Sous-Vide/Precision Cooking.
(The following is taken from my notes on Sous-vide as it is taught in a class called Art Culinaire at The International Culinary School at The Art Institute of Colorado in Denver, Colorado. The sources are; Harold McGee, Robert L. Wolke and Thomas Keller. (Note: This blog may be long and technical for some...).
The Freddie Mercury-led rock-band “Queen” and the eternally–interesting David Bowie (and/or “Ziggy Stardust” to the Baby-Boomers…) collaborated in 1981 on several songs for an album that the band was looking to produce and release. The song “Under Pressure” became a standard of the 1980’s and has nothing to do with The French Laundry, except that the title of the song is the English translation of a controversial cooking method known by its French name – Sous-vide. I attended the semi-annual meeting for the Thomas Keller Restaurant Group when I arrived in California and the video montage included a session on the Thomas Keller book, “Under Pressure” and the song played in the background – which was all quite amusing and entertaining.
Of all the ingredients in the kitchen, the most common is also the most mysterious. It’s hard to measure and hard to control. It’s not a material like water or flour, to be added by the cup. In fact, it’s invisible. It’s heat. Every cook relies every day on the power of heat to transform food, but heat doesn’t always work in the way we might guess. Cooks typically heat food to somewhere between 120 degrees (for fish and meats that we want to keep moist) and 400 degrees (for dry, crisp, flavorful brown crusts on breads, pastries, potatoes, or on fish and meats). At the bottom of that range, a difference of just 5 or 10 degrees can mean the difference between juicy meat and dry, between a well-balanced cup of coffee or tea and a bitter, over-extracted one. And as every cook learns early on, it’s all too easy to burn the outside of a hamburger or a potato before the center is warm.
The trickiest foods to heat just right are meats and fish. The problem is that we want to heat the center of the piece to 130 or 140 degrees, but we often want a browned, tasty crust on the surface, and that requires 400 degrees. It takes time for heat to move inward from the surface to the center, so the default method is to fry or grill or broil and hope that the browning time equals the heat-through time. Even if that math works out, the area between the center and surface will then range in temperature between 130 and 400 degrees. The meat will be overcooked everywhere but right at the center.The solution is to cook with more than one level of heat. Start with very cold meat and very high heat to get the surface browned as quickly as possible with minimal cooking inside; then switch to very low heat to cook the interior gently and evenly, leaving it moist and tender. Another solution is to cook the food perfectly with low heat, let it cool some, and then flavor its surface with a brief blast of intense heat from a hot pan or even a gas torch. More and more restaurants are adopting this method, especially those that practice sous-vide cooking, in which food is sealed in a plastic bag, placed in a precisely controlled water bath and heated through at exactly the temperature that gives the desired doneness.
Microwaving food was once unfamiliar territory. French for "under pressure", sous-vide is a method of cooking that is intended to maintain the integrity of ingredients by heating them for an extended period of time at relatively low temperatures. Sous-vide is the 21st C. version of the 19th C. bain marie. Food is cooked for a long time, sometimes, and often, well over 24 hours. Unlike cooking in a slow-cooker, sous-vide cooking uses airtight plastic bags placed in hot water well below boiling point (usually around 60°C or 140°F). The vacuum-packed bag is immersed into the water bath, heated exactly to the optimal cooking temperature.
In the USA and other English speaking countries, the technique of vacuum packaging may be known as cryo-vacking. Sous-vide is a professional cooking method which employs plastic oxygen barriers and precise temperature controls to reduce oxidization and extend the useable shelf life of inventory by diminishing contact with aerobic bacteria. The result is a final product with superior texture, amplified flavors and enhanced textural qualities. Professional cooks and chefs devote their time and energy in the pursuit of nutrition, food safety, and operational benefits of sous-vide in a restaurant environment. The vacuum-packed bag hugs the food, protecting it from contact with the water while transferring heat directly from the hot water. The bath is regulated by a device called an immersion circulator, a combination of thermometer, heater and pump that monitors the temperature, heats the water just enough to maintain the temperature you set it to, and moves the water around so the temperature is even throughout the bath.
“Sous-vide” isn’t really the best name for this method because the vacuum-packing - the term actually refers to - is less important than temperature control. “Precision Cooking” would be a better term. The heart of sous-vide cooking is the controlled application of low heat – just enough to cook the food properly, no more. A pot of boiling water or a hot oven cooks food at a higher temperature, so that by the time the center of the food reaches the proper temperature, the outside is at least partially overcooked. If you don’t get the timing just right, meats end up dry and vegetables mushy. But, if you heat food in water maintained at exactly the temperature you want the food itself to reach, it will end up cooked properly throughout. A greater appreciation of the term a point: The perfect doneness of any particular food from meats to vegetables.
Sous-vide Equipment & Foods.
