Freezing is a convenient way to prolong the shelf life of foods. With the exception of shelled eggs and canned food, anything can be frozen, according to the United States Department of Agriculture. Some foods freeze better than others, depending on their water content. Freezers must be kept at or below 0°F (-18°C).
Most fresh food contains 50 percent to 90 percent water. When food is frozen, water turns to ice and preserves the water content. The quicker the food freezes, the smaller the ice crystals within the food freeze. If food is frozen slowly, or is not kept cold enough, large ice crystals form, causing structural damage to the food and potentially affecting its taste and texture once defrosted. Use the quick-freeze option if your freezer has one, or place food at the bottom of the freezer where it is coldest.
Lack of moisture prevents any bacteria, yeasts or molds from multiplying once food freezes. However, any bacteria present prior to freezing does not perish and will continue to multiply as soon as the thawing process begins. Make sure food is fresh and within it's shelf life when it enters the freezer to ensure safe consumption once defrosted.
Color Changes and Freezor Burn
Freezer burn, which appears as dark grayish spots, occurs when air comes in contact with frozen food; this does not render food unsafe, but results in dryness, poor taste and texture. Remove freezer burn spots before consumption. Some foods may change in color, particularly red meats, which turn from red to a brown-like color. Discoloration results from lack of oxygen and will be particularly noticeable after long-term freezing. Vegetables kept in the freezer over long periods of time may appear duller in color as a result of dryness.
Freezing food does not alter its nutritional value. In fact, fresh produce better retains its nutritional value when frozen as opposed to being kept at temperatures above freezing. Fruits and vegetables for example begin to lose their nutritional value immediately after picking, so immediate freezing is the best way to ensure maximum nutritional value. Proteins also remain unaltered by the freezing process.