Sous Vide @ Home

I just finished a delicious meal of beef ribs with texture and tenderness as good as the best rib-eye steak, but a taste which was much more complex and more flavourful. So how did I make one of the cheapest cuts of beef taste like one of the most expensive? Sous Vide is the answer - using the technique I cooked the ribs for 48 hours @ 56 degrees Centigrade.

What is Sous Vide?
Sous Vide (SV) is a cooking technique where food is vacuum-sealed in a plastic bag and cooked in a water bath at a low temperature usually for a long time. It is mostly used for meat and fish, but good results can also be achieved with hard vegetables. (Green vegetables do not work at all).

Why would I do it?
There are a couple of good reasons for using SV. The first and most obvious is making delicious meals from the cheapest cuts of meat. The less obvious reason is that you can enhance the flavour and texture of even the best cuts of meat using the technique. Who developed it and when did it begin? SV was initially devised by Georges Pralus in the mid-1970s for the Restaurant Troisgros in Roanne France to minimise the wastage during the cooking of foie gras. Bruno Goussault further researched the technique and applied it to many other cooking tasks. He is usually cited as the “inventor” in the few books written on the subject.

How does it work?
It is a cooking technique which until fairly recently was not widely known outside professional kitchens. Sous Vide literally translates to: “Under Vacuum”.

The literal translation of the term doesn’t really explain how the technique works and is possibly misleading, as the “vacuum” plays a very little part in the transformation of the food from raw to cooked.

A better definition of SV is “long time low temperature” cooking.

While vacuum sealing may enhance flavor and nutrient retention, it is mainly used to isolate the food from the water it is cooked in. Moreover, removing the air keeps the bags from floating in the water bath and cooking unevenly.

Apart from having the food to be cooked sealed in a bag with no air the most important aspect of the technique is accurate temperature control. When using low temperatures for a long time a variance of even one or two degrees Centigrade can have a noticeable impact on the finished product.

SV is essentially poaching food in it’s own juices therefore it does not brown in any way. This is fine for fish and some poultry dishes, but meat straight from the bag is unappealing and lacking those nice “browned” flavours usually associated with grilled or roasted meat (The “Maillard Reaction”).

To substitute for the lack of browning most SV practitioners sear the cooked meat on an extremely hot cast-iron pan very quickly or brown the outside of the meat using a butane or propane blowtorch. I have used both methods to good effect.

The reason that tough cuts of meat become tender is that with long cooking the collagen (which is the main “tough” component in red meat) breaks down and becomes gelatin. In conventional cooking techniques this is usually only achieved by slow braising, but in that environment the meat loses most of its juice to the gravy by the time the collagen breaks down. In SV, the shape and form of the meat is unaltered by cooking and there is comparatively little loss of the meat’s juices during cooking. To tenderise tough meat with SV it is usual to cook at temperatures greater than 55C for periods ranging from 8 to 72 hours.

SV can also be used on the best cuts of meat. I have cooked top quality scotch fillet (Rib-eye for our US friends) SV and the result was better than my normal method of cooking from cold on a cast-iron griddle pan. For meat that is already tender the idea is to have the water bath temperature at the final temperature you want the interior of the meat to be when cooking is finished. For Rare to Medium-Rare steak this is 52C. Because the water bath is held exactly at 52C, the meat cannot become overcooked. The only real issue is food safety (see below) so it should not be held for longer than 4 hours at this temperature.

This is very convenient if you have to feed a large group. The steaks can be held at the desirable level of doneness while the rest of the meal is being prepared. All that is needed is a very quick sear in a hot pan or a blast with the blowtorch to brown the outside of the steak before plating.

One obvious difference between SV and conventional cooking techniques is that when the steak is cut you can see that it is uniformly cooked through to the desired level of doneness. A conventionally cooked steak will be overdone on the outside by the time the centre of the steak reaches its target temperature.

What sort of equipment do I need?
Firstly a vacuum packaging machine is needed. If money is no object get a small chamber based machine, although even the cheapest of these is still quite expensive.

Domestic packaging machines (like Foodsaver) have become more widely available recently and seem to work well for SV. The only downside of this type of machine compared to a chamber machine is that it is more difficult to cook something with a marinade or other liquid in the bag. A method used by some SV cooks is to freeze the liquid so that the air can be removed from the bag without the machine sucking the liquid out as well. Some SV cooks wrap their meat with marinade in cling film prior to vacuuming.

