Sous Vide Cooking

Today Polyscience made the demonstration that a non stired water bath cannot be as efficient as an immersion circulator. It is funny to see that Polyscience directly mentions Sousvidesupreme in the TAG of the article.

Polyscience video indicates clearely that a non stired water bath has a longer response time to reach the desired core temperature. Therefore, it is obvious that Douglas Baldwin cooking tables sould be used with care. Douglas Baldwin indicates in the Pratical Guide to Sous Vide “With all these digital controllers, I highly recommend setting the temperature offset (measured near the temperature at which you wish to cook) using a high quality digital thermometer. Indeed, at the default settings the thermistors used in the above controllers can easily be off 2–4°F (1–2°C)”.

Freshmealsolutions mentions clearely in the user manual of the SousVideMagic : “If you don’t have a proper food core temperature sensor probe, always cook at desired core temperature settings for the duration as specified by reliable recipes with an additional safety factor of at least 25% longer…”
In addition the manual indicates “The default settings are designed to overshoot 1 or 2 degree higher for safety reasons. You can reduce the overshoot by making your own PID adjustments. See the document “PID Tuning”.”

Jean-François

There is now some weeks I wanted to verify by myself if a sous vide equipment is more energy efficient than a “traditional” convection oven. Cooking sous vide some kind of meats can take even several days (for example 72 hours pork ribbs at 57°C). What are the electricity costs?

How to proceed to illustrate this point?
My first thought was to compare the quantity of energy used by a convection oven and an immersion circulator (or a PID controller) in order to obtain the same doneness (rosé) on a 1 Kg beef filet.
Therefore I purchased in a do it yourself shop a very cheap appliance (EUR 11) to calculate the quantity of energy used by an electrical appliance (“consomètre” – refer to the picture on the left).
Unfortunately this “consomètre” cannot be plugged to my convection oven (the electrical cables of the oven are directly connected in the wall.  In other word I have no mains where to plug this “consomètre”.

Thus I have decided to restrict my test to the assessment of the amount of energy used during a cooking process of at least 8 hours at 60°C. The final goal is to determine the cost of such cooking process.

I will not spend any time on the scientific explanation between Power and Energy since the purpose of this blog is only cooking. Nevertheless, for those who want to refresh their mind about physics basics I recommend reading this small article.

In order to determine the price of the energy consumption of an immersion circulator during 8 hours at 60°C I took a round pot of 15 liters and filled it with 28°C tap water.

It took 22 minutes for the swid to reach the target temperature of 60°C at full power (2,170 W).

Then the swid was stable very fast (some secondes only). At this stage the total energy consumption was 0.74 KWh which represents 8 cents (in France, 1 KWh = 0.11 €).

During the next 8 minutes the swid was struggling with power variation in the range from 50W to 600W. I would say the average could be in the area of 300W.
After 1 hour (excl. pre heating) the power variation was in the range from 14W to 200 W. At this stage (1:20 hours incl pre heating) the total energy consumption was 1.06 KWh.

Then I covered the tank with a plastic wrap in order to avoid water evaporation and let the swid run for additional 7:25 hours. When I came back in the morning the result was amazing. Power variation was in the range from 11 to 25 W. Total energy consumption was 2.05KWh (8:45 hours incl pre heating).

For France this represents a cost of approx. € 0.22 (0.33$ with currency rate of 1€ = 1.5 $). Astonishing isn’t it?

Jean-François

I received several questions of people interested by the swid of addelice. Their main worry was to determine if the swid is for professional purposes or for home cooks. To all of them I replied and said that I am not a professional and therefore don’t know their expectations as a professional. I realized that I tried the swid in  3.5 litres and 8.5 litres pots only. The manual of the swid indicates that the stability of the temperature is optimized up to 20 litres.

I went inside my uncle cellar and found an Ikea plastic box (€ 3) that I filled with 20 litres water.

I had to face a problem with the plastic container which is very flexible. Attaching the swid with the clamp to the container was not possible as the swid was too heavy. Therefore I found a glass cutting board that was perfectly the hight of the container. I put this board between the plastic container and the clamp. This generated an excellent stability for the swid to be attached.

I set the swid at 55°C only because I am not realy trusting in the Ikea container that could melt or not resit to higher temperatures. The manual of the swid indicates the Adaptive PID controller (that assesses the amount of the water i n the pot) was optimized if the starting temperature is at least 15°C lower than the target temperature. It took 15 minutes to heat the water from 25°C to 55°C and, after 5 more minute,s the stability of the water bath was excellent.

I decided to make an addition test: immersing a bottle of cold water (3°C) simulating a cold pouch in a water bath.

It worked perfectly.

To sum up I confirm the swid thermal circulator can heat easily a 20 litres water bath.

Jean-François

Three months ago I tried a soft boiled egg at 63°C during 1 hour. I have admitted that it was not the perfect egg for me and promissed to make another try. This time I cooked an egg 50 minutes at a constant 64.5°C temparature.

And here is the result!

(Soft boiled egg cooked at 64.5°C during 50 minutes)

 The egg at 64.5°C has nothing to do compared to the 63°C one (see the last picture down this post). The appearance of the 64.5°C is better, the white egg is more compact and doesn’t fall down like the 63°C one.

(Soft boiled egg cooked at 64.5°C during 50 minutes)

The yolk is also very different compared to the 63°C one.

(Soft boiled egg cooked at 64.5°C during 50 minutes)

See bellow the picture I made 3 months ago of the 63°C soft boiled egg with the Sousvidemagic and above the 64.5°C egg with the swid of Addélice. This is crazy to see how a difference of only 1.5°C can change so much the texture of an egg.
As I told it before I didn’t really like the 63°C egg but the 64.5°C was fantastic!! Absolutly incredible…I strongly recommend anybody trying it!
I read on internet that such egg was impossible to do without the precision and stability of an immersion circulator. I know understand why. If the temperature variation is equal or higher to 1°C then this can change the final texture of the white egg and yolk. The cool thing is also to be sure to reproduce the same result each time you set your immersion circulator at 64.5°C! I am definitely getting found of this cooking equipment.

(63°C soft boiled egg cooked during 60 minutes)

Jean François

Today I woke up and decided to “swid my salmon”!
I purchased 2 pieces of salmon, 20 mm thick, seasoned them with salt, pepper and a little bit of frozen olive oil.
A common problem when cooking salmon, is that the protein albumin leaches out of the fish and coagulates unattractively on the surface. Therefore I brined the salmon 10 minutes in a 10% salted water.

I had look to Douglas Baldwin table about temperatures & times for pasteurized and “mi-cuit” salmon.

Pasteurized salmon (20 mm thick):

55°C         57.5°        60.5C
4:20        1:52            41′

I decided to cook 41 minutes at 60.5°C

Salmon “mi-cuit” (20mm thick):

Very Rare          Rare Medium Rare          Medium Medium Rare
38.5°C                        47°C                                      52°C
26′                               28′                                           28′

The albumin was very present at the surface of the pasteurized salmon. The “mi-cuit” salmon had really less albumin and I could easily take it off before searing it.

(very few albumin appearing on the “mi-cuit” salmon)

I seared the salmon in a pan with a bit of olive oil.
As you can see on the pictures the difference of colour between the pasteurised and the Medium Medium Rare salmon is not obvious.

(left, pasteurized salmon – right, “mi-cuit”)

To sum up I would say the salmon “mi-cuit” 52°C cooked during 28 minutes was definitely the most flavorful. Next time I’ll try both “mi-cuit” 47°C and 52°C during 28 minutes.

Jean-François