Extractive Components of Frozen Short-neck Clam and State of Shell-opening during Cooking

Abstract

* To whom correspondence should be addressed E-mail:cyone@faculty.chiba-u.jp Live and frozen short-neck clams stored at -20°C for 2 weeks were cooked in boiling water, and the extractive components of each hot-water extract and cooked soft parts were examined. The levels of total free amino acids, total ATP and related compounds, and succinic acid in the hot-water extracts prepared from the live and frozen samples were not significantly different, whereas the levels of adenosine 5’-monophosphate (AMP), inosine 5’-monophosphate (IMP) and inosine in the extract of the frozen samples were higher than those from the live samples. A sensory evaluation revealed that the extract of frozen samples was stronger in umami and overall preference and weaker in fishy odor than that of the live samples. The state of shell-opening during cooking of the frozen short-neck clam was also investigated. Samples stored for 2 weeks at -20 °C and -40 °C, placed in water and then brought to the boil respectively resulted in 17% and 27% giving complete shell-opening. However, 66% of the frozen samples placed in boiling water gave complete shell-opening, irrespective of the temperature and duration of freezing. (Received August 5. 2010: Accepted in revised form February 5. 2011)