Depending on the food being cooked, temperature control can be very important for success with Sous Vide cooking. The more delicate a food is, the more finely temperature must be controlled to obtain optimal results. A good example is seafood, which typically should be minimally cooked for best texture and flavor. People who are big seafood fans or seafood vegetarians might want to to consider methods that offer finer temperature control.
Sous Vide on the stove – or digital thermometer in a large pot
This is the least expensive way to try Sous Vide cooking. But it is also the least precise method and requires your constant attention. No kidding you’ll hardly be able to walk away from the pot until food has completely finished cooking. For that reason you will want to keep portion sizes as small as possible to keep the cooking time short.
All you need is a thermometer and a pot. Analog thermometers (round display) take a much longer time to respond to and display temperature changes. Because of analog thermometer lag time they are inaccurate and we recommend that you use a digital thermometer. The average cost for a digital thermometer is $16.
The pot should be large enough so you can add hot water or ice without having to remove water as the pot fills up.
Here is how to do it: have some ice, or cold water standing by. Put the thermometer into your water and turn on the heat until you get to the temperature you want to stay at. If you go over—no problem, add a bit of ice and stir. The water will stay at that temp for about five or ten minutes (depending on if you keep a lid on it and how large a pot of water you have). Every five minutes you may need to add some heat to the stove. You can also do this by having a tea kettle near by and periodically adding some boiling water to it. The advantage of this—pretty cheap – and easy to add heat, or hot water, or cool down with a few ice cubes or cold water. Once you get used to how your heat source and pot work, this becomes a routine.
Stovetop Sous Vide is inexpensive to do but not suited for delicate foods such as fine seafood, or large cuts of meats that may take 70 some odd hours to cook. Seafood lovers should consider a Water Oven or Thermal Circulator.
Temperature controller on a rice cooker or crock pot
Temperature controllers are nothing more than a digital thermometer with a switch. When the temperature goes below your set point it turns a switch on supplying power to a connected appliance – in this case a rice cooker or crock pot. When your set point is obtained the switch turns off until the temperature goes low again and the cycle repeats. The unit has a probe that measures temperature and it is placed into water in the rice cooker or crock pot. The probe (thermocouple) is attached or plugged into the control unit which looks just like a digital thermometer. The control unit is set just like your digital alarm clock to a specific temperature set point. The rice cooker or crock pot plugs into an AC outlet built into the control unit. The control unit then plugs into the wall. Temperature controller electronics are not as good as Sous Vide Ovens or Thermal Circulators. They are not as accurate. You can spend more money and get more precision, but then you’ll get to the price point were you might just as well buy a Water Oven.
Another reason for a lack of accuracy using this method is that rice cooker and crock pot heating elements are not very precise. Typically the heat element is nichrome wire that is suspended haphazardly around the heated vessel. The vessel itself is thick with materials that absorbs and retains heat. So when heat is applied to the vessel it will initially become hotter than the set point. Then after a few moments the stored heat will transfer into the water spiking the temperature above the set point. The amount of the spike or overshoot will depend on the type of crock pot or rice cooker used. Crock Pots in general will have much higher spikes because they are made of thick ceramics that will retain heat much longer than metal walled rice cookers. Thin alloy walled rice cookers will offer the most accuracy using this method. When using this method I recommend starting out with warmer water and maybe adding a bit of ice to get it close to the temperature you want.
This is a great way to start doing Sous Vide ‘hands off’ without constantly having to adjust the temperature manually. You just set the temperature and walk away. Large cuts of meat would do fine using this method. Unfortunately the pots of these units aren’t all that big. On the positive side this is like a science experiment—and kind of fun. Many people already have a rice cooker or a crock pot. In that case all that’s needed to start is the temperature controller which will run about $50 at the low end.
Water ovens (sometimes called ‘water baths’) are designed specifically for Sous Vide cooking. Contrast thermal circulators, which were originally designed for chemical and semiconductor manufacturing processes. Water ovens can control water temperature within +/- 1 degrees centigrade, which is more than adequate to cook the most delicate food. Being an all-in-one unit the user does not have to consider anything other than putting water and food into the built in bath and setting the temperature. A water oven looks just like a standard appliance and fits well on any kitchen counter. The SousVide Supreme™ is the most popular brand of water oven. They offer a small oven (called a demi) which is about the size of a crock-pot® and a large oven which is about the size of a bread machine. SousVide Supreme water ovens offer plenty of capacity for large families. The small oven can cook 12 four-ounce portions of food, and the large 20 four-ounce portions. They are available in multiple colors too. At a price of $300 to $500, a water oven is as affordable as a good quality gas grill.
These are great units, because they have a lid that can close, and that helps to avoid evaporation and control temperature. I like doing short ribs in my unit—and they take about 48 hours to do—the lid prevents most water evaporation. Water evaporation can be a problem with Thermal Circulators when cooking foods for long periods of time.
Thermal immersion circulators
At the top of the lineup of Sous Vide Cooking methods, thermal immersion circulators can control water temperature within +/- 0.01 degrees centigrade. So they are suitable for cooking very delicate foods. At the other end of the spectrum is their capacity. They can be attached to large vessels allowing cooking of big slabs of meat or multiple single servings. Thermal circulators were developed and used in high tech industries. Water is sucked up into the unit by a pump and channeled through a very precise heater. The water is discharged with enough force to cause constant circulation within the vessel to which they are attached. Circulation causes the water to be very evenly heated. They are the most expensive method of temperature control for Sous Vide costing $800 to $1, 5000.
Did you ever get one of those immersion heaters for a cup of tea or coffee? These units are like that, but for much larger containers of water. I kind of think they look like an aquarium heater – and same process. When it comes to Sous Vide these are the units for the serious person in mind.
You can get these immersion heaters in some very expensive places—or less expensive. My heater came from PolyScience – and was purchased from William Sonoma stores. No doubt you can find one less expensive.
Sous Vide cooking – safety considerations
Some very dangerous bacteria grow in oxygen free environments. When you vacuum seal foods for cooking there are some things you need to remember to avoid botulism.
Uncontaminated food that is heated and served within 4 hours is safe. Eating undercooked food or raw food is unsafe. Any meat cooked for longer than 4 hours must reach a temperature of 131° F (55° C) within 4 hours and maintain a temperature of 131° F (or higher) over the subsequent span of cooking which must be at least 4 hours.
Foods to be stored should be chilled immediately. Research each individual food to determine the correct storage temperatures and timeframes.
Pregnant woman and people with compromised immunity should take extra precautions relative to cooking temperatures, cooking time and food storage.
Cooking in sheet plastic has not been proven to be either dangerous or safe. Only cook in bags that are temperature rated.
NOTIFICATION: Dr. Terry Simpson and all of his affiliated organizations assume no responsibility for personal injury or property damage sustained by or through use of this information.