PREACTIVATED IOTA-CARRAGEENAN AND ITS RHEOLOGICAL EFFECTS IN COMPOSITE SURIMI GEL

Hydrodynamically active iota-carrageenan was examined for the effects of its rheological properties and volume fraction on the textural, str uctural and thermal properties of composite surimi sol and gel, using dry, cold-water hydrated or thermally preactivated forms. To study the rheological effects, preactivated iota-carrageenans with different le vels of solids were added to Alaskan pollock (Therragra calcogramma) s urimi. For the effects of volume fraction, powdered or preactivated io ta-carrageenan was incorporated into surimi at varying levels. Preacti vated iota-carrageenan yielded a significantly weaker texture than the powdered and hydrated forms. A negative relationship was found betwee n the initial compressive force and viscosity of preactivated iota-car rageenan and composite gel strength. A similar relationship was found between the volume fraction and gel strength. The rheological manifest ation of dispersed biopolymers in composite surimi gel depended not on ly upon their rheological and hydrodynamic properties in the active st ate, but also upon the form in which they were dispersed, namely, stra nd or globule. The strands of preactivated iota-carrageenan may have s tructurally interfered with crosslinking required for gel network form ation, causing gel weakening.