Optimization of Preparation Process and in Vitro Digestion Study of Anthocyanin/Fe₃O₄ Nanocomposites by Response Surface Methodology

In order to improve the bioavailability of anthocyanins, a co-precipitation method was used to prepare anthocyanin/Fe₃O₄ nanocomposites in this study. The response surface method was used to optimize the synthesis of anthocyanin/Fe₃O₄ nanocomposites. The particle size analysis, Zeta potential measurement, scanning electron microscope, fourier transform infrared spectroscopy and in vitro digestion simulation of anthocyanin/Fe₃O₄ nanocomposites were carried out. The results showed that the optimum conditions for the preparation of anthocyanin/Fe₃O₄ nnanocomposites were anthocyanin/Fe₃O₄ mass ratio of 1:46, reaction time 19.6 h, reaction temperature 47 ℃. The encapsulation rate of anthocyanin under these conditions was 87.51%. The particle size distribution of anthocyanin/Fe₃O₄ nanocomposites was concentrated in the range of 100~1200 nm with uniform distribution, and the Zeta potential was −48.15 mV. The formation of spherical particles with smooth surfaces between anthocyanin and Fe₃O₄ nanoparticles was observed by scanning electron microscopy. The anthocyanin/Fe₃O₄ nanocomplexes showed anthocyanin C=O and C-H characteristic peaks at 1635 cm⁻¹ and 1083 cm⁻¹. The in vitro digestion simulation showed that the retention of anthocyanin was 91.99% and 46.23% in gastric and intestinal fluids. The scavenging ability of DPPH and ABTS⁺ radicals was increased in the intestinal fluid (P<0.05). Therefore, co-precipitation method can improve the bioavailability of anthocyanins, and provide technical support for the efficient utilization of anthocyanins.