You need practice to become good at drying food

July 27, 2004 (Reviewed December 20, 2007)
LouAnn Jopp
University of Minnesota, Regional Extension Educator, Food Science
St. Cloud Regional Center
(888) 241-4591
Email: joppx001@umn.edu

Drying or “dehydrating” is a method of food preservation that is simple, safe and easy to learn, but there are no absolutes and many variables. The only way to become more proficient is to practice!

In other words, a “trial and error” approach is often needed to determine the best times and techniques to use. The drying time will depend on the type of food, the thickness of the cut, the moisture content of the food and of course, the method used.

Drying is one of the oldest methods of food preservation. Drying preserves foods by removing enough moisture from food so bacteria, yeast and molds cannot grow. To dry foods successfully, you need:

• Low humidity--dry air will absorb the moisture that is released from the food


• A source of low heat--temperatures of 120° to 150° F. are adequate to draw out the moisture without cooking the food


• Air circulation--speeds the drying process by moving the moisture away from the food

The following are various methods for drying foods, but whatever the method is, drying food is a slow process.

Sun drying requires constant exposure to direct sunlight during the day and a relative humidity of less than 20 percent. Due to our high humidity and cool night temperatures, sun-drying is not recommended in Minnesota. Only a few U.S. regions, such as the Sacramento Valley of California or in Arizona, have these weather conditions.

Oven drying is slower than in a dehydrator because ovens do not have built-in fans to create the air movement. It will take two to three times longer to dry food in an oven than in a dehydrator; therefore, it is not as efficient and uses a great deal more energy than a dehydrator. An oven can only be used to dry food, if the oven dial can be set as low as 140° F. If the oven thermostat does not go this low, your food will cook rather than dry. For air circulation, leave the oven door propped open two to four inches and place a fan near the outside of the oven door to improve circulation. Placing an oven thermometer near the food will give you an accurate reading of the drying temperature.

Air drying is different from sun-drying, because it takes place indoors in a well-ventilated attic, room or screened-in porch. Herbs, hot peppers and mushrooms are the most common air-dried items. Tie the food items in bundles, enclose them in paper bags to protect them from dust, and hang them to dry.

Microwave drying is a quick way to dry small quantities of herbs, but is not successful for most other foods. Often, food that’s been microwave-dried tastes overcooked.

Dehydrators produce the best quality product as compared to any other method of drying. Most food dehydrators have an electric element for heat and a fan and vents for air circulation. Efficient dehydrators are designed to dry foods uniformly and to retain food quality.

There are many benefits for food drying; here are a few:

• Drying offers new and different nutritious snacks such as dried fruits, fruit roll-ups and meat jerky.


• Dried foods are lightweight and do not require refrigeration.


• Drying costs less than canning or freezing.


• Dried food is convenient – it can be eaten just the way it is.


• Canned foods, once opened, must be used promptly. But containers of dried foods can be repeatedly opened, ingredients added or removed, and closed again with no ill effects.

For the best retention of nutrients in dried foods, store in a cool, dry, dark place and use within a year.