It’s that time of year when gardens everywhere are producing at their peak and there are good buys at farmer’s markets and roadside stands. Whether you’re the lucky recipient of extra produce from your own garden or someone else’s, freezing is one of the simplest and least time consuming methods of preserving foods at home for later use. It is an especially useful way to preserve extra fruits and vegetables. When properly frozen, fruits and vegetables retain much of their fresh flavor and nutritive value.
Selecting freezing containers: To prevent evaporation and retain the highest quality, packaging materials should be moisture and vapor proof. Glass jars and metal or rigid plastic containers meet these criteria. Although not moisture and vapor resistant, commercially available bags and heavily waxed cartons designed for freezing also work well.
Shape and size are an important consideration when selecting containers for freezing. Try to select containers suited for both the shape of the produce being frozen and the quantity that will be frozen. Keep in mind, square or rectangular flat-sided containers make better use of freezer space than round containers.
Selecting, preparing and packaging produce: The quality of frozen vegetables depends on the quality of the fresh products and how they are handled from the time they are picked until they are ready to eat. For the best results, freeze vegetables at their peak in flavor and texture. Whenever possible, harvest vegetables in the early morning when it’s cool and freeze within two hours. Before freezing, always wash vegetables thoroughly in cold water and then sort by size for blanching and packaging. Nearly all vegetables, except herbs and green peppers, should be blanched and cooled before freezing. Once blanched, vegetables can be packed using either the dry pack or tray pack methods.
When freezing fruit, it is best to freeze berries and cherries soon after harvest. Peaches, apricots, plums, apples and pineapples may need to be held after harvest until fully ripened. To prepare fruits, sort, wash and drain them carefully, discarding parts that are green or of poor quality. Do not soak fruits in water, as they will lose nutrients and flavor. Consider how the fruit will be used and then prepare accordingly by stemming, pitting, peeling and/or slicing. Some fruits darken easily and should be treated with an anti-darkening treatment, such as ascorbic acid (vitamin C), citric acid, lemon juice or by steaming. Once prepared for freezing, fruits can be packed using several methods, including a syrup pack, a sugar pack, an unsweetened pack, or a tray pack.
Sealing, labeling and storing: Before freezing, close and carefully seal containers. Label packages with the name of the product, date and type of pack. Freeze immediately at 0 degrees Fahrenheit or lower. Because speed in freezing is important to retain best quality, put only as many packages in the freezer as will freeze within 24 hours. Most vegetables will maintain high quality for 12 to 18 months at 0 degrees Fahrenheit, while most fruits maintain high quality for eight to 12 months. Citrus fruits and citrus juices are best if used within four to six months. Longer storage will not make the food unfit for use, but may lower its quality.
For more information on freezing fruits and vegetables, including detailed preparation, blanching, and packing recommendations for specific fruits and vegetables, contact your local cooperative extension office and request fact sheets 9.330 Freezing Vegetables and 9.331 Freezing Fruits, or visit www.ext.colostate.edu and click on food and nutrition information online.
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by Pat Kendall, Ph.D., R.D., Food Science and Human Nutrition Specialist, Colorado State University, Cooperative Extension