Preserving Your Summer Harvest - June 20, 2001
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
If you grow fruits or vegetables, you may already be contemplating how to fully utilize your harvest. With a little time and knowledge, you can preserve that bumper crop of apricots or unclaimed zucchini for year-round enjoyment. Vegetables and fruits can begin losing their vitamins when they are harvested. Nearly half of the vitamins can be lost within a few days unless the fresh produce is cooled or preserved. This week's column will provide a brief overview of home food preservation methods and discuss advantages and disadvantages inherent in each.
Freezing is often the quickest food preservation method for small quantities. Start with fresh, tender vegetables. Wash them and cut them into desired sizes. Blanch (heat) vegetables before freezing to inactivate enzymes. This will prevent color and flavor loss. Blanching is done by boiling, steaming, or microwaving the prepared vegetables. The thicker the pieces, the longer they should be blanched. For example, peas should be blanched for 1 ½ minutes while whole ears of corn may take 10 minutes. Blanched food should be chilled quickly, drained, and then put into waterproof containers before freezing. This is the easiest way to preserve green chiles, but, rather than blanching, they are roasted. Advantages: quick and safe. Disadvantages: requires freezer space and energy inputs (electricity or propane).
Canning is the old reliable food preservation method. Today, most of us rely on others to do our canning (Del Monte, Green Giant, etc). The topic of canning is complex and adherence to food safety practices is critical. Many reference guides are readily available where canning supplies are sold and on the Internet. An excellent web resource is the USDA Guide 1, Principles of Home Canning available from the Utah State University web site listed below. Canning preserves food by inhibiting the growth of microorganisms (molds, bacteria, and yeasts), denaturing enzymes, limiting exposure to oxygen, and limiting moisture loss. The canning process may involve all or part of the following steps: selecting, washing, and peeling (some crops) the crop, hot packing, adding acids (lemon juice or vinegar), using sound jars and new self-sealing lids, processing in boiling water or a pressure cooker for a specified amount of time. Advantages: food lasts a long time and no refrigeration required. Disadvantages: time intensive and must adhere strictly to processing and safety instructions.
Dehydration is the world's oldest method of food preservation. Dehydration preserves food by removing most of the water and thereby severely limiting the ability of microorganisms to utilize the food as an energy source. Exposure to sunlight can cause some nutrients such as vitamin C to be lost. Blanching before dehydration will help preserve vitamin A and vitamin B losses are moderate during dehydration. Because dehydration removes water, the food decreases in size and weight. Yields of dehydrated food are directly related to the water content of the original product. Heat for dehydration is supplied by the sun or other heat source (electrical or wood fire). Foods should be dehydrated as fast as possible. However, if dried too fast, the outer cell layer may become hardened leading to uneven drying and decreased quality. Food should have good air circulation and be only one layer deep while drying. Dehydrated foods are good for backpacking and camping and homemade beef jerky is delicious. Food dehydrators consist of an enclosed cabinet, a controlled heat source, and a method of circulating the air to remove moisture. Dehydrators can be purchased commercially or home built. Advantages: less space is needed to store food and convenient to transport. Disadvantages: foods may lose some nutrients or become tough and water may be required to rehydrate.
Storage Areas should be kept above 32 and below 70 degrees F. The cooler the area, the longer the shelf life of the stored food. The storage area should also be kept below 15% relative humidity and adequately ventilated to prevent condensation of moisture on containers.
Storage Life varies with method of food preservation and storage area conditions. When food is stored too long, two things may happen: 1) color, flavor, aroma, texture, or appearance is deteriorate to a level where people will not consume the food, and 2) nutrient deterioration may be severe enough to render the food an unreliable source of nutrients. Stored food may deteriorate from natural decomposition processes (metabolic activity), infection with microorganisms, insects or rodents, contamination with non-food materials or off-flavors from containers, or chemical changes due to light exposure or oxidation.
Yavapai County residents may call the University of Arizona Cooperative Extension for food safety, storage, and preservation information. Marta Stuart is the Family Consumer Sciences Agent that can assist you with food safety and storage information. She can be reached at the Prescott Cooperative Extension Office (928) 445-6590. Utah State University also has a comprehensive web site on food preservation that covers freezing, canning, dehydration, nutrition, storage, and food safety at extension.usu.edu/cooperative/index.cfm/cid.249/. The information presented on this site is research-based and peer reviewed.
The University of Arizona Cooperative Extension has publications and information on gardening and food preservation. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/.
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Last Updated: March 15, 2001
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