Banjo Experiments with Sous Vide Shrimp

I haven't tried any shrimp yet via Sous Vide method (BTW- I have a SousVide Supreme.  I have also created my own cooking vessel using an Arduino to control the temperature, but this looks  a lot nicer in the kitchen.)

This is an experiment, so it may evolve over several iterations.  For this first iteration, I'm using a temperature I found on the internet: 140 dF for 1 hour.  I have misplaced my cook book, so that's the best I can do for tonight.

I've selected 1/2 lb of Kirkland's Fresh Frozen Shrimp, 21-25 count (shells off, tail on, deveined). This means they were frozen immediately on the shrimp boat after being caught, placed into netted bags, and immersed in the cooling brine.  The 21-25 count means that 21 to 25 shrimp would equal 1 pound of shrimp.  I don't know if this means before they were shelled and head taken off, or after this has been done.  At any rate, this is a common method of buying shrimp at a seafood market - it allows you to specify the size of the shrimp.  21-25 count is a nice shrimp size.  It's not a big huge prong, but it's much bigger than popcorn shrimp.  Kirkland's shrimp is the store-brand of Costco.  I've been impressed with their store brand to date.

The recipe for tonight's trial:
1/2 lb frozen shrimp, shell off, tail on, deveined.
3 oz butter
2 tsp Old Bay Seasoning

Steps

1. set the Sous Vide to 140 dF and allow it to come up to temperature.
2. While step 1 is completing, place 1/2 pound (this would be 10 - 12 shrimp) into a ZipLock Freezer Quart bag.  
3. Place butter and Old Bay Seasoning into the bag.
4. Use the water immersion method and remove air from the bag (or use vacuum seal machine of that's your preferred method).
5. Set timer (any timer will do...) to 1 hour 15 minutes.

Prep Time: 10 minutes

Cooking time: 1 hr 15 minutes

Total time: about 1.5 hours

Result of 2nd test - 141dF control temperature
We both felt like we liked this temperature better than the 140dF temperature.  Shrimp was slightly more firm.  Both test were conducted using shrimp from the same purchased bag.  We will try 142dF next.  Our intent is to keep bumping up the temperature 1dF at a time until we either don't like it as well as an earlier temperature, or can't detect any change.


Result of first test - 140dF control temperature
Hey!  This wasn't bad!  In fact, they were good!  However, if you think about it, we have all probably been eating overcooked boiled shrimp for most of our lives, just because the temperature control was so difficult.  Since the mass of something determines how long it has to be cooked, and shrimp has a low mass, and most people boil the water (212dF at sea level), then they've been way over cooked.  A shrimp can be represented as a narrow cylinder, with heat being applied from all sides.  Since heat migrates from hot to cold, and the distance from the outer edge to the middle (where the heat would meet the heat from the other side coming in), it doesn't take long for shrimp to come up to temperature.

So the Sous Vide method, or more preciously, an accurately controlled water-bath method, allows us, and for most of us this is the first time, to cook shrimp without overcooking it.

So how did we like it?  Well, considering that for all of our life when eating boiled shrimp, we have been eating over cooked shrimp, and this is the first time ever that we are not eating overcooked boiled shrimp, you should not be surprised to hear we thought the shrimp was under cooked!  Hah!  But I suspect the reality is that we need to recalibrate what we think is the proper temperature to cook shrimp.

Note that since we were cooking at 140dF, we were not cooking boiled shrimp; we would have had to cook at 212dF for it to have been boiled shrimp.

So we cooked the shrimp at 140dF as per outlined above, and we thought we would have preferred them a little more cooked.  In most cooking, you can increase the temperature of the cooked item by allowing it to cook longer.  However, in an immersion bath method, which uses precisely controlled temperatures at extended lengths of time, leaving to food to cook longer won't raise the temperature of the item being cooked - it's already reached the cooking temperature, in this case, of 140dF.  So to increase the temperature of the shrimp, and since leaving it in the cooking water bath for a longer length of time won't increase the temperature, then the only way to raise the internal temperature of the shrimp is to raise the temperature.  So for our next test, I will raise the temperature by 1 dF, to a control temperature of 141dF.

I'll let you know how we liked it!