Frozen surimi of walleye pollack was ground with 2.5% NaCl and cooked by a twin-screw extruder (Mitsubishi Heavy Industries, Ltd.) at 160-170°C of barrel temperature. The ex-truder-product thus prepared was solubilized with a 2% SDS-8M urea-2% 2-mercaptoethanol-20mM Tris-HCl (pH 8.0) mixture and subjected to analysis of the subunit composition of myofi-brillar protein by SDS-polyacrylamide gel electrophoresis.
Densitometric scanning data were compared among those from surimi as raw material, extruder-product from salt-ground surimi, and heated surimi by retort. The latter two were produced under varied temperatures and times for heating.
The results revealed that not only myosin heavy chain but also other components, such as actin, tropomyosin, troponin, and myosin light chains were all involved to form a high molecular weight product during extrusion cooking at 165 ?? 170°C of barrel temperature.
There was a cldear discrepancy between the modes of forming higher molecular weight product from myofibrillar protein of surimi, induced by extruder- and retort-cooking.