Mollusc Flavor Oysters, clams, and mussels are prized for their rich, mouth-filling taste, especially when eaten raw We owe this savoriness to their accumulation of internal taste-active substances as an energy reserve and to balance the external salinity of their home waters For osmotic balance, marine fish (and squid and octopus) use tasteless TMAO and relatively small amounts of amino acids, while most molluscs rely almost entirely on amino acids: in the bivalves, especially brothy glutamic acid And instead of storing energy in the form of fat, molluscs accumulate other amino acids — proline, arginine, alanine, and some combined forms — as well as glycogen, the animal version of starch, which is itself tasteless, though it probably provides a sense of viscosity and substance, and is slowly transformed to sweet molecules (sugar phosphates) Because shellfish use amino acids to counteract salt concentration, the saltier the water, the more savory the shellfish This fact accounts for at least some of the flavor differences among shellfish from different waters, and it is part of the rationale for “finishing” oysters for a few weeks or months in particular locations Because shellfish use up their energy stores as they prepare for spawning, they become noticeably less tasty as spawning approaches When molluscs are cooked, their savoriness is somewhat diminished because heat traps some of the amino acids in the web of coagulated protein and so withholds them from the tongue However, heating alters and intensifies the aroma, which is generally dominated by dimethyl sulfide, a compound formed from an odd sulfur-containing substance (dimethyl- -propiothetin) that molluscs accumulate from the algae on which they feed DMS is also a prominent aroma in canned corn and in heated milk: one reason that oysters and clams go so well with these ... savoriness is somewhat diminished because heat traps some of the amino acids in the web of coagulated protein and so withholds them from the tongue However, heating alters and intensifies the aroma, which is generally dominated by dimethyl sulfide, a compound...water, the more savory the shellfish This fact accounts for at least some of the flavor differences among shellfish from different waters, and it is part of the rationale for “finishing” oysters for a few weeks or months... formed from an odd sulfur-containing substance (dimethyl- -propiothetin) that molluscs accumulate from the algae on which they feed DMS is also a prominent aroma in canned corn and in heated milk: one reason that oysters and clams go so well with these