Although invented in 1970’s by a French butcher (Mr. Prelus) sous vide cooking has been slow in entering restaurant kitchens in North America and Europe.
It requires two pieces of equipment – a vacuum packing machine, and a water bath with an immersion circulator that regulates the temperature precisely.
Sous vide in French means under pressure, in actual fact it should be called precision cooking, since even one degree C difference in cooking makes an impact on the outcome.
This may be the reason why sous vide has been slow in penetrating commercial kitchens as most line cooks are blissfully unaware of the importance of precision.
Heat is the most important ingredient in cooking and sous vide cooking it rarely exceeds 85 C (185 F) which can result in great saving in energy consumption.
Heat is any transfer of energy from one body of system to another.
It is transferred by radiation, conduction or convection.
Induction cooking is the newest energy transfer technique, which occurs when a specially- designed and manufactured metal pot is placed above an induction coil. Induction coils work by electricity; they do not generate heat beyond the pot surface and are fast. Aluminium, glass or ceramic pots are not suitable.
Infrared heat is electromagnetic radiation and is used to keep plated food hot.
Microwaves heat by friction of molecules, i.e. dielectric heat. Microwave coking never browns food.
Percy Spence discovered it in 1940s in a Rytheon Research Laboratory. At first microwave ovens were huge and water-cooled. In 1947 the cost of a microwave oven was $ 5,000.00.
Microwaves heat more efficiently liquids than solid foods. No closed containers must be placed into any microwave oven.
Sous vide cooking
is gentle and requires much less fat than conventional cooking. Food can be portioned precisely, cooked in advance, quickly chilled to 6 C (42.8F), refrigerated or frozen.
It prevents oxidation, and the food can be rethermalized, plated, garnished, and served.
The only setback of sous vide cooking is that it never browns food. This must be done after the sous vide cooking has taken place in an conventional oven.
The cooking temperature and tome can be regulated as required and even tough meat cuts can be rendered very soft by long cooking.
The bags for sous vide cooking should be at least .003 inches.
Anaerobic or aerobic bacteria can contaminate food, the former grow in oxygen-less environment, the latter require oxygen.
Salmonella, clostridium botulinum, e-coli 0157:H7 and listeria live in anaerobic environments, as is the case in sous vide bags, therefore food must be removed from the danger zone 4.4 C – 60 C (40 – 140 F) as quickly as possible. After cooking, immerse pouches in ice baths to bring the temperature down.
Bacteria thrive between 40 – 50 C (100 – 120 F) and double every 20 – 30 minutes. Most exist on the outside of the food, except in ground meat and eggs. (Bacteria are unicellular microscopic organisms that multiply by splitting. They cause cholera, syphilis, leprosy, tuberculosis, bubonic plague, salmonella, clostridium botulinum, e-coli 0157;H7, listeria just to name a few).
Viri are sub-microscopic and need a host to survive and thrive. A virus is surrounded by a protective shield and causes common colds, flu, chicken pox, ebola, sars, influenza and aids).
Cooks involved in sous vide preparations must be well trained, and very conscientious in their work to produce healthy and nutritious food.
Of all the bacteria mentioned above, clostridium botilinum is the most dangerous, being heat resistant, and thriving low oxygen environments. It attacks the CNS, and in most instances kills the individual exposed to it.
Sous vide cooking
offers many advantages to restaurateurs, but must be exercised with due diligence. Keep sous vide cooked food up to three days refrigerated. For longer period the food must be frozen.
Important points to remember while cooking and storing cooked food.
Bacteria count can be minimized by refrigeration and keeping food of the danger zone.
Bacteria are on the exterior of the food, except for ground meat, chicken or turkey.
Buy the freshest meat and cook it as soon as possible.
Toxins on contaminated meat increase as storage period prolongs.
Toxins increase even on contaminated refrigerated meat, but at a reduced rate.
There are more than 2000 kinds of salmonella bacteria, which is highly heat resistant, is responsible for more than 1.4 million food poisoning incidences, of which several hundred are fatal.
Salmonella live in chickens, eggs and the intestines of animals, (clostridium botulinum is the most dangerous of all and is extremely heat resistant. It grows in low-oxygen environments, i.e canned foods etc. This is a concern of sous vide cooks.
E-coli 0157:H7 is dangerous bacteria found in meat and vegetables. It is responsible for approximately 60 deaths annually in the U SA.
It lives in the intestines of animals and is found mostly in meats and leafy greens.
Listeria is present in the soil and water. Pregnant women are particularly susceptible. In food processing plants, drains are the most prone locations.
Mostly hot dogs and products very finely ground processed meat at the cause of listeria.
Listeria bacteria cause septisemia, meningitis, and encephalitis. It attacks children, the elderly, and pregnant women.
Sous vide cooked food must be cold before placing it in the pouch and kept cold before cooking, but preferably should be cooked immediately.
After cooking food serve it immediately, or chill thoroughly and quickly, or freeze to take food out of the danger zone.
Sous vide cooked food can be refrigerated for up to three days.