loading
Canning and Preserving Class
Enroll
Lesson 7: Drying / Dehydrating
Ask a Question

Drying/Dehydrating is the oldest form of food preservation. From prehistoric to modern times, humans have used the heat from the sun, fanned by fresh air, to dry everything from mushrooms to fruit to herbs to seeds for planting the following season.

While it has always been an option in hot, dry climates, the advent of dehydrators (primitive to electric) have made drying and dehydrating foods for later consumption accessible and so easy!

In this chapter, we'll look at how we can adapt this ancient technique at home to properly air dry herbs and use a (not so ancient) dehydrator to make fruit leather and dried tomatoes.


Why This Method Works

Like us, both enzymes and the spoiler microorganisms need water. Without it, they can't survive and won't thrive. While dried foods do still contain a bit of moisture - from 2-10% depending on what it is - as long as the foods are properly stored, it isn't enough water content to support the growth of spoilers. (Take that Salmonellae!)

It's also recommended to steam-blanch vegetables before drying. I know this seems counterintuitive, exposing something to water before drying it out, but it works like it did in the freezing chapter to slow enzymatic action and help the veggies retain vitamins during the drying process. It also helps keep their colors bright! The only difference from the freezing chapter is that they should be steam-blanched instead of dipped in boiling water. Vegetables require longer blanching times in order to stop the enzymatic action that spoils low acid foods and they would get too waterlogged if we used the boiling water method.


Supplies

For Air Dried Herbs

Optional:


For Fruit Leather

  • dehydrator (or oven)
  • fruit leather dehydrator sheets (or parchment and spray on oil)
  • ripe fruit*
  • lemons
  • cutting board
  • paring knife
  • chef's knife
  • medium bowl
  • small bowl
  • citrus juicer
  • blender
  • measuring cup
  • measuring spoon
  • colander

*Apricots, peaches, plums, berries, apples, pears and grapes can all be used by themselves or mixed with one another. Yum!

Optional:

  • craft wood as spacers**
  • craft wood as leveler**
  • masking tape**

**These are used for a little system I made to get my leather to be a uniform thickness. Check it out in the fruit leather step! Similar wood strips are available at art supply or hardware stores.

For Dried Tomatoes

  • dehydrator
  • tomatoes
  • cutting board
  • paring knife
  • chef's knife
  • colander
  • large bowl
  • vinegar


What (and What Not) to Dehydrate

As with all forms of preservation, there are foods that are better suited to this method than others.

An important warning to mention about what you shouldn't dry/dehydrate before we get to what you should:

NEVER HOME DRY eggs, poultry, and meat (except for very lean meat that is being made into jerky). These foods are a favorite of Salmonella and Staphylococcus bacteria. It's not worth the risk. Leave these to the commercial professionals.

Now, onto a sample list of wonderful things to dry at home. Remember to only use food that is in prime condition, aka very fresh*, as for all forms of food preservation.

Fruit

  • pears
  • peaches
  • cherries
  • apples**
  • apricots
  • prunes
  • nectarines
  • coconut
  • dates
  • berries
  • bananas
  • blueberries***

*I do like my fruit to be on the ripe side of fresh for fruit leather because I find that produces a more flavorful product.

**In order for apples not to turn brown (aka oxidize) during the prepping and drying process, sprinkle a solution of 3 teaspoons ascorbic acid dissolved in 1 cup water over the pieces as you peel, pit, core and slice them. Peaches, apricots, pears, and nectarines also benefit from this practice.

NOTE: There are certain fruits that have a natural wax-like coating on them that need to be 'checked' in order to properly dehydrate. This means removing the coating by blanching them for 10 seconds and then plunging the fruit immediately into cold water. The fruit, other than blueberries, that require checking are: cherries, figs, grapes, prunes, dark plums and huckleberries.

Vegetables

Vegetables are less commonly dehydrated, but there are a few that work well with this process.

  • chili peppers
  • tomatoes
  • sweet potatoes
  • sweet corn
  • some herbs
  • mushrooms

*If you have more veggies to add to this list, please send me a note!


Air Drying: Herbs

If you're harvesting your own herbs to dry, it's best to pick them on the morning you plan to hang them, after the dew has dried. This will help prevent wilting. If you're buying herbs from the farmers market, handle them gently and keep them in water like cut flowers until you're ready to prepare them for drying.

Remove any dirt and dark, crushed, or otherwise unappealing leaves. Wash the remaining leaf filled stems carefully and lay them out on paper towel or a clean kitchen towel to air dry.

Herbs that do best with air drying in small bunches are the following less tender varietals:

  • rosemary
  • sage
  • thyme
  • summer savory
  • parsley

Divide them into small bunches and either wrap the bundle ends in butcher's twine for hanging, or use a rubber band to secure them. I prefer the twine because the dangling length offers more options for ways to hang the bunches.

NOTE: It's important the bunches are small otherwise, the moisture can get trapped near where the ends come together and cause mold to grow.

The herbs retain the best color and flavor if they are dried in a well ventilated indoor area that is out of direct sunlight. I like to use clothespins to hang them from a suspended dowel, but you can really hang them from anything as long as it's in an appropriate location.

