What makes tuna red

The high value of fresh tuna is largely attributed to the red colour and firm but tender texture of the thin pieces of raw flesh served as sushi or sashimi.

A range of factors has been reported to affect the colour and visual appearance of the tuna flesh, along with the rate of colour change, or stability of tuna flesh colour, writes Alastair Smart, SmartAqua. The red colour of tuna flesh is primarily due to the presence of relatively large amounts of myoglobin, an oxygen-binding protein similar to haemoglobin. In the presence of oxygen, the attractive red oxy-myoglobin is dominant, but will degrade during storage to ultimately form brown metmyoglobin.

Key management practices in tuna diets, fishing, farm husbandry and processing have the potential to optimise flesh colour and consistency. It involves exposing tuna meat to carbon monoxide CO gas, which binds irreversibly to the haem group producing carboxymyoglobin giving the meat a bright cherry red colour which looks quite different to untreated tuna this is why CO victims are found bright cherry red too.

The key issue here is that consumers are eating CO, not inhaling CO, and this is quite harmless. CO makes old tuna look visually fresh and brightly coloured. It also should be shiny and somewhat translucent, and not have slime or an off-smell. Long live maroon tuna. Edit Close. Toggle navigation Menu. Close 1 of 2. What fresh tuna should look like. Tags Tuna.

Your notification has been saved. There was a problem saving your notification. Manage followed notifications. Close Followed notifications. Please log in to use this feature Log In. Don't have an account? Sign Up Today. Trending in Restaurants. But why is tuna red? Does is come in any other colors?

And what about the deep red, nearly black spot in the middle of some tuna steaks? There is a protein in all muscles, called myoglobin. This protein carries oxygen into the muscle tissue, helping it regenerate and withstand continuous use, like a sort of marathon. This gives the meat its deep red color. You may also find lighter colored tuna, such as Albacore tuna. This fish has quicker movements, darting here and there.

Even so, Albacore tuna is not completely white but has some red muscle closer to its spine, since those muscles must always move. Myoglobin is responsible for bringing oxygen into the muscle tissue, and as you may know there are white and red meats. The red meats are a type of muscle that are continuously used, for slow but constant movement. This is why cattle and game have deeper, red meat, as they are always on the move but do no necessarily have to sprint.