Thermal stability of myofibrillar protein from Indian major carps

The characteristics and stability of natural actomyosin (NAM) from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) were investigated. The total extractable actomyosin (AM) was higher (7.60 mg ml(-1)) in the case of rohu compared with that from catla and mrigal (5 mg ml(-1)). Although the specific AM ATPase activity was similar (0. 43 -0.5 mumol P min(-1) mg P-1) among the three species, the total ATPase activity was lower in mrigal (25 mumol g(-1) meat) compared with the other species (37 mumol g(-1) meat). The inactivation rate constants (k(d)) of AM Ca ATPase activity showed differences in the stabilities of actomyosin among these fish, the actomyosin from catla being least stable. The NAM from these species was stable up to 20degreesC at pH 7.0. Catla AM became unstable at 30degreesC, while rohu and mrigal AM could withstand up to 45degreesC. The thermal denaturation with respect to solubility, turbidity, ATPase activity, sulphhydryl group and surface hydrophobicity showed noticeable changes at around these temperatures. (C) 2004 Society of Chemical Industry.