1National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama, Kanagawa 236-8648, 2Japan Sea National Fisheries Research Institute, Fisheries Research Agency, Suidocho, Niigata 951-8121, 3Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
The color of dried, seasoned and shredded squid products (“sakiika” in Japanese) often becomes brown, probably due to the Maillard reaction, which has been one of the most serious problems in “sakiika” product industries. In this study, we determined the change in the contents of neutral reducing-sugars such as ribose and glucose of common squid (Tedarodes pacificus ) in relation to the browning of the products during preservation. Sample squid frozen on board after fishing was thawed and mantle muscle was allowed to stand for 6 h at 5, 10 and 15°C. Samples with different grades thus prepared were boiled at 80°C for 20 min, freeze-dried, and ground into powder, which was named “dried-squid product browning model” and preserved for 30 days at 35°C. During thawing at 5°C and storage at 5, 10 and 15°C, ribose was accumulated in the mantle muscle of the squid, probably resulting from post-mortem degradation of ATP and related compounds. During preservation at 35°C, the browning rapidly occured with the model samples prepared from any grade. It was noted that the content of ribose before storage at 35°C was higher in the model samples prepared from less fresh mantle muscle.
The b* value of color difference measured as a parameter of the browning rapidly increased during storage at 35°C, showing a high coefficient in the linear regression against the decrease of ribose ( R2=0.76-0.83). On the other hand, the decrease of glucose in the model samples showed no apparent relation to the b* value．These results suggest that ribose plays a major role in the browning of “sakiika”.