Modelling of Thermal Degradation Kinetics of Ascorbic Acid in Pawpaw and Potato

Abstract

Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 ^oC for the drying of pawpaw and 60 -100 ^oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable. Changes in ascorbic acid degradation followed first-order reaction kinetics. Temperature dependence of the rate constant during thermal processing of pawpaw and potato obeyed the Arrhenius relationship with activation energy of 12.1 and 19.3 KJ/ mole for pawpaw and potato, respectively. A correlation between the loss of ascorbic acid and moisture loss in pawpaw was established with satisfactory statistical predictions(R= 0.996).