Dehydrating Food

Why dehydrate your own food?

Dehydrating food is one of the oldest forms of preserving, and it’s a brilliant skill to master if you’re interested in moving towards a zero waste lifestyle, as dried ingredients form the basis of so many delicious ways of enjoying food. It’s a comparatively low-energy way of preserving seasonal produce while it’s abundant, meaning you’re working long term to make the most of natural resources and reducing waste.

Once you’ve learnt to dry fruits, veggies and herbs, you’ll have ingredients you can use for making granola, flavor rubs, seasoning flakes, stuffing blends, stock powder, fruit leather, risotto mixes, bliss bomb blends, baked-goods flavourings, dessert toppings, and much much more. If you’re interested in learning more about dehydrating, we run one-on-one coaching sessions and the occasional workshop, so let us know if you’d like more details.

Basic dehydrating tips

  • You can dehydrate things in a commercial dehydrating unit; in baskets or on screens in the sun; by hanging in a warm, airy spot; in the oven; and even in the microwave.
  • The thinner you slice ingredients, the quicker they dry (more surface area means more places for inner moisture to escape). Grating or crushing some ingredients is useful if you want to speed drying times – this works particularly well for things you’re going to grind to powder.
  • Use lower temperatures (35-45C) for more tender ingredients, or things with volatile oils like soft herbs, thin leaves or flowers
  • More juicy things like fruits can withstand higher temperatures (45-70C), but at the higher end they may cook rather than dry, and can change the flavour & appearance.
  • Robust ingredients like firm vegetables dry well at higher temperatures (60-70C).
  • The lower the temperature, the longer it takes.
  • Use baking paper or reusable baking sheets under fruit leather paste, herbs, chopped/grated ingredients and soft fruit slices to stop them sticking to/falling through trays.
  • Allow ingredients to cool down completely before putting in airtight jars. Warmth creates condensation, and if you jar them hot, they’ll cause damp which makes everything rehydrate and can lead to spoilage.
  • But! Don’t let ingredients sit out for too long after they’re dried, or they will reabsorb moisture from the environment. It’s a fine balance.
  • When making flavoured powders, ingredients must be bone dry. If not, they’ll clog up your grinder, and the resulting powder will clump as moisture redistributes.
  • Store dehydrated ingredients in properly airtight containers (old jars are great, as long as the lids are undamaged and seal well), otherwise they’ll reabsorbed atmospheric moisture.
  • Chuck a silicone bead sachet (we collect these from friends who save them when they buy shoes or handbags) in the jar with your dehydrated ingredients to absorb any moisture and help preserve them for longer. If you don’t have any, you can use a bit of uncooked rice tied in a bit of cotton fabric instead.

Ways of drying food

There are several ways to dehydrate food, and it’s useful to know about each of them so you can make the most of your time, resources and energy. Below we give you a general rundown on:

Dehydrating food in the sun
Dehydrating food inside
Dehydrating food in an electric dehydrator
Dehydrating food in an oven
Dehydrating food in the microwave

Dehydrating food in the sun

Lay out ingredients, making sure to keep them single layer and leaving a bit of space around each piece. Place the tray in a spot you know will get full sun during the day, and bring inside at night. Repeat until you are happy with the dryness of your ingredients. Some people will utilise the dashboard of their car to dry small batches of food, which is a really clever use of resources. It also means they don’t need to take the food inside overnight, meaning it’s a more hands-off approach.

If using baskets, use ones with a fine flat weave, or lined with tea towels, muslin or thin paper (baking paper works, and so do clean wrappers from WGAC rolls) so ingredients don’t get stuck in the weave. You can also use mesh trays (cooling racks for baking are useful if lined), or our favourite for larger quantities- a window mesh screen. If you want to make your own screen, a piece of shade cloth tacked onto a basic wooden frame works really well.

You need to make sure there is airflow around the ingredients, so propping the basket/screen up on some bricks or a few bits of wood is a good solution. What you don’t want is to welcome wildlife, so positioning a cover of muslin or fine material (a clean, very thin scarf can do the job beautifully) like a tent over the food is a good idea. Of course, if you have one of those food cover domes/nets, they’d work well too.

You want as much heat as possible when dehydrating outdoors. You can maximise the thermal mass captured around your house by placing your setup over concrete, bricks, pavers or even a metal roof (of a shed etc) in a sunny spot. These materials absorb and store the heat from the atmosphere and release it slowly – that’s why some areas feel warm well after the sun has gone down. Basically, think of the spot outside that you avoid on stinking hot summer days because it captures the heat so much, and put your setup there!

Of course, if you want to do lots of solar dehydrating, you may like to consider building a specific unit to do so. Here’s a few designs we’ve been looking at while we consider making one with repurposed materials.

Dehydrating food inside

One dead simple way to dehydrate things is to utilise the heat that rises to the higher areas of an indoor room. Traditionally, farmhouses would have racks that could be lowered and raised by ropes so people could tie bunches of herbs and flowers to dry up in the eaves. Sometimes this was in the kitchen (away from the oils and fats of the stove though), sometimes in the larder, and sometimes in a room up above the barn or storage shed.

If you have a wood heater or radiator heaters, hanging things above them is a great way to dry things. If you have an old gas heater or ducted heating, positioning baskets in front or above them can be great for stacking functions during winter. Sunny north or west-facing windows are great for passively utilising the sun’s energy to dry things.

