Food dehydrators are useful for preserving fruit and vegetables, herbs, spices, and meat. They can also be used to make tasty snacks for school lunches and lightweight tramping meals.
They work by circulating warm air around food set out on mesh trays, causing moisture in the food to evaporate. The lack of moisture makes it difficult for bacteria and mould to grow, which in turn makes the food last longer.
Dehydrating food so that it dries evenly takes time – usually several hours, depending on the food’s moisture content.
Can I dehydrate food in my oven?
Different food types require different temperatures for optimal dehydration. Here’s a guide:
Herbs and spices: 35°C
Vegetables: 45°C–50°C
Fruits: 60°C
Fish and meat: 65°C–70°C.
You can use an oven that operates at these temperatures, and it won’t take up extra space in your kitchen. But ovens that have a higher minimum temperature might cook rather than just dehydrate the food. This can reduce nutrient levels, and change flavours, textures, and colours.
It can also cause the outside of some foods to harden before the inside is dry – referred to as ‘case hardening’. This can then make it difficult for internal moisture to escape.
And the force of some oven fans can blow lightweight items (such as kale leaves) into clumps, meaning they won’t dry evenly.
A fan oven will often dry food quicker than a dehydrator set to the same temperature. But it might be noisier because of its more powerful fan and the need to leave the oven door ajar to let moisture escape.
Ovens are more expensive to run too, because of their extra power (see Running costs).
Electric food dehydrators are the best choice if you want to dehydrate a range of foods frequently, because they’re purpose-built to dry foods optimally.
But if you won’t dehydrate foods often and you have an oven that can run at suitably low temperatures with the door ajar, you might not need a dehydrator.
Types of food dehydrator
Rectangular dehydrators
Rectangular dehydrators often have trays that pull out like a drawer, but some are stackable.
Drawer style models with removable inner trays make it possible to dry food pieces thicker than the height between trays.
Rectangular drawer style dehydrators typically have a fan at the back, providing good airflow and even drying.
Round dehydrators
Round dehydrators usually have stackable trays. Some models have the option to add extra trays.
A round dehydrator has a smaller drying area than a rectangular dehydrator of the same width.
The thickness of the food that can be dried is usually limited by the height of the trays. But it’s possible to buy a spacer ring for some models, creating more headroom.
The fan in stackable dehydrators is usually at the top or bottom of the unit. It’s best to rotate the trays a few times during the drying process so food dries evenly. Models with the fan at the bottom may risk small food particles falling into the mechanism and obstructing airflow.
Food dehydrator features
Size
Dehydrators are bulky – if you won’t need to dry much at a time, choose a smaller model to save space on your benchtop and in storage.
Temperature settings
Some dehydrators have a basic set of temperature settings equivalent to low, medium, and high. Others allow you to set the temperature in increments of one or five degrees, typically within the range 35°C–70°C.
One of the models in our test also allows you to pre-set an automatic change in temperature after a certain time.
Solid and fine food mesh sheets
Most models come with one or more fine food mesh sheets for small or brittle food items, and one or two solid sheets for puree or other wet foods. You’ll need to separately buy any extras you need.
TIP: If you don’t have enough solid sheets for what you’re drying, use a sheet of baking paper cut to size on a regular tray. Create a lip all the way around the edges so your puree can’t slide off.
Easy viewing
Drawer style dehydrators often have a transparent door to allow visual progress checks. Some stackable dehydrators have opaque tray walls, while others are transparent. Our test results show which models have easy viewing.
Noise
While you won’t need hearing protection for any of the food dehydrators in our test, a noisier model might be annoying. Our test results note which are quietest.
Running costs – oven vs food dehydrator
Food dehydrators are energy efficient. While a dehydrator will often take longer to dehydrate foods than an oven, it’ll usually be cheaper because it’ll use far less energy.
While the power rating of an appliance can indicate how much energy it uses, the power consumed in a given time period depends on the settings used. For example, an oven running at 40°C will use less power per hour than if it was set to 200°C.
Even so, the power ratings of different appliances can be used to get a rough idea of the differences in power consumption and running costs.
In the following examples, the food dehydrator’s power rating is 500W (0.5kW), and the oven’s is 2500W (2.5kW). The cost of electricity is 25¢ per kWh.
Example 1 – apple slices:
Oven cost: $1.88 2.5kW x 3 hours (time to dry) = 7.5kWh
7.5kWh x 25¢ = $1.88
Dehydrator cost: 75¢ 0.5kW x 6 hours (time to dry) = 3kWh
3kWh x 25¢ = 75¢
Example 2 – mashed potato:
Oven cost: $4.69 2.5kW x 7.5 hours (time to dry) = 18.75kWh
18.75kWh x 25¢ = $4.69
Dehydrator cost: $1.31 0.5kW x 10.5 hours (time to dry) = 5.25kWh
5.25kWh x 25¢ = $1.31
