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

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. Practical Application (Z)‐Lycopene isomers are biologically more active than the (all‐E)‐lycopene. This study has demonstrated the efficient E/Z isomerization of lycopene using iodine‐doped titanium dioxide as a solid catalyst. The isomerized lycopene product could be applied in foods and dietary supplements. In addition, the present results using a diffusion model could fairly support the conclusion that (Z)‐lycopene isomers are more easily absorbed than the (all‐E)‐lycopene.