A simple curing chamber
The above is a picture of my basic setup. It’s a little different to the one i describe below (which involves no wiring), but the principles are exactly the same.
What environment do you need?
Temperature
The temperature range should be high enough for the meat to cure properly and dry, but low enough so bad bacteria and mould doesn’t grow. This is between 10c and 15c.
Humidity
The humidity should be high enough to stop the outside of the product drying too quickly on the outside, forming a barrier and causing the inside to spoil (case hardening), but not too high as to encourage excessive mould growth. This is between RH65% and RH75%.
Air flow
There should be a little airflow, to stop excessive mould growth, but not so much that you cause the product to dry too quickly on the outside, forming a barrier and causing the inside to spoil (case hardening)
The chamber
My tried and tested method
I have found the easiest way to create the right environment is to buy a cheap, second hand, under counter fridge, without a freezer compartment. You can pick one of these up on Gumtree for around £30 - £50. Or you can buy a really basic model, new, at somewhere like Currys for around £100. You’ll want it to actually work as a fridge, so that we can control temperature. I then remove all the trays and shelves to make as much room as possible.
Can i use my loft / garage?
By all means, if it maintains the correct temperature and humidity. The only way to know is to test it with a temperature and humidity probe, over a period of at least a day. Make sure you take a lot of measurements, as unexpected fluctuations or variations could ruin your curing projects!
Can I cure in my normal refrigerator?
This may work for smaller projects, but as a normal fridge has a lower humidity than a purpose built curing chamber, you’ll find that you often get case hardening on larger cuts / projects.
Controlling the environment
Over the years, I’ve done this a number of ways, from guessing, using basic controllers, to building entirely bespoke computing solutions to monitor, alert and control conditions.
The simplest and most cost effective way i have found is to buy some humidity and temperature controllers that don’t require any wiring. These work by plugging into the mains, allowing you to specify an acceptable temperature or humidity range and supplying a socket to plug in two devices, one to turn on when the temperature or humidity goes over a limit and one to turn on when the temperature or humidity goes under a limit.
In my experience, i haven’t needed to warm a fridge, due to the ambient temperature in the UK and i’ve also never needed to artificially raise humidity in the chamber, as the small volume and presence of my curing projects means that its always above the desired RH75%.
This means that all I need to actively trigger is the cooling function of the fridge, every once in a while to keep it at the right level, and perform dehumidifying every once in a while, to keep it at the right level.
Controlling temperature
You’ll need to keep the temperature between 10c and 15c. The easiest, no wiring approach to this is to purchase an Inkbird controller like the below:
Once you have the device:
- Read the instructions
- Plug it into the mains and set a low of 10c and a high of 15c
- Plug your fridge into the socket marked “cooling”
- Run the temperature probe into the fridge and affix somewhere out of the way, not against the back wall. You can use tape or cable attachments (as you can see in my photos above)
Bingo, the fridge should now be able to maintain the correct temperature.
Controlling humidity
You’ll need a small dehumidifier for this, and one with a manual, physical bush button switch (not a digital one). This is because we want to leave the dehumidifier power switch in the “on” position, and will control the current to the device by another Inkbird controller.
Note: You will need to check and empty the reservoir in the dehumidifier every couple of weeks, if it fills up the unit will not dehumidify.
I’ve tried a number of small dehumidifiers and a few have had badly built power supplies that cause contact arcing and the physical relay in the Inkbird (and other controllers) to therefore “stick”, leaving the dehumidifier in “on” mode, when it should not be. If you haven’t any monitoring in place, this can quickly ruin your project. I’ve had to call my mother, from abroad, when the Oinkatron sent me a distress call telling me the humidifier was stuck “on”. She then drove over to my flat and was instructed to hit the unit until it unstuck itself. Weird. And embarrassing. She literally saved my bacon.
I’ve been using the below for a few years, with no problems:
You’ll need to keep the relative humidity between RH65% and RH75%. Again, the easiest, no wiring approach to this is to purchase an Inkbird controller like the below:
Once you have the device:
- Read the instructions
- Plug it into the mains and set a low of RH65% and a high of RH75%
- Plug your dehumidifier into the socket for dehumidification (check the manual, as it differs on various models)
- Place the dehumidifier in the curing fridge
- Run the humidity probe into the fridge and affix somewhere out of the way, not against the back wall. You can use tape or cable attachments (as you can see in my photos above)
Nearly there, the fridge should now be able to maintain the correct humidity.
Controlling Air flow
I’ve experimented a fair bit with this, from building computer fans into the actual fridge door, attaching them inside with variable speed controls and have settled on my favourite method: Open the door every couple of days.
I’ve found that installing a fan in any small fridge, even if set to a really low speed, causes case hardening. You’d need a small fan with something to control a duty cycle, to automate it (i’ve done this, but that’s the subject of another article). The simplest way to cycle the air in your curing chamber is to open the door every couple of days - it also means you get to check on your project and the water level in the dehumidifier!
Monitoring the environment
It’s pretty important to check that the temperature and humidity are within the correct ranges, often - as you can spoil your cures and end up with potentially dangerous products if things go wrong. The simplest way to do this is to eyeball the digital readout on the controllers, every couple of days. These will fluctuate, so it’s helpful to get an idea as to the range the environment goes through, to make sure it’s controlled properly.
Note: it will behave differently when its empty vs when its full of meat!
You can also go further by setting up some digital monitoring. I’ve gone as far as having a Rasberry PI computer monitoring temperature and humidity as well as the weight of salamis (using wheatstone bridges), and sending this data to cloud graphing services so that i can see temperature and humidity measurements, be alerted to any anomalies and also plot a prediction as to when the salami will have lost enough weight to be considered safe to eat! All areas for a further article however…
It’s also worth reading up on how temperature affects relative humidity - and run your curing chamber setup empty to start with. Watch how the environment fluctuates!
The below is some monitoring output from a friend Mats curing chamber setup, running empty, that shows the relationship (courtesy of Sussex and the City)
What next?
It’s time to try your first curing project! I’d recommend trying something like Coppa as an adventurous but straight-forward first go!
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