Freezing and Food Safety
oods in the freezer — are they safe? Every year, thousands of callers to the USDA Meat and Poultry Hotline have questions about the safety of items stored in their home freezers. The confusion seems to be based on the fact that few people understand how freezing protects food. Here is some information on how to freeze food safely and how long to keep it.
What Can You Freeze?
You can freeze almost any food. Some exceptions are canned food or eggs in shells. However, once the food (such as a ham) is out of the can, you may freeze it. Being able to freeze food and being pleased with the quality after thawing are two different things. Some foods simply don’t freeze well. Examples are mayonnaise, cream sauce, and lettuce. Raw meat and poultry maintain their quality longer than their cooked counterparts because moisture is lost during cooking.
Is Frozen Food Safe?
Food stored constantly at 0 °F or below will always be safe. Only the quality suffers with lengthy freezer storage. Freezing keeps food safe by slowing the movement of molecules, causing microbes to enter a dormant stage. Freezing preserves food for extended periods because it prevents the growth of microorganisms that cause both food spoilage and foodborne illness. Freezing to 0 °F or below inactivates any microbes -- bacteria, yeasts, and molds -- present in food. Once thawed, however, these microbes can again become active, multiplying under the right conditions to levels that can lead to foodborne illness. Since they will then grow at about the same rate as microorganisms on fresh food, you must handle thawed items as you would any perishable food. Trichina and other parasites can be destroyed by sub-zero freezing temperatures. However, very strict government-supervised conditions must be met. Home freezing cannot be relied upon to destroy trichina. Thorough cooking, however, will destroy all parasites.
Does Freezing Destroy Bacteria and Parasites?
Freshness and Quality
Freshness and quality at the time of freezing affect the condition of frozen foods. If frozen at peak quality, thawed foods emerge tasting better than foods frozen near the end of their useful life. So freeze items you won’t use quickly sooner rather than later. Store all foods at 0 °F or below to retain vitamin content, color, flavor, and texture. The freezing process itself does not destroy nutrients. In meat and poultry products, there is little change in nutrient value during freezer storage.
The Food Safety and Inspection Service (FSIS) is the public health agency in the U.S. Department of Agriculture responsible for ensuring that the nation’s commercial supply of meat, poultry, and egg products is safe, wholesome, and correctly labeled and packaged.
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Freezing and Food Safety
Enzyme activity can lead to the deterioration of food quality. Enzymes present in animals, vegetables, and fruit promote chemical reactions before and after harvest, such as ripening. Freezing only slows the enzyme activity that takes place in foods. It does not halt them. Enzyme activity does not harm frozen meats or fish and is neutralized by the acids in frozen fruits. But most vegetables that freeze well are low acid and require brief, partial cooking to prevent deterioration. This is called “blanching.” For successful freezing, blanch or partially cook vegetables in boiling water or in a microwave oven. Then rapidly chill the vegetables prior to freezing and storage. Consult a cookbook for timing.
Proper packaging helps maintain quality and prevent freezer burn. It is safe to freeze meat or poultry directly in its original packaging, however this type of wrap is permeable to...