Food preservation methods: Dehydration

We’ve had questions from new CSA members regarding home food preservation techniques and any relevant items that might make good holiday gifts. We’re thrilled that folks are thinking ahead to preserving next year’s bounty, as that’s the key to getting the most out of a CSA and building the economic sustainability of local foods in general. This series will present some of our experiences and advice, along with ideas for kitchen items that we’ve found to be useful investments as serious practitioners of home food preservation.


Dehydration, like canning, takes more up-front work but produces a shelf-stable food item that requires no further energy to store. Numerous fruits and vegetable can be dehydrated; our favorites include herbs, tomatoes, peppers (hot & sweet), okra, shiitakes, strawberries, and locally purchased peaches and apples. Some dried foods are quite good just as they are. Others can be rehydrated for a few minutes in boiling water and used in cooking.

In many cases, dehydration intensifies flavor and sweetness, especially for fruit (including tomatoes). For example, during wet summers, we’ve harvested cherry tomatoes with mediocre flavor and frustratingly quick splitting. These often did not meet our criteria for market quality, so we dried a test bunch as a salvage operation. To our delight, the flavor of the resulting product was superbly sweet and complex, and they served us well on pizza throughout the winter. Now we make a point of dehydrating cherry tomatoes every year; another way to utilize what would otherwise be a waste product on the farm.

In some climates, sun drying is an option; not so much in central Missouri. It’s generally too humid here to safely or effectively dry most foods. Some ovens can be set to low-enough temperatures to act as dehydrators, but this can tie up the oven for long periods of time. And it is possible to build your own dehydrator, but by the time materials and labor are accounted for, we’re not sure that would end up being cheaper than buying a good, reliable one. After researching the options and reading online reviews, we decided to invest in an Excalibur Food Dehydrator, and we absolutely love it. These are American made and sold direct from the California factory. And they work really well. Given the cost of many dried foods like sun-dried tomatoes, or dried fruit, a good dehydrator can pay for itself in a reasonable time period, especially if you have access to extra produce through a garden, CSA, neighbor, or other source.

We have the nine tray version with an automatic turn-off timer, which is really useful for letting items dry for the proper time even if that ends in the middle of the night or when we’re not near the house. We strongly recommend getting a version with a timer. Nine trays are actually quite a lot of space to fill; working with some smallish end-of-season sweet peppers, it took the two of us about an hour to fill nine trays. Some things are faster than others; with the help of an apple peeler/corer/slicer and a capable user, trays of apple slices go pretty quickly. (Our apple peeler/corer/slicer is from Back to Basics in Draper, UT, and we quite like it. We’ve used other versions that haven’t worked as well. We can’t find a website for Back to Basics, but this gadget is available from various online sources.)

Before buying a dehydrator, you might consider where you’re going to put it. Often a running dehydrator will smell like the food inside (it is running a strong fan in there, after all). This is not a big deal when it’s tomatoes or apples, but if it’s peppers (even sweet peppers), hoo boy. We can’t be in the same room as nine trays of drying hot peppers; we tend to keep our unit in an unused back room while it’s running. It certainly doesn’t need to be in the kitchen, as the unit is self-contained and not messy. You can do all the prep and tray-loading in the kitchen, then carry the trays back to wherever your drying chamber is (spare bedroom, closet, basement). It’s also helpful to be able to open a window. Just thought we’d mention it before someone with a one-bedroom studio chases themselves onto the street with a full load of drying jalapenos.

For most items, the basic idea is to cut up the produce, maybe seed it (like peppers), and spread the pieces on each tray before setting them in the dehydrator. You can dry some items whole (like hot peppers), it just takes longer. Generally it makes sense to at least halve things. Also, the smaller the pieces, the more trays you can fit in the dehydrator at a time. When I’m doing whole cayennes, for example, I can only get 5 trays in because they stick up so much, whereas sliced Anaheim peppers allow all 9 trays.

