Food Preservation - Freezing

Freezing has many advantages over other methods of food preservation. Frozen foods are often more like fresh, because they often retain their color, flavor and nutritive value. Freezing is also one of the easiest, less labor-intensive food preservation methods.

Foods naturally contain enzymes which cause chemical changes which lead to deterioration. In most cases, vegetables are blanched and fruits are treated to retard enzyme activity, prior to freezing.

When freezing most vegetables, you general want to heat-treat them for a short period of time to reduce the enzyme activity. This process is called blanching. Blanching is placing the vegetables into rapidly boiling water, or sometimes steam, for a short period of time. This step stops or slows down the enzymes that cause undesirable changes.. Refer to a reliable freezing reference for recommended blanching times for particular vegetable.

After blanching, it is recommended to immediately immerse the vegetables in ice water to stop the cooking process. Blanching is not intended to cook the vegetables, simply to inactivate the enzyme activity. You generally chill the foods for the same amount of time as is recommended for blanching. Now drain and I prefer to dry the foods before packing. Draining/drying reduces the formation of ice crystals which will affect the quality of the product. Finally, place the cooled, dried vegetable in an air-tight, vapor resistant container, designed for freezing. Remove as much air as possible, from the container. Label and store in a freezer, that is 0 degrees or colder.

Some prefer to completely cook certain vegetables before freezing, which is also acceptable. A couple of vegetables that are often prepared this way are, cream-style corn and greens. After cooking the food to the desired doneness, they also need to be cooled before freezing. These foods are generally placed in a large bowl or pot that is set in ice water and stirred until the food is cool.

Blanching softens the texture of fruits, so controlling enzyme activity in fruits is best accomplished by adding sugar and antioxidents. Darkening of fruit is caused by oxidation, when the fruit is exposed to air. Ascorbic acid, vitamin C, citric acid, or sugar syrup helps to prevent discoloration. Steaming fruit just until hot before packing will also control darkening. Steaming works best for fruit that will be cooked before use.

Three methods are generally used to pack fruit for freezing: syrup pack, sugar pack, and unsweetened pack. The syrup or sugar pack, help the fruit retain better texture, color and flavor. But, for those watching their weight or needing to limit their sugar consumption, dry pack is acceptable.

Some foods such as berries, and chopped onions an peppers are especially easy to freeze. After rinsing and drying, spread on a cookie sheet and freeze. Then quickly place in a freezer container, remove as much air from the container as possible and return to the freezer. By freezing this way, the desired portion is easily removed, and the rest can remain frozen for future use.

Freezer bags, rigid plastic containers and freezer jars are all suitable for freezing. Freezer bags are better suited for dry packed foods, while rigid containers and glass are especially recommended for liquid packs but also suitable for dry packs. If you use glass containers, make sure the jars are designed for freezing.

Keep these following tips, in mind, when freezing:
1. For optimal quality and storage life, your freezer should be keep at 0 degrees F. or lower.
2. Do not overload your freezer with unfrozen food – no more than 2-3 lbs. of unfrozen food per cubic foot of freezer space.
3. Leave space between unfrozen packages to allow air circulation. After the food is frozen, packages can then be stacked.
4. Be sure to label each package with the name of the product and the packaging date. Use freezer tape or pens and labels that are especially made for freezer use.