[conspire] sous vide question.

[Ross Bernheim]

Paul,

First, food safety. Normally you need to cook things hot enough to sterilize them for safety. Thus the hamburger should be cooked to well done to kill all the bacteria inside caused by grinding the meat. Chicken also to 165F. 

Not so for sous vide. With sous vide you can cook safely to lower temperatures because you are going to hold them there for a longer period. Long enough to cook the bacteria to death. In other words you are Pasteurizing the food for safety.

The minimum safe cooking time is determined by the temperature, the thickness of the food and the thermal transfer rate. For most foods you can easily exceed the minimum time without worrying about overcooking since you are cooking at the temperature of the doneness you want. With conventional cooking you are using a higher temperature and using timing to not overcook, but you will have a temperature gradient through the food.

I routinely cook most portions to 58C (136F) and even a bit lower for rare hamburgers that are still safe. Dark meat from chicken and turkey do need a higher temperature though.

Sous vide does require very precise temperature control to about 1degree F. This precise control lets you do many interesting and tasty things. Perfectly rare (or whatever doneness you prefer) steaks which you can then pat dry and sear. If you’ve seen those pictures of perfectly pink steaks with a narrow sear on the outside, that is how it was done.

If you want to do 2 and a half inch thick pork chops, sous vide can do them spectacularly! Done just right all the way through and juicy. Thick cuts like that cannot be done nearly as well any other way. (Best pork chops I’ve ever had in my life!)

The precise temperature control lets you do some amazing things with vegetables. The starches cook at 80C but the cellulose in the cell walls don’t begin to break down until 85C. Fully cooked sweet carrots that are still crunchy anyone?

Sous vide equipment ranges from home made jerry rigged to commercial units. In the last couple of years there have been a number of less expensive circulators available for around $200 or less. These have an immersion heater, PID temperature controller and circulating propellor. They vary in how big a container of water they can deal with, how quickly they can heat the water, precision of the temperature control, mounting and ease of setting and using. Read the reviews.

The other commercial units are the sous vide ovens like the sous vide supreme that I have.

Jerry rigged units vary all over the place and a search on-line will turn up how to’s.

When using a circulator, the container makes a difference. While you can use a large metal pot, they lose more heat and that means the limits of the circulator will be more apparent. Plastic containers reduce heat loss to the air, but don’t forget to cover the top to prevent heat loss and reduce evaporation.

Ross



> On Oct 23, 2017, at 1:41 PM, Paul Zander <paulz at ieee.org> wrote:
> 
> This is primarily directed to Ross, but might be of wider interest.
> 
> The benefits of sous vide have been will demonstrated. I have been thinking I should give it a try, but it is not my highest priority.
> 
> My wife was cleaning out the kitchen cabinets, found a crock pot, and was about to take it to Good Will.  I said to wait.  It would appear that a change in the temperature control would convert it to sous vide. 
> 
> 
> Is this a reasonable way to get a sous vide apparatus?  
> 
> The answer can be boolean. I fully expect that there will be the opportunity to discuss the various circuits at a future CABAL.  I just want to avoid having to go to thrift stores to buy someone else's crock pot.
> 
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