Arduino project: Sous-vide cooker

OK, I do a lot of cooking, but I don't "get" sous-vide.  For some reason, boiling food for up to 72 hours just doesn't sound very appealing.  Yet, not only is sous-vide quite a rage, the food can be very tasty and tender.

So for this arduino project installment, we are going to take a look at creating a sous-vide cooker.

This project comes from instructable user Etienne Giust.  According to the information, "You'll be set for approx 40$, maybe even less. That's not counting the rice cooker.", when a quality, consumer grade sous-vide cooker can cost 10 to 20 times that amount.

So, what exactly is sous-vide?  According to the wikipedia article on it, "Sous-vide (/suːˈviːd/; French for "under vacuum")^[1] is a method of cooking food sealed in airtight plastic bags in a water bath for longer than normal cooking times—72 hours in some cases—at an accurately regulated temperature much lower than normally used for cooking, typically around 55 °C (131 °F) to 60 °C (140 °F) for meats and higher for vegetables."

The instructable for creating this sous-vide cooker indicates only 7 steps, the seventh step is simply instructions on how to use it.

OK, I guess I'm understanding it better.  Like a slow cooker or smoker, there is nothing quite as tender or tasty as food that is brought to cooked temperature slowly, as it steeps in its juices over a long period of time.

This cooker was created with the following intentions:

• Works out of the box : no need for tweaking or tuning, the software adapts itself to the characteristics of your cooker : whether it is big, small, full of water, half-full, whether room temperature is low or high, it works.
• Efficient regulation in the range of 0.5°C
• Sound alarm warns when target temperature is reached
• Automatic detection of lid opening and closing : regulation does not get mad when temperature probe is taken out of the water (which is a thing you need to do if you want to actually put food in your cooker)
• Safety features :
  • automatic cut-off after 5 minutes of continuous heating providing no change in temperature
  • automatic cut-off after 24 hours of operation
    
  • automatic cut-off when temperature reaches 95 °C
    
  • allows target temperature only in the safe 50°c to 90°C range
    
• Dead cheap and simple : no expensive LCD or Solid State Relay

Aside from the cooker, which could technically be any size, the following parts are required:

• Arduino board - approx 20$
• Integrated 8 digits led display with MAX7219 control module (3 wire interface) - 5$
• Pushbutton x 2
• Piezo buzzer - 3$ (optional)
• Waterproof DS18B20 Digital temperature sensor - 10$
• 4.7K ohm resistor
• 5V Relay module for Arduino, capable to drive AC125/250V at 10A - 4$
• Rice Cooker
• A wood board, plastic box and silicone sealant for protection of the high current part of the circuit
• Drill

On any question of safety, considering the temperature, time the equipment will be powered, and the fact that water is involved, these concerns are taken into consideration.  For example, the power relay is fully enclosed and sealed.

So, once you have completed the sous-vide cooker, you might wonder why you made it, what it's good for, how it works, and how to use it, the instructable user provides the following information:

"Sous-vide cooking is a great new way of cooking food. I will not explain why and how it works here... for great recipes and explanations, you can check out those guys :
http://modernistcuisine.com/2013/01/why-cook-sous-...
 
Unfortunately, a good (and I mean precise to the half °C) sous-vide machine is very very expensive (500, 1000$ or more). If you wonder why you need such precision, I suggest you check this out :
http://hoerup.dk/how-to-cook-an-egg-sous-vide-the-..."

If you missed it earlier in the article, here is the link to the instructions for creating this cooker.  Enjoy your sous-vide.