Dehydrating times

There is no exact way of determining dehydration times as it depends on many factors:

The moisture content of the ingredient being dried
The thickness of the slices, cubes etc
The quantity of food being dried
Humidity levels (and these will vary from day to day according to where you live and the general weather)
How well you have patted your ingredients dry before adding them to your dehydrator
The make of your dehydrator

For fruit and vegetables, you can use a lower or higher temperature than those listed, but bear in mind that the lower the temperature, the longer it will takes, but at the same time, more nutrients will be preserved. However, when dehydrating raw meat and fish, you should use a temperature of 68-70°C to kill of any nasty bacteria.

Some of the ingredients can be ground into a powder, eg brassicas (for adding to green smoothies), onions and garlic, but make sure that they are thoroughly dehydrated before grinding or your powder may be lumpy.

As stated above, these timings are approximate and before storage you should check that ingredients are fully dehydrated and not sticky. Lightly spray the trays with oil and turn ingredients after 1-2 hours if they show signs of sticking. The higher the sugar content of an ingredient, the more likely it is to stick.

For the dehydration of wet ingredients, eg frozen food or for making fruit leathers, you will need to use silicone mats which are produced by the manufacturer of your dehydrator.

As for storage you have several options. You can keep them in airtight containers such as Lock&Lock boxes, preserving jars or seal in bags using a vacuum sealer. For short-term storage a non-airtight box or bag would be fine.

Ingredient and weights	Treatment	Dehydrating time and temperature
Apples (5mm slices. Original weight 930g, dry weight 135g.	Put in a bowl of lemon juice and water as you slice	13 hours 50°C
Aubergines (7-8mm slices, then chopped into squares). Original weight 800g, dry weight 160g.	Put in a bowl of lemon juice and water as you chop	5 hours 60°C
Bananas (4mm slices). Original weight 700g, dry weight 145g.	Put in a bowl of lemon juice and water as you slice	8 hours 60°C
Carrots (2-3mm slices). Original weight (topped, tailed and peeled) 408g. Carrots are roughly 88% water so looking for a dry weight of about 49g. Final weight was 44g	Put in a bowl of lemon juice and water as you slice	1 hour 55°C, 7 hours 50°C
Celeriac (3-4mm matchsticks). Original weight 700g, dry weight 76g.	Put in a bowl of lemon juice and water as you cut	3 hours 60°C
Celery (4mm slices). Original weight 1750g (about 3 heads), dry weight xxg.	Not necessary	2 hours 30 minutes 60°C or 7 hours 30 minutes 50°C
Garlic (3-4mm slices).	Not necessary	5 hours 60°C
Kale (leaves only, torn into pieces). Original weight 180g, dry weight 35g.	Not necessary	2 hours 30 minutes 50°C
Kiwi fruit (peeled and sliced 6-7mm thick). Original weight 820g (10 fruit), dry weight 155g.	Not necessary	12 hours 50°C
Olives (pitted, halved). Original weight 200g, dry weight xxg.	Not necessary	xx hours 50°C
Onions (1cm dice). Original weight 920g, dry weight 100g.	Not necessary	10 hours 60°C for 1st hour, then 50°C
Onion rings (4mm slices).	Keep slices whole	7 hours 60°C for 1st hour, then 50°C
Peppers (sliced, frozen). Original weight 675g, dry weight 40g.	Not necessary	8 hours 50°C
Potatoes (1) (3-4mm slices). Original weight xxxg, dry weight xxxg. (Purple Majesty illustrated)	Blanch in boiling water 4 minutes, transfer to bowl of iced water 15 minutes then pat dry	7 hours 60°C for 1st hour, then 50°C
Potatoes (2) (Whole). Original weight xxxg, dry weight xxxg. (Purple Majesty illustrated)	Wash and bake whole, complete with skins at 200°C / 400°F / Gas 6 for about 30 minutes, depending on size. Peel if desired and cut into 4mm slices	7 hours 60°C for 1st hour, then 50°C
Potatoes (3) (3-4mm slices). Original weight xxxg, dry weight xxxg. (King Edwards illustrated)	Wash, peel if desired and slice. Bake sliced, at 250°C / 500°F / Gas 10 for about 10 minutes, turn the slices over and bake for a further 10 minutes. If using a mini-oven, then 5 minutes each side	5 hours 60°C
Raspberries (frozen). Original weight 600g, dry weight 95g.	Not necessary	1 hour 60°C then 19 hours 50°C - on silicone mats until dry enough to place directly on trays
Tomatoes. Original weight 2.1kg, dry weight 86g	Cut in half if small, or quarters or even eighths if larger	12-20 hours 60°C, depending on size. Store in airtight containers and cover with olive oil, sprinkled with a little salt.