Sun drying is obviously the most economical and energy-efficient, though some argue the time spent in the sun leaches some of the nutrients from the food that would stay intact using other methods of drying. All that aside, there's something immensely satisfying about using the sun to preserve or cook food.
If you want to dry food in the sun, you need to live in the appropriate climate. Sun drying is, obviously, much more feasible in the dry Midwest and Southwest US than it is in the wet coastal Northwest. Trays need to come in at night. Also, bugs can be an issue. Food can be kept safe from most bugs when dried under a cheesecloth or nylon net, just be sure the material isn't laying on top of the food. A lot of it is just common sense. If you live next to a busy freeway, sun drying is probably not the method for you, lest you like sucking tailpipe. Yum, I love a little lead with my fruit. (Um, that was sarcasm, in case it wasn't obvious.)
To learn more about this method, google away or see if you can get your hands on a book explaining the best methods, tray construction techniques, tips, and tricks.
OVEN or DEHYDRATOR DRYING
These methods, though not as energy efficient, are more reliable and typically much faster. Food dried this way has more color, flavor, and nutrients than food dried in the sun. Dehydrators are the easiest to use but ovens are probably the most universally accessible and can be used to dry food year-round. Because dehydrators typically come with their own instructions and recipe books, I'll stick with oven drying for today's post.
The main issue with oven drying is temperature regulation. Ovens cycle on and off and you really want a steady temperature for drying. Also, many ovens cannot be set to the low temperature recommended for proper food drying - 120-150 degrees F. Most people purchase a freestanding oven thermometer to monitor the temperature and prop the oven door open to vent some of the excess heat. Gas ovens should be open at least 4-8 inches and some people recommend placing a fan just outside the open oven door to help circulate the hot air. Given all those guidelines, I've had great success drying fruit at 225 degrees F with the oven door shut. Just experiment and see what works for you.
I dry my food on a cooling rack nestled inside the edges of a sheet pan. This allows the air to circulate all around. The food needs some breathing room, so don't overstock your tray. Every two hours, the trays should be rotated, top to bottom, front to back, etc. Also, sometimes it's necessary to flip the fruits on the trays. Veggies may be done in 5-12 hours. Fruits may be done in about 6 hours.
Completely dried and brittle produce will keep indefinitely in an airtight container in the cupboard or pantry. If the food still has a bit of moisture in it, wrap it in plastic or place it in a container in the fridge. It'll keep that way at least a week and probably longer.
Since tomatoes are in abundance right now, tomorrow's post will offer detailed instructions on my favorite method for drying tomatoes.