myoglobins

During cooking, fish myoglobins denature and turn gray-brown at around the same temperature as beef myoglobin, between 140 and 160°F/60 and 70°C.

On Food and Cooking, The Science and Lore of the Kitchen

Each of these myoglobins—the red, the purple, and the brown—is present in red meat.

On Food and Cooking, The Science and Lore of the Kitchen