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Yellowfin Tuna Fish Coloring : Carbon Monoxide vs. Natural Coloring

Sep 27, 2019Fish

Yellowfin tuna Fish, All about Coloring Methods

In its natural state, yellowfin tuna fish is brown in color once caught, cut and prepared for distribution. In Europe, where it is forbidden to use chemicals to color food like tuna, the tuna fish available for sale in fish shops and grocery stores will look brown. By contrast, in the U.S., where food coloring is allowed, the tuna is colored red to look as everybody imagines fresh tuna to look.
The problem with coloring foods is that companies can use chemicals or other methods that may not be organic or healthy for you.

Methods exist that use natural, organic, and sustainable products to color yellowfin tuna fish.

In this article we will explain to you the differences between the methods of coloring yellowfin tuna fish and what you should look out for when buying it.

Contents :

Ccarbon monoxide treatment for coloring tuna fish

What is natural tuna fish?

What ares the differences between natural tuna and CO-treated tuna?

What about sushi grade tuna and frozen tuna?

Cooking ideas for tuna

Carbon monoxide treatment for coloring yellowfin tuna fish

In the carbon monoxide method, after the tuna is cut and ready to sell, the meat goes through a machine that injects carbon monoxide into it to counter the oxidation of the meat. This prevents the tuna from becoming brown in color and keeps it fresh longer. 

Without carbon monoxide, the meat will turn brown usually within a few days after it is in contact with the air.  

The injection of carbon monoxide ensures the fish will have the same red color as when it is freshly fished, and it will keep indefinitely. The advantage of this process is that the tuna will not only look brighter, but will also keep longer..

The down side of this process is that it is very hard for the customer to know how fresh the tuna is buying it. On top of that, most of the tuna that you can find in the U.S is imported from Europe, so it is impossible to trace back how, when and which company did the coloring.

In the U.S. a salmonella outbreak was attributed to  imported tuna fish treated with carbon monoxide. Because of these types of dangers  carbon monoxide treatment of tuna has been banned from the European Union, Canada, and Japan.

To make sure you get safe yellowfin tuna fish, always find out where it comes from and how it’s been processed.

If you would like to know more about carbon monoxide tuna treatment, you can check out this article.

What is natural yellowfin tuna fish?

A few companies put effort toward sourcing the healthiest, highest quality yellowfin tuna products. This tuna is treated using natural methods and is more valuable because of this. .

Natural yellowfin tuna is a tuna that hasn’t received carbon monoxide treatment. To keep it as red as possible, which is the way it looks after fishing, companies keep the tuna frozen at -60 degrees celsius. By comparison, when tuna is kept frozen at -20 degrees celsius it will start to lose its red color.
This doesn’t mean the tuna is going bad, but just that its meat is losing its red pigmentation.

When you want to buy natural tuna yellowfin tuna fish, make sure it is carbon monoxide free. The tuna might look less red, or may get darker in color once stored in your freezer, but it will be healthy and of better quality.

Some companies are working on a natural process to keep the red color even when the tuna is stored in conditions warmer than 20 degrees celsius. We are following the developments of this research and will update our blog as we learn more.

If you would like to make sure you buy the best tuna fish, always look at the details of the product and ask where it came from. You can check tuna fishing maps for ideas on where to find the freshest tuna. Here is an example of tuna fish that comes from Spain and is 100% organic and naturally treated carbon monoxide free.

What ares the differences between natural tuna and carbon monoxide treated tuna?

Natural tuna fish products and those treated with carbon monoxide are quite different. The primary difference: if you buy natural tuna, you can be sure that it won’t be bad for your health.

The taste is another big difference between a carbon monoxide treated tuna and a natural tuna. carbon monoxide treated tuna will have coloring like a watermelon whereas the natural tuna will be a little darker.

Finally, when natural tuna goes bad you will notice by its color as it continues to darken. You won’t be able to tell with a carbon monoxide treated tuna which stays red even once bad.

If you would like to learn more about the difference and how to know if the tuna you buy is healthy or not, real or fake, you should read this article.

Another great website to learn everything about the seafood you are buying is Fishchoice. They provide traceability of every seafood product on the market and deliver certifications to the company that sells the right fish, including yellowfin tuna.

What about sushi grade tuna and frozen tuna?

When you see “sushi grade tuna,” that means the tuna has been flash-frozen. This process kills all the parasites that can be inside the fish and prevents the growth of bacteria that can be present in the meat.

It also preserves the color, texture and flavour very effectively. Nowadays commercial fishing vessels are equipped with their own freezing facility. Once caught, the tuna is cleaned, cut, and froze within eight hours of getting out of the water.

Fish that has been flash-frozen can stay that way from two months to two years without showing any degradation in quality.

Flash freezing gives us the ability to have sushi everywhere. When you see sushi grade tuna, that usually means that the tuna has been flash-frozen to keep it as fresh as possible once thawed.

Flash-frozen tuna is a good alternative to CO2-treated tuna which is usually not flash-frozen since it has to go through the process of injection.

Cooking ideas for yellowfin tuna fish

A simple, delicious way to cook yellow fin tuna fish is in a pan.
1 – put some olive oil on both sides of the tuna.
2 – sprinkle with salt and pepper (and sesame seed if you like them).
3 – Cook the tuna in a heated and oiled nonstick pan.
4 – Cook each side for a few minutes until side is seared
5 – Cut it into thin slices, add some salt and pepper if needed

Enjoy !

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