Sous Vide—A Better Way to Cook?

“If I could pick only one new cooking method out of this entire book for you to try, sous vide would be it, hands down.” 

Strong words from Jeff Potter in his indispensable Cooking for Geeks.  If you're unfamiliar with the term “sous vide” (French for “under vacuum” and pronounced “Sue Veed”), you're far from alone; because the process involves a fair amount of time and some specialized equipment, its popularity in the home has been limited since its introduction to the culinary world in the 1970's.  But its use in many high-end gourmet restaurants and the publicity given to its strong advocates like Douglas Baldwin, author of Sous Vide for the Home Cook, have increased its visibility to the point where it bears some scrutiny, so let's start with the basic question...

What is Sous Vide, anyway?

Sous vide cooking is a process in which the food is vacuum sealed in a plastic bag and poached in a water bath at unusually low, but precisely controlled, temperatures for unusually long durations (as long as 72 hours in some cases!).  In essence, it is similar to using a slow cooker, but the plastic bag enables the water to heat the food inside without chemically interacting with it and eroding its flavor.  The advantage of this method is that it cooks the food uniformly from surface to center.  It also eliminates the possibility of overcooking, since the cooking temperature is approximately equal to the target temperature.  Thanks to this technology, the food comes out “just right” every time, and in fact, as Jason Logsdon's comprehensive Cookingsousvide.com website puts it, often yields “silky and smoothly textured food that is impossible to replicate with traditional cooking techniques.”

On his website, Baldwin, a mathematics professor and scientist by trade (and arguably the foremost authority on sous vide), explains the different types of sous vide cooking: cook-hold, in which the raw or partially cooking food is sealed, pasteurized (heated to 140°F), and held at 130°F (54.4°C) until it’s served., and the more popular cook-chill and cook-freeze, in which the cooking process is usually followed by rapid chilling of the (still sealed) food in an ice bath before being transferred to a refrigerator or freezer for later consumption.

“Sous vide processing is used in the food industry to extend the shelf-life of food products; when pasteurized sous vide pouches are held at below 38°F (3.3°C), they remain safe and palatable for three to four weeks,” Baldwin points out. 

But why so long?

The length of sous vide cooking time, along with the correct temperature, is dependent on a few factors, mainly the thickness of the largest food  particles and the amount of collagen contained in the portion of meat, poultry, or fish.  As Baldwin explains it in a Cooking for Geeks interview: “It's all about the conversion of collagen into gelatin.  This conversion is pretty rapid at the higher temperature...but at lower temperatures like 130-140°F/54.4-60°C, it can take 24 to 48 hours for the same conversions to occur.”  J. Kenji Lopez-Alt's website SeriousEats.com goes into greater detail as to why cooking chicken at lower temperatures requires so much more cooking time, as well as how deliciously worth it the time investment is.

If one is not quite inclined toward buying a pricey sous vide cooker, there are ample alternative suggestions.  Potter's book details how to make your own setup using a slow cooker, a thermocouple ($15-20) and a temperature controller ($75), and even suggests searching online for sous vide recipes that entail cooking in the dishwasher!

In any case, the point is that the process demands the ability to rigidly control the water temperature, and naturally, when cooking perishables for such a long time and at such a relatively low temperature, precautions need to be taken against bacteria growth.  This is to say that by now, many of you are undoubtedly wondering...

How can this possibly be safe?

Baldwin addresses this topic at length on his website, both in print and as part of an 11-minute video well worth watching, remarking early on that “In many ways, sous vide cooking is safer than traditional cooking, because we have much greater control of the temperature and the way in which we cook the food.” He then goes on to explain that of the three types of bacteria found in food – pathogens, spoilage, and beneficial – pathogens are the only ones that can make us ill (spoilage itself does not make us sick, he explains, but it can be an indicator of the presence of pathogens), and most pathogens cannot survive in temperatures above 126ºF. He dismisses the notion of the “danger zone” (40°F-140°F, 4°C -60°C). He  recommends that chicken breasts be cooked to140°F. (The lowest temperatures he suggests for chicken breasts is 134.5, but most he says that most people prefer the taste of chicken breasts cooked sous vide at 140 - 150°F.  For lower temperature (i.e, thinner, lower collagen) foods such as fish, he suggests cooking them at a temperature close to the  pasteurization temperature (140°F/60°C for 40-50 minutes). He also has some pretty extensive instructions for washing your hands before doing any sous vide cooking, and rigid rules for what temperatures to store cook-chilled foods, so the possibility of incomplete pathogen kill and regrowth are not issues he treats lightly.

