The Paleo Diet - Loren Cordain [61]
How to Be a Savvy Shopper for Fish
Yet the possibility of environmental contamination isn’t the only thing you have to worry about when you eat fresh fish and seafood. Another, much bigger concern is simply whether the fish has gone bad. Improper handling and warm temperatures offer great potential for bacterial contamination and spoilage as fish makes its way from wherever it was caught to its eventual place of sale. The freshness clock begins to tick immediately: most fish have a shelf life of seven to twelve days once they’re out of the water. But fish often remain on a boat for five to six days after they’re caught. They may spend another day or two in transit from the processor / wholesaler to the marketplace—and then may sit on a retailer’s display counter for several days more before they are sold. If the fish get too warm during any stage of transport, they’ll spoil even faster. Bacteria are the main culprits in the spoilage process, but enzymes in the fish tissue and even atmospheric oxygen can contribute. Fortunately, spoiled fish release a pungent warning—a compound called “trimethylamine,” which causes the telltale fishy odor associated with bad fish.
Fresh fish is practically odorless. If a fish smells, spoilage is most likely well under way—so stay away from smelly fish. Here are some other tips:
• If you’re buying whole fish—and it passes the odor test—check the gills. If they’re bright red and moist, the fish is probably fine. If the gills are brown or clumped together, the fish has been on the shelf too long.
• Buy fish last. If you’re making a prolonged excursion to the grocery store, don’t get the fish first and then let it sit in the cart for an hour while you get everything else on the list. Select it, pay for it, go home—and immediately refrigerate the fish in its original package in the coldest part of your refrigerator. Try to eat the fish no more than a day after you buy it.
• To protect yourself from bacterial contamination, wash the fish in cold water and then cook it thoroughly, until it’s opaque and flakes easily with a fork. This is important: bacteria and parasites sometimes live in raw fish. But if you cook the fish completely, you’ll minimize your chances of getting sick—even if you inadvertently eat fish that has partially spoiled.
• Avoid eating raw fish of any kind for the reasons above.
• If you can’t eat fresh fish within a day or two of buying it, freeze it. Freezing completely stops bacterial growth. However, once the fish thaws, the same deterioration process starts again.
• Be careful when you buy fish labeled “previously frozen.” This may be once-fresh fish that wasn’t bought, went past its expiration date, was frozen by the retailer, and was thawed again for quick sale.
• Look for light-colored, cottony spots on the fish—they’re freezer burns. Sometimes frozen fish is allowed to thaw and then is refrozen, sometimes several times. Also look for ice crystal coatings—and walk away if you find them. These are fish you don’t want to buy. The highest-quality frozen fish are caught at sea and then quick-frozen individually on board the ship. (Often, there’s a label to this effect, saying that the fish was “frozen at sea.”)
What about Farm-Raised Fish?
It’s called “aquaculture.” Many species of fish and shellfish—including salmon, trout, catfish, tilapia, carp, eels, shrimp, and crayfish—are produced in closed waters and ponds and fed soy-and cereal-based chows. This is similar to the situation of feedlot-fed cattle. What they eat causes their own meat to be low or deficient in the beneficial omega 3 fatty acids that help make fish so good for us. Numerous scientific studies have demonstrated the omega 3 fatty acid inferiority of farmed fish compared to wild fish.
Farmed fish are usually cheaper to bring to market than wild fish. In the United States, trout—unless you have caught it yourself in the wild—is almost