These days, we’re all counting on our food supplies at home to last longer between reduced trips to the grocery store. Your freezer is an important part of that strategy. The freezer can preserve food indefinitely without the danger of spoilage — and keep it in peak condition until you’re ready to eat it. That can’t always be said for the pantry or refrigerator. But how well your food holds up on ice is largely dependent on your freezer savvy. Have you wrapped the food sufficiently? Did you freeze it quickly? Should it have been frozen at all? Is your freezer cold enough? We have insight on all those questions, and more, in this handy guide.
How food freezes
When food is frozen, the water in its cells freezes and expands. Two methods are usually used.
In quick — or fast — freezing, the temperature of foods is lowered below 0 degrees within 30 minutes.
Pros: Produces many small ice crystals, which help maintain the food’s cellular structure and preserve its original texture when thawed. Cons: Requires special equipment. For faster freezing: Some freezers have a quick-freeze shelf that should be used.
In slow freezing, food is frozen within two to 24 hours.
Pros: Most common for household freezers. Cons: Larger ice crystals form, which damage the food’s cellular structure. That means more drip for meats and more leakage for vegetables.
How to freeze fresh vegetables while preserving their best qualities
For faster freezing
• Do not stack containers before freezing, but spread them in one layer on various shelves. Stack after the food is frozen.
• Freeze foods at 0 degrees or lower. Optimally, it should take no more than two hours to freeze a two-inch-thick package of food.
• When adding a large number of foods to the freezer, set the temperature to the coldest setting several hours beforehand.
• Do not overload the freezer with unfrozen food, which slows the rate of freezing and may compromise quality. Add only the amount that will freeze within 24 hours; usually two or three pounds of food per cubic foot of storage space.
What could go wrong
Freezing food cannot improve its quality. However, several factors can compromise good food that was frozen badly.
Microorganisms. Growth is stopped when food is frozen, but microorganisms are not destroyed. When food is thawed, they become active again and multiply; food must be cooked to be safe.
Ice crystals. Formation of small ice crystals is better for food. Large ice crystals tend to rupture cells and may cause a texture change.
Freezer temperature. The storage life of foods is shortened as temperature rises. A temperature of 0 degrees or lower should be maintained to keep foods at top quality. Fluctuating temperatures result in growth of ice crystals, further damaging cells and creating a mushier product.
Air. Oxygen may cause flavor and color changes if the food is improperly packaged. Many foods change color when frozen due to lack of oxygen or especially long storage. For example, red meat can turn brown; it is still safe to eat.
Enzymes. Freezing slows enzyme activity, and most food keeps when put in the freezer. In vegetables, however, enzymes must be inactivated before freezing.
To minimize the risk of freezer burn, caused by moisture loss, don’t thaw and refreeze food numerous times. That causes food to dry out faster. If food does suffer from freezer burn, cut off the affected areas — before or after cooking — and use the rest of the food.
The next time your freezer loses power, don’t panic. These food safety tips will save you.
If the power is off, food in a full freezer will usually stay safe for about two days with the door shut. A half-full freezer or the freezer compartment in a refrigerator will keep food safe for about 24 hours. When the power returns, food is safe if it is partially frozen, contains ice crystals or is “refrigerator cold” (40 degrees). Keep an appliance thermometer in the freezer to monitor the temperature.
Steps to keep in mind
1. Preparation and packaging
Packaging materials must be moisture and vapor resistant, durable and leak proof to maintain the quality of food. Leave head space of 1/2 to 1 1/2 inches to allow for expansion. Label packages on the date food is frozen.
Do use: Plastic freezer containers, plastic freezer-weight bags, aluminum foil, foil pans, coated freezer paper, heavy plastic wrap, milk in plastic jugs, zip-top bags.
Do not use: Cottage cheese or yogurt containers, bread wrappers, produce bags, wax paper. These are generally not airtight or thick enough. Generally, freezing in glass jars is not recommended, as they can break, but if you decide to, make sure you leave enough room for expansion and confirm the glass is tempered or freezer-safe.
Your guide to buying a stand-alone freezer — if you can find one
Generally, foods in larger containers freeze too slowly. Do not freeze fruits and vegetables in containers with a capacity over one-half gallon, and never freeze vegetables without blanching. Read Detroit-based digital cookbook author Angela Davis’s guide to blanching vegetables here.
2. Freezing points
Not all foods freeze alike. In fact, only foods with a high water content freeze at 32 degrees. Foods with a high protein, fat or sugar content require lower temperatures to freeze. Once frozen, all foods should be kept at 0 degrees or below to prevent moisture loss and preserve quality.
