Effect of sodium pyrophosphate on gelling property and cross-linking of myosin heavy chain in setting-heating gel from walleye pollack [Theragra chalcogramma] surimi

Frozen surimi from walleye pollack was ground with 2.5% NaCl in the presence 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 incubated at 20°C for setting, followed by heating at 90°C for 20 minutes. The Effects of pH, ionic strength, or PPi-ion caused by the addition of PPi-Na on gelling properties and cross-linking of myosin heacvy chain (HC) in the gels were examined. From the relation between breaking strength and breaking strain of the setting-heating gel, the softness of the gel was evaluated as the force (g) required to peretrate a half-maximal distance (1.0cm). 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 elevations of pH and ionic strength, whereas the PPi-ion suppressed the same reaction. These results suggested that the role of PPi-Na on improving the gel-forming ability of salt-ground meat is the result of a combination of two separate functions of PPi-Na addition.