Merck Design Sprint Part Deux

The second design sprint for the Merck Developer Portal. In this sprint, we build on top of our findings from the last sprint.

Crouching Tiger, Hidden Salami

July 9, 2012

I’ve been learning how to cure meat, and I thought I should share my setup. I’m currently on my third batch of meat (second time curing salami). Curing meat requires control of the environment, external and internal to the meat. This post is about the hardware I use for controlling the environment outside the meat. Specifically:

Temperature
Humidity
Wind speed

Temperature

I’m using a wine fridge, the Vinotemp VT-27 TS:

I chose this fridge because it has a temperature range of 39ºF to 65ºF, which is an ideal range for meat curing.

Most of the curing time is spent around 60ºF, but during the fermentation stage, you must keep the temperature at 70ºF. In order to maintain the higher temperature, (until recently) I used a Freezer Temperature Controller. I was able to figure out the wiring for the temperature relay coil that controls the fridge pump, so I’m currently using a TI Launchpad and a Humidity and temperature sensor to control the fridge directly:

Controlling the fridge directly is not necessary. The freezer temperature controller works great. I just wanted to control the fridge with a micro controller because I am a huge nerd!

Humidity

For the humidity, I am using a Crane Drop humidifier. I chose this humidifier because it’s ultrasonic, so supposedly the water molecules in the air are smaller (or so I’m told). More importantly, the humid air it produces is not heated, so it will not impact the temperature of your box as much.

To get the humid air in to the cooler, I drilled a hole in the back:

Click here to see a zoomed in version of the hole. I bought some tubing and hooked the humidifier in to the hole. This is a top view, showing the tubing hooked in to the fridge:

I didn’t want to constantly monitor and adjust the humidifier, so I also bought a Dayton Humidifier Controller. The controller sits inside the fridge. I have an extension cord running in to the fridge, the sensor plugged in to that, then the humidifier plugged in to the sensor:

Wind speed

The final piece is wind speed. On my first batch, I didn’t understand the importance of wind speed until my sausage got slimy and gross. Make sure you have fans in your curing box! I have two fans plugged in to the extension cord that is used for the humidity sensor:

Miscellaneous

The wire racks I have in the box are not stainless, so it’s important not to let the salami touch the metal (otherwise you get a metallic flavor). So I use a bunch of clothespins to hold on to the string that ties off my salami.

So far, I’ve found the best place to put the fans is above the meat pointing down. I found I couldn’t get good air circulation in other places.

This fridge was not meant to operate with such high humidity! When water condenses in your fridge, it drips to a tray outside the fridge where it will evaporate. But since this box operates with 70% to 90% humidity, there is way too much condensate for the drip tray. I had to remove the regular drip tray and run a pipe down to a container to catch the water:

Recap

My hardware list is:

The fridge cost me about $200. The humidifier and controllers ran about $150 together. I estimate the total cost was about $400 when I was done. The freezer controller can perform in the correct temperature range for curing meat, so one way to save money on this project would be to buy a used fridge from craigslist or something.

Another possibility is to buy a Temperature and humidity sensor. It requires a bit more assembly, but is cheaper than buying both the freezer controller and the humidity controller.

With a microcontroller, there are even more possible solutions. It just depends on how much you’re willing to spend, and how much you want to assemble yourself.

Here is my full setup:

I hope you’ve enjoyed this post! I think my next post will be “Hacking your sausage box” (how to hack the Vinotemp wine cooler), followed by “Real Time Sausage Monitoring” (publishing and monitoring sausage info in real time).

Cat:

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