Cool Food

Apart from being one of the latest fashions in food, what exactly is sous vide?

Like many chefs, John Placko is a huge fan of the cooking technique called sous vide. At the restaurants where he has worked and the culinary academy where he teaches cutting-edge “molecular cuisine,” foods cooked sous vide are an essential part of the menu.

“There’s so many benefits, particularly if you’re cooking, say, ribs,” says Placko, an Australian who lives and works in Toronto. “You would cook ribs for 48 hours and get an incredible, tender product, where the fat content in the meat and the connective tissue tend to dissolve and become gelatinous, releasing the flavor into the meat.”

Sous vide, which means “under vacuum” in French, typically involves vacuum-sealing a cut of meat or other food in plastic and submersing the package in a warm-water bath kept at a precisely controlled temperature, often for hours. The food is cooked evenly all the way through, the juices are preserved, and diners are ecstatic.

“You end up with ribs where the bone will basically just slide out completely clean, so people that have eaten those ribs never want to eat another kind of rib after that,” Placko says.

The popularity of sous vide has exploded in the past few years, spreading the delights of perfectly cooked meat and other foods to gastropubs and home kitchens. But that growth has also occasioned some consternation among regulators who worry that misuse of low-temperature cooking and vacuum storage could end up sickening some of the cooks who have eagerly adopted the method, not to mention their dinner guests or customers.

“It is a technique that does require attention, and you do have to understand that you’re dealing with people’s health,” Placko says. “You don’t want to have any kind of food-poisoning incident.”

Refining an Ancient Technology

The roots of sous vide cooking reach far back in history to traditional practices of wrapping food in leaves or animal bladders before cooking. Maori people in New Zealand used a very similar technique, lowering flaxen bags of food into naturally occurring hot springs and leaving them to cook slowly.

In the West the discovery of slow cooking at low temperatures is often credited to Benjamin Thompson, known as Count Rumford, whose wide range of interests included the study of heat and cooking. In one experiment conducted at the end of the 18th century, he tried to cook a shoulder of mutton in a machine he’d invented to dry potatoes with hot air. He gave up after three hours, feeling “rather out of humour at my ill success”; but the mutton remained in the apparatus until the next morning, when the maids found it perfectly cooked.

“It was neither boiled, nor roasted, nor baked,” Rumford wrote. “The gentle heat to which it had for so long a time been exposed, had by degrees loosened the cohesion of its fibres, and concocted its juices.”

An irony of today’s worries over sous vide safety is that vacuum-packing has always been used to prevent food spoilage. In 1900, Hills Bros. began selling coffee in vacuum-sealed cans to preserve the taste, and by the 1930s early efforts were under way to vacuum-pack raw meat in latex or other polymers.

In the 1960s researchers began cooking food sealed in plastic, according to Modernist Cuisine, an encyclopedic food-science guide and cookbook written by sous vide enthusiast and former Microsoft executive Nathan Myhrvold. During that time Swedish hospitals developed a system of vacuum-sealing cooked food, boiling it for a few minutes more, and delivering the packages to facilities around Stockholm.

True sous vide was created when hospitals in South Carolina and plastic-film manufacturer Cryovac collaborated to make the key innovation of vacuum-sealing raw ingredients before cooking. The process was refined by French experts, particularly chef George Pralus, who used sous vide in the early 1970s to minimize shrinkage of foie gras, and food scientist Bruno Goussault, who developed temperature guidelines and techniques that allowed commercial adoption. Their work dovetailed with a nascent movement to bring food science and chemistry into restaurants and home kitchens in order to create new dishes that ranged from sous vide steaks to nitrogen-chilled ice cream and even fruit-juice caviar.

An early proponent of sous vide was Nicholas Kurti, a Hungarian physicist at Oxford University who had created temperatures near absolute zero in his lab. During a 1969 talk at the Royal Society he reproduced Rumford’s slow-cooking experiment and made an “inverted Baked Alaska” pie—with a cold crust and a hot filling—using the newly invented microwave oven.

