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To clarify the process that possibly causes discoloration in boiled, dried, and seasoned squid products ("sakiika" or "ikakun" in Japanese), we investigated the relationship of squid freshness with the rate of browning using the boiled, freeze-dried, and ground squid product model. ATP and its related compounds in Japanese common squid (Tedarodes pacificus) decomposed gradually during storage, yielding hypoxanthine and ribose at 24 h postmortem. The browning rate of the model during preservation as revealed by the increase of the b* value showed a high coefficient in the linear regression against ribose content (R2 = 0.767). Only the model made from the squid stored for 24 h postmortem turned brown. These results strongly suggest that ribose produced during storage plays a major role in the browning of dried and seasoned squid products.

The mantle muscles from instantly killed and frozen then thawed specimens of the common squid Tedarodes paciˆcus were boiled at 80°C for 20 min, freeze-dried, and ground into powder, which were named``the dried, seasoned and shredded products (``sakiika '' in Japanese) browning models''. The models were measured for the contents of ATP and related compounds and reducing sugars such as ribose, glucose 6 phosphate (G6P) and fructose 6 phosphate (F6P) during preservation at 35°C for 30 days where the progression of browning was most likely caused by the Maillard reaction.While the hypoxanthine content of the live squid was much lower than that in the frozen one, the content of ribose in the model from the live squid was also much lower than that from the frozen one before preservation. During preservation at 35°C, the browning of the model from the frozen squid proceeded rapidly, whereas that from the live squid proceeded slowly. Concomitantly, the contents of ribose in the model from the frozen squid decreased rapidly, in contrast to the contents of G6P and F6P which decreased much slower. However, the contents of ribose and G6P in the model from the live squid were only slightly decreased.The bvalue of color diŠerence measured as a parameter of browning showed a high coe‹cient in the linear regression against the decrease of ribose (R 2 ＝0.724) for the model from the frozen squid, but not for that from the live squid with very low content of ribose. On the other hand, the coe‹cient of the bvalue against the decrease of G6P was very low for the model from the live squid (R 2 ＝0.394) and practically no correlation was observed with that from the frozen squid having a high G6P content. No correlation was found between the bvalue and F6P content for the two models. These results suggest that ribose, but not G6P and F6P, plays the major role in the browning of sakiika products.

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