Sunday, March 22, 2009

Crustaceans




Today we’ll look at the subphylum of crustaceans, which include such familiar creatures as shrimp, crabs, lobsters, and crawfish, but also such important critters as krill and barnacles. Now we don’t eat barnacles, those hard little filter feeding crustaceans that attach themselves to the bottom of boats and piers in tidal basins, but some varieties in Spain and Portugal known as percebes are an expensive delicacy. Krill are also unfamiliar to us, but these tiny shrimp-like creatures are one of the most important mainstays of the oceanic food chain, feasting on phytoplankton and other micro-organisms, converting these into suitable food for larger fish and mammals, like whales, for whom they comprise the majority of their diet.

Crustaceans, like spiders and insects, are anthropods, an invertebrate made up of segments with jointed limbs and an external skeleton. As a rule, crustaceans are not overly mobile, and their rigid appendages and large meaty tails allow for brief bursts of swimming short distances, crawling and attacking prey. Being both carnivorous and cannibalistic, farming these creatures, with the exception of shrimp, has not proven successful, so almost all are caught in the wild. Shrimp and prawns, however, as they grow rapidly and thrive on both plant feeds and small animals, lend themselves successfully to farming, with China and Thailand being the largest producers in the modern world. Almost all shrimp are frozen and come with the head off, but locally one can get head-on fresh shrimp from Maine on occasion, and if you see them, check them out as they are delicious.

Most edible crustaceans are decapods, with five pairs of legs, at least one of which is enlarged into claw(s), and the edible portion is skeletal meat like in fish and livestock. The cephalothorax is the forward portion, or “head,” and includes not only the mouth, eyes, and sensing antennae, but also the crawling appendages, and the main organs of the digestive, circulatory, respiratory and reproduction systems. The rear portion, or abdomen, known as the “tail,” is a large meaty block of muscle used primarily for propulsion. The main exception to this general body style is the crab, whose abdomen is a thin plate folded up underneath a greatly enlarged cephalothorax.

In lobsters and crabs the hepatopancreas, what we would call the “liver,” is the source of enzymes that assist with digesting food, and a reservoir for fatty materials that are stored to provide energy during the molting process, when the crustacean sheds its hard outer shell so it can continue growing. This “tamale” is very rich and flavorful, but is also a source for rapid spoilage if the crustacean is sold dead, but not cooked. For this reason, lobsters and crabs are available either alive or fully cooked, and shrimp, whose head includes their small liver, come mostly headless.

The flesh of most crustaceans is white, fast muscle fibers with more collagen that fish. They are usually boiled or steamed as these are the fastest cooking methods, preventing the active protein-breaking enzymes from turning the flesh mushy. They should be cooked in their shells as the cuticle prevents the leaching of flavor, and is in itself a mass of proteins, sugars and pigment molecules that can contribute flavor to the outer layers of the flesh.

Crustaceans are expensive and usually only served for special occasions. Rightly so as they also have high amount of cholesterol, so intake should be limited to once-in-a-while treats.

Here's a lobster thermidor recipe that is popular at our house.

Lobster Thermidor
Serves 4

2 (1 1/2-lb) live lobsters
1/2 stick (1/4 cup) unsalted butter
1/4 lb mushrooms, trimmed and thinly sliced
1/2 teaspoon paprika
1/8 teaspoon salt
1/4 teaspoon black pepper
2 tablespoons medium-dry Sherry
1 cup heavy cream, scalded
2 large egg yolks

Plunge lobsters headfirst into an 8-quart pot of boiling salted water*. Loosely cover pot and cook lobsters over moderately high heat 9 minutes from time they enter water, then transfer with tongs to sink to cool.

When lobsters are cool enough to handle, twist off claws and crack them, then remove meat. Halve lobsters lengthwise with kitchen shears, beginning from tail end, then remove tail meat, reserving shells. Cut all lobster meat into 1/4-inch pieces. Discard any remaining lobster innards, then rinse and dry shells.

Heat butter in a 2-quart heavy saucepan over moderate heat until foam subsides, then cook mushrooms, stirring, until liquid that mushrooms give off is evaporated and they begin to brown, about 5 minutes. Add lobster meat, paprika, salt, and pepper and reduce heat to low. Cook, shaking pan gently, 1 minute. Add 1 tablespoon Sherry and 1/2 cup hot cream and simmer 5 minutes.

Whisk together yolks and remaining tablespoon Sherry in a small bowl. Slowly pour remaining 1/2 cup hot cream into yolks, whisking constantly, and transfer to a small heavy saucepan. Cook custard over very low heat, whisking constantly, until it is slightly thickened and registers 160°F on an instant-read thermometer. Add custard to lobster mixture, stirring gently.

Preheat broiler.

Arrange lobster shells, cut sides up, in a shallow baking pan and spoon lobster with some of sauce into shells. Broil lobsters 6 inches from heat until golden brown, 4 to 5 minutes. Serve remaining sauce on the side.

* When salting water for cooking, use 1 tablespoon salt for every 4 quarts water.

Sunday, March 15, 2009

Fish #2

It has become generally known that fish is good for you. It has long been referred to as “brain food” as eating fish regularly contributes to the development and function of the brain and retina, to say nothing of the benefits of Omega-3 fatty acids that help with the health of our central nervous system. Fish oils have anti-inflammatory properties that benefit our immune system, and lower the incidents of heart disease and cancer. Fish are a good source of protein, usually between 15% and 25%, A and B vitamins, minerals, amino acids, iodine and calcium. Fish contain phosphorous, potassium and iron. Ocean fish are particularly valuable, as they reside in very cold temperatures and consume tiny oceanic phytoplankton, from which their Omega-3 fatty acids are derived. Freshwater fish do not has access to phytoplankton, thus they have negligible amounts of Omega-3s. However as all fish are low in saturated fats, whenever fish replaces meat in the diet, they lower blood cholesterol and the risk for heart disease. Some of us eat fish roe like shad roe or caviar, and it contains thiamine and riboflavin. A caution, however, as not all fish roes, are edible and if the wrong kind is consumed, like roe from the sculpin family of fish, it can make you very sick.

