Why to Use a Sous Vide Temperature Probe and Thermometer

One of the big divides between professional chefs using sous vide and home cooks is the use of probes with sous vide. The majority of professionals always probe and the majority of home cooks don't. But more and more sous vide cookers are coming with probes, such as the PolyScience HydroPro, the VacMaster SV10, and the Anova Precision Oven, as well as tools such as the MeatStick. So I thought it's important to talk about why you may want to use one.

In general there are several main reasons for using a thermometer when cooking sous vide: HAACP regulations, core-based timing, preventing overcooking during the sear and speeding up the cooking process.

Sous Vide HAACP Plans

I won't go into HAACP plans at all, since they can be very detailed, but it basically entails restaurants making sure the health department is satisfied they are following safety guidelines, and using a probe is critical to doing that. For guidance I recommend turning to a company like CREA or the Rich Rosendale Collective that offer consulting services, or many equipment manufacturers like PolyScience can help as well.

Core-Based Sous Vide Timing

Core-Based sous vide timing is the process of monitoring the temperature of the middle of your food and then pulling it out when it reaches the temperature you are aiming for. This replaces the thickness based estimates that most home cooks use.

Why Use Core-Based Timing?

Some of the experts, especially from CREA, believe that to achieve the highest possible quality you should not cook the food longer than needed. This seems to contrast with much of the advice for home cooks that "timing doesn't matter much", but it actually doesn't.

When cooking something tender sous vide, once it is heated through then the longer you cook it, the further away from that ideal state it will get. This is true even for home cooks, and is why I suggest not cooking something like a chicken breast for 6 or more hours, because the texture really does change.

The difference between a place like CREA, who consults with 2- and 3- star Michelin restaurants, and home cooks just comes down to the degree of margin they give the food.

While a home cook might be fine cooking a steak for an extra 30 to 60 minutes and not be able to even notice the (really small) reduction in quality, a chef trying to serve literally the best food in the world would never want the quality reduced in any way.

So for professional, higher-end restaurants, core-based sous vide timing is critical to maximizing the quality of the food. For the rest of us, we probably won't notice a difference within a much larger margin of cooking, so it's no where near as critical.

Preventing Overcooking On Sears

Another benefit of probing your food is to monitor it during the searing process. Many people complain about overcooking their food when they sear it, and using a probe is a great way to monitor the temperature of the food during the searing process.

This is especially true if you chill the food slightly before reheating it with a sear.

Speeding Up Sous Vide Cooking

The other big benefit of using a probe is to speed up cooking.

The obvious way this happens is because when measuring the core temperature you can pull the food right when it is done. So you can take "cook a beef tenderloin for 3 to 6 hours" and know exactly when it is done, shaving off an hour or so.

However, there is much more to it than that.

How Heat Travels in Food

Your food does not heat in a straight line, it actually heats quickly at first and then goes more and more slowly. In some cases those last 2 to 4 degrees can take up a full third of the cooking time. You can see that with the following image taken from a MeatStick Thermometer.

The curve flattens greatly as it gets closer and closer to the final temperature. This means that if you are measuring the core, you can often set your water bath a few degrees higher and reduce the cooking time by 20% to 40% because it will reach your desired core temperature before the biggest heating slowdown takes effect.

Here's a few examples.

Sous Vide Chuck Roast Core Temperature Graph

In this example it was a chuck roast that was just under 2 1/2 inches thick. Using the Sous Vide Thickness Times we'd expect it to take around 5 hours and it turned out to take 4 hours and 57 minutes.

However, a full hour of that was going from 130°F to 131°F (54.5°C to 55°C).

So if you had set the water bath temperature 1 degree higher, to 132°F, it would have taken 4 hours instead of 5. If you had set it 2 degrees higher, at 133°F, then it would have only taken 3.5 hours, 30% faster.

The returns on your time quickly diminish though, and the higher you go above your ideal temperature the more of a gradient in the food you will get.

Sous Vide Pork Loin Core Temperature Graph

This one is a pork loin that was under 2" thick. Since it's a cylinder we expected about an hour and 45 minutes or so according to the Sous Vide Thickness Times. It took an hour and 43 minutes, so again very close to what we expected. Just a reminder, this is to heat it through, to pasteurize it you'd have to cook it longer.

But again, you can see how long that final degree took. A full 20 minutes out of the overall 100 minutes of heating was for that last degree. So setting your bath 1° hotter would save you 20% of your cooking time, and setting it 3° hotter would be a full 30% faster.

Conclusion

While I still don't think using a probe at home is required it does offer the big benefit of speeding up your cook times, which can be critical for many people who are trying to get food on the table in a hurry!

If you like this you can get more than 85 inspiring recipes to get you on your way to sous vide success. It's all in my best selling book Modernist Cooking Made Easy: Sous Vide - Get Your Copy Today!

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