Most vegetables freeze fast at or just below 32 degrees. (Green beans are 90 percent water, for example.)
Fish, meat and poultry don’t freeze until they reach around 26 degrees because they contain high amounts of protein and fat. (Wild salmon is 68 percent water.) Tip: To help a package of ground meat thaw faster, create a deep indentation in the middle before freezing.
Foods with high sugar or butterfat content are harder to freeze. At 3 degrees, only about 75 percent of the water in ice cream is frozen.
Textural changes are more noticeable in fruits and vegetables that have a higher water content, and foods that are eaten raw. Changes from freezing are not as noticeable in food that is cooked later, because cooking also softens cell walls.
In the refrigerator (40 degrees or below): Slow but safe. Allow one day for every four pounds of whole poultry; one day for a one-pound package of meat, poultry or seafood; and two or more days for roasts, steaks or ham.
Safe to refreeze? Yes. Raw or cooked frozen food thawed in a refrigerator is safe to eat if refrozen.
In cold tap water: Faster than refrigerator thawing; must cook immediately after thawing. Submerge food in leakproof bags in a bowl of cold tap water. Allow about 1 hour per pound for small packages of food, 30 minutes per pound for whole poultry.
Safe to refreeze? No. Frozen food thawed by the cold-water method but not cooked is not safe to refreeze. You can refreeze it after cooking.
In the microwave: Fastest method; must cook immediately after thawing. Rotate and break up individual items to even the thawing process. For ground meats, scrape off thawed meat and return frozen portion to microwave. Follow manufacturer’s directions for setting your microwave.
Safe to refreeze? No. Frozen food thawed in the microwave oven but not cooked should not be refrozen. You can refreeze it after cooking.
Frozen in time
All frozen foods are safe forever. For best quality, use oldest packages first. These maximum recommended storage times are for best flavor and texture:
2 months: Smoked or cured (bacon, ham, hot dogs, lunch meats, sausage)
3 months: Cooked meats
4 to 6 months: Ground meats and burger patties
12 months: Beef, lamb, pork and veal (chops, roasts and steaks)
3 to 6 months: Fatty fish, such as bluefish, mackerel, salmon and tuna; cooked fish, shellfish and frozen breaded fish
6 to 8 months: Shellfish, such as crab meat, clams, crayfish, lobster, mussels, oysters, shrimp, scallops and squid
8 months: Lean fish, such as cod, flounder, haddock, halibut, perch and sole
2 to 3 months: Cooked chicken and turkey, lunch meats, pâté
4 to 8 months: Ground poultry, patties and giblets: cooked poultry and convenience meals, fried chicken and rotisserie chicken
12 months: Chicken, turkey, duck and goose (whole or parts)
Vegetables and fruit
1 to 2 months: Bananas, grapes, melon
2 to 3 months: Tofu
4 to 6 months: Berries, cherries
6 to 8 months: Vegetables
12 months: Soy meat substitutes, soy hot dogs, tempeh
3 to 4 months: Milk and buttermilk (it may separate)
4 to 6 months: Shredded cheese, ice cream and sherbet
12 months: Butter and margarine
2 to 3 months: Pies (pumpkin, pecan) and quiche
3 to 6 months: Cakes, cheesecakes, bread, rolls, bagels and tortillas
8 months: Pies (fruit and mincemeat)
12 months: Baked cookies (purchased or homemade); cookie dough
3 to 6 months: TV dinners, entrees and pizza; casseroles (lasagna, chili, meat sauces, etc.); cooked leftovers
Better not to freeze
Just because you can put any food in the freezer doesn’t mean you should. Some foods don’t freeze well and will have compromised quality when defrosted. Here are some examples and the results.
Cheese in blocks: Crumbles
Cottage cheese: Separates, becomes mushy
Cream pies: Custard becomes watery, crust gets soggy
Eggs: Cooked eggs become rubbery; cooked egg whites crumble; raw yolks become gummy
Gravy: Fat separates; whisk when reheating
Lettuce, green onions, tomatoes: Become watery and limp
Mayonnaise, milk, milk sauces, sour cream, yogurt: Some separation occurs
Potatoes, raw: Texture changes, may darken
About this story
Illustrations by Sergio Membrillas for The Washington Post. Design by Amanda Soto. Sources: United States Department of Agriculture; University of Illinois Extension Service; “So Easy to Preserve,” by Elizabeth L. Andress and Judy A. Harrison; North Dakota State University Extension Service