At the bargain basement end of the scale some people report acceptable results using high quality freezer bags (say from Zip-Lock or Glad); to use them, place the food and some sauce or stock in the bag, then place the bottom of the bag under water and as you seal the bag submerge the just sealed portion under water so as to squeeze as much air as possible out of the bag. Care must be taken to minimise the air in the bag as if the bag floats the food will cook unevenly.

The second thing you need is a water bath with very accurate temperature control (Typically accuracy and stability within 1C is enough – there are those who maintain that 0.1C precision is required, but I’ve not read any proof of this. In any case the more accurate and stable your set up is the better).

Professional kitchens tend to use scientific laboratory equipment for SV. Specifically they use either Immersion Circulators or Temperature Controlled Water Baths. These 2 devices are very similar in that the working part of a suitable water bath is pretty much the same as the immersion circulator. The main difference is that the bath is an integrated unit whereas the immersion circulator is intended to be used on any vessel large enough for a reasonable amount of water like a stockpot. Both devices work by pumping water through a heater that has a sophisticated thermostat. The water is circulated to maintain temperature consistency throughout the bath.

With the increasing demand for these devices by chefs a few of the science lab suppliers have re-packaged their devices to target the restaurant trade.

For home use you can have a very acceptable SV set up for much less than half of the cost of an immersion circulator.

There has been a lot of investigation done by many pioneers of this technique. The consensus is that the best gear to use for SV at home (excluding the Lab equipment if price is no object) is a Rice Cooker and a special thermostat called a PID Controller. It is important that the rice cooker is a “dumb” device with no electronic/software control as the intent is for the PID controller to “drive” the rice cooker. Cookers with intelligent controls do not lend themselves to this.

The rice cooker is selected in preference to other potentially useable domestic devices because the heating element is at the bottom – under the tank ensuring that convection will cause the water to circulate and minimise the temperature differences throughout the tank naturally. With devices like slow cookers the elements are usually around the sides of the bowl so the temperatures nearest the edges of the tank would be higher than those in the middle.

I obtained a large commercial rice cooker, which has a 12 litre tank. Depending on how much you intend to cook at any one time you could survive with a smaller/cheaper unit but if it was too small (say 3 litres or so) there wouldn’t be enough water to maintain the temperature as cold food was added. I would go for the largest you can find which sensibly fits into your kitchen . A PID controller is essentially a sophisticated thermostat. The thermostat in most appliances is simply an on/off device. Once the set temperature is reached power is cut to the heating element. Because the element is still hot the temperature continues to rise until the latent heat of the element is dissipated. Then the temperature starts to drop until a certain point somewhere below the set point when power is applied again. This has the effect of big swings in temperature around the set point. For most kitchen applications (or for the air-conditioning in your house for that matter) these swings do not make any difference and are not even noticeable.

With SV cookery the variance of only 2C or 3C can have a noticeable impact on the finished product. A PID Controller overcomes these swings. A discussion on how a PID Controller achieves its effect would take more space than this whole article. Suffice to say by using a rice cooker (one with no fancy electronics) and a PID Controller very accurate and consistent temperatures can be achieved.

There is another benefit of the rice cooker/PID over an immersion circulator or lab bath and that is energy consumption. Rice cookers are typically well insulated and once the target temperature is reached the PID controller only needs to supply very small bursts of electricity to maintain the temperature in the bath. The Lab style solution has the pump running 100% of the time and the heater on for most of the time as the stock pot or tank being used is typically not insulated – indeed some baths do not even have lids!

A company in Canada: Fresh Meals Solutions, markets a device called “Sous Vide Magic” which is a PID controller designed specifically for this purpose. There is another company marketing the same device: Auber Instruments in the USA. I went with Fresh Meals Solutions because of the helpfulness of the proprietor Frank Hsu (Who incidentally is an ex-Sydney resident now based in Toronto). The SVM cost less than AUD$240 landed in Sydney.

What to be afraid of…
Food safety! There is much written about this subject. I have referred to several sources of information below for those who want to get into the detail. I will summarise a few simple rules which if followed will guarantee food safety is not compromised. This doesn’t mean that these recommendations are at the edge of safety – on the contrary they are those which meet US FDA guidelines so are therefore “very conservative”. Suffice to say that normal kitchen hygiene practices apply. I am only commenting on the specific additional safety aspects of SV.

