The optimal time-temperature conditions for orange juice microwave−assisted pasteurization

Abstract

In this work, the inactivation kinetics of pectin methylesterase (PME) and degradation kinetics of ascorbic acid (AA) of batch microwave-assisted pasteurized orange juice were studied, at time-temperature conditions from (70–90) °C between (0 and 180) s. The two-component first-order and the fractional kinetic models were adjusted for PME and AA data, respectively. The microwave treatment was effective for the inactivation of PME with minimal AA retention of 85%. The adjusted kinetics parameters at Tref = 90 °C, for PME were: D1, 90 °C = 0.18 s, D2, 90 °C = 32. 8 s, z1 = 10.6 °C, z2 = 11.8 °C, with α = 0.91. For AA were: k90 °C = 0.02 s−1 and z = 55.4 °C with AA∞/AA0 = 0.85. A time-temperature diagram created from the kinetics parameters indicates the best isothermal conditions for orange juice from 78 s at 82.5 °C to 18 s at 90 °C.