Polyscience compaires an immersion circulator and a non stired water bath
by jean-francois on Jan.23, 2010, under Equipement, Time and Accurate Temperature
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
Sous Vide & Electricity consumption – Astonishing!
by jean-francois on Jan.17, 2010, under Equipement
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
Pear cooked Sous Vide at 80°C during 30 minutes
by jean-francois on Jan.02, 2010, under Books, Recipes, Time and Accurate Temperature
Bruno Goussault’s DVD mentions a recipe of a pear cooked sous vide:
- 1 pear
- 30 g chocolate
- 20 g vanilla sugar (vanilla extract plus sugar)
The recipes mentions puting the pear sous vide and immerse the pouch in a water bath set at a temperature of 8O°C until the pear is “done”.
Their is no mention of the cooking time. I checked several times the pear before it becomes too soft and therefore decided to stop cooking the pear after 30 minutes. I chilled the pear and kept it in the fridge one day before serving it.
The result is a very nicely cooked pear but I can’t say this pear was something special. It was good but nothing amasing. I think the main advantage of this way of cooking pears is the possibility to keep them 15 to 25 days in the fridge (at the condition to keep them in the pouch). This is definitely a very good point for professionnals.
Jean-François
Worldwide data base of Sous Vide Cooking courses – Help requested
by jean-francois on Dec.28, 2009, under General Topics
I am currently gathering information about culinary instituts, universities, courses where you can learn sous vide cooking. Wherever you are located, feel free to post a comment with the country, name of the culinary school, internet site link…I’ll group this information and make a specific page about it in some weeks.
Thanks a lot for your help!
Jean-François
Duck Foie Gras cooked sous vide at 58°C during 47 minutes
by admin on Dec.27, 2009, under Recipes, Time and Accurate Temperature
In France, during Christmas time, eating foie gras is very popular. Remember that the sous vide method was developed by Georges Pralus in the 70s in order to cook foie gras in an optimal way.
For the first time I tried to cook myself a duck foie gras sous vide.
First issue is to choose a good raw foie gras of quality…The South Ouest of France is the region where the foie gras is originally produced. If you choose one of those, there is a small risk to make mistakes.
Then, you must take off the veins of the foie gras (sometimes you can purchase the foie gras without the veins). This is where the problem started…This is not an easy part of work. I looked on internet some videos illustrated the key points and technique to take off veins of a foie gras and then I tried myself. The difficult thing is to find the veins, take them off without destroying the whole structure of the foie gras.
It was very hard to do. On the right you can see the pieces of foie gras containing the veins and on the left the foie gras I almost totally destroyed!
Then I added 13g salt per kilo and 3g of pepper per kilo of foie gras. Some people recommend seasoning the foie gras with Armagnac or Porto. I put no alcohol at all.
Next step is to create a “ballotine”.
The “ballotine” was also not easy to form. I took a food grade plastic wrap, put the foie gras pieces inside and compressed them, first to take off the air but also to create a cylinder. Several plastics wrap pieces were necessary to fulfill this step.
Next step was to vacuum the foie gras in a pouch. I read on internet that the best way to keep a frame while cooking was to use a “shrink” bag. I didn’t have any so I did it with a regular cuisson sous vide bag.
Cooking the foie gras ballotine: my foie gras cylinder was approx. 17 cm long and 6 cm of diameter. The more an ingredient is fat the best it conducts heat. I cooked my ballotine at 58°C during 47 minutes with immersion circulator.
During the cooking process air appeared in the ballotine and my pouche started to float on the surface. I have probably not compressed enough the foie gras and not vacuumed enough the pouch. Therefore I fixed the pouch with a heavy tool down in my cooking pot.
Next step was to chill the ballotine. As you can see I took this task very seriously.
My foie gras became slightly brown and a significant amount of yellow fat appeared on one side of the pouch (unfortunately you can’t see it on the picture). I was surprised to see that by ballotine kept its cylinder frame. My worry was to maintain this frame until the total cool down of the foie gras. For this purpose I took a piece of carton I curved like a half-cylinder and place the ballotine inside. After I left the ballotine in the fridge for a night with the carton, the whole ballotine kept its perfect frame of a cylinder.
The result was really not so bad! With a little bit of fig, the taste was marvelous and the texture fantastic.
In addition, a little bit of Sauterne Château de Rolland (Barsac) 2004…Très, très bon!
Jean-François
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