Kinetics of ascorbic acid degradation and colour change in ground cashew apples treated at high temperatures (100-180 °C)
2010
Lima, Janice R. | Elizondo, Nadiarid J. | Bohuon, Philippe
Ascorbic acid (AA) degradation and colour changes, measured by the lightness index (L*), were determined in cashew apples (at low dissolved O₂ 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 (Ea) 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 x 10⁻⁵ ± 3 x 10⁻⁵ s⁻¹) was twice that for the lightness index change (33 x 10⁻⁵ ± 2 x 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.
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