Curing chamber’s aren’t inherently complex, there have been cured meats since before modern technology as a means to preserve food, but that simplicity is exactly why automating one isn’t too hard. You simply need to control a few factors: temperature, humidity, and airflow. Below you will step through what parts are needed and why, where to get those parts, and how to bring everything together with the help of a Raspberry Pi.
After going through this guide you should understand the importance of being able to control environmental variables to your specifications in order to achieve better cures, and you should feel equipped to begin sourcing parts, designing, and coding your eventual curing chamber.
Step 1: What You Will Need and Why
This section covers the main types of parts you will need to eventually build a curing chamber, and how they fit into the design.
· Raspberry Pi - It makes up the backbone of the project and will allow you to automate the control temperature, humidity, and airflow of the chamber.
· Temperature Sensor – This allows for you to measure the temperature and send the data to the raspberry pi, where the code will decide if the refrigerator needs to be turned on.
· Humidity Sensor – Just like the temperature sensor but will read the humidity of the air and send it back to the raspberry pi.
· Chamber – The refrigerator chamber will allow you to regulate temperature. Since they come in all shapes and sizes it allows for you to customize your design to your needs. Most refrigerators turn of and on when plugged in which will allow for easier control.
· Humidifier – Controlling the humidity over the course of a cure can be extremely important for more complex meats, and thus more precise methods will allow you to produce these delicacies easily.
· Fans – Fans will be needed to provide airflow to the chamber which will in turn help regulate temperature, humidity, and stave off harmful bacteria and mold.
Step 2: Part Recommendations and Sourcing
Below is a list of all the parts talked about above, but with suggestions on what to look for when you're buying and some specific models that are highly recommended.
· Raspberry Pi – Check out the Raspberry Pi website
· Chamber – For this guide the recommendation is to use an old mini fridge or wine fridge as these can typically be easily found for a good price second-hand. When using old mini fridges look for ones that have minimal interior ‘accessories’ that can’t be easily removed and do not have a freezer component. If you have anything with a freezer component you’ll need to disable the freezing component during the build. Some people prefer wine coolers over mini fridges because many current models have temperature controls already built in, but because of this are more expensive than mini fridges.
Either way, your best bet is to find one on craigslist/local listings or Ebay.
· Temperature/Humidity Sensor – There are a few recommendations on this front. The first being to find a combined temperature and humidity sensor. It’s possible to find individual sensors with even higher precision, but for the sake of being economical and for the needs of a curing chamber, combined sensors will do.
Temp and Humidity Sensor and Controller (Better for large scale and higher price builds)
· Humidifier – It’s possible to simply put a pan of water at the bottom of the chamber, for the sake of this design, you want precision. It’s almost impossible to find a small humidifier that won’t take up precision room for cured meat, and a humidifier too large will easily overpower the curing chamber and make it hard to control. Below are two personal humidifiers that don’t break the wallet or overpower the chamber; however, any humidifier that fits the scale of your chamber will do. Anything that
· Fans – It’s pretty easy to find fans of all sizes, but having too large of fans will easily throw off the humidity and temperature of the chamber as you pump air from outside through the chamber. Because of this, it’s better to go smaller on the fans. Using different sizes and amounts of computer fans will most likely be your best bet. Below are a couple options but remember that 3.3V can be directly controlled by the Pi. Otherwise you might need to do another relay setup!
Step 3: Designing the Controls
The real meat of the design comes when you start adding all this together. You will need to write programs for the humidity, temperature, and airflow controls. In a simple manner this will consist of reading the temperature and humidity from the sensor, and then turning the fridge and humidifier off accordingly.
o Reading Humidity
o Turning Humidifier on/off
Depending on the humidifier it may be easier to follow one of the approaches that the fridge follows, but if you are using a small personal humidifier it may be easier to control it directly.
o Reading Temp.
o Turning Fridge on/off
It’s important to note that there are multiple ways of doing this. Either you can hook the fridge up to a wifi enabled switch that you can connect to the raspberry pi via software, or you can connect the fridge to a relay switch with safety so that the raspberry pi itself can turn the fridge on.
· Airflow – Generally speaking, the only rule about airflow is that it needs to exist. Because of this it leaves a lot of room in when designing the controls. You could set fans to run whenever the fridge or humidifier turns on, or at set intervals, or keep them on at all times. It’s important to note the effects of introducing airflow on temperature and humidity so you can alter your fan patterns to suit your needs. Below is code for
Relay Control via Raspberry Pi
Step 4: Time to Build!
At this point you have selected the main components for the curing chamber, understand why they matter, and designed code to run all the parts. It's important to note that the above is a recommendation, and if you plan on creating a chamber out of a room, closet, or garage then your scope is way beyond that of a simple fridge conversion. That being said, this guide should allow you to convert almost any fridge into a curing chamber with minimal extra research. Now it’s time to put it all together and actually build the chamber. For a lot of people this is the real daunting part. Dealing with 120V AC equipment and tiny wires all at the same time can seem scary and tedious, but with simple instruction and safety it’s as simple as following a recipe in the kitchen. Below you'll find a 10 minute instructional video on how to assemble everything.
Step 5: The Assembly Video
Insert Video Here