Subzero-temperature preservation of reactive fluids in the undercooled state. II. The effect on the oxidation of ascorbic acid of freeze concentration and undercooling.

The rate of oxidation of ascorbic acid has been measured in both frozen and undercooled solutions. A new interpretation is advanced for changes in the rate of ascorbic acid oxidation in freeze-concentrated solutions. The results obtained with undercooled solutions indicate a rate reduction in line with that predicted by the Arrhenius equation. It is also demonstrated that undercoohng provides a method for greatly extending the shelf life of reactive fluids.