Logsdon's book Beginning Sous Vide advises cooking at a higher than minimum temperature and longer than minimum cooking time to safeguard against equipment and thermometer inaccuracy.  Wikipedia adds this reasonable disclaimer, “Extra precautions need to be taken for food to be eaten by people with compromised immunity. Women eating food cooked sous vide while pregnant may expose themselves to risk to themselves and/or their fetus.”  In other words, if you’re in one of those categories, avoid sous vide. 

What it boils down to... (Sorry!)  

As Logsdon warns, “Sous vide is a new and largely untested method of cooking. It carries many inherent health risks that may not be fully understood...Anyone undertaking sous vide cooking should fully inform themselves about any and all risks associated with it and come to their own conclusions.”  Clearly, sous vide, like any other cooking method, is not without its risks, but fortunately, Baldwin and many others have researched the topic pretty thoroughly, so there is certainly no shortage of sous vide books and websites out there, packed with recipes, equipment recommendations and cooking time/temperature charts for the beginner. Experienced sous vide chefs guarantee that this cooking is rewardingly scrumptious. 

Editor’s note:  In posting this article about sous vide cooking; our goal is to educate readers about a trendy and interesting style of cooking.  We are not trying to convert readers to using this form of cooking at home. Sous vide chefs explain that, because sous vide cooks foods longer, they can be safely cooked at a lower temperature. When we asked two of the scientists on our Advisory Board—Dr. Catherine Cutter and Dr. Clair Hicks--about the risks of eating food cooked sous vide, both expressed concern and said they would not eat food cooked by this method. When we asked a third Board member, Dr. Joe Regenstein, he said that he had eaten sous food in restaurants and added this:  “It’s usually then ‘cooked’ to reheat and that is an additional kill step [that kills pathogens]. I don’t worry as long as the reheat is done properly.  I think this process makes sense institutionally but not at home.”  The FDA has told restaurateurs, “…it can be done safely.”  However, the risk is greater when an inexperienced at-home chef is in charge.

The main fear is that holding food at low temperatures (below 140°F, in what food scientists consider the “danger zone”) in vacuum packaging for a long period of time could allow the growth of pathogens that may cause food-borne illness.  The biggest danger is that the airless vacuum packaging could allow the growth of the bacterium botulinum. If the product is then held for a long time, the pathogen could develop enough botulinum spores to give the diner botulism, a disease that’s often fatal.

If you decide to experiment with sous vide at home, first you may want to further acquaint yourself with the safety issue by clicking on these sites:

Seriouseats.com “Sous-Vide 101: Low-Temperature Chicken”

http://www.seriouseats.com/2010/04/sous-vide-basics-low-temperature-chicken.html

findarticles.com “Sous vide safe?  Yes, concedes FDA, if it’s done carefully”

http://findarticles.com/p/articles/mi_m3190/is_n28_v22/ai_6494852/

quora.com “What are the risks of cooking sous vide?”

http://www.quora.com/Food/What-are-the-risks-of-cooking-using-the-sous-vide-method

Safe sous vide cooking requires the use of an accurate food thermometer. To read about two ways to calibrate your thermometer, click here: http://shelflifeadvice.com/content/thermometers-two-types-every-kitchen-should-have

Food scientist Dr. Joe Regenstein offers this final piece of advice:  “Don’t store these foods for long times and keep them properly refrigerated.”

Additional Source(s) besides those hyperlinked in the text:

Catherine N. Cutter, Ph.D., Pennsylvania State University, Dept. of Food Science

Clair L. Hicks, Ph.D., University of Kentucky, Dept. of Animal and Food Sciences

Joe Regenstein, Ph.D., Cornell University, Dept. of Food Science