By Wayne Gendel

As part of the raw food lifestyle, dehydrating food is a wonderful healthy addition for preserving foods or making healthy treats from saving produce in season such as tomatoes and grapes, to making veggie loafs, to delicious desserts such as raw brownies and truffles. It’s not only economical for preserving leftover produce, but great in transition to a healthier diet, short trips and even camping or hiking! Dehydrating foods at the proper temperature is crucial! It’s the difference of overheating and cooking the food, or not using enough temperature and the food having some mold and bacteria.

Four Factors To Successfully Dehydrating Foods

1. Moisture reduction – eliminate molds & bacteria
2. Air temperature vs. Food temperature – preserve enzymes
3. Time – dehydrate within 36 hours!
4. Storage – 1 to 2 years!

Moisture Reduction

Point Studies have shown that in order to preserve the enzymes, and reduce the risk of mold and bacteria, there should be a fluctuation in temperature. Enzymes and microorganisms can both live at the same temperature. Therefore we must be able to keep the food temperature low enough to preserve the enzymes, yet elevate the air temperature high enough to remove the moisture quickly to stop the growth of mold or bacteria. A fluctuation in temperature accomplishes just that.

As the air temperature rises, moisture begins to evaporate off the surface of the food. Now as the temperature lowers, moisture is drawn from the center of the food and then it becomes moist again.

The Ideal Temperature Is…. When all the moisture is dehydrated and evaporated out of the food, the food temperature will equalize. Enzymes are only susceptible to damage by high heat when they are in the wet state, therefore once the food is dehydrated the enzymes have become dormant, and can withstand much higher temperatures. Viktoras Kulvinskas says “dry enzymes can survive well up to 150ºF.” He tested seeds he sprouted and dehydrated and found he could sprout different kinds of seeds that were properly dehydrated! Viktoras has also found that turning the temperature to 140ºF for 2-3 hours then lowering it to 105ºF, speeds up the process of dehydrating while still retaining the enzymes!

Enzymes are affected by various temperatures. Dr Edward Howell (Enzyme Nutrition) recognized that when temperatures go above 118ºF all enzymes are destroyed. Dr. John Whitaker, a world recognized enzymologist, and a former dean of the Department of Nutrition and Food Science at U.C. Davis, stated that every enzyme is different and some are more stable at higher temperatures than others. Most enzymes will not become completely inactive until food temperatures exceed 140ºF – 158ºF in a moist, wet state. Again the exceptions are that the more dense the food, the longer it will take to totally destroy all its enzymes.

Food Temperature vs. Air Temperature

The difference between air temp and food temp is important when dehydrating foods. It is crucial to understand at which point in the dehydration process the enzymes are most susceptible to destruction by heat, which is while the food is in its wet state. After the food is dehydrated the enzymes can withstand temperatures up to 140ºF for short periods of time.
Food temperature is almost always 20 degrees cooler than the air temperature.

Setting your dehydrator thermostat at 125ºF will hold the food temperature at around 105ºF, the air temperature may get as high as 125ºF depending upon the moisture content of the food. The reason the food temperature is cooler is because of the moisture that is evaporating. As the moisture on the surface of the food evaporates, it cools the food keeping it about 20ºF cooler than the air temperature. Eventually the moisture is gone and you have your dehydrated food! No preservatives! All natural way to keep foods for 1 year or more!


There is a point where the moisture is eliminated and the food will no longer harbor bacteria or molds. This point is 48 hours or less. Most foods once processed will start to show mold and bacteria within 48 hours even if they are refrigerated! I recommend when dehydrating foods to make sure they are completely dehydrated within 36 hours! Any longer and your foods could be susceptible to molds and bacteria. If your dehydrated foods are going bad, or taste and smell like anything other than the food you’re preparing, discard immediately or re-compost back to the soil! If your food is taking longer to dehydrate than 36 hours try cutting the food thinner or make it less dense so it dehydrates quicker!


Ideally store in a cool dry place. If stored in a covered container dehydrated foods from raisins to raw brownies should remain fresh for up to 1 year. If you have mason jars or special plastic bags and a vacuum sealer, your dehydrated food should last up to 2 years! I also totally recommend a vacuum sealer for just regular use as it can be used for all produce to keep it fresh longer!

The evaporation process of the moisture in the food to be dehydrated, keeps food temp cooler than air temperature. A dehydrator with a thermostat is a must! The top 2 dehydrators are Excalibur and American Harvest.

The Final Words

Please remember that dehydrated foods should only be used in moderation! Because dehydrated foods are in-between a fresh ‘living’ food and a cooked food, there is no moisture in dehydrated food! That is why it can be preserved for years! Over-consuming dehydrated food will draw moisture from your body = translation = It will cause constipation if eaten in large amounts for too long a period! Dehydrated produce can be reconstituted with water before consuming such as tomatoes, raisins, etc. When reconstituting I recommend soaking for 30 minutes to 1 hour. Depending on the fruit or vegetable thickness soaking 15 minutes up to no more than 2 hours in purified water at room temperature is best! Longer than 2 hours and you will dilute the produce to much and you will have little taste or nutrition!

Raw snack treats should be used as a healthy treat or alternative to sugary refined processed “junk” foods. For a healthy person eating a dehydrated snack 2-3 times a week is a fun health treat! I recommend taking plant digestive enzymes when consuming dehydrated foods (cooked foods and eating large amounts of raw fats) as extra insurance.

Please Live Forever Healthy!
Wayne Gendel