Sous vide - uneven cooking

[Montizano]

I got an immersion circulator (anova PC) for my birthday and have been playing around with it. After looking into cooking times for steak and chicken breasts (and other meat that is not being tenderized) I'm quite confused. Most recipes for steak say cook a 1.5" steak at 129f for 1 hour for medium rare. While it is often stated that the time can go beyond 1 hour, 1 hour is the preference using serious eats page for reference).

However, based on the sous vide dash app it looks like the steak will have a core temperature below 129. For the 1.5" steak, it takes 3:20 to get up to temp and at 1 hour it looks like it is around 120f, almost a full ten degrees under the target temperature. Therefore the steak will come out rare, rather than medium rare. The case is similar for large chicken breasts (a .75" breast will be at temp in 1 hour) with a 1.5" breast taking 3:15 to get to 150 and typical times for cooking breasts listed at 1 hour.

I will mention that in both cases the surface pasteurization is complete within the hour.

Am I missing something, or are people cooking these items so the core temp is below the bath temp (which would lead to a temperature and doneness gradient within the meat)?

Monti

[Dave W]

It looks like you've stumbled upon some potentially sloppy recipe writing, but it also sounds like you have the tools (knowledge, sous vide dash app) to make sure your food is the way you want it.  

[cdh]

No harm in leaving them in longer.  Though since you're shooting for less than 130F, you can't just toss it in and leave it.  130+ is getting into bacteria killing range.  129 might still be in the bacteria growing zone.

[paulraphael]

The reason is that the SV-dash app calculates everything precisely, while recipes are more typically written with a little fudge-factor thrown in. It has to do with the long stretch of time it takes for the core of a piece of meat to rise that last degree or fraction of a degree to get to your target temperature.

 

If you were creating the recipe based on look and feel and taste, you'd call the meat done quite a while sooner than that. The temperature at the very core would be a degree or two lower than the bath temperature, and you wouldn't notice.

 

My method for using the app is this: Suppose you want the core temperature to be 55°C. Set the core temperature in SV dash half a degree low, to 54.5°. And set the circulator water a full degree high, to 56°C. 

 

This is for the kind of short, non-tenderizing cook you're asking about. It works perfectly, and gives reasonable cooking times. This is probably like what the recipe writers are actually doing; they're just not spelling it out.

 

For more details check out my blog post on the topic.

Edited July 29, 2015 by paulraphael (log)

[Montizano]

Paul,

 

I think you hit the nail on the head.  Thanks to the link to your post, that's pretty close to the method I was planning to use.  

 

I was just surprised the seemingly expert sous vide websites don't explain this in regards to cooking time for tender meat.  

 

Looking at the seriouseats recipe for strip steak (http://www.seriouseats.com/2015/06/food-lab-complete-guide-to-sous-vide-steak.html), if I have a 1.5" steak (the minimum suggested) and use 131f and 1 hour cooking time (based on their chart) the final core temperature of the meat is at about 116f according to sous vide dash!  this is a full 15 degrees f below the desired finished temp! So the steak would actually come out BELOW rare even though you would be expecting a medium rare steak.

 

-Monti