1Ibaraki Prefectural Fisheries Rsearch Institute, Hitachinaka, Ibaraki 311-1203, 2Laboratory of Marine Biochemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, 3Department of Home Economics, Faculty of Education, Chiba University, inage, Chiba 263-8522, Japan
We investigated the relations of different water environments between Hinuma Lake and a downstream region of the Hinuma River with differences in the composition of the extract from brackish water clam Corbicula japonica and with those in the taste of soup made from the clam by boiling. Water salinity in the Hinuma River was higher than that in Hinuma Lake due to the tidal effect in the former. Accordingly, the alanine content in soft tissues of the clam from the Hinuma River was higher than that from Hinuma Lake. However, the total free amino acid content in the soft tissues was not significantly different between the two locations. On the other hand, the total amino acid content was higher in the soup made from the clam of Hinuma Lake than that of the Hinuma River, whereas the before-taste and after-taste were stronger in the former than the latter as revealed by the organoleptic test.