Whatever size pieces you choose, best practice is to make all pieces roughly the same size so the whole tray or batch finishes at the same time.  Judging doneness can be difficult, and somethimes I think we’ve erred on the side of over-drying just to be safe. Over-drying results in a crispy product that won’t be as good, while under-drying risks the product molding or otherwise going bad in storage. Rotating the position of the trays can also help to ensure even drying. We consult the references mentioned below to know which products should be leathery and which brittle. Examples of the latter would include items you intend to grind or powder later, like herbs and some hot peppers (one of our standard winter spice mixes involves blending lots of different dried peppers in a food processor to make an intense pepper powder, great for salsas and sausages). There are lots of good books, manuals, and online resources (such as this University of Georgia site) for getting drying times right (our dehydrator also came with a reference manual). We’ve also relied heavily on the book Making & Using Dried Foods.

Many dehydration books are full of oddball ideas for things to dry, including lettuce (???). We’ve tried unusual things like mustard greens, which were really neat to powder into a broth, but took lots of space for almost no resulting product. It’s fun to play with trying different things. Herbs can work quite well as a way to preserve summer bounty and cut the need for purchasing old spices from a store.

Washing all the trays can be mildly annoying, so we often try to do multiple batches of the same thing before changing. Washing between different items can be quite important, though. We once dried mint, then went straight to apples thinking the uncut herbs couldn’t have left any residue. We ended up with a batch of apple rings that tasted like toothpaste. Wash your trays; no one wants hot-pepper dried strawberries.

Also, we once had an insect outbreak in some tomatoes, so we’ve started to put products in the freezer for a week or two after dehydration as an extra way to kill insects. It’s easy and increases the storage life. Just don’t open the container or bag until it comes back to room temperature, or condensation will decrease the storage life by partially rehydrating the food.

Storing & using dried foods:
Dehydration results in a substantial volume reduction, since vegetables and fruit are mostly water. This sometimes feels a little depressing when nine trays of peppers fit in a few small jars, but it also means a lot of food can be stored in a small space. We store most of our dried items in old glass canning jars that we don’t trust for canning anymore. They arrange nicely on storage shelves and seal well enough to preserve the food. Sometimes we’ll use sealed plastic bags, but these aren’t as reuseable. Masking tape labels ensure we know when the food was dried (so it doesn’t sit too long) and what exactly it is (you can’t always tell which peppers are which, hot or sweet, once they’re dried).

Apple slices, halved strawberries, and cherry tomatoes are great snacks just as they are. Others we use in soups and stews, like onions or okra, or as pizza/pasta toppings, like tomatoes, peppers, or mushrooms. These can be easily rehydrated by soaking in boiling water for a few minutes; in some cases I’ll just toss dried stuff into a simmering soup broth and let it absorb the liquid already there.

2 thoughts on “Food preservation methods: Dehydration

  1. Couple of neat tricks, 1 we do, 1 I've seen but would like to do.1. "Under dry" a batch of tomatoes (or two!) and pack them in good olive oil in a jar (for extra credit, add a bit of garlic & oregano, or other herbs). Keep them in the fridge to be safe, but holy delicious treat. Great with pasta, with bread, with cheese, etc. Best with small-ish sized tomatoes (we get a whole bunch of "Amish Paste" but we also did a batch of Green Zebra and have done cherry or grape types). And the flavoured olive oil? Almost worth the process just for that!2. Masking tape is certainly effective for jar labeling, but it can be fun to get more cute with it, especially if they may be visible. Perhaps chalkboard paint on an area to let you write what's inside in chalk. Could be a fun DIY gift/project. Or get kids involved in decorating jars… especially if you know you'll always dry the same thing each year (e.g. oregano, hot peppers, tomatoes, etc).

  2. Joshua,Great ideas. We freeze basil packed in oil, but have not tried dried tomatoes that way. In retrospect, seems obvious as that's the way some high-end ones come in stores.