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 and was often stung by jellyfish. I noticed that water in some areas tasted saltier than others, due to fresh water streams converging with the Atlantic.
At one of my first restaurant jobs, the cooks about killed me one day when I submerged a crab in fresh water. The cooks said when cleaning crabs you want to clean them with as little water as possible. They told me you got to “steam ‘em – you’ve got to steam crabs.” They didn’t approve of the big pot of boiling water I was about to cook them in.
I often wondered why your skin in fresh water gets wrinkly and in salt water it doesn’t. This has to do with the scientific 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 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.
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, steam ‘em!
And the wine – I enjoy white Rhone varietals with crab. Marsanne and roussanne are a pair of my favorites.