1. Freezing Does Not Destroy Bacteria & Parasites
Freezing to 0 °F 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 food-borne 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.
2. Freshness & 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 lower to retain vitamin content, color, flavor and texture.
3. Enzymes
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.
4. Freeze Rapidly
Freeze food as fast as possible to maintain its quality. Rapid freezing prevents undesirable large ice crystals from forming throughout the product because the molecules don't have time to form into the characteristic six-sided snowflake.
5. Safe Thawing
There are three safe ways to thaw food: in the refrigerator, in cold water, or in the microwave. It's best to plan ahead for slow, safe thawing in the refrigerator. Small items may defrost overnight; most foods require a day or two. And large items like turkeys may take longer, approximately one day for each 5 pounds of weight.
For faster thawing, place food in a leak proof plastic bag, or in an airtight watertight stainless steel container and immerse it in cold water. (If the bag leaks, bacteria from the air or surrounding environment could be introduced into the food. Tissues can also absorb water like a sponge, resulting in a watery product.) Check the water frequently to be sure it stays cold. Change the water every 30 minutes. After thawing, cook immediately.