Chamber Vacuum-Packing Machine
Thermal Immersion Circulator (heats the water, maintains precise temperatures, and circulates the water).
All-Purpose .003-inch-thick bags (regardless of the material, the bag should be rated for use with food products and for use at boiling temperatures).
Sous-vide may be applied to the majority of foods. However, the color of green vegetables (broccoli, asparagus, peas, etc.) is harmed by sous-vide.
Grains & Cereals (rice and pasta, for example) do not benefit in any appreciable way when cooked sous-vide.
Sous-vide allows the aware cook to achieve the exact internal temperature – medium in lamb loin, medium-rare in squab breast, every time.
With sous-vide you can achieve the same temperature throughout the entire cut, not just at the center, if that is the desired result.
Uses for Sous-vide.
a. Tough cuts of meat.
b. Fish.
c. Seafood.
d. Hard Root Vegetables.
e. All Non-Green Vegetables.
f. Marinating.
g. Compressed textures and coloring.
h. Shaping (i.e., gentle shaping for roulades).
i. Pre-cooking to allow efficient a la minute cooking during service.
j. Frees up oven and stove space.
k. Requires less “on-hands” time.
l. Consistency.
m. Immersion Circulators are portable, requiring only an electrical plug.
n. Storage space.
o. Increased shelf-life (cooked and raw), i.e. custard pasteurization.
p. Efficient service.
q. Nutritional benefits addressing food.
Food Safety Issues and Proper Handling Procedures.
By identifying critical control points and establishing hurdles to microbial growth, all of the safety concerns related to vacuum packaging and sous-vide cooking may be virtually eliminated:
· Only the freshest, highest-quality ingredients must be used when preparing sous-
vide packages. This can significantly lower initial microbial levels, extending shelf life and product freshness.
· It is also critical to calibrate equipment on a daily basis and quality-check all seals and packages for leaks.
• Raw packets must not be stored for more than two days before pasteurization above 60 C (140 F), and must be cooled below 3 C (37 F) within two hours.
• Pasteurized inventory should be stored below 3 C (37 F) and consumed or frozen within a specified time period.
• The date and time of packaging, pasteurization, and expiration must be documented and labeled on the package.
• The entire production process must be governed by a Hazards Analysis Critical Control Point (HACCP) system to ensure compliance and corrective actions.
The most critical factor in restaurant food handling is temperature control. No other restaurant handling procedure has a greater impact in suppressing bacterial reproduction than ensuring that perishable items, especially proteins, stay out of the ‘danger zone’ of 3 C (37 F) to 60 C (140 F). Under ideal conditions, bacterial counts can double every 20 minutes. In a mere 12 hours, a single bacterium may multiply exponentially into a colony of over 9 billion.
Chilled sous-vide items must be stored within walk-in coolers in covered pans with alternating layers of ice in order to maintain strict temperature control. Walk-ins are typically accessed several times per hour, which can bring the ambient temperature – and everything inside – as high as 14 C (57 F). Since the sous-vide bags are packaged and hermetically sealed, there is no certain way of knowing the core temperature of the packaged product unless it is buried in ice at all times.
Sous-vide is a cooking technique that exists at the cook’s disposal; the same as sauté, roast, grill, etc. Three basic principles that govern sous-vide cooking are;
- pressure
-temperature
-time
The fundamental advantage of sous-vide is precision. The degree of precision that sous-vide allows is extraordinary, but you still have to know how to cook. The craft of cooking is the striving precision of execution - daily, hourly, and minute-by-minute. Sous-vide has consistency at its heart. Sous-vide technology is a thoroughly modern application of an ancient, cross-cultural cooking practice- applying long, slow heat to enhance flavors while preserving texture. Industrial food producers have embraced sous-vide as a safe, effective method of packaging wholesome, minimally processed food with superior sensory characteristics. Restaurants have been slower to adopt the technology, due to the complexity of the technique, a lack of training, and the cost of the equipment.
Sous-vide cooking brings multiple benefits to restaurants in the form of increased service efficiency and lowered food costs. Preserving inventory in vacuum sealed bags is an excellent way of extending the shelf life of a product, provided proper handling procedures are followed. Precision heating and cooking offers unprecedented control over texture and flavor. Consequently, there are more textures and flavors to choose from. Cooks can now choose from an unprecedented range of ingredients from all over the world. Cooking is becoming less traditional – thus, cooking is becoming more personal and more and expressive of each cook’s individual imagination.
Sous-vide should not define a dish – the goals of the dish should be first defined and then techniques chosen that help to achieve those goals. Sous-vide is not the answer for all products and perceived uses. Eliminate the need to pay attention and you eliminate the craft. When you eliminate craft, you eliminate some of the spiritual rewards and soulfulness of cooking. Some dishes are still wrapped up in the emotions of cooking itself and help us to appreciate what it is we do. Sous-vide is thus, a part of professional cooking repertoire.
~R
