Study of vitamin C degradation in acerola pulp during ohmic and conventional heat treatment

Vitamin C degradation in acerola pulp during thermal treatment by ohmic and conventional heating was evaluated. The ohmic heating technology was studied using a Central Composite Rotatable Design, and two variables were evaluated: the solids content of the pulp (2-8 g/100 g) and the heating voltage (120-200 V). The results indicate that ascorbic acid degradation was significantly influenced by both of the aforementioned variables. The total vitamin C degradation was influenced by the linear and the quadratic effects of the voltage. A comparative evaluation of the conventional and the ohmic heating processes showed that ohmic heating, when performed with low voltage gradients, promoted degradation of both the ascorbic acid and the total vitamin C in a manner similar to conventional heating. However, high voltage gradients induced greater ascorbic acid degradation because of electrochemical reactions. These reactions increased when high electric fields were applied, producing compounds that catalyzed the degradation pathways of ascorbic acid in the presence of oxygen. (C) 2012 Elsevier Ltd. All rights reserved.