Science Scene: Sous vide offers an alternative cooking method

Hannah Jane DeCiutiis

Whether you are a burgeoning Iron Chef or you get nervous just watching Ina Garten, the concept behind cooking is fairly universal: to kill harmful pathogens and to make the food tastier to eat. 

Over the past two decades, DIY kitchen enthusiasts and restaurant chefs alike have been perfecting a method called sous vide to achieve both pasteurization and a surprisingly tasty result.

Sous vide, meaning “under vacuum” in French, is one of the most logical cooking methods out there. Vacuum-seal the raw food, place it in a water bath that is consistently held at the desired temperature, wait until the food reaches that temperature and don’t worry about overcooking — the food can’t possibly go above the temperature of the water.

The result? Evenly-cooked food that retains many of its natural flavors, which are often amplified. 

DIY sous vide setups traditionally involve at-home components like pressure cookers and temperature controllers. As sous vide has become trendier, much more elegant machines have become easy to find with a simple Google search and a hefty amount of cash. 

Aside from being hailed as more delicious, sous vide-cooked foods are often touted as being significantly safer and more nutritional than traditionally cooked foods. After all, since everything is sealed up, the nutrients stay in and the bacteria stay out, right?

Well, sort of.

Sous vide foods are considered to be healthier for several reasons. First, they’re cooked in an environment with little oxygen, so the lack of oxidation preserves more of the essential fatty acids obtained from meats and fish that your body needs. 

Sous vide foods have also been found to retain many more of their vitamins and minerals than traditionally cooked foods. Plant cell walls won’t deteriorate the way they do during traditional steaming or boiling, so vegetables keep their nutrients rather than leaching them out into the water they are cooked in.

Despite the apparent health benefits, sous vide is not entirely without risk. An introductory biology class will teach you that all raw food items contain millions of bacteria microbes — some good, some bad. Cooking food sous vide at more than 140 degrees and then serving it while it is still hot will successfully pasteurize it, meaning you will kill the active bacteria and any pathogens of interest.

But some bacteria produce spores. Spores are harmless on their own, but can turn into active bacteria if they spend enough time in the “danger zone,” between 40 and 140 degrees, which is why you need to serve the food soon after taking it away from the heat. These spores aren’t killed by
pasteurization — you have to completely sterilize the food to get rid of them, which is difficult to do with sous vide.

This can be problematic with restaurants and industrial food processors, which often employ the cook-chill method of sous vide. Food is cooked under vacuum and is then quickly chilled or frozen. When done properly, the shelf life of cook-chilled food is much longer, and few people will be able to tell the difference between the pre-cooked food and a freshly prepared meal.

If a restaurant takes too long when chilling or freezing the packaged food, the spores can easily become active bacteria. Storing vacuum-sealed foods improperly can also lead to an outgrowth of Clostridium botulinum, which creates a toxin that produces botulism, which can be fatal in doses the size of a particle of baking powder.

Even with these risks in mind, cooking sous vide at home is no more dangerous than traditional cooking. In fact, it can actually be safer in many cases. Pasteurization is a function of temperature and time, so having precise control over both exact temperature and cook time is a flexibility that the sous vide method provides.

As a result, the rave reviews about the texture and flavor profiles of sous vide foods are only increasing. With emerging sous vide technologies becoming more sophisticated, and hopefully cheaper, it won’t be surprising if sous vide machines soon become staples in the home cook’s arsenal of kitchen gadgets.