Drying chamber setup

I was able to purchase a “scratch and dent” wine fridge (Frigidaire Gallery 55 bottle) for use as a proper drying chamber. This means that I will now be able to dry meats and sausages year-round. It also means the Rubbermaid bin drying chamber is being retired. Once it warms up a bit outside, I have a left over piece of granite that I will cut and polish to set on top to cover the dents and dings.

The Inkbird humidity controller will be used to control the humidifier and dehumidifier that will reside in the chamber. They will tighten up the humidity swings seen when the compressor of the fridge kicks in to cool it down. The trick is to not have the humidifier and dehumidifier “tail chasing” each other, wasting energy and having the fridge compressor cycle on too often. One thing to be careful of is that you need the humidifier and dehumidifier to have mechanical on / off switches so that they will automatically come back on when the humidity controller re-applies power. Unfortunately most of the models on the market will not (requiring a user to press the power button)

First step is to run the chamber unloaded at the proper temperature to see that it is stable and get an idea of how often the compressor cycles on in the steady state. I am using the Ecowitt sensor in the chamber to monitor the temp and humidity levels and provide the logging via the ecowitt.net website (free service). The initial run of the empty chamber looks like this:

Empty fridge set for 49F

Next I checked the calibration of both the Ecowitt sensor and the Inkbird sensor. Using the damp salt box method (see the end of this page) they were both reading 78% after adjusting the cal offset of the Inkbird.

Once the humidifier and dehumidifier arrived, I then did a test run with them in the chamber but without any meat yet. The temperature plot is a sawtooth curve with the temperature slowly rising and then rapidly dropping as the compressor cycles on , cooling the fridge.

Testing with humidifier and dehumidifier in place.

Comparing the plots, you can see that the temperature cycle (left side) is a LOT faster initially. This indicates that the humidifier is putting out too much moisture and the tail chasing has started. Mid way through the plot, I reduced the output of the humidifier and you can see that the compressor is now cycling much less often (but still a bit more frequently than if the chamber was empty. At this point it is ready for the meat after it gets sanitized with a spritz of Star San over the entire interior.

The first thing to be dried is a new 12 lb (6 kg) batch of “Papa’s Pepperoni”. After fermenting overnight in the oven it was placed in the chamber.

Pepperoni in the drying chamber

The temperature and humidity plots a day later looked like this:

Pepperoni in the chamber

It still needs the humidifier turned down a bit but this is close. The telling sign is the nice mold growth seen at day 3.

Pepperoni on day 3.

The mold is penicillium nalgiovensis (Mold 600 culture) The sausages were inoculated with this prior to fermenting. The mold is important as it helps the flavor and a healthy growth of this desirable mold, should out-compete the nasty wild molds that may come in.

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Calibration of humidity sensors:

The second year I was using the drying chamber, I had a failed batch of Lonzino that took an inordinately long time to dry. Electronic humidity sensors can easily lose calibration over time. So before starting the next batch, I bought an Ecowitt temperature and humidity monitor. The Ecowitt and the Inkbird humidity values were different by 9 points! I had a hunch the Inkbird was off but needed to prove it.

With a bit of research, I found a cheap and easy way to check calibration. If you have ordinary salt (NaCl) that is saturated with water in a small closed container, the humidity will be 75% after a few hours as things reach equilibrium. This is perfect!. I don’t really care about the accuracy over the entire range of 0-100% but want it right when around 75%. It turned out the new Ecowitt was within 1 percentage point and the Inkbird was reading low by 10 points. So now I just set the Inkbird for 85% and it maintains the correct humidity level. I will probably re-check both devices, a couple of times per year. I did another check when setting up the new drying chamber.

A s you can see above, I set up the saturated salt in a small plastic box along with both the Ecowitt and the probe for the Inkbird and it was readily apparent the Inkbird was reading way low.


For an authoritative reference see: https://hal.archives-ouvertes.fr/hal-01434816/document This is a nice scientific reference and provides other options for other humidity levels.