1The Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, 2Food Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, 3Nagasaki Kakuyo High School, Nagasaki city, Nagasaki 850-0991, Japan
The taste of the gonad of longspine black urchin (Diadema setosum) was characterized in order to utilize it as a foodstuff, since it is one of the main causes of rocky-shore denudation. Proximate components, adenosine triphosphate (ATP) and ATP-related compounds of D. setosum gonad were similar to those of the gonads of Strongylocentrotus intermedius, S. nudus, and Loxechinus albus, which are commercial sea urchins. However, the free amino acid composition of D. setosum gonad was extremely different from those of other sea urchin gonads: the ratios of sweet and bitter-tasting amino acids of D. setosum gonad were lower and higher, respectively. Sensory evaluation of synthetic extract composed of free amino acids and inosinic acid, which was prepared by reference to the contents in each sea urchin gonad, showed that the synthetic extract of D. setosum tasted less sweet and more bitter than those of other sea urchin gonads. The data suggested that one of the reasons for the unpalatable taste of D. setosum gonad was its free amino acid composition ratio: lower in sweet-tasting amino acids and higher in bitter-tasting amino acids.