I wish with everything in my little cooks heart that Harold McGee wrote for the NY Times every Wednesday.
This week we are treated to an introduction to an ingredient every cook uses every day with very little understanding. In this weeks article, he talks about heat.
Having been in the kitchens I have been in, I have been exposed a bit to the thought of better using heat to cook foods. Take sous vide, a word that we hear thrown around with trendy modern food is actually an exercise in the most efficient manner to apply heat to food. Yes, the method of putting food in vacuum sealed bags and cooking it in water has been used for a few decades now. However it’s the more recent study into how the energy of heat changes and effects the molecules in our food that resurrected this method from the depths of reheating catered dinners, introduced perfectly controlled thermobaths from laboratories, and brought it to the forefront of haute cuisine.
While much of the study of heats effects on food relate to meat cookery, where our use of the energy is at it’s most inefficient, the application I found most interesting was for potatoes.
Almost every restaurant has mashed potatoes on their menu. It seems to be a game of chasing the white rabbit, that of making the perfect, fluffiest, creamiest, mashed potatoes. We as cooks hear legend of different kitchens and their ethereal potatoes, like Joel Robechons, “passed through the tammis 5 times! Mounted with twice their weight in butter!” Every kitchen has their spin on making theirs better.
At WD-50 I saw something done to the potatoes that makes a cook scream, “yes!” A method of cooking the potatoes with an explanation using true understanding of the molecules inside the potatoes and the effects of heat on them.
The potatoes are peeled, sliced, and cooked in a water bath at 65 degrees celsius for 30 minutes. The potatoes are transferred to an ice bath to cool completely. At this point the potatoes are still crisp, seemingly unchanged. Once cooled, the potatoes are cooked just as you would have had you just peeled them. If the potatoes are seemingly unchanged, you might ask what on earth did they just do?
Well, working with a method used by the commercial mashed-potatoes-in-a-box companies, they use just enough heat to cause the starch granules inside the potatoes to swell. Think of these granules as little sacks of starch molecules. They absorb water, and the starches inside grow. If they are mishandled, or bounced around by too much energy, say that of boiling water, these little bags break open freeing all those starch molecules. These rouge starches are now free to retrograde, recrystallize and cross-link forming long gummy chains. This is not good.
So, after cooking the potatoes in gentle heat, just long enough to make these starch bags swell, the potatoes are then cooled in an ice bath. The starch in the potatoes are allowed to recrystallize, or retrograde.
Wait, didn’t we just say that was bad? Well, it’s bad when the starches aren’t contained. Because of the gentle application of moderate heat those little starch sacks are intact with swollen starches inside. The ice bath forces these starches to retrograde, gel, set, what every you may, inside their sack. Retrograde is permanent. The starches are now cemented into place safely inside their granules, and you can now cook the potatoes with a more aggressive heat, and break apart the starch sacks by mashing and passing through a tammis, processing the potato. You can manipulate these particles into a nice smooth, even mashed potato with out risk of releasing the starches from their containment. No gummy paste, no stringy gluey mashed potatoes.
And the best part? You can cool the mashed potatoes, and reheat them for service with no change in texture.
Pretty cool, huh?