a b s t r a c tOsmotic dehydration of banana (Musa sapientum, shum.) was optimized with respect to temperature (25e55 C), salt (0e10 g/100 g) and sucrose (30e60 g/100 g) concentrations through response surface methodology. The solution of Fick's law for unsteady-state mass transfer in a cylindrical configuration was used to calculate the effective diffusivities of water, sucrose and NaCl. Analyses were conducted in triplicate for moisture, sugar and salt contents. Peleg's model was used to predict the equilibrium condition, which was shown to be appropriate for water loss and solute uptake. For the above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the range of 5.19e6.47 Â 10 À10 m 2 s À1 , the sucrose effective diffusivity between 4.27e6.01 Â 10 À10 m 2 s À1 and that of NaCl between 4.32e5.42 Â 10 À10 m 2 s À1 . The working conditions that simultaneously optimize these 3 variables were the temperature of 25 C with a solution composed of 30 g/100 g of sucrose and 10 g/100 g of sodium chloride. This condition provided values of 4.80 Â 10 À10 m 2 s À1 for effective diffusivity of water, of 3.21 Â 10 À10 m 2 s À1 for effective diffusivity of sucrose and 4.49 Â 10 À10 m 2 s À1 for effective diffusivity of sodium chloride.

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Degradation kinetics of monomeric anthocyanins in acerola pulp during thermal treatment by ohmic and conventional heating was evaluated at different temperatures (75-90°C). Anthocyanin degradation fitted a first-order reaction model and the rate constants ranged from 5.9 to 19.7 × 10(-3)min(-1). There were no significant differences between the rate constants of the ohmic and the conventional heating processes at all evaluated temperatures. D-Values ranged from 116.7 to 374.5 for ohmic heating and from 134.9 to 390.4 for conventional heating. Values of the free energy of inactivation were within the range of 100.19 and 101.35 kJ mol(-1). The enthalpy of activation presented values between 71.79 and 71.94 kJ mol(-1) and the entropy of activation ranged from -80.15 to -82.63 J mol(-1)K(-1). Both heating technologies showed activation energy of 74.8 kJ mol(-1) and close values for all thermodynamic parameters, indicating similar mechanisms of degradation.

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