How Sous Vide Times Work
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When determining how long to sous vide certain items the confusion often comes down to the difference between cooking by thickness and cooking by tenderness. I want to take a more in-depth look at those types of cooking to help clear up any uncertainty around them.
When cooking food, either via sous vide or traditional methods, there are three goals: heat the food; make the food safe to eat; and tenderize the food.
I’ll take a look at each one of the goals, discuss how it relates to the other goals, and tie it in to how sous vide times and temperatures are determined. At the end, you should understand why different cuts of meat have different time requirements, even if they are the same size.
In the discussion below, we will use a 1” thick chicken breast (25mm), a 1” beef filet (25mm), and a 1” chuck steak (25mm) to highlight the differences.
Heat the Food
When it comes right down to it, the whole purpose of cooking is to heat the food. Heating the food has several benefits including increasing the flavor, making the food safe, and breaking down the tough fibers in the food.
Regardless of the reason, adding heat to food is arguably the most critical component of cooking.
With traditional cooking, your food has a temperature gradient to it, popularly referred to as the “bulls-eye effect”. This is because cooking at high temperatures overcooks the outside of the food while the inside of the food is heating up. Because of this discrepancy, it is hard to accurately judge when a piece of food will be fully heated through with a traditional cooking method.
With the precision and static temperatures used in sous vide cooking, you can predict how long it will take the center of a piece of food to come up to temperature to within a good degree of accuracy. There are a few variables including the density of the meat and water temperature, but most meat heats through roughly at the same pace regardless of the water bath temperature or the minor density differences between steak and chicken. Fatty fish is one of the few foods that heats differently.
To help you out, you can view the tables on the Cooking by Thickness page to determine the amount of time it takes to heat up a piece of meat. It has a detailed listing for different thicknesses of red meat as well as chicken, and fish. You can also download my sous vide thickness ruler that you can print out and use at home.
Because all meat heats in about the same time frame, all three of our example pieces of meat would heat up in about an hour and 15 minutes, regardless of the temperature.
However, if we had cooked them all at 131°F (55°C) then, despite being the same temperature, they would taste very different. The beef filet would be perfectly cooked and tasty after a quick sear because it is already a tender piece of meat. The chuck steak would be very chewy, because it is a tough cut and wasn’t tenderized at all. And the chicken would not be safe to eat, since it would not have become pasteurized yet.
Make the Food Safe to Eat
While the information I discuss in this section normally only comes up in discussions about sous vide, they actually apply to all forms of cooking. Many people do not understand them (though they think they do) and this can lead to generally unsafe cooking practices, overcooked food, and other issues. Just one more benefit of being familiar with sous vide...you’ll be more informed and safe in your general cooking as well.
As I mentioned, the main concern with making food safe to eat is “pasteurization”. Pasteurized food has had the amount of dangerous bacteria and parasites in it reduced to acceptable levels (the US Government suggests killing all but 1 in a million, or 1 in 10 million, depending on the pathogen).
Pasteurized food is then generally safe to eat, provided it is eaten within a few hours so the remaining bacteria do not have time to re-grow. Pasteurization is achieved by holding food at a specific temperature for a certain length of time, with higher temperatures resulting in faster pasteurization.
When to Pasteurize Meat
Some meat needs to be fully pasteurized, and other types of meat are safe to eat as long as you sear them.
There are a variety of factors that go in to whether or not you need to pasteurize a type of meat, including the conditions the animals were raised (factory farmed meat and wild game both introduce different risks) but I’ll focus on standard types of meat generally found in US supermarkets. If you are eating an unusual type of meat, or wild game, then it is best to pasteurize it just to be safe.
Pork is often pasteurized as well, though high quality pork is usually fine without being pasteurized.
When deciding whether or not to pasteurize your food, you need to worry about parasites and bacteria. Different types of meat have different parasites, and the bacteria also behaves differently depending on the density of the food.
When to Pasteurize Chicken and Poultry with Sous Vide
Chicken and other poultry should always be pasteurized since the bacteria can penetrate to the inside of the meat. Because of this penetration, the entire piece of meat needs to be heated through and pasteurized. This is why chicken tartar or medium-rare chicken is never served. Through sous vide, you can actually pasteurize chicken at a medium-rare temperature, but I’m not a fan of the texture.
