Don't Boil Your Crabs

I have always been curious of estuary waters and their effects on seafood.  Spending summer weekends at the Jersey Shore, I often went crabbing in estuary inlets.  I remember being stung by jellyfish.  I noticed that water in some  areas tasted saltier then others—don't ask why...  We would take the catch from the traps and boil the crabs with local corn.    I harassed the crabs with my plastic sand castle shovel just before they were to meet their boiling destiny.

Buyin' Shrimp in Mississippi after Hurricane Katrina

At one of my first restaurant jobs, the cooks about killed me one day when I submerged a crab in fresh water.  They told me you got to “steam ‘em—you’ve got to steam all crustaceans.”  They said when cleaning shellfish you want to clean them with as little water as possible. 


I often wondered why your skin in fresh water gets wrinkly and in salt water it seems to shrink—like I just had a face lift.  This has to do with a concept called osmotic equilibrium.  The balance of salt through osmosis will effect whether your skin swells or tightens. 


Naturally, solutions want to be in equilibrium, and move from areas of high concentration to low concentration, hence osmosis. This happens through the semi-permeable cell membranes.  Fresh water with higher osmotic pressure moves into your skin with lower osmotic pressure causing it to poof and wrinkle.  The lower osmotic pressure in the skin is due to the salt that exists naturally in our bodies.  The salt concentration is higher in the skin, but the pure water concentration is lower.  The reverse effect happens when you are swimming in salt water. Your skin tightens,  feeling like you just had surgery performed by Dr. 90210.

Osmotic equilibrium may help to explain why some fish mongers argue never to boil shellfish, but steam them.  The natural flavors will be lost.  Steaming is a gentler cooking method then boiling.  So please don't boil your crabs.