The dictionary defines ‘conditioning’ as a means to change a behavior or strengthen muscles. In the realm of food preservation safety, ‘conditioning’ is the process used to equalize moisture left in food after dehydrating to decrease the chance of spoilage or mold growth. While conditioning could be used for all dried foods (herbs, vegetables, and fruits), conditioning is most important for fruit including tomatoes.
The moisture content of home dried fruit should be about 20 percent1 or less when removed from the dehydrator or oven. However, due to the size of the pieces, location in the dryer, or uneven drying, the remaining moisture may not be evenly distributed among the pieces. Even drying can be hard to obtain in a home dehydrator and naturally some pieces will likely have more than a 20% moisture. Because there is no sure way to test for moisture at home, conditioning becomes necessary and is the last step before final storage. Conditioning is not necessary if the fruit is dried for immediate snacking rather than storage; dried fruit for snacking should be stored in the fridge and eat within 3-4 days.
Conditioning is easily done following these steps:
- Cool foods on trays and test for dryness. Dried fruits should be leathery and pliable when cool. Squeeze a handful of the fruit. If no moisture is left on the hand and pieces spring apart when released, they are dry.2
- Place the food into non-porous, food grade containers (glass or clear plastic jars work great) filling about two-thirds full. Seal the container with a lid.
- Shake or stir the contents daily for 10-14 days. During this time, the drier pieces will absorb the excess moisture of the less dried pieces.
- Check for condensation on the lid or sides of the container or food pieces sticking together. Also, look for signs of spoilage. If condensation is noted, return the food to the dryer for additional drying time followed by another conditioning. If there is any sign of mold, discard the product.
If drying the same food in successive batches, freshly dried fruit may be added to a conditioning batch within the first five days with conditioning time lengthened to accommodate the additional food.3 Conditioning is also recommended for fruit leathers.
What about conditioning vegetables and herbs? It is easier to tell when vegetables and herbs are thoroughly dry. Dried vegetables should be hard and brittle. For more information on individual vegetables, check out Drying Vegetables – 9.308 to help determine dryness. Herbs are dry when they are crisp and crumbly. Conditioning of vegetables and herbs is an option to reduce concern.
Once fruit is conditioned, it is ready for packaging in glass jars, food-grade plastic containers or plastic food-storage bags. The packaging used should provide an airtight seal. An oxygen or moisture absorber may be added but is not necessary. Packaging in smaller amounts is recommended as once the package is opened, quality begins to deteriorate; the food may lose flavor or absorb moisture and odors from the air. Storing in a cool, dry, dark location is best. The same packaging recommendations apply to vegetables and herbs.
So while the dictionary doesn’t define the conditioning of dried foods, perhaps a third definition should be added. Conditioning is an essential step in the safety of dried foods, particularly fruits and tomatoes.