On Ice: You Probably Underrate Your Freeser. It Can Server You Better

I NEVER THOUGHT that my freezer could be good for much besides stocks, soups, and leftovers I hadn’t gotten around to eating, until I read Michael Roberts’s new Fresh From the Freezer. Roberts is one of the very few original thinkers writing about food, and a terrific cook, too: as the chef and co-owner of Trump’s, he has managed to keep a Los Angeles restaurant popular for ten sears, which is quite an achievement. I was already an admirer of his Secret Ingredients, a 1988 book both wild and lucid in its suggestions of food combinations like lobster and vanilla, and grilled turkey with a burnt peanut butter marinade. After reading the new book, I went out and bought a freezer, realizing that the

small compartment above my refrigerator, usually blocked by icy crags, wasn’t good enough to test some of Roberts’s provocative theories. When a number of them worked, dramatically, I starterd talking to scientists about why. I learned just how mistakenly I had been using my freezer for years.

I was taking the wrong approach, it became clear, in treating my freezer like a bomb shelter. Certain things can be frozen successfully for six months to a year, notably beef (ground beef for only four months), chicken, stocks, and most cooked vegetables; many things store well for three to six months, such as veal and stews and cookie and pastry doughs; some things store well only for

a month or two, such as bacon and many kinds of fish; nothing in the freezer lasts forever, and nothing that is less than first-rate going in will be first-rate coming out. That freerange chicken in my old freezer compartment, carefully seasoned and readied to roast for guests who at the last minute couldn’t come, won’t be very good four years later. “This isn’t a cryogenic cookbook.”Roberts told me recently. “ Things change in the freezer,”

ONCE I DISPOSE of my fossils, I plan to use the compartment as a luxury few people have: a place to freeze food before putting it in my new freezer. The message from the scientists I spoke to was that home freezers are better for storing foods that are already frozen than for freezing foods. Books and instruction manuals insist that you chill food before freezing it; I always thought the idea was that it would freeze more evenly and thus better, and the food could have the benefits of flash freezing, which ads trumpet. But the quality of what you keep in your freezer is much less dependent on how fast or at what temperature the food is frozen than on how it is kept after ward. The chief advantage of quick freezing— many smal ice crystals rathe than fewer big ones, resulting in a better texture upon thawing— starts to dissipate within days anyway. Ice recrystallizes, as anyone who has raided a pint of ice cream bit by bit knows.

It constantly seeks other crystals and forms larger ones.

The real goal is to avoid warming up the air around the already frozen food, because that causes recrystallization. Chilled food put in to freeze warms the air less. The ideal in a large freezer is to free a shelf near the top, where cold air comes in, for freezing. A solution for those who don’t have a large freezer is to try to leave room around the food being frozen.

Every time you open the freezer door, you encourage recrystallization, by introducing warm air. Bothersome ice crystals on the surface of frozen food will form whatever you do, but their formation is slowed by a steady low temperature; “in-package ice,” the trade term, doesn’t indicate a failure to freeze things correctly, as people seem to believe. The most convenient place to keep food is unfortunately the worst—inside the door.

Temperature fluctuations are less of a problem in a freezer that is cold enough in the first place. It’s worth the electricity to keep your freezer at the coldest setting, preferably so that the temperature stays below zero; below minus 5° is even better, but feu freezers get this cold. Most freezers in double-door units can’t do any better than 5° to 10° above zero. Chest freezers offer less temperature variation and preserve frozen food better, but are inconvenient unless you are an enthusiastic archaeologist and have exceptional circulation in your hands. Because a “frost-free” freezer guarantees constant cycles of warming and cooling, freezers that you defrost yourself are superior—if you remember to do it.

It’s dispiriting to find a puddle of liquid under food you have thawed, since the liquid appears to contain all the moisture and flavor. But there’s not much you can do about it. The usual explanation for “drip loss” from frozen food is that big ice crystals puncture cell membranes and let water leach out. That theory is too simple, according to Owen Fennema, a professor of food chemistry at the University of Wisconsin. It does apply to fruits and vegetables, whose rigid cellular structure doesn’t easily incorporate ice crystals; hence the loss of texture in berries (some strawberries are bred for cell structures that can better withstand freezing). But in meat the cells, or fibers, are more flexible, and so can be better stored frozen.

The enemy of quality that you can fight is not water but oxygen. In any food you freeze, some water remains unfrozen, because it is so intimately bound to dissolved solids that it can’t break free to form ice crystals. The viscous, concentrated liquid allows oxidation to occur. Oxidation causes off flavors that signal rancidity—the worst thing that can happen in the freezer, not because it’s bad for your health but because it’s disgusting. Rancidity is easily confused with the dreaded freezer burn, which in fact doesn’t affect flavor much. “Freezer burn" refers to the sere patches on the surface of food where ice crystals sublimate — pass from solid to vapor without ever being liquid (what happens to snow in cold, dry weather). Careful wrapping guards against it.

