Influence of total solids concentration and temperature on the changes in redox potential of tomato pastes

The influence of total solid concentration, heating time and temperature on the changes in redox potential of tomato pastes was studied. Results showed that the reducing properties of the tomato samples were greatly affected by these parameters. In particular, low temperature long time treatments led to the greatest increase in redox potential, which can be attributable to a loss of naturally occurring anti-oxidants. On the contrary, treatments at high temperatures caused little overall change in the redox potential. It was concluded that when severe heating is applied, the formation of heat-induced Maillard reaction products, with anti-oxidant properties, might balance the increase in the redox potential caused by the thermal degradation of tomato natural anti-oxidants.