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Preserving Food - Drying

Source: NDSU Extension Service Nutrition Specialists

Drying is a method of food preservation that is simple, safe and easy to learn. Drying also creates new food products such as fruit leathers, banana chips, pumpkin seeds and beef jerky.

Drying removes the moisture from the food so bacteria, yeasts and molds cannot grow. Drying also slows down the action of enzymes, which cause food to ripen.

Because drying removes moisture, the food shrinks, and becomes lighter in weight. When the food is ready for use you add water and the food returns to its original shape.

Foods can be dried in an oven, or in a food dehydrator by using the right combination of warmth, low humidity and air current.

In drying, a warm temperature allows the moisture to evaporate. Air current speeds up drying by moving the surrounding moist air away from the food. Low humidity allows moisture to move from the food to the air.

Drying food is a slow process. It will take 6 or more hours in a dehydrator, and in your oven, it will take 8 or more hours. Drying time depends on type of food, thickness, and type of dryer. Don't be tempted to speed up the drying time by turning up the oven. You will cook the food on the outside before it dries on the inside. This is called case hardening.

The food may appear dry on the outside but may be wet on the inside. Moisture left in the food will cause it to mold.

After foods are dried, allow 30 minutes to one hour cooling time to prevent condensation. However, too long a cooling period allows moisture from the air to re-enter the food.

Proper storage prevents insects and rodents from eating food. It also keeps moisture out and saves valuable nutrients. Glass jars, metal cans or boxes with new tight fitting lids, or vapor-proof freezer cartons make good containers. The jars do not need to be heat processed. Heavy duty plastic bags with press together seals are acceptable, but are not insect and rodent proof.

Dried foods will keep from four to twelve months, but proper storage is very important. Cool, dry, dark are best. For best quality, the storage temperature should not go over 60 degrees. Refrigerator or freezer storage does provide a low temperature which extends the shelf life.

After packaging, check containers within seven to ten days to see if any moisture is present. If you see any moisture, food must be redried. If it is moldy, discard the food. Dried fruits can be eaten as nutritious snacks, or they can be soaked for one to two hours and used in favorite recipes.

Some vegetables can be eaten dried as tasty vegetable chips or used in dips. Most vegetables are refreshed with water before use.

If you have further questions, please contact your county office of the NDSU Extension Service.

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For More Information Contact your North Dakota County Extension Office of the NDSU Extension Service for additional information or see our main NDSU Web Page for publications and articles on Agriculture, Horticulture, Youth and Family, Business and Community and Food and Nutrition at  http://www.ag.ndsu.nodak.edu/