Cold air, hot air, no air, and radioactive rays — all can be used to make food safer for longer periods of time by reducing or eliminating damage from exposure to air or organisms (microbes) that live on food.

The methods described in here all have one important thing in common: Used correctly, each process can dramatically lengthen food’s shelf life. The downside? Nothing’s perfect, so you still have to monitor your food to make sure that the preservation treatment has, well, preserved it.

Keeping food cold, sometimes very cold, slows or suspends the activity of microbes bent on digesting your food before you do. Unlike heat, which actually kills many of the microbes, chilling food (or freezing it) may not kill all the microbes, but the cold will reduce the microbial population to some degree depending on the microflora present and will sideline them for a while.

For example, mold spores (hibernating mold organisms) snuggle inside frozen food to sleep quietly like so many comfy bears inside a wintry cave. When spring comes, the bears bounce back to life; thaw the food, and the mold does the same.

How long things stay safe in the refrigerator or freezer varies from food to food and to some extent on the packaging (better packaging, longer freezing time). Table below provides a handy guide to the limits of safe cool storage.

Food	Refrigerator (40°F)	Freezer (0°F)
Eggs
Fresh, in shell	3 weeks	Don’t freeze
Raw yolks, whites	2–4 days	1 year
Hard cooked	1 week	Doesn’t freeze well
Liquid pasteurized eggs or egg substitutes, opened	3 days	Doesn’t freeze well
Liquid pasteurized eggs or egg substitutes, unopened	10 days	1 year
Mayonnaise, Commercial
Open jar	2 months	Don’t freeze
TV Dinners, Frozen Casseroles
As originally packed, until ready to serve	Don’t refrigerate: Keep frozen	3–4 months
Deli and Vacuum-Packed Products
Prestuffed pork and lamb chops, chicken breasts stuffed with dressing	1 day	Doesn’t freeze well
Store-cooked convenience meals	1–2 days	Doesn’t freeze well
Commercial brand vacuum-packed dinners with USDA seal, unopened	2 weeks	Doesn’t freeze well
Soups and Stews
Vegetable or meat-added	3–4 days	2–3 months
Ground Meats and Stew Meats
Hamburger and stew meats	1–2 days	3–4 months
Ground turkey, veal, pork, lamb, and mixtures of them	1–2 days	3–4 months
Hot Dogs** and Lunch Meats*
Hot dogs, opened	1 week	In freezer wrap, 1–2 months
Hot dogs, unopened	2 weeks	In freezer wrap, 1–2 months
Lunch meats, opened	3–5 days	In freezer wrap, 1–2 months
Lunch meats, unopened	2 weeks	In freezer wrap, 1–2 months
Bacon and Sausage
Bacon*	7 days	1 month
Sausage, raw — pork, beef, turkey	1–2 days	1–2 months
Smoked breakfast links, patties	7 days	1–2 months
Hard sausage — pepperoni, jerky sticks	2–3 weeks	1–2 months
Ham, Corned Beef
Corned beef in pouch with pickling juices*	5–7 days	Drained and wrapped, 1 month
Ham, canned, label says to keep refrigerated	6–9 months	Don’t freeze
Ham, fully cooked — whole	7 days	1–2 months
Ham, fully cooked — half	3–5 days	1–2 months
Ham, fully cooked — slices	3–4 days	1–2 months
Fresh Meat
Steaks — beef	3–5 days	6–12 months
Chops — pork	3–5 days	4–6 months
Chops — lamb	3–5 days	6–9 months
Roast — beef	3–5 days	6–12 months
Roast — lamb	3–5 days	6–9 months
Roasts — pork, veal	3–5 days	4–6 months
Variety meats — tongue, brain, kidneys, liver, heart, chitterlings	1–2 days	3–4 months
Meat Leftovers
Cooked meat and meat dishes	3–4 days	2–3 months
Gravy and broth	1–2 days	2–3 months
Fresh Poultry
Chicken or turkey, whole	1–2 days	1 year
Poultry pieces	1–2 days	2–3 months
Giblets	1–2 days	3–4 months
Cooked Poultry, Leftover	3–4 days	4 months
Fried chicken	3–4 days	4–6 months
Cooked poultry dishes
Poultry pieces, plain	3–4 days	4 months
Poultry pieces covered with broth or gravy	1–2 days	6 months
Chicken nuggets, patties	1–2 days	1–3 months

* Follow date on package.
** Caution: Even when food is in date and has been properly refrigerated, always boil or broil hot dogs to an internal temperature of 165°F. Food Safety and Inspection Service, “A Quick Consumer’s Guide to Safe Food Handling,” Home and Garden Bulletin, No. 248 (U.S. Department of Agriculture, August 1995)

These ranges depend on foods being fresh to start out and on the refrigerator/ freezer maintaining a constant temperature. Whenever these conditions aren’t met, food may spoil more quickly. Use your common sense: If food seems in any way questionable, throw it out without tasting. Or as the catchy saying goes: When in doubt, throw it out.

How freezing affects the texture of food

When food freezes, the water inside each cell forms tiny crystals that can tear cell walls. When the food is thawed, the liquid inside the cell leaks out, leaving thawed food dryer than fresh food. Beef that has been frozen, for example, is noticeably dryer than fresh beef.

Dry cheeses, such as cheddar, turn crumbly. Bread dries, too. You can reduce the loss of moisture by thawing the food in its freezer wrap so that it has a chance to reabsorb the lost moisture that’s still in the package. You can’t restore the crispness of vegetables that get their crunch from stiff, high-fiber cell walls.

After ice crystals puncture the walls, the vegetable (carrots are a good example) turns mushy. The solution? Remove carrots and other crunchies, such as cabbage, before freezing the stew.

Refreezing frozen food

The official word from the U.S. Department of Agriculture is that you can refreeze frozen food — as long as the food still has ice crystals or feels refrigerator-cold to the touch. The personal, unofficial word from me is that I confess to feeling safer when I simply throw out partially thawed food that I’m not going to use right away.

I’m particularly wary of sauced frozen food, such as frozen macaroni and cheese, because it seems to me that there just have to be hidden pockets of thawed food where the bacteria are whooping it up as we speak. Call me a worrywart, if you will, but for me, following this rule is just easier: Partial thaw? Out the door.