The following tender leaf herbs have a higher moisture content and benefit from being dried inside paper bags with holes cut out of them for air flow. (The bag absorbs some of that extra moisture.):

  • basil
  • oregano
  • tarragon
  • lemon balm
  • mints

Here's how to prepare a bag for drying herbs in:

Cut down a standard paper lunch bag so that it's slightly shorter than the herb bundle it will envelope.

Use scissors or a hole punch to cut holes in the bag for air flow, making sure to put one in the center of the bottom of the bag for the string and herb stems to go through.

Like so!

String the end of the twine up through the hole in the bottom of the bag and pull the herb bunch up until the stem ends poke though.

It is now ready to be hung and dried in a well ventilated indoor area that is out of direct sunlight. Depending on the humidity in your house, air drying herbs should take anywhere from 4-7 days. They are ready to be put in storage containers when they are crispy dry and crumble easily when crushed between your thumb and forefinger.

Beautiful dried herbs!

NOTE: Another way to dry larger leaved herbs like mint, sage, and bay is to remove the individual leaves from the stems and lay them in single layers, without touching, on paper towel. Top with another paper towel and continue layering and stacking leaves and paper towels. You can go as high as five layers! Leave the stack in the (cold) oven overnight and the oven light of an electric or pilot light of a gas range is plenty warm to help these dry out quickly (but not too quickly).

Once the herb bunches are dry, remove the leaves by running your (clean) thumbnail down the stem, scraping off the leaves or picking the larger ones off one by one.

Like so!

Store the herbs in airtight containers (I love using canning jars) and keep in a cool, dark and dry place like a drawer, cupboard or pantry.

NOTE: Dried herbs are 3 - 4 times stronger than fresh herbs, so when replacing fresh with dried in a recipe that calls for fresh, add 1/4 to 1/3 the amount of dried herbs.


Using a Dehydrator: Fruit Leather & Dried Tomatoes

If you plan on doing a fair amount of dehydrating, I highly recommend investing in a good quality electric dehydrator. It doesn't have to be the fanciest on the market, but things to look out for are:

  • metal racks (if you're concerned about warm/hot food touching plastic like I am)
  • a side mounted fan* instead of a bottom mounted fan

*A side mounted fan more evenly distributes the air to all racks so that you don't have to shuffle the racks throughout the drying process.

Using an Oven Instead

If you'd rather try out these recipes to see if you like the results before investing, not to worry! The oven will work just fine, but will require some extra attention during the drying process.

The dehydrating processes can take anywhere from 6-24 hours (depending on what you're drying) and most home ovens don't have low enough settings to replicate the dehydrator settings, so you end up having to use (and monitor) an oven thermometer and attempt to keep the temp low enough by turning the oven off and on repeatedly, so that it doesn't over heat the foodstuffs. But it IS possible and a good way to start out if that's the only resource you have. If you are lucky enough to have a convection setting on your oven, always use that for dehydrating, as the air flow created cuts down the oven drying times by almost half.


Fruit Leather

Fruit leather is a personal favorite. and PEAR fruit leather is at the top of my leather favorites pyramid, so that's the recipe I'm sharing.

I will also confess up front: I like PAPER THIN fruit leather. I like it to be so thin that it melts on my tongue. So if you want a thicker, more traditional result, not to worry, I'll let you know where and when to make changes to my instructions.

Recipe

  • 4 cups of washed ripe pears* (approx. 8)
  • 4 tsp lemon juice (fresh or bottled) OR 1/4 tsp ascorbic acid

*If pears aren't your jam, you can substitute them for apricots, peaches, plums, berries, apples, or grapes. These fruits can all be used by themselves or mixed with one another. Yum!

NOTE: Also feel free to add any dried herbs or spices to the mix. Cinnamon Pear? Lavender Pear? Mint Apricot? Yes!!

Tool Reminder

  • dehydrator (or oven)
  • fruit leather dehydrator sheets (or parchment paper with spray on oil for use in the oven)
  • baking sheets (if using an oven)
  • cutting board
  • paring knife
  • chef's knife
  • medium bowl
  • small bowl
  • citrus juicer
  • blender
  • measuring cup
  • measuring spoon
  • colander

Optional:

  • craft wood as spacers**
  • craft wood as leveler**
  • masking tape**

*These are used for a little system I made to get my leather to be a uniform thickness. Check it out below!

How to Make Fruit Leather Like A (Lazy) Boss

Gently wash the beautifully ripe fruit.

Either juice some fresh lemon juice or take your bottle of store bought juice out of the fridge.

Add a sploosh of lemon juice to a medium sized bowl filled with cool water. This is where we'll put the pear slices as we cut them, to keep them from turning brown.

Use a paring knife to cut away any soft spots or bruises on the fruit.

Cut the pears into cored and speared pieces (like above).

Place them in the lemon water as you go until they are all hanging out together in their temporary pool.

