Ground & Dehydrated Foods
Dehydration is the oldest form of food preservation. Dried food is preserved because the lack of moisture inhibits the growth of microbes that are the cause of food spoilage. Almost any kind of food can be dehydrated, and dried foods can have a shelf life of many years, even decades. Modern dehydration methods reduce the moisture content to 2 or 3 percent, well below the 15 percent needed for the growth of bacteria or mold.
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Ground Foods
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Dehydrated food is often ground. For instance dried legumes can be ground to make flour or a thickening agent for other foods. Grinding dehydrated foods also eases the rehydration process by exposing more surface area to the liquid. Ground dried herbs such as parsley and basil and bulbs like garlic and onion are widely used for cooking.
Methods of Dehydration
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Being sun dried is a marketable asset for raisins. Sun and air drying is the oldest method, and it is still the method most commonly used for commercially dried foods. Foods can be oven dried, but they may have a darker color and may be more brittle than sun-dried foods. An electric dehydrator can also be purchased, or you can build your own dehydrator--anything that will keep your food between 110 and 150 degrees F for 10 to 12 hours can do the job. It's possible to dry herbs in the microwave, and some herbs can be air dried with a steady, warm breeze.
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Effects
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Properly dehydrated and packaged vegetables and fruits can have a shelf life of 10 years or more provided they are stored at or below 70° F. Their containers should be airtight, and lower temperatures can extend the shelf life. From sweet peas to broccoli and from apples to mangoes, almost all fresh vegetables and fruits can be dehydrated. Dehydration causes them to lose vitamin C, but adding citrus juice or sulfur before drying can reduce that loss.
Properly packaged and stored, dried grains and legumes can have a shelf life of over 10 years and retain almost all their nutritional value.
Effects on Meat, Eggs and Milk
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Dehydrated eggs can last many years. Dried meat or jerky can be made from most lean meats and, according to the National Center for Home Food Preservation, it will keep for two weeks at room temperature in a sealed container. Some vendors claim that their vacuum-packed beef jerky has a shelf life of more than one year. Dehydrated or powdered eggs can last a decade when stored in a dark, cool place, and dehydrated or powdered milk has a shelf life from three to five years.
Expert Insight
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A study done for the University of Southern California and the office of the U.S. Quartermaster General 50 years ago concluded that "the diets made from dehydrated foods may be equally as nutritious as those prepared from fresh foods." However, a more recent study by Brigham Young University in 2005 found that most of the vitamin C in fruits and vegetables is destroyed by dehydration, and that a year's supply of mostly dehydrated food was also lacking in vitamins A, B12, and E and in calcium. In general it is advisable to supplement dehydrated foods with fresh foods.
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References
Resources
- Photo Credit beans image by dinostock from Fotolia.com raisins on white image by Kathy Burns from Fotolia.com eggs image by Allyson Ricketts from Fotolia.com
