Engineering a Steak: Sous Vide

[ivymike]

okay, since most probably have not heard of Sous Vide (if it hadn't been for in-flight magazines, I wouldn't have), here's a primer:

http://www.seriouseats.com/2010/03/how-to-sous-vide-steak.html

One of the available Sous Vide machines is the SousVide Supreme, which retails for $400 or more, not counting a vacuum sealer.

http://www.surlatable.com/product/i...-75E6-DE11-974B-0019B9C043EB&mr:referralID=NA

My wife has a crock pot (an insulated container with thermostatically and timer-controlled heat source), but it only has 5 settings, and the lowest one, warm, seems to reach steady state at about 129 deg F. (I'm still letting it stabilize to be sure) The next step up, labeled "10 hours" reaches steady state at 201 deg F.

So task number one is to find a way to hit the right steak temperature (135F) before grilling. some ideas:
- insulate the tub of cooking water from the tub of heated water, so that the steady-state temperature of the cooking water is 65deg lower, perhaps by nesting a couple of plastic bowls to leave an air gap, and floating them in the heated water.
- find a way to circulate a small amount of cooler water into the bath, to lower the steady-state temperature.
- open up the crock pot and modify the circuitry to change the "10 hours" setting to a "Sous Vide" setting.

comments?

 

[ivymike]

another option - improve the insulation over the top of the crockpot to bump up the SS temp of "warm" by a few degrees... still waiting to verify SS has been reached.

 

[MintJulep]

What's the equilibrium temperature of a big pot of water in your oven with the setting at "warm"?

 

[Pud]

If you ever go to France and ask for a "well done" / "medium rare" or any other version all you will get is a rare steak with a lovely crispy outer. I once had raw steak, cut into thin petals, arranged like a flower, with a small piece of green lemon in the center of each petal. Small pile of woodland fungi in the middle of the dish. Eating technique was to roll up each petal with fingers and pop in mouth. Meltingly gorgeous. Bottle of local vin noir to wash it down. (Terminus Hotel restaurant, Cahors, France)

Yummy

H

http://www.tynevalleyplastics.co.uk

 

[ivymike]

thought of that first, but my oven has no settings below 200F.
A dishtowel over the crockpot lid brought the water temp all the way up to 154F, so perhaps a little fine tuning of that technique will suffice.

 

[jte]

What is the ambient temperature in your kitchen? A degree or two on the ambient temp might make a larger difference on the inside of the pot.

You've already played with adding insulation in the form of the towel over the (glass?) lid. How 'bout just cutting the bottom out of a cardboard box and setting it around the crock pot? With and without the lid?

And finally... Are you certain that your thermometer and its placement provides temperatures accurate to 5°F? Though I guess that precision is more important than accuracy here as you try different temperatures.

So now that I'm hungry for dinner right after a quick lunch... Would Zip-Lock style bags work? Does the plastic degrade? How many temperature settings does my wife's Crock Pot have? (Ok, I'll have to answer that one myself.)

Finally... One of my last jobs while in university was at an industrial design shop. Spent some time cleaning up the shop archives. Including the designs for the Crock Pot. And other designs ranging from the M-1 tank to devices used during open heart surgery. That job was an amazing experience.

jt

 

[ivymike]

I don't think that a degree or two on the ambient temp can possibly make a larger difference on the inside of the pot, if we hold the temperature of the heating element constant, along with the conductivities and HTCs between the element and the outside world... but I haven't yet written out any example calcs to demonstrate that. My gut tells me that for any set of resistances I pick, if I keep the heat source at a constant temp and increase the temp of the heat sink (ambient) by a given amount, the temperatures at the in-between surfaces and masses will increase by a fraction of that amount.

The digital temperature probe is a bit better than that. It reads 33F in a glass of icewater, and 208F in a shallow pot of boiling water if I keep it off the bottom (measures 211F if it touches the bottom). I measure the temperature of the water while stirring it with the probe, and the value will fluctuate up and down by about a degree while stirring.

There are zip-lock "steaming" bags which should work great. We have special vacuum bags that are supposed to be good for the temp range in question (although they melt at a higher temp to seal, as a matter of design).

 

[MintJulep]

Turn the crock pot control up and plug in a cheap controller to turn the power on and off.

I'm not sure how expensive cheap controllers are these days.

 

[jte]

You're looking for a 135-129 = 6°F temperature gain. Simplifying drastically to focus solely on Crock Pot to ambient delta-T, and assuming your current kitchen temp is 65°F (mine is) and the wattage to the Crock Pot doesn't change: Existing DT is 129-65= 64°F. Keeping the heat flow constant means that increasing the ambient temperature by 6°F while maintaining all else constant would necesserely result in a 6°F increase in the pot. Raise the ambient to 71°F and you should be pretty close to 135°F inside.

I'll put the zip-lock steaming bags on the shopping list...

jt

 

[evelrod]

I sure hope all you fellas don't contract some awful thing from eating at one of the "fine dining establishments". For me, I rather like the way my wife cooks my steaks...not so coincidentally, so does everyone who has ever eaten at my home.

Yes, Isaac, we actually do have one of those vacuum sealing/cooking machines (somewhere, probably out in the garage). Given to us several years ago as a gift. I think she tried it a couple times and then it just sat there taking up counter space. Probably how it ended up in the garage.

'Course, I'm just an old Texas country boy raised on grass fed beef and venison...What the hell do I know about cooking?

Rod ;o)

 

[zdas04]

DON'T try this with Ziplock bags. We've been cooking ribs this way for several years and find that with a perfect seal (that we generally get) and the deepest vacuum that our Food Saver can accomplish, at the end of an hour the outgassing of the meat has the bag about to burst. With a Ziplock, the outgassing would pop the seal in 5 minutes and then you are boiling meat (which gives you boiled meat, good for some stuff, lousy for a steak).

The key is a really good seal and a pretty deep vacuum.

David

 

[patprimmer]

Ziplock bags are normally PolyEthylene. Std ones are normally Medium Density PE which is softening by about 70 to 80 deg C and melted at 100 to 105 deg C

High Density PE is used for oven bags and melts at about 120 to 125 deg C, but has lost a fair bit of tensile at 90 to 100 so it will blow with pressure.

Cook in bag material is normally nylon which has good strength to well over 100 deg C

My experience with electrically heated water baths for moisture conditioning nylon mouldings is that they are very prone to uneven temperature unless you use a lot of mechanical agitation. I have seen spots vary from 40 to 80 deg C in the same bath at the same time.



Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[ivymike]

I did a shoulder roast this evening... gave it about 2hr @ 140F bagged w/Uncle Te's Laos BBQ marinade (didn't see any gas coming off), then about 1min per side on the grill at high heat.

With Ziplock bags, what would stop you reaching in to let some air out & reseal? 140F water isn't too hot to stick your fingers into for a few seconds.

 

[Latexman]

Seems like a lot of trouble and expense seeing as it's going to get stripes on the grill anyway.

I like my new infrared grill. It's fast and no flare-ups.

Good luck,
Latexman

 

[zdas04]

My experience is that if the bag doesn't inflate some, then it has a leak and there is water coming in. The first few times we tried this we didn't double seal the ends and the bags failed and we boiled the meat.

David