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Estimation of the kinetic parameters of anthocyanins degradation at different water activities during treatments at high temperature (100–140 °C) using an unsteady-state 3D model

Jiménez, Nadiarid, Bassama, Joseph, Bohuon, Philippe
Journal of food engineering 2020 v.279 pp. 109951
activation energy, anthocyanins, blackberries, chemical reactions, fruit juices, heat transfer, heat treatment, regression analysis, temperature, water activity
A 3D model of a reactor was developed, combining heat transfer and chemical reaction, to identify kinetic parameters under non-isothermal conditions for intermediate-moisture foodstuffs. In particular, the model was used to assess the impact of high-temperature heat treatments (100–140 °C) on anthocyanin degradation in blackberry juice. A quartz-sand system was used at 25 °C, with three different water activities (aw = 0.34, 0.76 and 0.95). Heat transfer resistance and kinetic parameters were identified, using a nonlinear regression method. Estimates of kinetic parameters showed that the constant for the anthocyanin-degradation reaction rate (k₁₂₀°C) increased from 0.9 to 4.1 × 10⁻³ s⁻¹ with decreasing water activity, with a maximum rate at aw = 0.76. No significant difference (p < 0.05) was found between the corresponding activation energies (Eₐ= 94 ± 7 kJ mol⁻¹). Reduced water activity therefore negatively affects anthocyanin stability at high temperatures.