SOLUBILIZATION AND THERMOSTABILITY OF WATER DISPERSIONS OF MUSCLE STRUCTURAL PROTEINS OF ATLANTIC HERRING (CLUPEA-HARENGUS)

Fillets of Atlantic herring (Clupea harengus) were cut into small piec es and washed in cold water at a ratio of 1:3 (w/v), then in a 0.5% (w /v) solution of sodium bicarbonate, and finally in cold water again. T he washed meat was homogenized in ice-cold water at 12.5-20.0% (w/v). The apparent viscosity of the homogenate was dependent upon protein co ncentration. Heating of the homogenate up to 45 OC decreased the appar ent viscosity, while at higher temperatures proteins were precipitated . Addition of acetic acid to lower the pH of the dispersion to 3.5 dec reased the apparent viscosity without causing protein precipitation. T he proteins in the acidified dispersion were highly stable to combinat ions of heat (100 degrees C for 30 min), centrifugation (up to 13500g) and presence of NaCl or CaCl2 (20 mM each). However, increasing the p H above 4.0 resulted in the precipitation of proteins. The amino acid composition of the acidified; heated dispersion was comparable to that of the unwashed herring meat. The treatment, however, caused cross-li nking of proteins as suggested by the sulfhydryl group content of the dispersion.