Drying foods is one of the oldest forms of food preservation. Using the sun or the heat from a fire were the methods used by ancient peoples. Drying removes the moisture from fruits and vegetables, preventing the growth of bacteria or mold.
As with many types of food preservation, the recommendations are often changing and improving as more research is conducted into food safety. Food safety experts recommend the oven or a dehydrator for drying food as it keeps the food at a consistent temperature. In a humid environment, it is extremely difficult and not recommended to dry foods without an oven or dehydrator.
Before & After: Drying Kadota Figs
There are solar dehydrators available, but drying using only the sun is often discouraged because of the inconsistency in temperature and the risk of contamination of foreign materials like dirt and dust. If you are laying trays of food outside they could have insects or birds take interest in them, or you even risk a chance of rain ruining your efforts.
While drying is a pretty simple form of preservation, calories and sugar are condensed in dehydrated foods, and often Vitamins A and C are greatly reduced or eliminated by the process. Since the moisture is removed, the foods are lighter in weight making them ideal for backpacking.
Freeze Drying Foods
Freeze-drying involves the sublimation of water, where it transitions from a solid (ice) to a gas (vapor) skipping the liquid phase. The food is frozen at an extremely low temperature under pressure. Then a mild heat is applied, which causes the water in the fruit or vegetable to sublimate, and there is also a secondary drying step.
I always learn something new when I research these articles. Did you know that way back in the 13th century the people of Bolivia and Peru were some of the first known to practice freeze-drying food? The unique conditions of the Andes mountains allowed them to freeze-dry potatoes, also known as chuño.
Modern freeze-drying does require special equipment, and the cost and storage space for that equipment can put it out of reach for many gardeners. On the plus side, freeze-drying does preserve more of the nutrients that can be lost in traditional drying. However, the heat step in freeze-drying is not sufficient to kill harmful viruses or bacteria which may reactivate and begin to grow when the food is rehydrated. This uncertainty can be eliminated by properly cooking the food either before or after freeze-drying.
Freeze-drying also prolongs the storage time. On average when stored properly, regularly dried foods can be kept for six months to about a year without risk of nutrient loss or degradation. Freeze-dried foods, on the other hand, can be stored for decades.
What Should I Dehydrate?
There are many fruits and vegetables suitable for drying. I’m leaving my jalapenos on the plant this fall and letting them turn red to see if I can then successfully smoke them and turn them into chipotles. This summer I dried herbs like lemon verbena and Mexican oregano, Thai chiles, and figs. I used the sun/air-drying method, placing trays on shelves in my skylights. I’m not too concerned about the safety aspect because, with the larger foods, like the figs, I’ve also stored them in the fridge and plan to reconstitute them by boiling them, which should clear them of potential pathogens.
For fruits with tough, wax-like skins such as figs, cherries, grapes, and plums, it’s recommended to crack the skins, basically by blanching. This will allow the moisture to pass out of the fruit more easily. I skipped this step when drying figs, as I chose to cut them in half instead to further speed up the drying process.
I also dried goji berries, but have decided that I’m not a fan of their flavor. In years past, I have also dried blackberries, sumac, rose hips, Oregon grapes, and juniper berries. Most of these I add to broths or teas.
Kale chips are a popular idea for drying greens. I also like to make what I call a green, super-food powder. I dry the leaves of kale, spinach, carrots, beets, strawberry spinach, or even wild edibles, like common mallow. Once the leaves are completely dry, I crush them into a powder and store them in a glass jar. The powder can be added to smoothies, sprinkled on soups, and mixed into casseroles, mac & cheese, or pasta salads.