“I think it is a sad reflection on our civilization that while we can and do measure the temperature in the atmosphere of Venus, we do not know what goes on inside our soufflés,” he told the audience.

Kurti partnered with French food chemist Hervé This, who developed techniques to perfectly boil (and to “unboil”) eggs and also tested the efficacy of traditional cooking tricks. (For example, This found oil does not prevent boiling pasta from sticking together.) Author Harold McGee and TV chef Alton Brown have further popularized the notion that knowledge of food science enriches the cook’s toolkit and the diner’s pleasure.

Critics have described methods developed by This and famous chefs like Spain’s Ferran Adrià as weird tricks that produce something other than food. In the foreword to Modernist Cuisine, British chef Heston Blumenthal dismisses the complaints.

“There are people who determinedly resist the use in the kitchen of things like liquid nitrogen and evaporators, seeing them as somehow inappropriate and ‘not cooking,’” he writes. “Yet many of the technologies and tools we rely on every day in the kitchen—our fridges, freezers, and food processors, and even our non-stick pans and super-sharp carbon steel knives—are products of equally complex science.”

Anaerobic Anxieties

When it comes to sous vide, concerns have focused less on its strangeness and more on safety. In 2006, after the New York Times published a long article about the technique, inspectors visited some of the city’s finest restaurants, ordering them to stop using their hot-water baths and to destroy vacuum-packed foods. These establishments were required to submit detailed plans describing their packaging processes and cooking temperatures and times, which are normally only required of industrial food companies and large caterers. Similar crackdowns have occurred in Chicago and Las Vegas, cities known for culinary innovation.

Food scientist Goussault told the New York Times that tough regulation was necessary to ensure all restaurants used sous vide safely, though it might be “too much” for top chefs who already followed the rules carefully. Myhrvold described New York’s new regulations as “draconian” and attacked their “excessively high temperature standards” that made it impossible to prepare fish sous vide without overcooking it.

Sous vide is carefully regulated when used in factories, so its unmonitored use in restaurants drew concern. Vacuum-sealed bags are considered a type of “reduced-oxygen packaging,” which can allow the growth of anaerobic bacteria, such as Clostridium botulinum. The microorganism produces a neurotoxin that is one of the world’s most poisonous substances (and the main ingredient used in Botox for antiwrinkle injections and various medical treatments).

Unlike aerobic spoilage bacteria, which create the familiar smell and appearance of rotting food, anaerobic bacteria are not instantly detectable, says Donald Schaffner, a Rutgers University food microbiologist who has helped develop FDA safety guidelines.

“You put something in a bag, and you seal it; you put it under vacuum, and you change the microbiology such that the spoilage organisms that might normally trigger a ‘Yuck, I’m not going to eat that! That’s disgusting!’ may be there in lower numbers, or may not trigger overtly,” Schaffner says. “So that’s really the concern.”

C. botulinum and other bacteria can be killed off quickly by boiling at 212°F, as is done during canning of food to ensure long shelf life. But in sous vide, meats are cooked at lower temperatures to achieve their vaunted juicy tenderness, often around 130°F or 140°F. Cooks must be sure to hold the temperatures long enough to kill off any Salmonella and Listeriabacteria, but C. botulinum can survive this cooking. That isn’t a problem if the food is eaten immediately, but waiting for more than a few hours can potentially give the C. botulinum bacteria enough time to release toxins, unless the food is acidic or kept at near-freezing temperatures.

As a result, pushing the envelope on traditional cooking techniques, which so excites chefs and foodies, can set off alarm bells among regulators who hear about sous vide cooking techniques.

Botulism poisoning from food is exceedingly rare and almost never fatal, and Schaffner says he is unaware of any reports of people getting sick from eating foods prepared sous vide. Salmonella and Listeria poisonings from other sources happen all the time, though, and the last thing an ambitious chef wants customers to think about is the potential harm that could come from biting into one of his or her steaks.

“People jumping into sous vide that don’t take it seriously could actually create some harm if they’re trying to cook products at a lower than safe temperature for less time than is required. It can be an issue,” Placko says. “So if you’re going to do it, do it right or don’t do it at all.”