Functional properties of protein from frozen mantle and fin of jumbo squid Dosidicus gigas in function of pH and ionic strength.

摘要

Functional properties of protein from mantle and fin of the jumbo squid Dosidicus gigas were investigated by microscopic analysis of muscle fiber and SDS-PAGE evaluation of protein fraction profiles. Fin had a higher content of connective tissue and a complex fiber arrangement. Fin gels were, as predicted, harder than other gels. Myosin heavy chains (MHC) were found in sarcoplasmic, myofibril and soluble-in-alkali fractions of mantle and only in sarcoplasmic and soluble-in-alkali fractions of fin. Salt concentration and pH had an additive affect on solubility and foaming properties. Fin and mantle proteins yielded similar results in solubility tests, but significant differences occurred at specific pH and concentrations of salt. Foaming capacity was proportional to solubility; foam stability was also affected by pH and salt concentration. Hardness and fracture strength of fin gels were significantly higher than those of mantle gels; gels from proteins of both tissues reached highest levels in the folding test. Structural and molecular properties, such as MHC and paramyosin solubility, arrangement of muscle fibers and content of connective tissue could be used to explain the differences observed in these protein properties. High-strength gels were formed from squid mantle or fin muscle. Fin displayed similar or better properties than mantle in all tests.