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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 wanted 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 3 goals. Those goals are:
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 time 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.
Note: If you prefer, you can jump right to the Lesson Recap.
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 when using 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 pretty differently.
To help you out, I've created a Sous Vide Cooking Times By Thickness article that is a great tool to help you 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 (beef, lamb, pork, moose, rabbit, etc), chicken, and fish. It also includes a link to my downloadable 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.
Showcase Recipe: For a good example of a beef filet cooked through, you can look at my Sous Vide Filet Mignon Recipe with Blue Cheese Mousse.
Note: While the information I discuss in this section normally comes up only in discussion 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, over-cooked food, and other issues. Just one more benefit of being familiar with sous vide...you'll be more informed and safer in your general cooking as well.
As I mentioned in the previous lesson, 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.
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 variey of factors that go into whether or not you need to pasteurize a type of meat, including the conditions the animals were raised (factory farmed meat vs wild game both introduce different risks) but I'll focus on standard type 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.
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.
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.
Chicken and other poultry should always be pasteurized because the bacteria can penetrate into the inside of the meat. Because the bacteria penetrates to the inside, the entire piece of meat needs to be heated through and pasteurizated. 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.
Denser meats like beef, lamb, and duck breast are too dense for the bacteria to pentrate below the surface. This means that to make them safe to eat, all you have 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.
This means 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.
I particularly liked this video description:
It's important to remember that 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. This is the reason hamburgers are rarely served medium-rare, cooking the outside doesn't make the inside safe. Special precautions have to 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 carries bacteria to the inside. Many Costco steaks utilized this method, and it leads to potential sickness if those steaks aren't pasteurized during cooking.
The amount of time something needs to be cooked is dependant 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 specific time and temperature combinations, you can refer to my Sous Vide Cooking Times By Thickness article and go to the type of food you are interested in. 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 and shares 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.
Showcase Recipe: For a good example of chicken pasteurization, you can look at my Sous Vide Chicken Recipe with Bulgar Salad and Za'atar Onions. It discusses the pasteurization times for chicken and general cooking times.
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 2 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 more bland. 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 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.
Showcase Recipe: For an idea of how to cook our 1" (25mm) chuck steak, you can look at my Sous Vide Chuck Steak Recipe with Fried Brussels Sprouts.
You can view my comprehensive sous vide time and temperatures for more specific recommendations. In the next lesson I will take a much longer look at how temperature affects food and how it is combined with times to create good meals.
In this lesson we discussed the three goals of cooking food. They were:
You should also now have a good idea of when each goal applies to different types of meat!
I also shared some key links with you, namely
Thanks again and happy cooking!
Jason Logsdon, Amazing Food Made Easy