Patrick Ogheard, Associate Dean of Practical Arts at Ecole hôtelière de Lausanne, explains the many wonders of cooking ‘sous-vide’.
Sous vide, the French term for "under-vacuum," is a method of precision cooking in which food is vacuum-sealed, then submerged in a water bath at a specifically regulated temperature and gently cooked. The process, expounded by food scientist Bruno Goussault in 1971, has many positive aspects, most notably maintaining food textures and flavors without compromising its natural integrity. For Goussault, sous vide began as a way of improving the tenderness of roast beef. He discovered that if the beef was vacuum-sealed in a specially designed pouch and cooked slowly at a lower-than-usual temperature, it turned out softer, juicier and full of natural flavors compared to when using conventional cooking methods involving more heat and less time.
EHL’s Patrick Ogheard launched the school’s Research and Development workshop with Goussault and gleaned many prestigious sous vide techniques from the master.
PG: “The method of cooking sous vide has been around in different forms for a long time. Think of the traditional African ‘earth oven’, a cooking pit, or the French ‘en vessie’ (meat cooked slowly in a pig’s bladder). Anything that’s cooked gradually in a protective layer is basically sous vide. It’s very good for certain meat, fish and vegetables. It’s especially successful in turning the tougher cuts of meat – usually found in stews – into something very tender and tasty. This is due to the slow cooking times, often overnight – sometimes even three days, and the low temperatures that respect the meat’s fibers.”
The guidelines are strict and scientifically precise, hence the occasional criticism from the old-school traditionalist chefs who claim that sous vide takes the ‘messy fun’ out of cooking. Prodding fingers and thumbs are replaced by thermometers and gadgets, making the process foolproof and totally devoid of guesswork. However, as the proverb says, the proof of the pudding is in the eating: the sous vide results are always tender, flavorful, succulent and evenly cooked throughout, making it a winner in big kitchens that rely on churning out big quantities of uniformly beautifully-cooked food.
Important points and cooking practices:
Food is vacuum-sealed in a plastic pouch devoid of any air, this ensures not only better flavors but also thorough and even cooking.
Do not vacuum-pack at room temperature, best to seal your food item straight from the fridge.
Be precise with the seasoning before sealing the pouch. When cooking protein, measure 1% of salt and 5% of fat. For vegetables, measure 0.8% of salt.
Anything cooked at under 52*C will not be pasteurized and cannot be stored safely, (hence why a dish like ‘warm sushi’ must be served immediately).
Cooking temperatures have to be determined based on desired outcomes. For example, a medium-rare steak should be cooked at 62*C when it turns from red to grey. A well-done steak needs to be cooked just below 68*C when the meat becomes a bit drier because the water is lost from inside the muscle tissues.
Once cooked, the food item should be left to cool down to room temperature, then immersed for ten minutes in cold water, followed by another ten minutes in ice. This enhances the osmosis process. After this, the food can be taken out of its pouch and further cooked on a higher heat for the purpose of glazing, searing, caramelizing and fixing the flavors with fat or alcohol.
Once cooked, sous vide food can be kept for quite a long time in the fridge as long as it is still in its vacuumed pouch.
Do not use clingfilm which is hazardous when heated, but a specially-developed plastic cooking bag designed for sous vide purpose.
Essential sous vide equipment
Admittedly, having a vacuum-sealing machine is key to ensuring the basic premise of sous vide: no air in the pouch! Air acts as a thermic insulator, so any air bubbles in your bag risk the food not getting cooked evenly throughout.
“My laboratory thermometer is my favorite piece of equipment” says Bruno Goussault. This essential item, also known as a ‘sous vide stick’ or an ‘immersion circulator’, is what ensures the chosen temperature is reached and remains constant during the entire cooking process. Temperature accuracy is after all the defining characteristic of sous vide cooking.
Not to be confused with:
Boil-in-bag. A popular ready-made meal format that is similar to sous vide simply because it involves a plastic bag, but in reality the cooking temperatures are all at boiling point and hence go against the main principle of using low, slow-heat.
Pressure cooker. Again, here the temperatures used are too high and cooking times are too fast compared to sous vide practices.
Steamer. Still a question of too much heat since water has to be heated to 100 degrees centigrade to produce steam.
In brief, for a perfectly-cooked juice-bomb of a meal, cooking sous vide is a scientifically fool-proof method that ensures constantly even results. It could be compared to a gently-heated jacuzzi with water gradually cooking your dish avoiding any heated metal surface, flame, smoke or steam. It’s an insurance policy in the kitchen that admittedly removes all guesswork and surprises, but does guarantee a certain freedom for other jobs to be done while the slow sous vide magic simmers away. Some essential equipment is recommended for those wanting to try sous vide at home, but once purchased, the benefits of being able to store the cooked food safely for longer periods should outweigh the expense.