CROSS-LINKING OF MYOSIN HEAVY-CHAINS FROM COD, HERRING AND SILVER HAKE DURING THERMAL SETTING

Cross-linking of myofibrillar proteins extracted from cod (Gadus morhua), herring (Clupea harengus) and silver hake (Merluccius bilinearis) was studied in 0.6M NaCl, pH 6.5 at 40-degrees-C and evaluated turbidimetrically and by SDS polyacrylamide gel electrophoresis coupled with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a zero-length crosslinker. Turbidities of heat-treated cod and silver hake myofibril/myosin solutions were significantly higher than those of herring. Electrophoretic results showed that the myosin heavy chain (MHC) was the principal myofibrillar protein cross-linked to form a polymerized complex during the heat treatment. Cross-linking ability of MHC from the three fish species was different; herring MHC formed only small polymers (n less-than-or-equal-to 3) but cod and silver hake MHC formed both small and large polymers (n greater-than-or-equal-to 6).