Is Grey Tuna Safe To Eat? Examining This Common Concern

Tuna is one of the most popular fish used in sushi, sandwiches, salads and more Its meaty texture and mild flavor make it a versatile ingredient. But sometimes when you go to prepare tuna, you notice it has turned from red to an unappetizing gray color. This discoloration naturally raises the question – is grey tuna safe to eat or has it gone bad?

When tuna changes from its normal deep red hue to a dull gray, it’s understandable to be hesitant about eating it. Let’s closely examine what causes tuna to turn grey and whether it’s still OK for consumption when it loses its vibrant color.

What Causes Tuna to Turn Grey?

Tuna flesh gets its reddish-pink color from myoglobin, a protein found in muscle tissue. Myoglobin contains iron, which oxidizes and turns brown when exposed to air. This chemical reaction causes the color change in tuna from red to grey/brown.

Specifically, here are three things that can cause tuna to turn gray:

• Oxidation Exposure to oxygen causes the iron in myoglobin to oxidize This oxidation turns the tuna greyish-brown

• Age: As tuna ages and myoglobin begins to break down, its color fades to grey even without air exposure.

• Frozen storage: Freezing tuna for lengthy periods can degrade enzymes and proteins, causing discoloration.

Is Grey Tuna Unsafe to Eat?

The safety of grey tuna depends on the specific color and a few other indicators. Here are some guidelines:

• Light grey tuna is likely still fine to eat. It may have a slightly different texture and flavor, but should be safe if properly stored.

• Dark brown or greenish tuna has likely spoiled and should be discarded. These hues signal bacteria growth.

• Check for an off smell or slimy texture, which also indicate spoilage.

• Grey tuna beyond its expiration date should not be consumed.

So in many cases, grey or brown tuna is still safe to eat as long as extreme discoloration and other signs of spoilage are not present. The taste, smell and texture can be good indicators.

Storing Tuna Properly

To avoid premature tuna discoloration, it’s important to store it correctly. Here are some tips:

• Keep tuna chilled at under 40°F, ideally closer to 32°F.

• Wrap tuna steaks tightly in plastic wrap or foil if storing more than 1 day.

• Place tuna in a container or bag with ice to keep cold.

• Don’t let tuna contact air or water excessively, as oxygen exposure causes oxidation.

• Freeze tuna if storing over 2 days. Thaw in fridge before use.

• Look for “sushi-grade” tuna which has been handled properly.

Proper chilling preserves freshness and color. Sushi-grade tuna specifically has been frozen to kill parasites and prolong shelf life. Follow these guidelines for maximum fresh tuna quality.

Controversy Around Carbon Monoxide Treated Tuna

You may have heard about the controversial practice of treating tuna with carbon monoxide gas to artificially maintain its red color. This process, banned in many countries, uses carbon monoxide to bond to myoglobin and keep tuna looking red and “fresh.”

However, the carbon monoxide does not actually keep the tuna fresh. It simply acts as a color preservative. Tuna treated this way can be weeks old but still look red, making it deceptive and higher risk for foodborne illness.

When buying tuna, opt for reputable sources that don’t use carbon monoxide gas treatment. And remember—a bright red color alone doesn’t signify freshness!

High Quality Tuna Brands

If you want confidently fresh, responsibly sourced tuna, here are some top brands to look for:

• Wild Planet: Albacore and skipjack tuna sustainably caught using pole and line.

• Safe Catch: Lab tested for mercury levels and eco-friendly fishing.

• American Tuna: Sustainably caught yellowfin and albacore tuna.

• Henry and Lisa’s Naturals: Pole and line caught, no carbon monoxide.

• Whole Foods 365 Everyday Value: Responsible sourcing practices.

Buying reputable brands ensures you get quality tuna whether the color is red or grey. With proper handling, grey tuna from these sources is likely still safe to eat.

Cooking Grey Tuna to Eliminate Risk

If you’re still unsure about eating grey tuna raw, cooking it eliminates any risks. The FDA recommends cooking tuna to an internal temperature of at least 145°F to kill any potential bacteria.

Here are some safe cooking methods for grey tuna:

• Sear tuna steaks briefly on high heat until rare or medium rare inside.

• Make a tuna casserole or tuna melt.

• Skewer and grill tuna with vegetables.

• Sear tuna and add to a pasta dish, salad or rice bowl.

• Bake tuna loins, kebabs or burgers until cooked through.

Cooking grey tuna provides peace of mind while still allowing you to enjoy its flavor in recipes.

Is it Worth Eating Grey Tuna?

While grey tuna may not look very appealing, it still retains much of its nutritional value and delicious umami flavor when properly handled. If you’ve invested in high-quality tuna, it’s likely worth consuming even after some oxidation, rather than throwing it out prematurely.

Check carefully for signs of spoilage, and be diligent about storage conditions. With good judgement, you can feel confident that grey tuna is safe to eat and enjoy in cooked dishes or raw sushi and poke bowls. Don’t let a little discoloration stop you from reaping the healthy benefits of fresh tuna.