The paper is also the first to document the rate of
hydrogen peroxide generation in relationship to the rate of ascorbic
acid degradation in simple buffered solutions at concentrations
of ascorbic acid, oxygen and copper relevant to food products.
Furthermore, the occurrence of a feedback mechanism is demonstrated
where the hydrogen peroxide and daughter radicals generated
during ascorbic acid oxidation in turn contribute to the
oxidation of the residual ascorbic acid molecules. The findings of
this paper most closely support the proposed mechanisms of
Jameson and Blackburn (1976); however, the existence of a hydrogen
peroxide/hydroxyl radical feedback mechanism greatly complicates
these reactions. The findings of this current study also
demonstrate the optimum levels of ascorbic acid affecting the generation
of hydrogen peroxide under the conditions examined.
When the level of ascorbic acid is decreased or increased from this
optimum range (0.1–0.2 mM), the amount of hydrogen peroxide
generated decreased. Knowing the optimum level of ascorbic acid
in these ROS-generating reactions can be used to control the generation
of hydrogen peroxide and daughter radicals, and minimise
oxidative damage in food products.