NOTE: At this point, some experts say that it's important to par-cook the fruit before blending it into the spreadable deliciousness that gets dried into sheets of YUM. As previously mentioned, I'm lazy when it's safe to be, so I skip that step and just store my finished product (fruit roll up) in the freezer in the off chance that there were any spoiler hitch hikers in the un-cooked blender mix. It's also fair to mention that the National Center for Home Food Preservation doesn't think it's necessary to par-cook the fruit before blending for fruit leather either. So I'm justifiably lazy this time. :)

Drain the pears in a colander and measure out 4 cups of spears. Add both the pears and lemon juice to the blender.

Blend on high to puree. When the mix is smooth without any chunks, transfer to a pouring vessel (like a measuring cup).

And here's where my MacGyver/OCD spirit kicks in and I show you how to make super even fruit leather sheets using just 3 pieces of craft wood and some masking tape.

  • For paper thin fruit leather like mine, use two 1/8" (3mm) side wood pieces.
  • For a more traditional fruit leather thickness, use two 1/4" or 3/8" side wood pieces.

NOTE: The side wood pieces dictate the thickness of the pre-dried fruit sheets. The thickness of the third piece that is used to push and pull the pulp, isn't as important. It just has to be wider than the drier racks and no bigger than 1" x 1/2", although thinner/smaller is easier to handle.

Here's the how-to in sped up video style:

  • Use the masking tape to secure the two side pieces of wood to the counter or to a cutting board.
  • Pour a few splooshes of pureed pear onto a drier sheet OR onto parchment paper with a thin coating of spray canola oil.
  • Use the third piece of wood to push and pull the puree around on the sheet until you've created an even and nicely shaped sheet of 'future leather'.

Flip up the side pieces of wood if they're covering the edges of the drier sheet or parchment paper. Slide a dehydrator rack (or if you're using an oven, a baking sheet) under the sheet edge and pull it up onto the rack or baking sheet. Place in dehydrator and repeat for 2-3 remaining racks (depending on how thick you're making your fruit leather). If using an oven, set first sheet on top of oven and make one more sheet of leather on parchment.

To process in a dehydrator: Turn the dehydrator to 140°F and set the timer to 4 hours. Check it after those 4 hours (there should be no indentation when pressed with a finger) and keep processing it at 1/2 hour intervals until it's done.

To process in an oven: Set oven to 140°F, leave the door cracked open a bit using a dish towel or a wooden spoon handle and follow the above directions. If your stove doesn't have that low of a setting, you will need to get a oven thermometer so you can gauge your 'warm' setting and keep adjusting the heat manually by shutting it off and turning it back on periodically.


Faux Sun-Dried Tomatoes

All you need for this recipe is TOMATOES! And of course the tools listed below.

I like to use vine ripened and cherry tomatoes, but other great 'maters for drying are roma, plum, or any paste tomato. I had never tried an heirloom varietal before, and they are so delicious fresh...so added one into the mix. The best thing about drying tomatoes, is that they don't need to be blanched first, so they're quite quick to prepare.

The results are in on the heirloom test: It turns out its water content is much higher than its vine ripened cousins and it required way more drying time than their smaller, less moist counterparts. Not worth the extra expense and energy output in my opinion.

Recipe

  • tomatoes
  • vinegar

Tool Reminder

  • dehydrator or oven
  • cutting board
  • paring knife
  • chef's knife
  • colander
  • large bowl
  • parchment paper, if using the oven

To remove any surface spoilers, wash the tomatoes and place them in a large bowl of cold water mixed with one cup of white vinegar for 10 minutes. Be sure to periodically flip the tomatoes that are floating so that both sides get soaked.

On a clean cutting board, use paring and chef's knives to remove the stem end and slice them into 6-8 wedges.

NOTE: We'll be standing the pieces up on their skin sides, so the wedges have to be wide enough to stand without falling over.

Place a fruit leather sheet or some tin foil in the bottom of the dehydrator to catch any drips.

Lay the wedges, skin side down, on the dehydrator trays or on baking sheets layered with oiled parchment paper. Leave plenty of space between the pieces so theres a lot of air circulation around each piece. This will help them dry faster and prevent mold.

If you're using any cherry tomatoes, slice them in half lengthwise and lay them out skin side down on the trays.

Like so! Now you're ready to bring the heat. Turn your dehydrator or oven to 140°F. If you're using an oven, don't forget to prop the door open a bit. And because of the high moisture content in tomatoes, it also helps to set up a little fan to blow into the oven opening if you have one.

They will take anywhere from 6-18 hours to dry depending on the thickness of the pieces and moisture content of the tomatoes you chose. Check in with them at 4 hours and then monitor them every hour after that until they're done.

To rehydrate your dried tomatoes for use, place them in a heat-proof bowl and cover them with boiling water. Let them sit for 15 minutes. Remove them from the water and use.

NOTE: As they soak in the boiling water, some of their vitamins and minerals AND flavor leach out into the water. So don't throw the water out! Save it and use it in a sauce, to make risotto, or a delicious soup.


Storage Tips

Place all dried/dehydrated foods in airtight containers, label/date them and store in a cool, dry, dark place like a cupboard or pantry. As long as moisture doesn't get introduced into the containers, the dried foods should last indefinitely.

CLASS PROJECT

Share a photo of your finished project with the class!

Nice work! You've completed the class project