Cooking for Geeks: Real Science, Great Hacks, and Good Food (38 page)
Read Cooking for Geeks: Real Science, Great Hacks, and Good Food Online
Authors: Jeff Potter
Tags: #COOKING / Methods / General
Short ribs and other high-collagen cuts of meat aren’t difficult to work with, they just require time at temperature (collagen takes many hours to hydrolyze). The trick is to cook this type of meat “low and slow” — for a long time at low temperature. Too cold, and the collagen won’t break down; too hot, and the water in the meat will evaporate, drying it out. Using a slow cooker cooks the meat in the ideal temperature range. After all, this is what they’re designed for!
This is an intentionally easy recipe, but don’t let this fool you: slow-cooked meats can be
amazingly
good, and if you’re cooking for a dinner party, they make for easy work when you go to assemble the dinner. If you have a rice cooker, check to see if it has a “slow-cook” setting. In this mode, the rice cooker will heat foods to a temperature typically between 170–190°F / 77–88°C, which is warm enough to be safe from bacterial contamination and cool enough to not steam-dry the meat.
Pour a bottle of barbeque sauce into the bowl of the rice cooker or slow cooker. Add the short ribs, arranging them in a layer so that the barbeque sauce covers the meat.
Slow-cook for at least four hours (longer is fine). Try starting this in the morning before going to work — the slow cooker will keep the food safe, and the extra time will help ensure that the collagen is fully dissolved.
Notes
- Ideally, you should pan sear the short ribs (in a cast iron pan) for a minute or two before cooking. As discussed at the beginning of this chapter, this will cause browning reactions, bringing a richness to the final product.
- Keep in mind the danger zone rule covered earlier. Don’t load up a slow cooker with so much cold meat that the cooker will be unable to raise the temperature above 140°F / 60°C within a two-hour period.
- Try adding other ingredients to the sauce, or making your own sauce if you like. I’ll often pour a tablespoon or so of wine or port into the empty BBQ sauce jar to “rinse out” the thick sauce, then pour the port-sauce slurry into the slow cooker.
Duck confit — duck legs cooked in fat — tastes entirely different from duck cooked almost any other way. It’s like bacon and pork — to quote Homer Simpson, they’re from “some wonderful, magical animal.” Good duck confit is succulent, flavorful, tender, mouth-watering, and perhaps a bit salty. Even if you’re not otherwise a fan of duck, give duck confit a chance.
As you can probably tell, I’m a pragmatic cook. Traditional recipes for duck confit prescribe a long, drawn-out affair, which is fine for a leisurely Sunday afternoon spent in the company of friends and a bottle of good wine, but doesn’t line up well with my idea of keeping things simple.
Cooking duck “confit-style” is all about converting tough collagen proteins into gelatin. While this isn’t a fast chemical reaction, it’s a simple one to trigger: hold the meat at a low temperature for long enough, and the collagen proteins denature and eventually hydrolyze.
The secret to duck confit is in the time and temperature, not the actual cooking technique. The upshot? You can make duck confit in a slow cooker or in an oven set at an ultra-low temperature. The fat that the duck is cooked in doesn’t matter either; some experiments have shown that duck confit cooked in water and then coated in oil is indistinguishable from traditionally cooked duck confit. Regardless, definitely skip the exotic block of duck fat; duck legs are expensive enough as it is.
Rub salt into the outside of the duck legs, covering both the side with skin and the side with meat exposed. I use roughly 1 tablespoon (18g) of salt per duck leg; you want enough to coat the outside thoroughly.
Place the salted duck legs in a bowl or plastic bag and store them in the fridge for several hours to brine.
Remember: store raw meats in the bottom of the fridge so if they drip the runoff won’t contaminate fresh produce or ready-to-eat foods.
Salting the meat adds flavor and draws out a little bit of the moisture, but if you’re in a real rush, you can skip this step and just lightly coat the duck legs with a few pinches of salt.
After dry-brining the duck legs, wash off all the salt. At this point, you have a choice of heat sources. Duck confit is about cooking via convection heat with the energy being imparted into the meat by the surrounding fat. Regardless of heat source, the duck legs should be entirely submerged in oil. With careful arrangement and the right size pan, you’ll find that it doesn’t take much oil to cover them. I generally use olive or canola oil and save the oil after cooking for use in other dishes.
Note that the oil after cooking will be a blend of duck fat and your starting oil. You can also use it for things like sautéing greens and shallow-frying potatoes.
