EFFECT OF SODIUM PYROPHOSPHATE ON GELLING PROPERTY AND CROSS-LINKING OF MYOSIN HEAVY-CHAIN IN SETTING-HEATING GEL FROM WALLEYE POLLACK SURIMI

Frozen surimi from walleye pollack was ground with 2.5% NaCl in the pr esence and absence of 0.1-0.65% Na-pyrophosphate (PPi-Na) and made up to become the same pH and ionic strength with small amount of NaOH and NaCl. The salt-ground meats containing 0-0.65% PPi-Na were then incub ated at 20 degrees C for setting, followed by heating at 90 degrees C for 20 minutes. The Effects of pH, ionic strength, or PPi-ion caused b y the addition of PPi-Na on gelling properties and cross-linking of my osin heacvy chain (HC) in the gels were examined. From the relation be tween breaking strength and breaking strain of the setting-heating gel , the softness of the gel was evaluated as the force (g) required to p eretrate a half-maximal distance (1.0 cm). It was thus shown that the softness of gel given by the addition of PPi-Na was developled largely through the action of PPi-ion but not through the elevation of pH and ionic strength. Meanwhile, the rate of the cross-linking reaction of myosin heavy chain in the salt-ground meat was accelerated by the elev ations of pH and ionic strength, whereas the PPi-ion Suppressed the sa me reaction. These results suggested that the role of PPi-Na on improv ing the gel-forming ability of salt-ground meat is the result of a com bination of two separate functions of PPi-Na addition.