Processing and Pigment Stability of Cooked and Frozen Cockle, Fulvia mutica

Processing condition and pigment maintenance of cockle, Fulvia mutica were studied. Proximate composition of whole meat was $82.3\%$ moisture, $10.8\%$ crude protein, $0.8\%$ crude lipid, $2.5\%$ carbohydrate and $3.1\%$ crude ash, and that of foot muscle was $80.6\%,\;12.3\%,\;0.3\%,\;2.9\%\;and\;3.3\%$ respectively. When the living cockle was soaked in $2\%$ NaCl solutions, about $90\%$ of silt and mud was removed after 10 hours soaking, and over $92\%$ was removed when the pH was adjusted to 7.5. When the pigment destruction was tested by 40 seconds at $75^{\circ}C,\;80^{\circ}C,\;85^{\circ}C,\;90^{\circ}C\;and\;95^{\circ}C$, retention ratios of pigment in cockle were above $95\%$ at all temperature. Soaking in ethanol for 5 minutes resulted in strong adhesion of pigment to meat. Soaking in seasoning liquid containing $10\%$ soy sauce, $5\%$ wasabi, $5\%$ sugar, $2\%$ vinegar, $2\%$ powdered garlic for 3 minutes was effective for instant processing of cooked and frozen cockle after thawing. After 60 days storage at $-20^{\circ}C$, the contents of moisture, crude lipid, carbohydrate, ash and salinity were not changed so much, and pH and TBA values increased to 6.6 and 0.3 compared with 6.2 and 0.2, respectively, while pigment absorbance at 226 nm was decreased from 2.7 to 2.3. However, in case of 60 days storage at $-45^{\circ}C$, there was no change in these compositions.