April Reese Sorrow and Elizabeth L. Andress, Ph.D.
National Center for Home Food Preservation
Freezing is one of the easiest, most convenient and least time-consuming ways to preserve foods at home. The extreme cold stops growth of microorganisms and slows down changes that cause spoilage and affect quality in food.
The National Center for Home Food Preservation, hosted by the College of Family and Consumer Sciences at the University of Georgia, recently conducted a survey of home freezing practices. The survey revealed that 94.4 percent of respondents home freeze some type of food item. Plastic bags are the most frequently used packaging material for freezing food items.
Other containers suitable for freezing fruits and vegetables, however, are plastic freezer containers, or glass canning/freezing jars.
"Don't use paper cartons, like milk boxes," said Elizabeth Andress, director of the National Center for Home Food Preservation. "Many plastic containers that foods are packaged in for purchase, like yogurt, dips and sour cream, do not provide characteristics for preserving quality in the freezer. Freezer foil and coated paper are good for odd shaped foods."Preparing the food
Fruits should be washed and sorted before freezing. Discard those that are not yet ripe or of poor quality. Allowing fruit to soak in water will cause lose of nutrients and flavor.
"Stem, pit, peel or slice fruit as desired; prepare enough fruit for only a few packages at a time to prevent browning," Andress explained. "Do not use galvanized equipment in direct contact with fruit, the acid in the fruit dissolves zinc, which can be harmful in large amounts."
Use vegetables at peak flavor and texture. Whenever possible, harvest in the morning and freeze within a few hours. Wash vegetables thoroughly in cold water and sort according to size for blanching and packing. Blanching, which is scalding vegetables in boiling water or steam for a short period of time, should be done to ensure highest frozen food quality and shelf life."Blanching stops the action of enzymes that can cause loss of flavor, color and texture," Andress said. "Blanching time is crucial and varies with the vegetable and its size. Underblanching stimulates the activity of enzymes and is worse than not blanching at all; overblanching can cause loss of flavor, color, vitamins and minerals."
Specific blanching times can be found at the Web site below.
Water blanching is the most widely recommended method for blanching vegetables. Use one gallon of water per pound of vegetables. Put the vegetables in a blanching basket and lower into vigorously boiling water. Place a lid on the pot and start counting blanching time as soon as the water returns to a boil.
As soon as blanching is complete, cool vegetables quickly to stop the cooking process by plunging the basket of vegetables immediately into a large quantity of cold water. Cooling vegetables should take as long as blanching. Drain vegetables completely after cooling.Fruit Packs
"There are several ways to pack fruit for freezing, such as a syrup pack, sugar pack, dry pack or unsweetened pack," Andress said. "Most fruits have better texture and flavor if packed in sugar or syrup, however, sugar is not needed to preserve the fruit."
Sugar syrups can be made by dissolving sugar in water completely and then pouring it completely around and over fruit in the packed container. You may need to heat the water to get all of the sugar dissolved, but completely cool or even refrigerate the syrup to get it cold before using on fruit. Use 2¾ cups sugar to 4 cups of water for most fruits. For mild flavor or very sweet fruits, use 1¾ cups sugar per 4 cups of water. About ½ to 2/3 cups of syrup is needed per pint of fruit.
To make sugar packs, simply sprinkle sugar over the fruit and mix gently until the juice is drawn out and the sugar dissolved. Dry packing works best with berries and smaller fruits that give good flavor without sugar. Pack the fruit, seal and freeze.
Peaches, apples, pears and apricots darken quickly when exposed to air and can darken in thawing. Use ascorbic acid in the package to prevent discoloration of fruits during the freezing process.
"Ascorbic acid in a powder form is available at some drugstores or where freezing supplies are sold," Andress said. "Add ½ teaspoon (1500 milligrams) pure powdered ascorbic acid to cold syrup shortly before using, stir gently, not to add air. To use in sugar or dry packs, dissolve in 2 or 3 tablespoons of cold water and sprinkle over fruit just before adding sugar."
If you use a commercially sold fruit color preserver that is not pure ascorbic acid, follow the directions on the box.Packaging and Labeling
Most foods require headspace between the packed food and closure to allow for expansion as food freezes. Headspace recommendations can be found at the Web site listed below.
All packaged food should be room temperature or cooler before putting in the freezer. Do not overload your freezer with too much warm food at one time. Quick freezing is best for frozen food quality. Spread the new packages around until they are frozen, then they can be stacked together if desired.
"Be sure to label all foods with name of food, date and type of pack," Andress said. "Most fruits and vegetables will remain high in quality for eight to 12 months. Longer storage will not make the food unfit for use, but may impair its quality."
It is a good idea to post a list of the frozen foods with freezing dates near the freezer and check the packages off the list as they are removed.
For more information on home-preserving fruits and vegetables or for recipes contact the National Center for Home Food Preservation online at http://www.homefoodpreservation.com.
April Reese Sorrow is a writer with the National Center for Home Food Preservation in the College of Family and Consumer Sciences, The University of Georgia, Athens.
Elizabeth L. Andress is an Extension Food Safety Specialist with the Cooperative Extension Service, Department of Foods and Nutrition, College of Family and Consumer Sciences, The University of Georgia, Athens.