Effect of polyphosphate salt on gel forming ability of walleye pollack frozen surimi in relation to frozen storage

The frozen surimis were prepared on addition of 8% sorbitol (S) or 0.25% so dium polyphosphate (P), or their combination (SP), and stored at -25 degree s C for 8 months. The quality of the frozen surimis was evaluated by determ ining breaking strength (BS), breaking strain (bs), and gel stiffness (GS) of the two-step heated gels. The results obtained were as follows: (1) The quality of the gel formed from the surimi with SP was much superior than those of the others. Even if the P was mixed at a grinding step with NaCl, the quality of the gel formed was compatible to that from the surimi with SP. (2) In particular, the bs of the gel from the surimi with P was of much hig her value, although the effect of P reduced when the gel was formed from fr ozen surimi with S;after long-term storage. (3) The linear relations between the BS and the GS (=BS/bs) were very close between the two types of gels formed from the surimis with SP, while that of the gel formed from the surimi with S alone was clearly different. These results indicated that a role of the P in the frozen surimi was to im prove the quality of the two-step heated gel by a reinforcement of bs.