冷凍すり身の加熱ゲル形成の耐凍性に及ぼすソルビトールと重合リン酸塩の協調作用

The frozen surimis were prepared on mixing with various combinations of 8 % sorbitol (S), 0.25% polyphosphate salt (P), and 0.1% K[2]CO[3] (K), and stored at -25℃. The frozen surimi was thawed,ground with 3% NaCl (w/w),and preheated at 25℃ for up to 8 hours,followed by heating at 90℃ for 30 min. The preheating time-dependent changes in breaking strength (BS) and breaking strain (bs) of two-step heated gel were measured.The gel forming ability of frozen surimi was evaluated from the maximum value of BS and linear relation among BS vs Gs (=BS/bs) plots of heated gels formed. The results are ;

(1) The gel forming ability and its cryostability of the surimi (S) were behind of those of surimi (S+P). The rate of gelation was found to be suppressed by sorbitol.

(2) The suppression of gel forming ability of the surimi (S) was restored with a supply of 0.25% polyphosphate salt into the salt-ground meat.

(3) The cryostability of the surimi (S) was improved to stabilization by further addition of 0.1% K[2]CO[3] although the gel forming ability was unaffected.

(4) A long-term storage for more than 9 months caused irreversible deterioration of surimis (S) and (S+K) in their gel forming ability.

The results indicate that polyphosphate salt is carrying cooperatively with sorbitol to retain the quality of frozen surimi.

8%ソルビトール(S),0.25%重合リン酸塩(P),0.1%K[2]CO[3](K)を組合せて混合し冷凍すり身を調製した.解凍後3%食塩と塩ずりし,25℃で数時間予備加熱後,90℃で30分間加熱した.予備加熱に伴う破断強度と破断凹みの変化から加熱ゲル形成能とその耐凍性を評価した.結果は以下のとおりである.

(1)すり身(S)のゲル形成能はすり身(S+P)より劣り,Sによる抑制が認められた.

(2)Sによるゲル形成の抑制は塩ずり時にPを添加すると回復した.

(3)すり身(S)の耐凍性はさらにKを加えるとやや改良されるが,ゲル形成能は変わらなかった.

(4)凍結貯蔵9ヵ月以上になると,すり身(S)と(S+K)のゲル形成能は一部不可逆的に劣化した.

以上の結果は、SとPが冷凍すり身の品質を保持するために協調的に作用していることを示している.