Monday, March 5, 2012

When is a Sous Vide not a Sous Vide?

When you are using it like a crock pot! (Insert evil laugh here)

Well, ok it's always sort of used like a crock pot, but as I was scratching my head over the whole cooking dried beans problem, and the making chili problem, the time I spent using the SousVide as a yogurt (and dulce de leche) maker came floating back into my head.

Is it so important to have a package that conforms to the ingredients if your ingredients will conform to any package?


Attacking the "SousVide a liquid" problem

So what is the vacuum doing anyway?

The magic is in the lower pressure created by the vacuum!  Right?
I, like many others, have labored under the mistaken idea that the vacuum sealer was imparting some superior virtue to the "food stuffs + flavorings" combinations in those vacuum sealed bags.  My main mistake was bolstered by the correct but completely out-of-context knowledge that water boils (changes from liquid phase to gas phase) at lower and lower temperatures as the pressure on it is decreased.  The pressure has somewhere between NOTHING and Practically Nothing to do with the magic of Sous Vide.

(thanks MIT)

But the vacuum pump is sucking out all bubbles so all the food surfaces contact water through a solid with out the interference of air.  We're not creating an importantly lower pressure.
The magic is in the full contact of the highly efficient heat-transfer-medium (water) to the surface of the food.  And the plastic vacuum bags allow the water to be in contact without draining the food-of-choice of flavor by water logging it.  (And protecting it from the the drying and oxidizing properties of hot air.)

So not magic at all - just poaching with a barrier to the liquid.
Similar experiences in texture are available through poaching, but keeping the water at the desired "just below a simmer" is quite a trick on a stove top.  And the liquid is still above the optimal cooking temp.  Braising and stewing get one there as well, but again, water logging, and losing luscious flavor and texture (come back gelatin!).  Wrapping in foil and baking at low temps works too, but always risks drying the food out and is horribly inefficient (air is a low density, low heat capacity, heat transfer medium.  Seriously, would you rather stick your hand into a box of 400˚F air for 5 seconds or 400˚F liquid for 5 seconds?)

So that explains why fried fish is the best!
Frying does it exactly.  Wrap the food in an oil proof coat (batter), and fry until it floats.  This occurs because an appreciable amount of the water in the food has converted to steam (gas) and pops the food to the top of the liquid (lower density).  This also explains why frying is best with small pieces of food, or objects with a large-surface-area-to-actual-amount-of-matter ingredients (don't plug the hole in that turkey you are planning to fry), but isn't so poplar with large chunks of stuff (french fry, YES!  entire potato, NO!).  And whatever you do, keep water away from the hot oil, or you are a Mythbusters Episode without the insurance.
But when the cooking is complete, there's all that hot oil.  And not all foods respond well to that quick cooking. Deep fried dried beans anyone?  (Yes, the Chinese and Indians have made this good too, but that's another topic for another day.  And they are no longer the low-fat nutrition delivery systems they began as.)

The real magic is just better technology.
Two words, temperature control.  By today's standards "old fashioned" (Ya' know, ancient times, like from the 1970's) crock pots have wild fluctuations in temperature, but manage to make a go of it since they depend on the slow-motion-power of the ceramic crock to keep the transfer of temperature fluctuations to the food encased within to a minimum.

Today, when I sous vide my chicken breast to 140˚F (60˚C), I want it at 140˚F.  Not 138˚F (58.9˚C), not 142˚F (61.1˚C).  With eggs, the same thing. 64˚C (147.2˚F) means just that, and let me tell you, a degree of difference makes a whole different egg (protein folding thermodynamics, of course).

Which brings me back to the dried beans.

Crock pots are great for cooking them.  Long, low and slow with minimal power input.*  But I only want a small bowl of beans - enough for 3 people, not an entire baby-bathtub of beans.  I'm not feeding a hockey team here.  Which is what kept me from using my crock pot most of the time.  Sure if I were part of bigger family, large amounts of food at one time would make more sense.  But I've chosen the minimalist route, so my food needs on a given day are smaller.  And I can only eat the same meal so many days in a row before I go a bit batty (never would have made it as a wild-west prospector).

What your are saying is, cooking beans is different from cooking meat!
I know, crazy, right?  But the time/temperature/liquid combinations that are good for fresh meats are are different than for dried plant protein sources. (Hmmmm, bacalao?)  But the real key here is the beans are already in a liquid medium.  And all I need is a way to keep my small amount of liquid away from the large amount of heat bearing liquid.  Canning Jars!  They are supposed to be boiled - or even pressure canned.  (That is, heated to above boiling.)  So having them hang out below boiling for several hours seems like a great idea.  And they are easier to clean than the darn bags.  And they are in exactly as good a shape the second or tenth time as they were the first, no curly edges and problems shutting them.

Well, what do your experiments reveal?
Using 2C jars, I filled each with 1/2C dried beans and 1 1/2C liquid (water).

Ratio - 1:3 beans to water
A garlic clove, a pinch of red pepper flakes and some cumin seed

I popped them in the SousVide at 195˚F (90.5˚C) for the recommended 6 hours.

I placed the lids on top and barely screwed on the rims so any gasses could escape easily, same as when canning.

After 6 hours....

I did cook with the lids on.
This was removed for peeking in and testing purposes.
Black eyed peas!

They looked cooked...

Delicious, tender beans!  The long cook did make them extra flavorful.

Pro Tip:  The jar lets you test the beans along the way.  Especially handy if you are working with a new sort of bean.  You can take them out early if you need to, and let them cook longer if they need to.

Next: Hacking the Caramelized Onions

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