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Astaxanthin-loaded liposomes were prepared by a thin-film ultrasonic method, and the effects of the different membrane surface modifiers chitosan hydrochloride (CH) and lactoferrin (LF) on the physicochemical stability of the liposomes and bioaccessibility of astaxanthin were studied. Based on the negative charge characteristics of egg yolk lecithin, LF and CH with positive charge were assembled on the surface of liposomes by an electrostatic deposition method. The optimal concentrations of modifiers were determined by particle size, zeta potential and encapsulation efficiency. The interaction between the liposomes and the coatings was characterized by Fourier Transform infrared spectroscopy. The stability of astaxanthin in different systems (suspension and liposomes) was investigated, and its antioxidant capacity and bioaccessibility were determined. The results showed that both membrane surface modifications could interact with liposomes and protect astaxanthin from oxidation or heat degradation and enhance the antioxidant activity of the liposome, therefore membrane surface modification played an important role in stabilizing the lipid bilayer. At the same time, the encapsulated astaxanthin exhibited higher in vitro bioaccessibility than the free astaxanthin. CH and LF modified liposomes can be developed as formulations for encapsulation and delivery of functional ingredients, providing a theoretical basis for the development of new astaxanthin series products.

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Protein-polysaccharide covalent complexes exhibit better physicochemical and functional properties than single protein or polysaccharide. To promote the formation of the covalent complex from lactoferrin (LF) and beet pectin (BP), we enhanced the Maillard reaction between LF and BP by using an ultrasound-assisted treatment and studied the structure and functional properties of the resulting product. The reaction conditions were optimized by an orthogonal experimental design, and the highest grafting degree of 55.36% was obtained by ultrasonic treatment at 300 W for 20 min and at LF concentration of 20 g/L and BP concentration of 9 g/L. The formation of LF-BP conjugates was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) spectroscopy. Ultrasound-assisted treatment can increase the surface hydrophobicity, browning index, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radicals scavenging activity of LF due to the changes in the spatial configuration and formation of Maillard reaction products. The thermal stability, antioxidant activity and emulsifying property of LF were significantly improved after combining with BP. These findings reveal the potential application of modified proteins by ultrasonic and heat treatment.

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