Resumen
- The effect of water activity on anthocyanin degradation and non-enzymatic browning (NEB) indices was de-termined in a blackberry juice system heated to high temperature. Blackberry juice samples mixed withquartz sand at three different water activities (awof 0.34, 0.76 and 0.95) and having the same concentrationof anthocyanins (51±4 mg 100g−1WB) were heated in a hermetically sealed reactor under non-isothermalconditions (100 to 140 °C). Reaction kinetics were well-represented by fi rst-order reaction models. A non-isothermal method was used for the identification of kinetic parameters, and the confidence interval foreach parameter was determined via Monte-Carlo simulations. The estimated parameters revealed an increasein the anthocyanin degradation reaction rate constant (kref) from 0.9 to 3.5×10−3s−1as the water activitydecreased from 0.99 to 0.34. The corresponding activation energies (Ea) for anthocyanins and NEB index weremodified to a lesser extent by variations in water activity. Hence, the reduction of water activity had a neg-ative effect on anthocyanin stability at high temperatures.