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Freezing and Thawing 101

How to get safe, delicious results


from Fine Cooking
Issue 67

We all have a favorite kitchen appliance, one that we couldn’t imagine being without. For me, it’s the freezer. It holds everything I need—frozen tortillas and breads, an assortment of vegetables and meats—to make tasty meals within minutes of arriving home from work. And when time is on my side, I know I’ll have chopped herbs, homemade stock, berries, pastry dough, and many other ingredients at hand to prepare more elaborate dishes.

How does the freezer make all this possible? Well, when you freeze food, a couple of important things happen. First, the pathogens that cause food-borne illness can’t grow, which makes food-safety experts like me jump for joy. In fact, as long as food remains frozen, it’s as safe as the day it was put in the freezer. (It’s thawing that invites trouble, but we’ll get to that later.) Second, freezing also preserves food’s quality by slowing down the microbes and chemical reactions that degrade food. But some of these reactions do continue during frozen storage, so eventually, the flavor, color, and texture deteriorate to the point that the food just isn’t appealing, even if it’s still technically safe to eat.

Not all freezing is created equal

It might seem like the only role you play in freezing is finding space in the freezer, but actually there’s a lot you can do to streamline the freezing process and to keep your food in optimum condition.

Faster is better. The packaged frozen foods you see at the supermarket were most likely “flash frozen” in a super-cold industrial freezer. The faster food freezes, the better—because freezing is a bit injurious to food. As the water in food freezes, ice crystals form and rupture cell walls. Rapid freezing keeps the ice crystals tiny and reduces the time for cells to leak fluids, which is good for the food’s quality. Large ice crystals can damage meat or produce, leading to texture and moisture loss when the food is thawed.

Your home freezer can’t mimic the efficacy of an industrial freezer that freezes food in minutes and stores it well below 0°F. But you can still get decent results at home by using the tactics listed below.

Help your freezer do its job —

  • Set the freezer to 0°F or lower and monitor the temperature with a freezer thermometer (available at supermarkets and hardware stores).
  • Store food in containers that provide a barrier to air and moisture. Well-sealed plastic freezer containers work, as do heavy-duty plastic freezer bags or wrap, freezer paper, or heavy-duty foil. (Many foods expand upon freezing, so don’t overfill, but at the same time don’t leave too much air space.)
  • Small items freeze faster, so freeze food portions you normally use in recipes: one or two cups of stock, a cup of sliced bananas, a tablespoon of tomato paste.
  • Arrange unfrozen packages in a single layer, slightly separated from one another, so they freeze faster.
  • Try to place foods on the freezer’s floor or near the walls.
  • Don’t overload the freezer with too much unfrozen food at once. And once food is frozen, keep the items stacked closely together. Freezers are most energy efficient when full. If your freezer is running low, consider freezing jugs or containers of water.

Freezing isn’t forever. Commercially frozen foods often have a “best if used by” date, which makes inventory-control easy. But what about all the food you’ve frozen yourself: Can you eat that chili from 1999?

I don’t think there’s a simple answer. Storage guidelines, like those at the end of this article, give wide estimates because they depend on many variables: How fresh was the food when it was frozen? How quickly did it freeze? What was the storage temperature, and was it consistent? How will the food ultimately be used? And, perhaps most important, how discriminating is your palate? For the sake of flavor, I’d probably make a new batch of chili before consuming vintage 1999, but some people wouldn’t give it a second thought.

Use the kitchen freezer for fast turnover. The refrigerator’s freezer is best for short-term storage, one or two months. The temperature inside a kitchen freezer fluctuates over a broad range because it’s opened often, and also because the self-defrost feature includes programmed heating and cooling to melt frost before it builds up.

Those temperature fluctuations cause microscopic melting and refreezing in foods, which encourages ice-crystal growth. Over time, this harms the food’s texture. And as water moves from one area in the food to another, the surface of the food dries out -- a condition known as freezer burn. Water migration can also create visible ice crystals. If you’ve kept ice cream for longer than a couple of weeks, you know what I mean.

So for long-term frozen storage—up to 12 months—stash food in a stand-alone freezer that won’t be opened often and doesn’t have a defrost feature.

Thawing foods safely

There’s one thing I don’t like about frozen food: thawing it. From a food-safety perspective, that’s when you court trouble. As food thaws, the outer surface warms up first. Cells that were damaged during freezing release nutrients and moisture. And in some foods, this can create ideal conditions for pathogens to grow and multiply.

Thaw food at the temperature you plan to store it. Baked goods—breads, cakes, cookies—can be safely thawed and stored at room temperature. But meat, prepared entrées, fruits and vegetables, and raw dough should be thawed and stored in the refrigerator to minimize pathogen activity. Just like slow freezing, slow thawing can lead to moisture loss, but food safety always trumps quality.

Q: Is it OK to refreeze food that’s been thawed?

A: Food can be safely refrozen within 48 hours of thawing if the thawing took place in the refrigerator or in cold water and the temperature of the thawed food has remained below 40°F. But the food’s quality might suffer because fluids that seep from cells during refreezing and subsequent thawing can adversely affect texture and flavor.

Admittedly, doing things the right way can try one’s patience: It can take more than two days to defrost a 12-lb. frozen turkey in the fridge. To safely hasten thawing, seal the frozen item in a leakproof container or plastic bag and immerse it in cold tap water. (Check the water every half an hour to be sure it remains cold.) Once thawed, refrigerate the food until you’re ready to use it—which, ideally, should happen quickly. Thawed frozen food spoils as fast as, or faster than, its never-frozen counterpart because cells ruptured during freezing and thawing release nutrients for microbes to consume.

If you’re in a real hurry to put something on the table, you can use your microwave’s defrost feature to thaw food you plan to prepare and eat right away.

Or, better yet, skip thawing entirely. My favorite frozen foods are those that can go straight from the freezer to the oven or microwave for reheating: Frozen vegetables can go right from the freezer into a steamer or pot of boiling water. And, of course, frozen fruit can go right into the blender for a quick, satisfying smoothie.

To freeze -- or not to freeze?

The table below lists foods that freeze well and those that don’t. Before you put an item in the freezer, stick a label on it. Write the item’s name and the date it was prepared. The guidelines below will help you calculate a “use-by” date.

Foods that freeze well

  • Red meat: 4 to 12 months
  • Poultry: 9 to 12 months
  • Seafood: 3 to 6 months
  • Raw bacon: 1 to 2 months
  • Some casseroles: 1 to 4 months
  • Soup, stew, and stock:
  • 2 to 4 months
  • Cooked legumes: 4 to 6 months
  • Whole berries: 8 to 12 months
  • Peeled ripe bananas:
  • 2 to 4 weeks
  • Blanched vegetables:
  • 2 to 12 months, depending on the vegetable
  • Bread: 6 to 8 months
  • Pie dough: 6 to 8 weeks
  • Nuts: 6 to 12 months
  • Butter: 6 to 9 months
  • Egg whites: 12 months
  • Flour: 6 to 12 months

Foods that don’t freeze well

  • High-moisture vegetables like lettuce, celery, and cabbage become watery.
  • Cream and custard fillings separate.
  • Meringue toughens.
  • Milk undergoes flavor changes.
  • Sour cream and yogurt separate.
  • Heavy cream won’t whip after being frozen.

Photo: Scott Phillips


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