1Shizuoka Prefectural Research Institute of Fishery, Yaizu, Shizuoka 425-0033, 2The School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka 424-8610, Japan
To investigate the relationship between freshness, washing frequency and quality of washed meat, fresh and unfresh dark muscles of skipjack tuna Katsuwonus pelamis were subjected to washing at various frequencies. Meat washed immediately (0 h) after thawing and that washed after storage for 4 h at 25℃ were analyzed for color values (L*, a*, b*), lipid content and volatile compounds. The a* values, lipid content and total aldehyde content of the meat washed at 4 h were higher than those of meat washed at 0 h. Although washing frequency was increased, these values were higher for the meat washed at 4 h than those for meat washed at 0 h. These results indicate that the decline in freshness of the dark muscles resulted in lower quality of washed meat. In addition, insolubilization of sarcoplasmic proteins in the dark muscles increased under low pH. Therefore, it was suggested that deterioration in the quality (color and fishy odor) of surimi prepared from dark muscles can be prevented by removing lipid from raw materials and suppressing the denaturation of sarcoplasmic proteins by maintaining a high pH of raw materials.