Dual protein-cyclodextrin carriers regulated by metal ions and tannic acid for encapsulation and functional protection of lycopene.

In this study, a carrier system for encapsulating lycopene was established using soybean globulin (SG) and β-cyclodextrin as the primary carrier matrices. After pre-encapsulating lycopene with β-cyclodextrin, the supramolecular self-assembly of soybean globulin was induced by zinc ions (Zn2+). Then, the cyclodextrin-lycopene inclusion complexes bound to the surface of SG through non-covalent interactions were incorporated within the carrier particles. By covalently modifying SG to different extents with tannic acid (TA), the strength of the carrier particles was adjusted in a controlled manner. The results demonstrated that the pre-encapsulation of lycopene with cyclodextrin improved the encapsulation efficiency of the carrier matrices. Meanwhile, the addition of TA also enhanced the stability of carrier matrices under different pH conditions, as well as the stability of lycopene under light, heat, and oxygen conditions. The combined effect of TA and Zn2+ facilitated the formation of metal-polyphenol network structures and metal-protein coordination bonds, thereby strengthening the structure of the microparticles and providing antioxidant protection to lycopene. After cyclodextrin pre-treatment, the microparticles exhibited higher content of bio-accessible lycopene and antioxidant activity after in vitro digestion compared to the untreated group. The dual-layer encapsulation strategy using cyclodextrin and TA-Zn-induced SG contributed to the broader utilization of lycopene.