Thoreau Foods Dehydration Info

Dehydrate your Garden Harvest

Dehydrating foods at or below about 110 degrees F allows for the maintenance of nutrition of the food with most of the enzymes remaining intact.  Enzymes are destroyed or "denatured" at  higher temperatures.  An enzyme is defined as a protein molecule which the body uses to perform specific functions such as digesting food, building protein in bones, skin and muscle, aiding in detoxification and numerous other bodily functions.  According to Dr. Edward Howell, in Enzyme Nutrition, he theorized that the body is born with a "bank account" of enzyme potential and when it is exhausted, chronic disease is inevitable.   By taking in more "raw" or "live food", we may assist the body in maintaining its enzyme reserves.  While dehydrated foods are not as high in life force energy and enzymes as fresh produce, it still contains enough enzymes to assist the body in digestion and its other functions.

A food dehydrator is the closest a raw or living foodie gets to the oven. The process of removing water by warming foods at such low temperatures enables the foods to maintain most of their nutritional value creating new textures and variety in food choices.   Dehydrators allow you to preserve fruits and vegetables, that have been farmed and harvested in quantities too large for immediate use, when they are at their best both in taste and nutrition. Food is preserved by lowering its moisture content thereby slowing bacterial growth and spoilage providing for a longer shelf life.

The fruits become sweeter with the water removed and they work as great substitutes for sugar and other refined sweeteners.  The vegetables make excellent on the run snacks or as an addition to salads, cold soups and more.  In addition to fruits and vegetables, seeds and nuts can be dehydrated and blended along with the fruits to provide delicious and highly nutritious versions of crackers, granolas, yummy raw toppings, spreads, breads, phenomenal good for you desserts and even pizza crusts.

Water content and acidity are the limiting factors in preserving foods (1).  Water content includes the moisture level of the food and more importantly the water activity or the amount of available water in the food.  Available water is water that is not already chemically bound and is thus "available" for microorganisms to use.  The water activity of pure water is 1.0 or 100% relative humidity while a dry cracker is about .2 and jam is about .85.  At low levels of available water in the food, less than .85, Staphylococcus aureus as well as other pathogens cannot grow.  Acidity refers to the pH, or the level of hydrogen ions, in the food.  A low pH (3.5) is considered highly acidic while a high pH (8.5) is alkaline with 7.0 being neutral.  Food is regulated by the State and Federal government to be shelf stable without requiring refrigeration at a water activity equal to or below .85 or a pH equal to or below 4.6.  Sugar and salt can be used to lower water activity levels and acid in the form of vinegar will decrease the pH of the food.

  Fruits and vegetables that are dehydrated can be combined with other dry products such as muesli to provide for a longer shelf life for the product. Thoreau Foods Mueslis are an example of this. Nutrition is maintained with dehydration as it utilizes the removal of water without the use of high heat.

Dehydrating times vary as much as 18 to 26 hours depending on the particular food you are dehydrating, the thickness of the food, how full the dehydrator is, and the humidity in the outside air while drying.  A  good rule of thumb to determine when something is "done" is to check it by breaking apart the food and if is it darker in the center or still wet compared to the outside, then it is not "done".  Food that isn’t completely dehydrated will get moldy within days, so to be sure, it’s best to continue dehydrating until it’s fully dry.

Dehydrated or dried foods should be stored in cool, dry, dark areas. Recommended storage times for dried foods range from 3 months to 1 year. Because food quality is affected by heat, the storage temperature helps determine the length of storage; the higher the temperature, the shorter the storage time. Most dried fruits can be stored for 1 year at 60 degrees F, 6 months at 80 degrees F. Vegetables have about half the shelf-life of fruits (3).  Foods that are high in fats or that are partially dehydrated have a lower shelf life and should be stored in the refrigerator or freezer.

Foods that are dehydrated and packaged can reabsorb moisture and spoil.  It is necessary to check dried foods frequently during storage to see if they are still dry. Glass containers are excellent for storage because any moisture that collects on the inside can be easily seen.  Foods affected by moisture, but not spoiled, should be used immediately or redried and repackaged. Moldy foods should be discarded.

For best results for dehydrating foods, follow these quick tips:

Here are some great drying items to get you started:

* Conditioning Fruits

The moisture content of home dried fruit should be about 20 percent. When the fruit is taken from the dehydrator, the remaining moisture may not be distributed equally among the pieces because of their size or their location in the dehydrator. Conditioning is the process used to equalize the moisture. It reduces the risk of mold growth.

To condition the fruit, take the dried fruit that has cooled and pack it loosely in plastic or glass jars. Seal the containers and let them stand for 7 to 10 days. The excess moisture in some pieces will be absorbed by the drier pieces. Shake the jars daily to separate the pieces and check the moisture condensation. If condensation develops in the jar, return the fruit to the dehydrator for more drying. After conditioning, package and store the fruit as described above.

Selecting a Food Dehydrator

If you are committed to healthier eating and wiser food choices, dehydration could help you in achieving this goal.  Although food dehydrators have been around for decades, the models on the market today are far superior in features and functionality than those available in the past. The two main types of food dehydrators are vertical airflow and horizontal airflow.  Horizontal airflow units provide consistent heat between the trays. In addition, you don’t get as much flavor mixing between the trays when dehydrating different types of foods at the same time.  Vertical airflow units, with the fan on the bottom allows for good heat distribution because heat rises. However, it is more difficult to clean as you can get drippings on the fan. Factors to consider when researching different models are size requirements.  Some dehydrators are very large and give you the ability to dry many different items at once. Others are meant for limited home use and allow you to only dry a few different items at once. A machine that offers an adjustable timer as well as thermostat is a necessary consideration when selecting a food dehydrator.  One of the most popular and highest quality food dehydrators available on the market is the Excalibur Food Dehydrator. Offering horizontal air flow and up to 25% more drying space than standard dehydrators, this unit also features faster drying and the best overall versatility. Click here to order the Excalibur Food Dehydrator direct from our website.


(1)"So Easy to Preserve", 5th ed. 2006. Bulletin 989, Cooperative Extension Service, The University of Georgia, Athens. Revised by Elizabeth L. Andress. Purdue Extrepreneurship Series, Purdue University. Food Preservation and Processing Technologies

(2) Enzyme Nutrition, Dr. Edward Howell

(3) Purdue University, Food Preservation and Processing Technologies, Deidre Bush and Kevin Keener