed β-cyclodextrin (β-CD) to encapsulate β-carotene (β-C), which was subsequently incorporated into liquid egg white to suppress photosensitizer activity and quench ROS within EWP. Results showed that β-CD encapsulates the polyene chain and β-ionone ring of β-C within its hydrophobic cavity, driven primarily by hydrophobic interactions. The 2:1 β-CD/β-C composite showed superior thermal stability and a high thermal decomposition temperature of 425 °C. This complex may gradually release β-C to quench singlet oxygen ( 1 O 2 ) and scavenge triplet riboflavin ( 3 RF), thereby preventing ROS from attacking EWP side chains, inhibiting protein cross-linking, and lowering viscosity. The 4:1 β-CD/β-C-EW preserves bulk EWP structure but causes partial amino acid oxidation and fast β-C breakdown from surplus free β-CD, even with high starting β-C levels. In comparison, optimal host-guest matching in the 2:1 formulation securely entraps β-C within cyclodextrin cavities, preserving greater β-C retention and the minimum riboflavin fluorescence throughout storage. In contrast, the physical mixture group of β-CD and β-C due to the inclusion lag, and the pure β-C group due to easy oxidation inactivation, show decreasing protective effects with storage time. The 2:1 β-CD/β-C complex effectively suppresses photooxidative damage in EWP, providing a basis for controlling photooxidation of egg white during processing and storage.