Effect of the environment on beta-carotene reactivity toward oxygen and free radicals.

The effect of oxygen partial pressure and solvent on the kinetics of beta-carotene consumption and oxygen uptake in the course of beta-carotene oxidation has been studied. The reaction of free radical formation, i.e., the chain initiation reaction that occurs via interaction of beta-carotene with oxygen and chain branching reactions that occur via interaction of intermediate products with oxygen, are found to be the most sensitive to the effect of environmental factors. These reactions determine the dependence of the beta-carotene consumption and oxygen uptake rates on oxygen partial pressure. The reaction rates increase in polar solvents which causes the increase in the beta-carotene consumption and oxygen uptake rates. The rates of peroxyl radical destruction and/or isomerization increase in polar media, which leads to the formation of low molecular weight polar oxidation products.