How to Build a Multi-Purpose Curing Chamber

 

After attempting to make cheese once in the fridge with marginal results, and having eaten some amazing salami while traveling last summer, I decided to make a curing chamber at home. My goal is to build a single multi-tasking box where I could control the temperature and humidity and create ideal environments to make various products such as salami, cheese, tempeh, koji, and even kimchi.

There is a wealth of resources out on the interwebs to avail yourself of (here’s a really good one), but I still want to share my particular build and experiences with mine.

The Box

You’ll need a chamber in which you can control temperature and humidity. The box will ideally be large enough to hold several hanging things at once, contain racks, and also allow for small appliances such as a humidifier, dehumidifier, or other heat source. I found a thermoelectric (as opposed to a compressor-based) wine refrigerator that holds 48 bottles. (It’s always easy to find good used fridges cheaply on sites/apps like craigslist, offerup, letgo, etc.) The seller was getting rid of it because it was too big for their space. $50. Deal! Small dorm fridges or even full-sized ones would work too if you have the room. This one has multiple metal racks (highly configurable and simple to keep clean), a manual dial control (which I would override anyway; more on that later); a light bulb with a toggle switch, a dark interior and smooth, easy-to-clean surfaces (i.e. not overly grooved or molded).

I make copious use of wire shelving, and almost everything in my fermentarium is a wire shelving rack that’s on wheels. I wanted to keep the chamber way up off the floor, for cleanliness sake, and also to make it easier to access. So I managed to fit the box perfectly inside a 24 inch wide rack system. Now, it is a bit “front-heavy”, that is, the glass door is by far the heaviest part of the box, so if you’re going to build something like this, make sure you have enough counterweight low and towards the back end to keep it from tipping over.

The Brains

Regardless of what you’d like to make in the chamber, chances are you’ll need to manage and monitor both temperature and humidity during the curing period, which could be anywhere from several days to several weeks or longer.

One controller to rule them all! Inkbird ITC-608T

Unless you’re an avid tinkerer/frequent Radio Shack customer (is that even still a thing?!), I  recommend buying an all-in-one controller that manages both temperature and humidity.

I’ll save you some time and effort: Get the Inkbird ITC-608T Temperature & Humidity Controller. Everything comes is in one handy package. It measures both, comes with two kinds of probes, and offers an easy to use programmable interface. $70. Deal!

I mounted the controller above the box, closer to the hinge side of the box (this keeps the wires out of the way), and attached it to the rack with zip ties, for easy access and visibility. Then I ran both probe wires (one for temperature and one for humidity) from the bottom directly into the box through the front door. This works well, as the rubber gasket around the door easily molds around and is not obstructed by the thin wires. to keep them out of the way. You could get fancy with mounting the wires inside the box; I have been lazy and just set them on top of the top rack for now.

Managing Temperature

Work 1 outlet controls temperature; Work 2 controls humidity. Fridge cord is labeled and plugged in here.

To create a cold chamber, you would simply plug the refrigerator into the controller, and let it regulate how much it would need to run to keep the desired temp. I set the refrigerator’s own control to maximum cooling. That way, it will most likely always kick on when the controller does.

To create an incubating (heating) chamber for applications like yogurt, koji or tempeh), leave the fridge unplugged (from the wall and controller), and instead plug a heat source into the controller. For me, a clamp lamp with a 60 watt bulb does a fine job of heating the space. Yes, the light can affect various microbial ferments adversely. I usually just turn the bulb to face downward, away from whatever I’m incubating. The bulb still generates enough heat to keep the chamber within the right temperature. If you can find another compact small heat source, feel free to improvise.

Managing Humidity

A heavily-salted (35%) water pan at the bottom of the box manages humidity. Salt keeps molds at bay.

A similar principle as temperature applies here. That is, you may need either or both a humidifier and dehumidifier to keep the relative humidity (RH) for your application within the desired range. Interestingly, at my house here in southern California which has a fairly dry Mediterranean climate most of the year, I have not needed either device yet, at least not for curing meats (which need to be in the 60 to 80% RH range). I tested placing containers of varying sizes filled with water and then tracking the RH. I found that keeping about 1L of water in a wide, shallow pan at the bottom of the chamber works great. As the controller will tell you with fantastic accuracy, the RH does vary within that range, straying outside it occasionally, usually at times during or right after when the fridge runs. For the most part, it does well with no second appliance. PRO TIP: Add 33% salt to the water pan to keep mold from forming.

I noticed that the more items I added to the box at one time, the higher the RH grows, all else being equal. So I wound up switching to a smaller water pan after adding 2 more loins. This shouldn’t be a surprise, since I added a lot more humidity (via the water in the meat!) to the system. You may need to tweak your system to maintain the right range for humidity.

 

Keepin’ it Clean

Antimicrobial dynamic duo. Inexpensive, natural non-toxic cleaners

Sanitary conditions are a necessity in this environment, in which we are (a) potentially dealing with meat and the remote but real possibility of botulism toxin formation, and (b) purposely creating a moist environment in which we are, in most cases, trying to grow fungi or molds.

I use a combination of two natural cleaners. One bottle contains a 1:1 vinegar/water solution with about 1 teaspoon (5 ml) of baking soda, and the other contains 3% hydrogen peroxide (which you can now buy with built-in spray nozzles!) This combination provides an extremely effective and natural antimicrobial one-two punch. [source] Clean all inside surfaces of the box between curing– top, bottom, sides, back, inside the door, and the gaskets, too. I remove the racks and wash them separately with hot soapy water, and then let them drip dry.

 

Ferment All the Things

L to R: paprika-koji pork tenderloin, pepper/fennel loin with spontaneous koji coating, black pepper koji pork tenderloin

This particular refrigerator normally operates at temps from 42F to 66F (5.5 to 19C), so it would not be ideal as a kimchi refrigerator, which simulates the near-freezing (32 to 35F (0 to 2C) temperatures of buried earthen pots during a Korean winter in order to maximize kimchi fermentation. But it still could be used for many other applications.As of now, I am using it to learn the art of charcuterie. I came across the wonderful primer in the form of a freely published book by Rey, aka @home.charcuterie. You can download a copy for yourself at his website, Home Charcuterie Master.

Next, I will use the chamber to incubate koji, the inoculated grain that’s used to make wonderful things like miso.

Shout out to @ourcookquest for posting some mad delicious science about using koji to quick cure meats!

I will also be exploring making aged cheeses, and tempeh in the box. Stay tuned!