When to Pasteurize Beef and Lamb with Sous Vide
Denser meats like beef, lamb, and duck breast are too dense for the bacteria to penetrate below the surface. This means that to make them safe to eat, all you need to do is heat the surface, usually through searing it.
That heat applied to the outside effectively pasteurizes it because the inside is considered sterile. You can also remove the surface, which is often done when there is no cooking involved, such as with tartar.
Therefore, as long as you sear the outside, the inside can stay whatever temperature you prefer. A well-done steak is no safer to eat than a just-briefly-seared rare steak, neither will have any bacteria inside. This is why with our example cuts, the beef heated through was safe to eat but the chicken wasn’t.
It’s important to remember this only stays true when the outside of the meat is really the outside. For example, if you grind the meat for hamburgers, the outside is now on the inside and a sear won’t fix that.
Note: I particularly liked this video that describes why beef is safe to eat when eaten at lower temperatures.
This is the reason hamburgers are rarely served medium-rare, cooking the outside doesn’t make the inside safe. Special precautions must be taken when serving under-cooked ground beef, such as using only high quality beef, and sterilizing or trimming off the outside before grinding.
Another time when the outside can become the inside is with “blade tenderized” or “jaccard” steaks. These steaks are tenderized by pushing blades though them, which also carry bacteria to the inside. Many Costco steaks utilized this method, and it leads to potential sickness if those steaks aren’t pasteurized during cooking.
Warning: It is also worth mentioning again that for immuno-compromised individuals like the elderly and pregnant women it is best to pasteurize all food.
How to Pasteurize with Sous Vide
The amount of time something needs to be cooked is dependent on both the type of meat and the heat it is cooked at. For our 1” (25mm) beef and chicken examples, they will be pasteurized if they were cooked as follows.
For time and temperature combinations, you can refer to the Cooking by Thickness page then go to the type of food you are interested in. Also, if you are a sucker for partial differential equations, then Douglas Baldwin provides a lot more information on pasteurization and the specific pathogens you are trying to kill, including his mathematical models behind it.
If we cooked our example cuts for the amount of time listed above they would all be perfectly safe to eat, even if they had been blade tenderized. Both the beef filet and chicken breast would be ready to eat and would taste delicious. However, the chuck steak would still be really chewy and tough, which leads us to our third reason to heat food: tenderization.
Tenderize the Food
The third reason to heat food is to tenderize it. As food gets hot, the muscle, collagen, and protein undergo transformations that cause the food to get more and more tender. The higher the temperature the food is cooked at, the faster this tenderization happens. This is why pressure cooked foods cook faster than roasted or braised food.
Like braising or roasting, the longer you cook food with sous vide the more tender it becomes. The main difference is that adding time to sous vide cooking doesn’t overcook the outside layers of the food.
Also, because the sous vide temperatures are so low, the tenderization happens much more slowly, resulting in much longer cooking times. To really enjoy that chuck steak, you’ll want to cook it for about two days.
The upside of using the lower temperatures is that you can cook your food to any doneness you want. If you braise a roast, it will always turn out well-done, but using sous vide allows you to turn out a perfectly medium-rare roast that is still tender.
This is possible because using the temperature control of sous vide allows you to break down and tenderize meat without cooking it above medium-rare and drying it out. Once temperatures in beef go above 140°F (60°C) the meat begins to dry out and become blander. Using sous vide, you can hold the meat below 140°F (60°C) for a long enough time for the tenderizing process to run its course.
The length of time needed for cooking increases as the food gets tougher and the temperature you are cooking it at gets lower. Here are some general guidelines which will vary a little by the specific cut.
After 36 to 48 hours our example chuck steak would be fully tenderized and have a texture similar to a filet or ribeye. The tenderization continues to happen throughout the cooking process though, so if our tender beef filet was cooked for the same 48 hours as the chuck steak, it would have little internal structure and taste very mushy.
Compared to traditional methods there is actually a lot of wiggle room though, so the filet would still be good for a few hours after it was heated.
You can view my comprehensive sous vide times and temperatures for more specific recommendations. In the next video I will take a much longer look at how temperature affects food and how it is combined with times to create good meals.