Unsaturated fats, the kind everyone is told to eat, are particularly prone to oxidation. Thus pork, a significant amount of whose fats are unsaturated, doesn’t keep well for very long frozen. Beef, though, with mostly saturated fats, is “practically indestructible,” in the words of Hugh Symons, of the American Frozen Food Institute. Chicken is in between, and it keeps for a longer time. Bacon and salted luncheon meats don’t keep for long. At high levels salt encourages oxidation, resulting in changed flavor.

Fish are poor candidates for storing frozen longer than three months, partly because of their unsaturated fats. Most fish do fine in short-term storage, however. Frozen fish at the market, in fact, are often superior to “fresh" fish, which may have been sitting, half-frozen on ice, for the same amount of time as frozen fish that were carefully and thoroughly frozen on the boat.

Roberts has devised several ways around the fish problem. He freezes lean fish, such as whiting, and also meaty fish, such as tuna and mahimahi, in a wine-and-mustard marinade whose acid softens and flavors the flesh. He leaves sea scallops in lemon juice for an hour before freezing them “open"—uncovered and separated— on an oiled pan and then storing them in bags. They taste remarkably fresh when defrosted, still sweet and with their texture seemingly unchanged. Cook them straight from the freezer, to avoid drip loss. Roberts says that shad, one of my favorite fish, is actually improved by a light salting and then freezing—something I’m eager to try.

Perhaps Roberts’s most remarkable trick is his way of preparing salmon (and other fish) for the freezer, by rubbing steaks or fillets with a mixture of one part salt to two parts sugar, and refrigerating them under a weight, such as a heavy can, for two and a half hours, turning them after an hour and a half. This sounds like a recipe forgravlax, but once cooked the salmon doesn’t taste the least bit cured. It does taste wonderful—even better than when fresh, because the flavor deepens. It certainly has far better flavor and texture than a piece of untreated salmon frozen and cooked, which by comparison seems dry and bland.

Fruits and vegetables, too, pose challenges. Some of their enzymes break down fats or catalyze oxidation of fats in their cell walls, causing off flavors. Certain vegetables, strange as it sounds, are better bought frozen than fresh: the sugar in peas and corn converts to starch in hours, and processors are able to cook and freeze them before the conversion—which you can’t do unless you have a garden. And other commercially frozen vegetables may soon improve, according to David Reid, a professor of food science and technology at the University of California at Davis. All the vegetables in the frozen-food case have been blanched (boiled briefly) to inactivate enzymes. Researchers at Davis have pinpointed which enzymes cause problems in which vegetables, and are developing enzyme-inactivation tests that could shorten blanching times for string beans, broccoli, and cauliflower, among others. Since the effects of cooking on flavor and texture are much more pronounced before freezing than after, this could result in better vegetables from the frozen-food case.

In a very useful dictionary at the back of Fresh From the Freezer, Roberts gives instructions for blanching many vegetables at home, usually for just one to five minutes, and freezing them; he says they’ll be good for up to a year. Vegetables that work well, he says, are brussels sprouts, cabbage (either in whole leaves or shredded), carrots, celery root, corn, kale, okra, parsnips, bell peppers (best roasted and peeled first), and turnips.

Roberts hit on an ingenious technique for freezing asparagus, which is in season far too briefly and which if blanched before being frozen “ends up being strings with water that runs out when you defrost it.”He soaks raw asparagus in salted water for ten minutes, freezes it, and serves it defrosted at room temperature, at which point, he says, it tastes as if it had been briefly cooked. The problem is that asparagus frozen this way lasts only eight weeks— but that’s two months more of something that would be nice year-round.

Many fruits should be blanched or otherwise treated to inactivate enzymes that cause browning. Commercially frozen fruit is often sold in syrup, because sugar helps keep out oxygen and lessens browning. Some small frozen berries, such as wild blueberries and huckleberries, thaw without too much loss of texture, but most thawed berries turn to mush. Pureeing the fruit before freezing overcomes the texture problem, and briefly cooking the puree inactivates enzymes that after a few months could cause browning. Mangoes freeze well, however, as do avocados. And pears, pineapple slices, and figs can be frozen raw as long as you cook them after defrosting.

IF YOU WANT to avoid oxidation and make things last a long time, buy good packaging material. The best keeps oxygen out and water vapor in, thus avoiding both oxidation and freezer burn, Freezer paper, which is coated on one side with plastic, is fine if you’re good at wrapping things as neatly as a butcher and are generous with the paper.

Many foods, for instance chicken pieces and green beans, as well as scallops, are better frozen without any wrapping; be sure to oil the surface of what they freeze on, so the food won’t stick. Then put the food into bags, squeezing out as much air as possible, or wrap it in plastic, which will more readily cling to the surface ol the food. The clingiest plastic wrap, PVC (widely marketed as Reynolds Plastic Wrap), is unfortunately permeable to air. The plastic film PVDC (widely marketed as Saran Wrap) provides a very good barrier.