In SV cookery we are attempting to perform one of 2 kinds of transformation of the food we’re cooking:

•	For tender meats and most seafood we cook at temperatures between 45C and 55C. For safety reasons it is important that cooking time in this temperature range (or any lower temp) is less than 4 hours (fridge to plate time).

Typical temperatures would span from about 45C for most Seafood, 48C for Rare Beef to 54C for Medium Beef.

Note: In general there is little benefit in cooking any tender ingredient for much longer than the time needed to get the internal temperature up to the desired level. For example a steak which is 30mm thick will reach its final temperature for rare (48C) in about 1 hour. Holding it in the bath for another hour or even 2 is well within food safety guidelines and will not over cook the meat nor compromise it’s safety.

•	For tough meats where the intention is to use SV to break down the collagen in the meat the temperature should be greater than 55C and the time can be for as long as you like. Times ranging between 8 hours and 72 hours have been used to good effect.

Irrespective of the temperature and time used for SV cookery, if the food is not to be consumed immediately it is important that it is chilled very quickly. Putting the sealed bags into an ice-bath is the best way to quickly reduce the temperature. The bags can then be held in the refrigerator for up to 5 days (at normal domestic fridge temp of 5C), or frozen indefinitely.

Where to find more information?
•	By far the largest single source of information about SV is the eGullet forum on the topic: http://forums.egullet.org/index.php?showtopic=116617 This forum is quite daunting – there are thousands of posts and some of the information is conjectural.

There are two contributors to the forum who have become the resident experts:

o	Nathan Myhrvold (ex CTO of Microsoft) was a very early contributor to this space and has been actively investigating SV for several years. He has done extensive research on the food safety aspects of SV and has exploded several myths in the process. He is soon to publish a book on the subject, which I expect to become “the” trusted reference on SV.

o	Douglas Baldwin is a mathematician with a serious interest in cooking. He has published a document, which is probably the best concise source of SV facts available at the moment. Anyone interested in pursuing SV further should read his document: http://amath.colorado.edu/~baldwind/sous-vide.html In addition to the technical information on eGullet there are a large number of recipes many of the SV cooks have prepared together with a lot of follow up information and suggestions for recipe improvement.

•	Fresh Meals Solutions web site:

http://freshmealssolutions.com/ Tell Frank I sent you ;-)

•	There are 3 cookbooks I have found which are centred on SV cookery:

Under Pressure by Thomas Keller ISBN 978-1-57965-351-4 - Artisan Thomas Keller is Chef/Owner of The French Laundry in California and Per Se in New York.

Sous Vide – Cooking in a Vacuum by Viktor Stampfer	ISBN 978-3-87515-027-8 Matthaes Viktor Stampfer became famous in his native Germany. He now consults in Dubai.

Sous Vide Cuisine by Joan Roca & Salvador Brugues ISBN 84-7212-112-7  Montagud Editores Joan Roca is the Chef/Owner of El Cellar de Can Roca near Girona (north of Barcelona) in Spain.

All of these books are interesting and I am please to have them all in my library. I will add though that if I hadn’t read the eGullet forum and Douglas Baldwin’s article referred to above and had relied solely on the information in these books I would have a different understanding of SV. All of the books come from a professional kitchen perspective and therefore are necessarily conservative in some ways – particularly with respect to food safety. It is clear from the research done by Douglas Baldwin and Nathan Myhrvold that much of what is taught about food safety is not correct. See note about food safety above.

•	There are some excellent articles on food safety in the following web pages:

o	http://www.hi-tm.com/RFA/food-path-summ.pdf o	http://www.hi-tm.com/homeprep/titl-tabl.html o	http://www.hi-tm.com/homeprep/Home-2006-2col-forpdf.pdf

Acknowledgements:
•	Thanks to Douglas Baldwin for reviewing the document and providing some useful suggestions for improvement.

•	Thanks to Robert Jueneman for his suggestions and for reminding me that the whole world doesn’t necessarily understand Australian terminology.

•	Thanks to Peter Gruber for the extra food safety references.

Peter Black 19 May 2009

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