Effect of fat crystal network structure on β-Carotene bleaching

In recent years, bioactive lipophilic substances belonging to the lipid family have received an increasing interest due to their health protecting capacity. Unfortunately, they are highly prone to degradation through the development of oxidative reactions when added to foods. Although great efforts have been taken in the past to understand the chemical reactions involved in bioactive oxidation, only recently increasing attention has been paid towards the effect of lipid structure on oxidation rate. The presence of fat crystal networks could induce a cascade of chemical and physical chemical changes in the matrix able to modify the interactions among reactants and thus the kinetics of oxidation. According to some studies, the inclusion of lipophilic compounds into a solid core improves their chemical stability (1,2). On the contrary, other authors found a greater degradation rate of biomolecules in solid lipid carriers than in liquid lipid ones (3,4). These contradictory observations can be ascribed to the complexity of parameters affecting lipids crystallization. The crystal polymorphism as well as the solid/liquid ratio could influence the molecule movement inside the lipid systems and, thus, the degradation rate of the bioactive molecule. In this study, β-carotene was chosen as target bioactive molecule and it was included into different fat mixtures showing different crystal network structure. The β-carotene bleaching was investigated as a function of fat system structure and their thermal properties.