Structural modification of β-Lactoglobulin by cold plasma and its stability on astaxanthin-loaded high internal phase emulsions.

The impact of cold plasma (CP) treatment on the structure of β-Lactoglobulin (β-LG) and its role in stabilizing astaxanthin-loaded high internal phase emulsions (HIPEs) were studied. The results indicated that CP induced partial cleavage in the backbone of β-LG, as confirmed by SDS-PAGE analysis. Secondary and tertiary structural analyses revealed the unfolding of the compact spherical structure of β-LG, accompanied by exposure of its internal hydrophobic groups. Additionally, CP treatment promoted the generation of intermolecular disulfide bonds t as displayed by non-reducing SDS-PAGE and sulfhydryl group (-SH) content analysis, where the content of disulfide bonds increased from initial 19.72 ± 0.29 μM/g to 22.56 ± 0.19 μM/g after 8 min of CP treatment. The co-effects of multiple structural alterations of β-LG led to its structure transformation from a compact sphere-like state to an unfolding form, facilitating the generation of higher strength of astaxanthin-loaded HIPEs, which was supported by rheological properties analysis. Further thermal, centrifugal, freeze-thaw, and storage stability analyses showed that the thermal, centrifugal, and storage stabilities of astaxanthin-loaded HIPEs were improved by encapsulation with CP-modified β-LG, which was positively correlated with CP treatment time. Notably, CP-modified β-LG significantly improved the astaxanthin retention rate of HIPEs. After 60 d storage, HIPEs stabilized by 8 min CP-treated β-LG showed a 75.60 ± 2.24 % astaxanthin retention rate, compared to 57.67 ± 3.58 % for those stabilized by untreated β-LG. This study implies that CP treatment is an effective and reliable method for modifying protein structure to enhance the stability of HIPEs.