As mentioned last week, the key to good fish is how it has been harvested, and handled after harvest before it reaches your fishmonger’s. Oceanic fish, due to the really cold water it lives in, must be packed in ice or frozen, immediately after harvest. As these deep-water fish live in such a cold environment, their fats and cell membranes must remain fluid and operational at temperatures approaching 32 degrees. Failure to maintain an icy environment will result in these fats and oils becoming rancid, stale smelling, and the flesh to deteriorate. Just keeping your fish in the refrigerator is not cold enough to maintain fish freshness, so plan on cooking it the same day you purchase it.

Remember, every pollutant on our planet has a tendency to leach through the ground, run off the land, and find its way into our rivers and oceans. These pollutants end up in our fish as evident by the widespread contamination of certain species with polychlorinated biphenyls (PCBs), mercury, lead and other heavy metals, carbon containing pollutants, and toxins. Some species of fish contain so much mercury that the FDA recommends that children and pregnant mothers avoid swordfish, shark, tilefish and king mackerel, or limit their consumption to 12 oz or less a week. Even tuna, one of the most popular fish in the US, is best if eaten on a limited basis. Fish that don’t accumulate mercury and other poisons are small, shorter lived fish like Pacific salmon and soles, talapia, catfish, mackerel, trout and stripped bass, many of which are raised on fish farms where the water is filtered.

Next week we’ll learn more about mollusks, cephalopods and crustaceans, some of my personal favorites.

Thursday, March 5, 2009

Fish #1




Fish are aquatic vertebrates with fins, used for propulsion and
balance, and gills for breathing. They are an important source of
human food, whether derived from salt water or fresh. The
number and variety of saltwater fish greatly exceed the fresh water
varieties, with over 30,000 oceanic species identified.

Generally speaking, fish are divided into two broad groups,
according to their skeletons: cartilaginous fish like sharks, rays and
skate or bony fish, the largest group, characterized by salmon, cod
and bass. Various body shapes also exist with the round fish,
considered the most flavorsome, and the flat fish, a more mild or
delicate flavor, being the predominate varieties. Mollusks,
crustaceans and cephalopods are considered fish in the broader
sense, but these clams, lobsters and squid or octopus are outside of
today’s discussion, much as I love them as food.

All fish should be purchased, if not caught directly by the eater,
from reliable sources where inventory turnover is rapid. Fish are
highly perishable and, if not frozen, should be stored on flaked ice
if not eaten immediately. Fresh fish, whether steaks or fillets,
should be firm to the touch with no “fishy” smell. If purchasing a
whole fish, the gills should be red with no browning or
discoloration, the skin taunt and springy and the eyes bright and
shining. If any of these conditions do not exist, reject that fish and
find something else for supper.

Fish are harvested wild by fishermen on the ocean or farmed from
a controlled environment where they are fed protein pellets. As a
rule, wild fish are more desirable than farmed, but the real key to
good fish is how it was harvested, how soon it was processed, and
how carefully it was handled after leaving the boat. Many large
trawlers freeze their catches within hours of being caught, so often
frozen fish can be of better quality than fresh. I have read that
most sushi-grade fish, over 90%, are frozen right after being
caught.

Fish lends itself to a large number of cooking methods from
broiling or grilling, to steaming, poaching, baking, pan frying or
deep-frying, and smoking. Whichever method is chosen, the
challenge for the cook is to get the texture of the cooked fish right.
The cooking process transforms the muscle proteins, and one must
control the coagulation process so it doesn’t proceed too far,
resulting in the muscle fibers becoming too hard and the natural
juices drying up completely. A good rule of thumb on fish is to
cook it to between 120 degrees and 140 degrees when measured
with an instant read thermometer, where the fish is still moist and
succulent. Many recipes call for cooking fish until it “flakes,” but
to my taste that’s just a little too much. An old rule, if you don’t
have a thermometer, is to cook it for 8 minutes to each 1 inch of
the fish’s thickness, but one can also make a small incision in the
fish to see if it’s interior is still translucent or has turned opaque, or
try pulling on a bone to see if the connective tissue has dissolved
enough to release it.

Here's a simple but delicious way to cook stripped bass, salmon, halibut or any firm fleshed fish with skin on.

Sauted Wild Stripped Bass With Crispy Skin

4 stripped bass fillets with skin (5-6 oz each), scaled
Salt & pepper
Extra virgin olive oil
1 non-stick saute pan

Take the fish out of the refrigerator about 10 to 15 minutes before using. Pat the skin dry with a paper towel and season the fish on both sides with salt and pepper. Heat a the saute pan coated generously with extra virgin olive oil over medium heat until the oil is hot.  Gently place the fish fillets skin side down in the saute pan.  Cook the fish slowly one the skin side for most of the cooking time.  As fish cooks it turns from translucent to opaque as can be seem on it's sides. The idea is to cook the fish 2/3s of the way on the skin side and flip it over for the last 1/3 of the cooking time. The rule for fish is about 8 to 10 minutes per inch of thickness, a little less if you like your fish more on the rare side.