Diffusion of nitrate and water in pork meat: Effect of the direction of the meat fiber

The effect of the direction of the meat fiber on the diffusion of sodium nitrate and water in Semimembranosus pork muscle during curing was studied at different temperatures. Nitrate and water diffusion were modelled based on Fick's second law. The nitrate diffusion coefficients ranged from 0.007.10(-1) to 0.034.10(-10) m(-2)/s (parallel) and 0.89.10(-10) to 1.41.10(-10) m(2)/s (perpendicular), while for water the values ranged from 9.87.10(-9) to 12.46.10(-9) m(2)/s (parallel) and 5.22.10(-10) to 9.29.10(-10) m(2)/s (perpendicular). In every case, these values increased as the temperature rose. The activation energy for water diffusion perpendicular to the meat fiber (31.86 kJ/mol) was greater than when the diffusion was parallel (15.06 kJ/mol). The opposite was observed for nitrate diffusion (96.44 kJ/mol when parallel vs. 24.71 kJ/mol when perpendicular), which implies that nitrate needs more energy for parallel diffusion and, consequently, curing is slower in that direction. (C) 2017 Elsevier Ltd. All rights reserved.