Chilli Drying - Chillis Dried Using Wasted Heat From a Monitor




This year produced a good crop of chillies, far more than could be eaten while they remain fresh. In order to preserve the chillies for year round cooking, I decided to dehydrate them to crispy dried chillies.

In this instructable I use the hot dry air produced by monitors and TVs to slowly air dry the chillies. There is not really any need for a food dehydrator or drying cabinet when electrical devices are already pumping out hot air. Air vents are usually hidden behind devices, and dissipate heat in a gentle waft. An infra-red thermometer demonstrates how hot and useful this wasted energy can be.

Dried chilli can be rehydrated in hot water, or crushed and sprinkled into sauces. The large cayenne chilli peppers shown here are traditionally ground to make cayenne pepper, the orange spice used in hot food. I also dry some small fiery Apache chillies.

Step 1: Harvest Some Ripe Chillies

Removing the already red chillies will promote new growth. Flowers should continue to form as long as the weather is warm. Even under ripe chillies will rapidly change colour to deep red once picked and dried.

Step 2: Find a Source of Hot Dry Air

Zapping electrical devices with my infra-red thermometer identified the best drying positions. The trusty 21" Iiyama monitor vented the warmest air. As shown below, air leaving the vents was a consistent 45 degrees centigrade across the device.

You'll want to find hot air with a temperature of between 40- 55 degrees Celsius.

Other devices to try;

  • The long thin vents above a LCD or Plasma TV screen
  • Cooling fins and air vents above a fridge or freezer
  • Computer air vents, especially the power supply vent
  • Radiators

Step 3: Lay Out the Chillies

Allow enough space for air to flow freely between the chillies. There is no point placing chillies on plastic areas where air does not exit the device, also try to avoid blocking the vents completely. It's probably best to dry a few chillies at a time rather than piling up 2 kg on top of a device and it overheating.

If you can't dry everything at once, keep fresh chillies in the fridge until there is space in the hot air.

Step 4: Drying Time and Turning Your Chillies.

Allow about one week for the chillies to dry. My monitor is turned off at night, so probably only produces hot air for about 15 hours each day.

Every couple of days the chillies can be turned. This is a good time to inspect them for crispiness. If some are drying faster than others, move them around a bit. Ensure that all sides have dried evenly.

Step 5: Store Those Nice Dry Chillies

Put them in an air tight bag or box. After removing all that water, you don't want it rushing straight back into the chillies!

What to do with dry chillies;

  • Rehydrate. Place a dry chilli in warm water and leave for 20-30 minutes. You can then chop it up as you would a fresh one.
  • Crush the dry chillies into flakes. These are great for sprinkling into sauces or onto food. The super hot epithelial membranes will have dried onto the seeds. It's up to you whether or not to leave the seeds in your flake mixture. Flakes can also be used in bird feeders to keep squirrels away. Birds are insensitive to the heat, so happily eat the nuts and seeds. Squirrels experience the same heat sensations that we do.
  • Powder the dry chillies for your own cayenne pepper seasoning

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    10 Discussions


    Reply 10 years ago on Step 5

    Hello. It works with oranges and apples as well as chiilis. I see no reason why it would not work with tomatoes as well. You would need to take precautions against juice dripping into the device, perhaps use a thick aluminium foil disposable BBQ tray. Good luck with that, if it works please post some photos and advice in a follow up comment. Regards, tz1_1zt


    Reply 10 years ago on Introduction

    Glad it came in useful. I could have done with your instructable a while back. Two books were ruined when a house mates radiator leaked into my room. I had no idea freeze drying could be used to save books, we have a freeze dryer in the lab at work.


    10 years ago on Introduction

    plasma TVs get very hot the might start to evaporate the liquid a little too fast, the vapor that is produced can sting your eyes.

    Mr E Man

    10 years ago on Step 5

    I want one of ur Thermometers thats cool. Where'd you get it? I'm growing 3 types of chilli's, and plenty of herbs. And being a computer tech, I have plenty of herb and chilli drying space. So thanks for pointing out that herb dryers are a waste of money, Plus the house now smells like basil, thyme, oregano, and chilli's.

    1 reply
    tz1_1ztMr E Man

    Reply 10 years ago on Introduction

    The thermometer is a are great toy, I zap everything to see how hot it is. Have a google for "infra red thermometer", or check eBay where there are thousands. I picked up mine in a sale at Maplin, but they are just in the UK. The consumer versions (like my one) are cheap these days. Glad the chilli drying is working for you as well. It's such a simple idea, I discovered it by accident when I misplaced a small orange ;-)


    10 years ago on Introduction

    Great idea, and nice use of wasted heat! But can your thermometer also tell whether the air is too humid? I can see this working in California or other desert states, but what about other, muggy ones?

    1 reply

    Reply 10 years ago on Introduction

    Hello. The thermometer can only measure IR radiation from an object, I have no way of measuring humidity. My photos can't communicate quite how dry the chillis are. You will have to trust me, they are crispy, thin and crumble into tiny flakes between your fingers. So the dehydration has worked. There are a few things to bare in mind. Modern houses with central heating have notoriously dry air, so much so it damages antique wooden furniture. There should be no problems with humid air indoors. Having said that, the humidity is not really a factor here. Drying is occurs rapidly by the constant movement of warm air. The raised temperature is sufficient to promote accelerated evaporation of the water content, while the air movement ensures evaporated water is transported away from the chillis surface. Chillis grown in the UK will dry perfectly well when hung up in a cold greenhouse over winter. The air temperature will be very low and sometimes humid. With good ventilation and protection from rain, the drying process can happen slowly and give the same results shown here. However, it takes weeks rather than days in a cold green house. hth