Estimation of the diffusivities of sodium chloride, potassium sorbate and sodium bisulphite in mango slices processed by hurdle technology

The fractional amount of sodium chloride, potassium sorbate and sodium bisulphite were evaluated in mango slices immersed in limited volumes of syrup at 25, 50 and 70 °C. The syrup contained 250 g sucrose, 1.5 g sodium chloride, 0.5 g potassium sorbate and 0.25 g sodium bisulphate per kilogram of solution. The sodium chloride concentration in the syrup was confirmed with a flame photometer, and the concentrations of potassium sorbate and sodium bisulphite were determined using high-performance liquid chromatography (HPLC). Fick’s second law was used to calculate effective diffusion coefficients and to predict solute content in the mango slices. Diffusion coefficients were affected by temperature and were correlated by the Arrhenius equation. The experimental data fit the proposed mathematical model well, allowing prediction of the system’s behavior at different temperatures. The resultant diffusivities ranges were 2.63–3.54 × 10−9 m2/s for sodium chloride, 3.88 × 10−9–8.3 × 10−10 m2/s for potassium sorbate and 1.83 × 10−7–5.98 × 10-8 m2/s for sodium bisulphite.