Hang small, loosely bound bunches of herbs upside down from their stems. Fruit slices such as apple and orange can all be carefully threaded onto sturdy cotton cooking twine and suspended across a wider area (leave space between each piece so air can circulate). This method was traditionally used for drying mushrooms too.

Softer things like berries (elderberry and hawthorn in particular) can be laid out in their bunches on lined baskets and propped on top of heaters or above wood stoves.

Dehydrating food in an electric dehydrator

This one’s pretty easy, as most dehydrating units come with an instruction guide, so we won’t go into much more detail here. The best advice we have for using dehydrators is to look for units that have metal trays rather than plastic ones, as plastic will deteriorate over time and begin to break. Rectangular units are easier to use than circular ones, especially when it comes to making fruit leathers, as it’s simpler to lay items out neatly and efficiently on a large rectangular tray than have to navigate a ring shape.

You can mix and match the foods you’re drying at one time if they require similar drying temps and times, but be aware that strong flavours/aromas will permeate all items in a dehydrating unit. Therefore, drying chilli or garlic alongside apples may not be ideal. Bananas are notorious for sharing their aroma, so we always advise drying them separately.

It’s good practise to swap and rotate the trays in your dehydrator a few times during a drying cycle, as certain areas/trays will get hotter because of their proximity to the heating unit and can lead to uneven drying otherwise.

Dehydrating food in an oven

Dehydrating using an oven is possible, but when it comes to energy usage, it can rank quite high so if you plan to do lots of dehydrating, you will probably want to investigate other options. It’s also important to remember that as soon as you heat most foods above 100 degrees Celsius, you enter into the realm of Cooking rather than Dehydrating, so if your oven doesn’t have temperature settings below this, your options to use an oven will be further limited.

There are three basic ways you can use an oven to dehydrate food: on a low setting for a continuous session; in repeated short sessions as the oven cools after other cooking; on top of or above the oven as it cools (wood fired ovens). Each have different conditions, so here’s a rundown.

Regardless of which method you go for, the way you prepare your food for drying remains the same: cut thin, uniform-thickness slices, lay them out on a flat surface or hang on strings/skewers with space around each piece. If using trays, lining them with baking paper or a wire rack/mesh is useful to stop food sticking to the tray. Using a rack (like a cooling rack for baking) also allows for increased airflow, thus speeding the drying process.

In repeated short sessions as the oven cools after other cooking.

If you’re a household that uses the oven daily, this may be the best option for you. It involves having your fruit/veg/herbs laid out on trays that you can spare for a few days, and every time you turn the oven off from regular cooking, you pop the trays in once it’s dropped to 100C and leave them in there with the door ajar as the oven cools down completely. You can then leave the tray in the oven until you next need to turn it on again. It will often take several days to dry food thoroughly using this method, but it’s a good option for the energy conscious person, as it uses the residual heat from cooking rather than requiring ‘new’ energy to generate heat.

Mixed dried wild mushrooms make for delicious pizzas
On a low OVEN setting for a continuous session.

Set the temperature to as low as it can go. Many modern electric ovens will get down to 55C, which is a good place to start for fruits. Anything above 70C is getting a bit hot. If your oven has a ‘warming’ compartment, it’s worth working out how to use it for dehydrating rather than the whole oven.

You will need to keep the door open slightly throughout the drying process so the moisture from your food escapes as it dries. Be aware that knobs or handles above the oven door can become very hot (and potentially melt if they’re plastic) due to the open door, so be careful. You may also need to rotate the trays partway through if your oven has hotspots.

Drying in one continuous session means you will need to have the oven running for around 8 hours and potentially longer, so prepare for that: don’t attempt this on a Summer day, as the whole house will heat up!
You’ll also want to maximise your usage of space, otherwise this is a highly unsustainable use of energy to create a small amount of food. This might mean that you investigate different ways of positioning your produce to make the most of space – hanging slices from skewers between racks like below is one way of doing this.

On top of or above the oven.

This is primarily for wood-fired oven users. You can hang bunches of herbs and strings of fruit or veg high above the oven to take advantage of the heat generated while cooking, or you can lay out trays of food and place them on top of the oven as it cools after cooking, much like the second oven-drying method above.

Dehydrating food in the microwave

This is handy if you want to dry very small batches of things quickly, but would be unsustainable for larger quantities. It’s great for doing a quick batch of herbs.

For herbs:
Lay herbs between two pieces of paper towel or clean teatowel. Cook at standard power in bursts of 15 seconds until crispy.

For fruit or veg:
Lay thin slices of fruit or veg directly onto the clean turntable plate. Cook on the Defrost function for 15 minutes and check. Repeat for a further 10-15 minutes if required. When dry to touch and no longer ‘squishy’, they are done.  This works well with apples, bananas, mushrooms and zucchini. Not so ideal for juicier foods.

So there’s a range of ways to dehydrate fruits, veg and herbs using a variety of resources which can hopefully give you the confidence to look at your home system and see how dehydrating could fit in as a way of preserving food when it’s most abundant. Once you have a pantry filled with dehydrated ingredients, you’ll find yourself making more of your own food from scratch, which is great for long-term reduction in packaging waste and also better for your health as you’re less likely to be ingesting preservatives and excess salt or sugar. So our advice is to dehydrate all sorts of things as and when they are in abundance, and then work out what you ca make with them later down the track. Some of our most inventive recipes have come about because we decided to add a dehydrated ingredient at the last minute!

Permaculture Principle 2: Catch & store energy; 6: Produce no waste; 9: Use small and slow solutions.