Freezer bags are made of heavygauge polyethylene, which is also excellent. (The bags dispensed at supermarket produce departments, however, are of very thin polyethylene, and are terrible for freezing.) I’m taken with the neatness of Dow’s Ziploc freezer bags; Reynolds sells the similar product Sure-Seal. A disadvantage to bags is that the only way to keep straight in the freezer what looks like a pile of weird rocks is to put them in boxes or, better, the wire baskets sold in many sizes for organizing closet shelves. Rigid plastic freezer containers can be easily stacked, and they don’t let in air or allow water vapor ro escape. Unless they’re exactly the right size, though (leave headroom for liquids, which will expand), they will trap air with the food, and the flavor and quality will deteriorate faster.

If you want meat to last at all, rewrap it, because supermarket plastic wrap is usually thin and porous. It’s good to rinse poultry pieces and dry them with paper rowels. Roberts says that once you’re repackaging food, you might as well season it, since the salt, pepper, and garlic or paprika that you’ll put on chicken for broiling, for example, will have a chance to flavor the chicken pieces while they thaw. Poultry frozen on the bone will have better texture after thawing, and the skin functions like a built-in barrier, so leave it on. Whatever you use for packaging, do what your mother told you: label and date everything. It’s hard enough to tell what something is after it’s frozen, let alone remember when you put it there.

Don’t freeze food in portions larger than you will need at one time. Most people know to freeze sauces in an icecube tray, and then keep the frozen cubes in a plastic bag. Roberts extends the method to tomato paste and chutney, and to sauces of his like a creamy walnut pesto and a mushroom sauce with onions and sherry, for pasta. He recommends against freezing minced raw onions, saying that sautéed chopped onions freeze much better. But chopped fresh ginger and pureed raw garlic or basil leaves mixed with oil are good candidates for the ice-cube tray (you might want to buy a tray for mini-cubes). Some herbs, including parsley and sage, can be successfully frozen in whole leaves.

AWORRISOMK problem is that refreezing thawed food is risky, in terms both of quality and of safety. Owen Fennema and Susan Templin, the manager of the meat and poultry hotline at the Department of Agriculture’s Food Safety Inspection Service (800-535-4555), each gave me a good talking-to about leaving something on the counter to defrost while you’re at work. Because refrigeration only retards microbial growth, it can be dangerous to refrigerate for a few days something that reached room temperature while being defrosted. The choice is between defrosting in the refrigerator, always keeping the food temperature below 40°, and defrosting it fast—for example, in a microwave oven — and cooking it right away. The problem with the microwave is that it can cook part of what you’re defrosting, especially if it’s something big; hot water poses the same problem.

It might come as a surprise that freezing does not sterilize. The only things it reliably kills are some parasites in fish and pork. Everything else remains dormant. Even if the amount of pathogenic bacteria such as salmonella is reduced during freezing, after a fairly short time at room temperature it can easily come back to or exceed the level it was at before being frozen. You can refreeze meat and fish if its temperature has never gone above 40°. Some conservative scientists, however, warn that freezing may also inhibit the activity of the many kinds of bacteria that naturally slow the growth of pathogenic bacteria, and they counsel against all refreezing.

AN IMPORTANT lesson from Roberts is to separate solids and liquids in any cooked dish, including soups and stews, before freezing them, to preserve texture and individual flavors. Many of the recipes in FreshFrom the Freezer axe for “mother" soups and stews, frozen in this way and in portions as large as you’ll use when finishing the recipe. A chicken fricassee, for example, can become chicken with balsamic vinegar and green olives, chicken with broccoli and that creamy walnut pesto, or chicken with fresh ginger and snow peas. Roberts says, “People should think of the freezer as their personal shopping center, which they’ve stocked with ingredients they’ve done something to, not just stuff from the freezer case.”

And many of those prepared ingredients can go straight from the freezer into the oven. All vegetables, for instance, can be cooked in the microwave oven or boiled. (You shouldn’t try cooking food you freeze in plastic bags as you would commercial frozen food packaged in boil-in bags. Manufacturers recommend against cooking anything in freezer-storage bags, even though they probably won’t melt; there is some question about whether they leach harmful chemicals into food, especially if the plastic comes into contact with fat.) You can cook frozen chicken breasts in any recipe, for instance, if you increase the cooking time. The key is the thickness. If something is more than an inch thick or if meat is on the bone, the outside can dry out or burn before the inside is cooked.

But the technique can improve certain foods. If you like things breaded but shy away from the fat that breading usually requires, you can use fresh bread crumbs, which you’ll need far less of than dried; they will adhere better than dried after freezing; and baked chicken cutlets or, say, homemade fish sticks will taste fried. Lasagna, that dish that always takes twice as long as it should, will taste freshly made if you prepare it with uncooked sheets of pasta and freeze it. While thawing and heating, the broad bands absorb moisture, and after the lasagna is baked, the flavors of the sauces and cheese, already melded in the freezer, infuse the pasta. It’s a dish that argues for the freezer as an invaluable cooking tool.