Mathematical modelling of the effect of solution concentration and the combined application of pulsed electric fields on mass transfer during osmotic dehydration of sea bass fillets

The objective of the study was to evaluate the effect of osmotic solution concentration and a pretreatment with pulsed electric fields (PEF) (1.6 kV/cm, up to 1500 pulses/19.7 kJ kg⁻¹) on mass transfer during osmotic dehydration (OD) of sea bass fillets. Osmotic solutions of 40–60% glycerol and 5% NaCl were applied at 15 °C for processing times up to 240 min. The increase in glycerol concentration enhanced significantly mass transfer expressed by the effective diffusivities of water (D_ew values ranged from 1.9 to 3.6 × 10^-9 m²s⁻¹) and solubles (D_es values ranged from 1.8 to 4.1 × 10^-9 m² s⁻¹). PEF pretreatment further increased D_ew and D_es values up to 50% and 66% respectively (for 1500 pulses/19.7 kJ kg⁻¹). The energy input correlated with the calculated D_ew and D_es values, following a logistic mathematical model. The logistic model had a center point at 7.28 kJ kg⁻¹ and 7.15 kJ kg⁻¹ for water and solubles, respectively and showed a sharp increase of the diffusivity values between 3.3 and 9.8 kJ kg⁻¹ ranging from 3.0 × 10^-9 m² s⁻¹ to 4.0 × 10^-9 m²s⁻¹ for D_ew and from 2.7 × 10^-9 m²s⁻¹ to 4.1 × 10^-9 m² s⁻¹ for D_es.