Abstract
Summary Ascorbic acid (AA) degradation and colour changes, measured by the lightness index ( L *), were determined in cashew apples (at low dissolved O 2 concentrations) heated at high temperature (100–180 °C) in a hermetically sealed cell. A nonisothermal method was developed to estimate thermal degradation kinetics. The results showed that reaction kinetics during heat treatments were well represented by first‐order reactions. The temperature dependence of the kinetic constants was described by an Arrhenius type equation. The activation energy ( E a ) for AA degradation and lightness index were 94 ± 3 and 98 ± 3 kJ mol −1 , respectively. The reaction rate constant at 140 °C for AA degradation (64 × 10 −5 ± 3 × 10 −5 s −1 ) was twice that for the lightness index change (33 × 10 −5 ± 2 × 10 −5 s −1 ). Results allow generating temperature profiles of heat processes that would help preserve the AA of cashew apples as well as control the colour formation during high‐temperature processes.