Lycopene: Heterogeneous Catalytic E/Z Isomerization and In Vitro Bioaccessibility Assessment Using a Diffusion Model

Abstract

Highly efficient heterogeneous catalytic E/Z isomerization of lycopene was achieved using an iodine-doped titanium dioxide (I-TiO₂ ) catalyst prepared by sol-gel method. The effects of reaction temperature and reaction time were investigated in detail. The maximum total Z-ratio of lycopene exceeded 78% after 2 h of refluxing at 75 °C in ethyl acetate. Moreover, lycopene samples with a series of total Z-ratios were prepared and the bioaccessibility of these samples was estimated using a diffusion model, the results showed that the bioaccessibility of lycopene markedly increased conforming to a linear regression model with increasing of the total Z-ratio of lycopene from 3.6% to 78.5%. Furthermore, the specific role of the microstructure and melting point of 3.6% and 78.5% total Z-ratio of lycopene was also investigated to understand the probable mechanism for the enhanced bioaccessbility of (Z)-lycopenes.

Keywords: carotenoids; catalyst; iodine; titanium dioxide; tomato.