LIQUID-HOLDING CAPACITY AND STRUCTURAL-CHANGES IN COMMINUTED SALMON (SALMO-SALAR) MUSCLE AS INFLUENCED BY PH, SALT AND TEMPERATURE

The loss of liquid in salmon muscle comminuted with salt was studied a s a function of pH and heating temperature. A factorial experiment was designed to compare the effects of the raw material, NaCl concentrati on, pH, degree of comminution and heating temperature in order to eval uate both main effects and interaction effects. The liquid-holding cap acity was measured by a low speed centrifugation net test. The changes in microstructure in the samples were investigated by light microscop y using fat- and protein-staining techniques. The heating temperature, pH, NaCl concentration, variation of raw material and degree of commi nution influenced liquid loss according to a second-order interaction linear model. The interaction effect between low pH, low salt concentr ation and high temperature was strongest Addition of salt extracted th e myofibrillar proteins and resulted in a homogeneous protein matrix w ith few intact fibres and uniformly dispersed fat droplets. Liquid los s was closely related to the microstructure of the comminutions. When heated above 30 degrees C, enlarged pores and gaps, some of them formi ng channels, occurred in the protein matrix. In comminutions prepared with a low salt concentration and/or a low pH the more frequent presen ce of pores and gaps enhanced the liquid loss.