Sausage Curing Chamber

If you are going to make artisian meats beyond brats and meatballs, you are probably going to want to make a curing (and perhaps separate fermentation) chamber. This is essentially a box within which you can control both temperature and humidity. Here is an overview of my first attempt at making on in the garage. The Box First, the best thing that you can start with is a fridge, since it is insulated, easy to keep clean, and can be found for free (or at least cheap) in your area. I had a mini fridge already available and this is what I used. Here it is with the front door taken off. image

There are two general kinds of fridges you can get ahold of:

  1. A mini fridge uses a cold plate (that thing at the top that is the integrated “freezer” part. This runs freon through it and chills the air, great for temperature, but bad for humidity. As the air is cooled, moisture condenses on the bottom of the plate and collects in the pan. As a consequence, humidity in the chamber can get pretty high. So for these boxes, you have to worry about removing humidity.
  2. A normal size fridge uses another method for cooling (it isn’t just a giant freon plate in your freezer), a side effect of which is that it dehumidifies the air that is circulating. This is also how you do not get a huge buildup of frost and ice in your modern-day freezers. The benefit here is that with this kind of cooling, you will be assured that you will not be too humid but you’ll have to add some moisture to the system. However, if you are going to go with something like this, aim for a over/under type rather than the side-by-side kind.

Overall Design

I went with the #1 option because that was the first free fridge I was able to get my hands on. A consideration with this choice is that the interior is a bit smaller than a normal fridge so anyauxiliarymaterials you need to add for environmental controls should be planned carefully. You do not want a chamber with all equipment and no room for the meats…

_Temperature Control:_The fridge has its own built-in temperature lowering mechanisms (its is a fridge after all) so these are pretty easy. The problem is that we need to keep the inside a bit warmer than the average fridge. The homebrew people have been converting fridges and freezers into keg holders for a while and many have used in-line temperature controllers. Here is one like I picked up off ebay.

It is a “Johnson Controls” Temperature controller. Basically, the box has a rheostat on it where you select the temperature. This model is a single action controller, if the temperature goes above the designated level, it turns on the fridge. If it goes below that level (to some degree of error), it turns it off. The fridge is just plugged into the controller plug in a fashion similar to how you string christmas tree lights. Pretty simple, pretty easy. Since I have a small chamber, I mounted the box on the outside and inserted the probe through a hole drilled in the side. If you have a full sized fridge, you can mount this on the inside (and actually just run an outlet into the inside of the box and mount everything in there).

_Humidity Controller: _The humidity in the box was also directly manipulated. Here I used a controller that had two options, one for increasing humidity, the other for decreasing it. The model of this one is HUM-1 and can be found on ebay for much cheaper than buying it new.

A potential problem with this unit is that it is BIG! Think the size of a lunch box. That is great except that everything I put on the inside reduces my hanging space. So, perhaps violating my warranty (if I had one), I deconstructed the controls on this box. The actual humidity sensor is in the dial. I removed the dial fromt he box and mounted it inside the chamber in a plastic outlet box. This was one of those cheap ones you get at the local DIY store for outside electrical wiring. This is a sealed box (great for outside) and needed to be ventilated a bit (drilling holes in the bottom of it) so that the humidity inside the chamber is in equilibrium with that inside the control box. The connection between the rest of the HUM-1 controls and the dial is made up of two wires. I would imagine that if you mounted the internal box immediately on the other side of the wall as the HUM-1 external box, you could use the standard red & yellow wires. I opted to move my controller box and put it in the back of the chamber so it was out of the way, which required a bit of rewiring. Not a big deal, just make sure you have the same gauge wire (width) and pick up some connectors. Here is a picture of it mounted inside the box (it is the grey box with the dial hiding behind the bresaola…) image

So I ran this setup a while to see how I needed to deal with too much or too little humidity. At this time, fall/winter on the east coast of North America, I find the too much humidity to be a bigger deal than too little. Given that this is a DIY project, I opted to deal with this immediate issue first. The easiest way to lower humidity in the chamber I could think of was to make a fan an draw dry air from the outside of the chamber. It generally is not over 80% humidity in the winter. There are times in the summer here that get pretty sticky and I’ll have to deal with that issue when it comes next summer. I went out and picked up a 4” computer case fan (get the AC one) and a AC converter (that little plug with a box on it that you plug into the wall). Both of these were sourced from the local thrift store for almost nothing. image

I cut a hole in the bottom of the chamber and wired up the fan to pull air from the box. I also mounted a screen on the inside so as to prevent any unwanted visitors to my meat collection. On the opposite side of the chamber at the top, I drilled some ventilation holes. The cross-draft of pulling dry air from the exterior and removing the more humid (lower) air seems to be working pretty well so far. I mounted a pair of doors on the incoming and outgoing holes using a pair of outside electrical outlet covers (see below) so that when I don’t need these open, they can be sealed up. I also mounted an internal plate on the exhaust opening (see image above with the meat, it is the grey plate on the bottom left). To add humidity to the chamber, you can add a humidifier. Preferably an atomizing humidifier. I have not purchased one yet, however, when I do I may be looking again at the pet store. There are a lot of options for reptile cages to keep the humidity level high and the benefit of these are that they are external to the tank (or chamber as it were), which fits into the overall gestalt of mounting everything externally in this project. _Environmental Monitoring:_I imagine that the accuracy of these pieces of equipment is pretty high (or it just comes from companies that are associated with quality to the layman). However, I like a bit or redundancy in the monitoring. I went to a local pets store and picked up a digital temperature/humidity gauge. This has a probe that can be on the inside and a readout I mounted to the outside. The Final Box So, at present, here is what I have. All the controls mounted on the outside and able to keep a fairly stable environment inside the chamber. I’m getting ready for a pair of Coppa’s and some lamb prosciutto to hang in here for the New Year. image

Father, Husband, Brewer, Professor

Middle aged guy trying to keep it all together and figure out how to best navigate the world as it is. Technology geek, practitioner of fermentation sciences, researcher, biologist.