Arrange duck legs in bowl of slow cooker or multipurpose rice cooker. Cover with oil and set to slow-cook mode for at least 6 hours (preferably 10 to 12).
Arrange duck legs in an oven-safe pan and cover with oil. Place in oven set at 170°F / 77°C for a minimum of six hours. (200°F / 95°C will work, but avoid anything hotter to prevent steaming the meat.)
The duck legs will become more tender with longer cook times. I’ve cooked batches of 36 duck legs overnight using a large pot held at temperature in an oven. If you do cook a large batch, remember that the core temperature needs to get to about 140°F / 60°C within two hours. In this case, heat the oil up to ~250°F / 120°C before placing the duck legs in it. This way, the hot oil will impart a solid thermal kick to get the cold legs up to temperature faster.
Duck leg that has been cooked at low heat for a long time falls apart easily, because most of the collagen and connective tissues that normally hold muscles together are gone.
After cooking, the duck skin will still be flabby and, frankly, gross. But the meat should be tender and yield with a bit of poking. You can either remove the skin (pan sear it by itself for duck lardons!) or score the skin with a knife and then pan sear the skin side of the duck to crisp it up.
If you are not going to use the duck legs straightaway, store them in the fridge.
Notes
- Traditional recipes call for duck fat instead of olive oil. One advantage to the duck fat is that, upon cooling to room temperature, it solidifies, encasing and sealing the duck leg in a sterilized layer of fat, somewhat like how some jams are preserved with a wax seal. If you were living in France a century ago, this would’ve been a great way to preserve duck legs for a long winter, but with the invention of refrigeration and modern grocery stores, there’s no need for the duck fat to store the meat safely for the few days it might last. Use olive oil. It’s cheaper and healthier.
- If you pour off the oil and liquid into another container, a layer of gelatin will separate out on the bottom once it cools. Use that gelatin! Try tossing it into soups.
If all this talk about collagen and texture isn’t gelling for you, do the following experiment.
Take a few pieces of beef stew meat, and proceed as though you’re making beef stew. (See
Simple Beef Stew
in
Chapter 2
.) Once your beef is in the slow cooker, set a timer for 30 minutes.
After 30 minutes, remove a few pieces of the beef. Use a probe thermometer on one to record the internal temperature; it should register somewhere around 160–180°F / 71–82°C, although it’ll depend on your slow cooker. Stash the 30-minute sample in a container in your fridge.
After six hours of stewing, repeat the procedure: remove a few pieces, verify that the temperature is about the same, and stash the second batch in a second container in the fridge. (You could heat up the 30-minute batch, but then we’d be changing more than one variable: who’s to say that reheating doesn’t change something?)
Once both samples are cold, do a taste comparison. Got kids? Do a single-blind experiment to remove the placebo effect: blindfold the kids and don’t let them know which is which. Got a spouse and kids? Do a double-blind experiment to control for both placebo effect and observer bias: have your significant other scoop the beef into the containers and label them only “A” and “B,” not telling you which is which, and then go ahead and administer the blindfold test to your kids.
Whereas meat is predominately proteins and fats, plants are composed primarily of carbohydrates such as cellulose, starch, and pectin. Unlike proteins in meat, which are extremely sensitive to heat and can quickly turn into shoe leather if cooked too hot, carbohydrates in plants are generally more forgiving when exposed to higher temperatures. (This is probably why we have meat thermometers but not vegetable thermometers.)
Temperatures related to plants and cooking.
Cooking starchy vegetables such as potatoes causes the starches to gelatinize (i.e., swell up and become thicker). In their raw form, starches exist as semicrystalline structures that your body can only partially digest. Cooking causes them to melt, absorb water, swell, and convert to a form that can be more easily broken down by your digestive system.
As with most other reactions in cooking, the point at which starch granules gelatinize depends on more than just the single variable of temperature. The type of starch, the length of time at temperature, the amount of moisture in the environment, and processing conditions all impact the point at which any particular starch granule swells up and gelatinizes. See the section
Making gels: Starches
in
Chapter 6
for more about starches and gelatinization.
Leafy green vegetables also undergo changes when cooked. Most noticeably, they lose their green color as the membranes around the chloroplasts in the cells rupture. This same rupturing and damage to the cell structure is what improves the texture of tougher greens such as Swiss chard and kale.
