Microstructural Changes in Pork Tissue by the Presence of Sodium Chloride

PINOTTI, A; CALIFANO, A; ZARITZKY, N

Journal of Scanning Microscopies

FAMS, Inc., D. C. Joy (Ed)

Año: 2001 vol. 23 p. 219 - 220

The objectives of the present work were: a) to establish the effect of NaCl on tissue microstructural (SEM),.and denaturation of myofibrillar proteins by DSC, b) to determine the effective diffusion coefficients of NaCl in pork tissue (Dm) from measurements of NaCl uptake as a function of time, fitting theorical curves of the diffusional model to the experimental data. Samples of  Longissimus dorsi pork tissue  were immersed in brines of different NaCl composition (1, 7, 14 and 33%). Meat tissue samples were observed by SEM,. DSC studies to analyze denaturation of proteins were performed within a range of 10 to 100°C. The mass of NaCl was determined using a Chloride Electrode on dry tissue. Water holding capacity (WHC) was determined as the changes in the amount of water refered to the initial water content. A radial (unidirectional) diffusion system was adopted using long cylinders of muscle The microscopic mass balance was considered for an infinite cylinder with radial diffusion and constant interfacial concentration. Typical DCS thermograms of whole muscle display three major peaks, corresponding to myosin (I y II, 58°C), collagen and sarcoplasmic proteins (II, 65°C) and actin (III, 80°C) for the samples of untreated tissue. As NaCl concentration increased, peaks areas were progressively reduced, and maximum temperatures changed due to protein denaturation.The diffusion coefficients obtained for sodium chloride concentrations of 7% and 14% a 4 °C were 7,8 and 10.10-10 m2/s, respectively. In conclusion NaCl affect the microstructure and produce protein denaturation increasing the effective diffusion coefficients of NaCl.