Ultrasound-assisted pH-shifting to construct a stable aqueous solution of paprika oleoresin using egg yolk low-density lipoprotein as a natural liposome-like nano-emulsifier.

[Display omitted] • pH-shifting induced the dissolution of PO in aqueous solution. • LDL improves the stability of PO aqueous solution. • Ultrasonic treatment promotes the stability of LDL-PO aqueous solution. • The stable LDL-PO solution was applied to the processing of aqueous foods. In this study, a stable aqueous solution of paprika oleoresin (PO, the natural colorant extracted from the fruit peel of Capsicum annuum L) was constructed. The solubility of PO in an alkline aqueous solution (pH 10.95–11.10) increased rapidly. However, the aqueous solution of PO (pH 12.00) was unstable, obvious stratification was observed, and the color retention rate was only 52.99% after 28 days of storage. Chicken egg yolk low-density lipoprotein (LDL) was added combined with ultrasonic treatment to improve the stability of LDL-PO solution. The method could decrease the turbidity by 17.5 %, reduce the average particle size of the LDL-PO solution (13.9%), and enhance the interaction and combination of LDL and PO. The prepared PO aqueous solution was used in yogurt, egg white gel, fish balls and soymilk, and it could significantly improve the color of products and provided potential health benefits. [ABSTRACT FROM AUTHOR]