Wednesday, January 09, 2013

Recipe: Pressure Cooker Chicken Stock

I should have some details on the Food Plan tomorrow, but in the meantime I thought I'd go back and touch base on the chicken stock I mentioned yesterday.

I had long heard about the value of making chicken stock yourself--not only for the richer flavors and nutrients over the store-bought varieties, but the fact that you can make it out of scraps of leftover chickens and vegetables. Sharon and I have each made some on a number of occasions in an enormous stainless steel stockpot, slowly simmering away for 6+ hours on the stove.

However, I found a better way to do it in Heston Blumenthal At Home:

 If you're not familiar with him, he's a very influential British chef who works with a lot of high-end scientific methodology, often called (either favorably or unfavorably) "molecular gastronomy." I have one of his previous books, which was interesting enough to read, but given the number of recipes that (a) required equipment on the order of lab-grade centrifuges to separate vegetable matter (no, that it not an exaggeration) and (b) seemed to think that I had the space and staff of a professional kitchen, I wasn't able to get a lot of functional recipes out of it.

However, his follow-up is far more approachable. He's pretty up front about the fact this his earlier books are exactly what he produces in his restaurant. He lists them as such for the sake of thoroughness, but admits himself that it's not the kind of food he eats at home or feeds to his family. However, his At Home cookbook is full of interesting flavor combinations and methodologies that you can use... well, at home.

It's his use of the pressure cooker to make a variety of stocks that I use most often. For those who don't know: a pressure cooker works by clamping down a heavy grade lid on the top of the pot. This allows the air pressure inside to build up, which means that the boiling point of liquid inside increases (in the case of my pressure cooker, to 250 degrees). There are built-in safety features which prevent (a) someone from opening the lid until it cools back down to normal pressure, and (b) from any excess pressure building to dangerous levels.

When it comes to stock, this offers us two advantages. The first, of course, is time: what once took at least 6 hours of hovering around a giant stock pot of water now is done in around 3, with minimal attention to the stove (at least, far less than we used to). What used to be an all-day, wait-for-Saturday kind of thing is now something I can do after work. To reach 250 degrees, I crank the heat as far as it will go. Once it reaches maximum temperature, the safety release valve on top will whistle, telling me it's time to turn the heat back down to a simmer (still at 250 degrees). Not only does the whole process take less time with less attention (and risk of mistakes), but we pull far more nutrients from the meat. No matter how long we would let the stockpot sit and simmer, the chicken bones would still be pretty firm when we finished. After two hours in the pressure cooker, the bones literally crumble to dust when I press them with my finger.

The other big advantage (what, the first wasn't enough for you?) is that by getting the water to a higher temperature, we're actually able to get the Maillard reaction to occur in the pot. Short version: the Maillard reaction occurs when certain proteins and sugars react at high heat, creating flavor compounds. It's the same basic process that makes the crust of bread brown and flavorful, the sear on a properly-cooked steak, or the golden brown skin on a roast chicken. In short: Maillard means flavor, and because the pressure cooker gets to the kinds of temperatures you need for the reaction to take place, you're going to get stock with far more depth of flavor than you'd get normally.

Something else interesting I learned (or re-learned) from Blumenthal: many flavor compounds are chemically delicate, particularly from herbs and vegetables. We lose a lot when we throw them all into a big pot together and simmer for hours and hours. Better to parse them out to give them just enough time to be drawn out into the stock, but not so much that they dissipate (this is the same reason why I need to adjust a lot of recipes involving mushrooms--by the time the sauteed mushrooms have simmered in the soup pot, they've lost most of their flavor).

In any event, here's my go-to Pressure Cooker chicken stock recipe. All normal caveats apply--read the user manual, don't fill over the maximum fill line, etc. I use one of these guys:

and am able to just barely fit this recipe inside. Of course, you can play around with the particular vegetables and herbs (I keep dreaming of doing some Indian-inspired stock), just make sure it doesn't go over the max fill line of your pressure cooker. Also, I highly recommend using a mandoline slicer to break up the vegetables (even a cheap one like I use), as the increased surface area will mean more nutrients are drawn out into the stock. If you need to use the stock immediately and don't want to skim the fat off, I recommend putting ice in a ladle (or better yet, a stainless steel bowl) and running it over the top of the stock. The ice will cause the fat floating on top to immediately congeal, and you can wipe it away (have a few paper towels ready for this one).

Tom's Pressure Cooker Chicken Stock
4 lb chicken drumsticks or wings
1 leek
4 medium carrots
1 onion
1/2 tbsp black pepper corns
1/2 tbsp dried thyme
1/2 tbsp dried parsley

Place the chicken in the pressure cooker with three quarters of water (I'll usually put in half and heat the other half in an electric kettle). Place over high heat and bring to a boil. Allow to boil, skimming the top clean. Lock the lid in place and bring pressure cooker to maximum temperature. Bring to a simmer for 1 hour.

Using the thinnest setting on a mandoline, clean and slice the leek, carrots and onion.

Remove from heat and allow to cool sufficiently to remove top (I will run it under cold water in the sink with the drain plugged up until the safety valve just barely releases--be careful, as it will still be boiling hot when you remove it). Add in vegetables, affix the lid and bring back to a simmer at full temperature for another 30 minutes.

Remove from heat and allow to cool a second time to add in the herbs and pepper corn. Affix the lid, bring back to full heat and allow to simmer for a final 30 minutes before cooling.

Drain stock through a fine mesh strainer and/or cheesecloth into a large metal pot. Place pot in sink with drain stopped up and fill sink with cold water. Repeat 1-2 times to bring to room temperature (or cooler), then cover with saran wrap and place in refrigerator overnight. Skim fat from top of pot and use or portion and freeze. When reheating, be sure to allow frozen stock to boil for 2 minutes before using.

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