Effect of Moderate Electric Fields on Sodium Chloride Diffusion in Porcine Muscle
Curing of meat products is dependent on the distribution of brine throughout the muscle structure. Sodium chloride is added to produce desired product characteristics and modify water holding capacity for juiciness and succulence in the finished product. The time course for brine equilibration is lengthy, and governed by the rate of diffusion into the tissues. Moderate electric field (MEF) processing has been shown to enhance diffusivity of ionic solutes in vegetable tissues. However, effects have yet to be investigated in animal tissues. Diffusion coefficients in porcine Longissiumus dorsi were determined in a diffusion cell at three frequencies (10, 50, and 100 Hz) and three electric field strengths (68, 136, and 189 V/m). Concentration profiles after five hour treatments were calculated from a linear relationship between electrical conductivity and mass percent sodium chloride. Computational modeling with Fick's second law of diffusion determined effective diffusion coefficients, Def, which ranged from 0.93x10-9 - 1.37x10-9 m2/s. No statistical differences (p>0.05) in Def were found between MEF and conventional treatments. Sensitivity to thermal denaturation limits the range of electric field strengths potentially suitable for enhanced mass transfer. Lack of cell wall and muscle cell structure have been identified as potential limitations for extension of MEF processing to meat. Mathematical description of salt and water uptake during curing may require a non-Fickian diffusion model.