Food drying is a convenient way to store foods as it concentrates flavour, takes up little space, and since dried fruits and vegetables can be powdered in a blender, it’s easy to slip some extra nutrients into just about anything. Drying or dehydrating removes enough moisture from the food so moulds, bacteria, and yeast do not grow. Dehydrated foods are convenient, store easily and have a long shelf life when properly stored in airtight containers in a cool, dry, dark location. Food drying does not improve the quality of vegetables or fruit, so its important to select high-quality products at the desired stage of ripeness.
Drying requires a constant temperature hot enough to dry foods without cooking, plus enough air circulation to ensure even drying and to carry away any moisture given off by the food. You can use your home oven or purchase a specialized food dehydrator. While microwave ovens are a useful kitchen appliance, they are not designed for drying food.
Dedicated food dehydrators are versatile, dry evenly with the best quality, and use less power than your oven. Dehydrators typically feature stacking mesh racks with either horizontal or vertical airflow. Some experts suggest horizontal models are more efficient as several kinds of similar foods can be dried at the same time without flavor mingling. Costs vary depending on the features offered. Important features include an enclosed heating element, enclosed thermostat, fan, mesh trays that are easily washable, dial for regulating temperature, and a timer. You may also want to invest in liner sheets for making fruit and vegetable leathers (more on that in a future article).
Drying food in a conventional oven requires time, patience and scheduling. While cookie sheets do work, placing your cut food onto mesh cooling racks will allow for better air circulation. Make sure your trays holding the food be no closer than 3 cm (1 1/2 inches) from oven walls and 7.5 cm (3 inches) between racks. To achieve the best results when drying, maintain a low temperature of 40º to 70º (100º-150ºF). Place an oven thermometer near the food to get an accurate reading of the drying temperature. Your oven door should be open slightly throughout the drying process, so experiment to see what temperature you need to set your oven at to maintain low heat. Placing a fan near the oven door opening will create more air circulation and help speed the evaporation process. Rotate your food every hour to promote even drying.
Whatever method you’re using to dry, cut your food to a uniform size no matter if slicing, dicing, cubing or leaving whole. As well, arrange food in a single layer, and keep enough space between the pieces on the tray to encourage even drying. Drying time varies greatly depending on the method, humidity levels, size of produce, and preference. Be patient and don’t be afraid to experiment – you can always put it back in to dry longer if it isn’t ready!
Before drying vegetables make sure to wash, blanch, and then slice, dice or shred your vegetables. Blanching helps slow enzyme activity, preserving quality during storage, as well as helps preserve color. See our blanching article for detailed instructions on how to blanch and suggested times.
After blanching, dip the vegetables briefly in cold water. When they feel only slightly hot to the touch, drain the vegetables. Cut into uniform pieces or, for firmer vegetables like carrots, shred into larger shreds. The smaller the pieces, the faster the drying time providing that you still have good air movement. Place your vegetable pieces in a single layer on a prepared baking sheet or dehydrator trays and place immediately into the dehydrator or oven. Rotate and turn trays every hour.
Drying time depends on the type of vegetables and size of pieces. The heat left in the vegetables from blanching will cause the drying process to begin more quickly. Watch the vegetables closely at the end of the drying period as they will begin to dry much more quickly and could scorch. Vegetables should be dried until they are about 10 percent moisture. Vegetables like broccoli, celery, corn, kale and eggplant should be dry and brittle. Beets, cabbage and carrots will be tough and leathery. If you want a crispier end result, shred your vegetables whenever possible. Crispness is necessary if you intend to powder your vegetables. Once dried, condition vegetables by storing in an airtight container for 10 days to distribute remaining moisture evenly throughout the food. Store in airtight containers in a dry, cool, dark location.
Dried vegetables are good in stews, soups, and casseroles and require no presoaking as they rehydrate during the cooking process. Dried vegetables may also be powdered in a dedicated coffee grinder or food processor and slipped into other recipes, soup or smoothies. To reconstitute diced dried vegetables, soak them for up to 2 hours in water to rehydrate, using a ratio of two parts water to one-part dried product and use as fresh vegetables in your recipes.
Most fruits can be successfully dried with the exception of high water content varieties like citrus. Use only firm, ripe, high-quality fruits. Smaller fruits and berries, like grapes, cherries and blueberries can be dried whole once their skins are broken by water blanching for 30 to 60 seconds. Larger fruits like apples, pears, or pineapple do not require blanching but must be cut into uniform slices. The thinner the slice, the faster the drying time. Aim for under ¼ inch thick in most cases.
Some fruits, like apples, tend to brown once cut. When preparing larger batches of these types of fruit use a holding solution such as an ascorbic acid water solution or a commercial antioxidant like Fruit Fresh to soak the cut fruit in until you’re ready to process it. When you’re ready to dehydrate soaked fruits, take the time to pat them dry before arranging them on the drying trays.
Dry your fruits using the same basic drying directions above, skipping the blanching for cut fruits. Once fruits are dried, cool them completely. Some fruits will remain pliable after drying, but they should not feel sticky. Condition newly dried fruits for 7 to 10 days in a plastic or glass container no more than 2/3 full. Check daily for condensation on the container lid or any signs of spoilage. Once conditioned, package them in clean moisture-vapor-resistant containers.
Keep in mind that dried fruit has intense flavors and concentrated fruit sugars. They can be eaten as is or reconstituted and used in crisps, cobblers, pies and sauces. Since they tend to be more leathery, dried fruits do not tend to powder readily. If you want to powder your fruit, ensure you cut the pieces small and dry them until they’re crispy.
Keeping your newly dried produce in the best quality long term is simple. Glass jars, metal cans or freezer containers are good storage containers if they have tight-fitting lids. Plastic freezer bags are acceptable too. Whatever container you choose, make sure to label and date it. Store your dried produce in a cool, dry, dark location. Most dried fruits stay their best up to 1 year at 16ºC (60ºF) or 6 months at 27ºC (80ºF). Dried vegetables have about half the shelf-life of fruits before quality starts to decline. To store any dried product longer, place it in the freezer.