What’s the Yellow Stuff Inside a Crab?

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If you’ve ever been to a crab boil, then you know that the boil isn’t complete without cracking open a few crabs and digging your fingers into the gooey yellow stuff inside.  

This is a hotly debated topic at the dinner table as some believe you shouldn’t be eating this part of the crab while others prize it for its unique musky flavour.

This gooey yellow substance is sometimes referred to as “mustard” and is not fat or roe as is often assumed but rather the crab’s hepatopancreas a vital organ responsible for filtering impurities from the crab’s blood.

What is crab mustard?

Crab mustard is the yellow substance found inside a cooked crab. It is the crab’s hepatopancreas, an organ responsible for filtering impurities from the crab’s blood. You should only eat the mustard if the crab has been sourced from freshwater due to its ability to contain concentrated contaminants if pulled from polluted waters.

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Is it safe to eat crab mustard?

Yes, it is safe to eat crab mustard. With that being said caution should be given when choosing which crabs to eat the mustard from. You should only eat the crab mustard if the crab has been sourced from clean waters that do not contain pollutants of any kind.

This is important as the hepatopancreas can contain concentrated amounts of containments found in the water.

The best way to avoid any problems when eating crab mustard is to just ensure you don’t eat too much of it too often. Moderation will allow you to get your fair share of this edible delight without risking any issues, though it’s suggested that children under the age of 5 do not eat it.

If you are trapping or catching your own crab then you will want to check with your local state government offices to determine which waterways are clean. If you are purchasing crabs ensure they are from a trusted seller. 

How to clean crabs before cooking

If you are looking to clean the crab and remove the mustard you simply have to give the crabs a brief boil (approx 1 minute) then remove them from the water and scour them thoroughly. 

Once they’ve been cleaned on the outside you will want to remove their face, including mouth and eyes, then remove the abdomen from the crab. This is the portion of the crab that looks like a small flap on the underbelly of the crab.

After you’ve removed the abdomen you can proceed with rinsing any existing guts from the crab meat. The guts will be a brownish-green substance.

With the guts removed and the crab thoroughly rinsed they’re ready for you to remove the meat and cook them up!

Additional Questions & Notes

Are Dead Man’s Fingers edible?

Dead man’s fingers, otherwise known as the crabs lungs are not edible. The crab’s lungs filter all harmful toxins and pollutants found in the weather and are generally bad for humans to eat. 

What the Professionals Say

Crab experts are torn on whether you should be eating the “mustard” otherwise known as the hepatopancreas. L. Eugene. Cronin, the former head of the University of Maryland’s Chesapeake Biological Laboratory notes, “Crabs taken from open waters I wouldn’t worry about” but he goes on to say that more polluted waters he’d probably pass on. Others abstain from eating the food altogether.

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Ryan W

Ryan is the owner of Fisherman First and manages the team of expert writers on the site. He's fished his entire life and has been to locations across North America to catch a range of fish and crustacean from crabs and prawns to minnow and trout.