The following is an excerpt from Modern Homestead: Grow, Raise, Create by Renee Wilkinson (Fulcrum, 2011). The excerpt is from Chapter 4: Preserving the Harvest.
Drying foods is a simple and space-saving way to preserve the harvest. Things like dried berries and fruit can be delicious, healthy snacks to get you through the winter months. Dried vegetables can add a punch of flavor when cooked into stews, soups, and casseroles. Although not as sexy as a jar of jam, dried foods tend to retain more of their nutritional content than canning.
As a preservation method, the drying process removes 80 to 90 percent of the moisture in food. This creates an uninhabitable environment for food spoilers like bacteria, yeast, and molds. When done properly, dried foods can last anywhere from six months to a couple years. Roughly four pounds of fresh produce will dry down to about one pound–lightweight and taking up little space in the cupboard. If you live in a tiny apartment or condo, drying the harvest may be an excellent option with your digs in mind.
The key to properly dried foods is air circulation and warm temperatures. Air needs to reach under, over, and into the sides of the foods you are drying. The ideal drying process does several things: air circulates evenly, hot temperatures are slow and steady for evaporation, and food is protected from insects and pollutants. Maintaining the perfect temperature is often the trickiest aspect of drying to control.
If the temperature is too low, it will take forever to dry the food or they may not dry out at all. You also run the risk of encouraging bacteria to multiply, which is bad, bad news. The drying temperature needs to stay above 95 degrees Fahrenheit to prevent this from happening.
If the temperature is too high, you will end up cooking the food instead of drying it. The outside cooks and creates a hard outer shell, trapping moisture inside the food, which is called case hardening. The trapped moisture will eventually cause spoilage. The hot temperature may have also killed off valuable nutrients and vitamins. You will want to keep the temperature below 140 degrees Fahrenheit to avoid cooking your beloved produce.
Food is typically dehydrated using one of the following methods: dry air and hot sun, the oven, or a food dehydrator. Of these methods listed, the food dehydrator offers the most control over the drying process in terms of air circulation, protection from unwanted particles and bugs, and keeping a steady, proper temperature throughout the process.
Using the sun to dry food is simple and rather straightforward. You will need about three days of hot, sunny weather with low humidity. In some climates, this can be most of the days of the year. In others, you may need to wait until late August to have a hot enough, dry enough few days. It is not recommended to use this method if you live in an area of high pollution, like a rooftop in Manhattan where city pollutants in the air will settle on your otherwise delicious and nutritious food.
Determine in advance where the best place will be to dry your food by hanging a thermometer outside in different locations. Ideally you want a place that will have a temperature range of 95 to 130 degrees Fahrenheit. Look for little microclimates, like near a dark exterior wall or in an unvegetated corner of the yard.
Food should be set out on racks to dry in the morning when all dew has evaporated. Racks can be made from a variety of material including thin wood, nylon, or cheesecloth, but metal should be avoided as it can have unwanted reactions with food. The racks raised above the ground allow air to circulate over and under the cut pieces. To protect the food from bugs and dust, cover it loosely with cheesecloth. Air can still penetrate underneath while tiny critters and things floating through the air have a barrier. Turn the food pieces often throughout the day to encourage even drying.
Depending on how much the temperature drops at night, you can cover the drying racks with a towel to absorb any nighttime moisture. Or simply bring the trays inside and setup again in the morning if it gets too cool or damp at night.
Some people choose to up the ante on outdoor drying by building a simple homemade solar dehydrator. The constructed frame should be fairly airtight, but have a few vent holes drilled in for continual air circulation. Ideally the vents would be able to close at night, to prevent losing too much heat. A thermometer hanging inside helps to monitor the temperature throughout the drying process. Some get even fancier and include a fan inside to help move air around.
Solar dryers can be as complex or simple as you have the motivation for. On the simple end of the spectrum, use old windows to surround the drying trays. This increases the intensity of both the sunlight and heat while protecting the food from bugs. Using foil on the walls will direct additional sunlight onto the trays. Use your creativity to put together something that works for you with salvaged or found materials. It doesn’t need to be fancy to be useful.
