Sous Vide "Beer Cooler Hack" Calculator

I was introduced to the sous vide cooking method by Kenji Alt in his blog article Cook Your Meat in a Beer Cooler: The World's Best (and Cheapest) Sous-Vide Hack, which is a very interesting read (along with the supporting articles mentioned therein) if you're interested in learning about this exciting and versatile way to cook food.  "Sous vide" is French for "under vacuum", which refers to the fact that you put the food inside of a vacuum-sealed bag (I use a Ziploc bag), and then submerge it in hot water.  To cook sous vide in a beer cooler (ice chest), you simply put water in the ice chest that is slightly hotter than the final desired temperature of the food.  Pop the food into the ice chest, the water cools down, the food warms up, and hopefully you end up with everything reaching equilibrium at the desired final food temperature.

In trying this, the biggest question in my mind was "how much hotter must the water be?"  It obviously depends on several factors, mainly being the amount of meat vs. the amount of water.  The more water there is, the less the water temp will drop as the meat is heated up.  In addition to that, you lose some heat through the walls of the ice chest.

Of course, being the geek that I am, I resorted to Excel to solve my problems.  I put together a spreadsheet, based on some published specific heat capacity data for various foods, that will predict how hot the "bath water" needs to be in order to arrive at the desired result (download HERE.)  I still need to validate it, but it's based on this fairly simple equation for heat transfer between two quantities of two different materials reaching equilibrium in a closed system:

mass(food) * specific heat(food) * deltaT(food) = mass(water) * specific heat(water) * deltaT(water) - some heat lost

DeltaT(food) will be positive, deltaT(water) will be negative, and everything will end up at the same final temperature (the desired done temp). All of these parameters are pretty well-known, so the result should be predictable.  The beauty of having it in a spreadsheet is that you can play with the numbers and realize that you don't need a huge ice chest full of water to do this... it can be done with a fairly small quantity of water.  The last tri-tip I did only used 2 gallons of hot water.  Without this spreadsheet, I would never have guessed that 2 gallons would be enough, but it was!

FYI, I included in the spreadsheet the ability to account for frozen meat by taking into account the latent heat of fusion of the meat as well as its different specific heat capacity as frozen vs. thawed.

Click on the image to download the spreadsheet.

Low-Cost Plug and Play Sous Vide Controller

I was doing a search for a PID controller enclosure, and ran across the website for Auber Instruments (http://www.auberins.com). They make a plug and play sous vide controller that will directly operate up to an 1800W heated vessel, such as a rice cooker or a crock pot. This is a great alternative for someone who has a rice cooker and sitting around, and it's worth $139.50 to not have to cobble up something to control it. The controller can be found here.  Nice, clean design!  I like it!

They also make a variety of other controllers suitable for sous vide cooking, as well as other applications.  They sell sensors, solid state relays and PID controllers for those who want to build their own system as well.

Sous Vide Tri-Tip

Well, I decided to start a blog. What's the saying? "Blogging: Never before have so many people with so little to say said so much to so few." Well, I hope this isn't the case here. I'm going to keep it concise and interesting, or at least I'll try.

So, on with the topic at hand. I've been playing with Sous Vide cooking, where food is cooked inside of plastic bags in heated water very slowly. It works very well on steaks, vegetables, eggs, etc. For meats, it allows you to cook the piece of meat to a desired doneness consistently through its thickness. It's pretty much foolproof. If you want your meat to end up at 135 F, you make sure your water bath stays at 135 F and leave the meat in there long enough to reach that temperature. So far, I've been doing the "beer cooler hack" version of sous vide cooking, and more information on that can be found here: http://www.seriouseats.com/2010/04/cook-your-meat-in-a-beer-cooler-the-worlds-best-sous-vide-hack.html

I've done ribeye steaks and *tried* to do some tri-tips so far, but was short on time on both occasions.  The steaks came out pretty good, but I didn't have time to get the tri-tips up to the desired temperature and had to grill them until they were done. Tonight I cooked a 1 lb, 13 oz. tri-tip, and it turned out great. Here's the story.  

The piece of meat shown here is a USDA choice tri-tip from Costco. It's not the pre-marinated variety... it's just straight up tri-tip. I put a McCormick's Grill Mates Steak rub on it. Pretty tasty stuff.

Next, I filled my ice chest with hot water. The plan was to cook the meat to an internal temp of 130 F (medium rare), so I started the water off at 141 F (based on the prediction by a spreadsheet I put together here). I either made a bad spreadsheet or more heat was lost through the sides and top of this ice chest than I expected, because I had to add hot water a couple times while it was cooking in order to maintain bath temp.

After taking out the meat at 130 F and feeling how floppy and raw it seemed, I decided to take it up to 135 F. I put more hot water in there and let it sit until the water was 137 F and the center of the meat was 135 F. Done cooking!

Ready to come out of the water. Visible here is my water temp probe (on the right) and my meat temp probe (on the left, going into the bag and into the center of the meat). The corner of the bag where the probe wire comes out is kept above the water level so no water can get into the meat.

Technically, it's fully cooked. 135 F throughout.

Like I said, "technically" it's cooked. It isn't seared though, and that's no good. It's gotta have that browned meat flavor to it. I was going to hit it with my propane blowtorch, which is very common for this type of cooking, but it didn't seem to be going the way I'd expect it to. Also, the chunks of reconstituted garlic that you can see in the picture here were burning and turning to glowing coals before the meat was seared, and that wouldn't taste good. Consequently, I scraped all of the garlic pieces off with a butter knife and resorted to pan searing. I cranked up the burner, got the pan of olive oil smoking hot, slapped this bad boy in there, and gave it some color.

And here's the beautiful result: A piece of meat with constant doneness throughout, and that doneness is determined by the water bath temp. It's so easy! I'll never screw up a steak again!

With an iron skillet or a similar pan that holds heat better, the gray zone at the outer edges of the meat would be even thinner, but I'm not complaining. This is the best piece of beef I've ever cooked, and I have a feeling that this is gonna be a good summer. As it is, people know that if they come over to my house for dinner there's gonna be plenty of decent food, but lemme tell ya... we ain't seen nothin' yet.

This is definitely gonna be a good summer.