Effect of high pressure on cod (Gadus morhua) desalting

The effect of high pressure on salt and water diffusion in the desalting process of cod was studied. Under pressure, up to 300MPa, the osmotic equilibrium is reached much faster, compared to desalting at atmospheric pressure. Water (D-ew) and salt (D-es) effective diffusion coefficients reached a maximum at 200MPa, increasing 500- and 160-fold, respectively, compared with desalting at atmospheric pressure. Increasing pressure up to 300MPa causes a reduction in both effective diffusion coefficients, although they were still about 70-fold higher than at atmospheric pressure. Up to 200MPa, a linear correlation was found between D-ew and D-es and pressure. However, the total diffused amounts of water and salt, when the osmotic equilibrium was reached, were lower under pressure. At atmospheric pressure cod water content increased 1.65-fold, but under pressure the increment was on average 1.25-fold, while salt content decreased to 0.51-fold the initial value at atmospheric pressure and to around 0.75-fold under pressure.