Ovens set on low bake temperatures can also be used for drying foods, although they suck up lots of electricity. Hang a thermometer inside the oven, as they can easily get too hot and end up cooking your food to pieces. The temperature should never exceed 145 degrees Fahrenheit. The warm setting can help you hover in this range.
Place food directly on the racks and rotate the racks in the oven often for even drying. Begin with the pieces cut-side up, so they dry and harden before flipping over to dry the other side. Keep a close eye on them, as it can take anywhere from four to twelve hours for the process to be complete.
The most foolproof method of drying food is using a commercially made food dehydrator. Simple models can be found on the cheap at estate sales, garage sales, thrift stores, and through online classifieds. Only consider models that have a thermostat, as most models do include.
Food dehydrators can be a little noisy and they do take up some room. They are only needed during one time of the year, so perhaps you can find room on a shelf in the closet, under the bed, or inside a footstool to house it in the off season. My handy grandfather helped me make a bench whose seats can lift up for storage. This has become my favorite storage space for the dehydrator.
As with other drying methods, rotate the trays throughout the process for even cooking and flip the food pieces periodically. Line the trays with cheesecloth if the openings are too big and food pieces can potentially fall through. Dehydrators with built-in fans are extra helpful for even drying.
Start with good quality produce for drying. Cut out any bad spots, overripened areas, or bruises. For everything other than herbs, wash thoroughly. Cut food pieces relatively evenly for a uniform drying time. Then determine if the produce needs to be blanched prior to drying.
Blanching is sometimes recommended for low-acid foods–often vegetables and not as often for fruits. It destroys the enzymes in low-acid foods that can deteriorate the flavor over time. It also helps to preserve the color. Blanching also softens the tissue of the food, allowing moisture to escape easier.
Blanching should be done after you are done cutting everything up. Check the chart in this chapter for a guide to recommended blanching times. You can either steam the cut pieces for the recommended time or throw into a pot of boiling water. Pat the pieces dry to get rid of excess moisture before laying them out on drying racks.
Herbs do not need to be rinsed if they are relatively clean, as washing can remove flavorful oils. Be gentle with them–crushed leaves release flavor oils. Crush them only before use in cooking. Herbs can easily be dried by hanging them upside down in a place away from moisture, as they require lower temperatures than vegetables and fruits.
The ideal drying temperature for herbs is roughly 100 degrees Fahrenheit. Fruits and vegetables should be dried somewhere around 120 to 130 degrees. Meats and fish should be dried at higher temperatures, around 145 degrees.
Drying is complete when the food is leathery but still pliable. The exceptions to this are beans, peas, and corn, which should all be hard when done. Remove a piece and let it cool when you think a batch is done. Once cooled, check the texture to determine if it is ready for storage. They can sometimes harden further once cooled. Remove individual pieces as they dry, rather than removing them all at once.
Store your dried goodies separately in airtight ceramic, glass, or plastic containers. Wood should be avoided because it breathes and can allow in moisture. Metal should also be avoided because it can leave a metallic taste on the food, unless you line the container with a plastic or paper bag.
This is your opportunity to make dried goods look more attractive, so shop around for pretty containers. I buy cases of vintage glass jars from estate sales. They are no longer recommended for canning, but they work well for holding dried goods. Arranged on a shelf together, it gives me a sense that I have a well-stocked homestead.
Give the stored goods a good turn after about a week to make sure the moisture level is even in the container. You can always dry it a little more if it seems too moist. Drying is nice and forgiving in that way. A dark, cool but not cold place is best for storage–like your kitchen cupboards. How convenient!
Most fruits will keep for up to six months or more. Vegetables vary anywhere from two to six months. Try a nibble first to make sure it still tastes great. I will openly admit to eating dried goods well over six months that tasted just fine.