For starchy plants (think potatoes), cook them so that they reach the temperature at which they gelatinize, typically in the range of 180–190°F / 92–99°C. For green leafy plants, sauté the leaves above 140°F / 60°C to break down the plant cell structure.
Cellulose — a.k.a. fiber — is completely indigestible in its raw form and gelatinizes at such a high temperature, 608–626°F / 320–330°C, that we can ignore it while discussing chemical reactions in cooking.
Starch levels in common vegetables.
Microwave ovens make quick work of cooking veggies. In a microwave-safe container, place asparagus stalks with the bottoms trimmed or snapped off, and add a thin layer of water to the bottom. Put the lid on, but leave it partially open so that steam has a place to escape. Microwave for two to four minutes, checking for doneness partway through and adding more time as necessary.
Notes
- This technique cooks the food using two methods: radiant heat (electromagnetic energy in the form of microwaves) and convection heat (from the steam generated by heating the water in the container). The steam circulates around the food, ensuring that any cold spots (areas missed by the microwave radiation) get hot enough to both cook the food and kill any surface bacteria that might be present.
- Try adding lemon juice, olive oil, or butter and sautéed, crushed garlic to the asparagus.
Pectin
is a polysaccharide found in the cell walls of land plants that provides structure to the plant tissue. It breaks down over time, which is why riper fruits become softer.
Cooking also breaks down pectin, and as a kitchen chemistry experiment, you can capture the pectin from cooked fruits. It’s an easy way to see that some food additives aren’t so industrial after all, at least not in their sources.
The pectin we use in cooking — primarily in jams and jellies, as a thickener — is divided into two broad types: low- and high-methoxyl. High-methoxyl pectin requires a high concentration of sugar in order to gel; low-methoxyl pectin will gel in the presence of calcium. (The difference between the two types has to do with the number of linkages in the molecular structure.)
If you’re making jams or jellies, using a low-methoxyl pectin (such as Pomona’s Pectin) removes the variable of sugar concentration. See Tim O’Reilly’s tips for making jam in
Chapter 5
in
Tim O’Reilly’s Scones and Jam
.
Making your own pectin is similar to making your own gelatin: start with a couple of pounds of tissue, boil away, and then filter it out. Instead of animal bones, pectin comes from the “bones” of cell walls in plant tissue.
Start with a few pounds of crisp apples. (The firmer the better! They don’t need to be ripe.) Chop them into quarters and place the pieces in a stockpot. Cover with water and simmer on low for several hours, stirring occasionally. (This is exactly the way stock is made.) After several hours, you should have a slushy sauce. Filter this through a strainer. (See the section on filtration in
Chapter 7
for tips.) The slimy liquid that you filter out is the pectin.
Using homemade pectin will be a bit trickier than Pomona’s Pectin, for two reasons. First, it’s high-methoxyl pectin, so you’ll need to have a proper balance of sugar in whatever you’re attempting to gel. And secondly, the concentration of pectin to water will be unknown, so you will have to experiment some. Add a small quantity and test if it gels; if not, add more. If the liquid pectin seems too thin, you can boil it down further to create a more concentrated pectin.
For more ideas and tips on testing homemade pectin, see
http://www.wildflowers-and-weeds.com/The_Forager/pectin.htm
.
In a sauté or nonstick pan preheated over medium heat, add:
- 1 bunch Swiss chard, collard greens, or other hardy leafy green vegetable; stems and thick veins removed, and sliced into 1” strips
- 2 tablespoons (26g) olive oil (enough to coat the pan)
Using tongs, quickly toss the greens to coat them with oil. Your pan should be reasonably hot so that the greens quickly heat, but not so hot that the oil burns. Continue tossing while cooking so that the greens wilt evenly. Add salt and pepper to taste.
Notes
- Depending upon your tastes, extend this by adding one of these combinations:
- 5 cloves garlic, minced; juice from half a small lemon (about a teaspoon)
- 2 teaspoons balsamic vinegar, and possibly a pinch of sugar
- 1 teaspoon sherry vinegar, ¼ teaspoon crushed red pepper flakes, 1 can cannellini beans, 3 cloves garlic
- ¼ red onion, sliced thin and sautéed to cook; ½ apple sliced into bite-sized pieces and cooked; handful of chopped walnuts, toasted
- 5 cloves garlic, minced; juice from half a small lemon (about a teaspoon)
- The same technique can be applied to spinach (it’s great with sesame seeds). Or try cooking some strips of bacon, removing the bacon, and then sautéing the spinach in the rendered bacon fat, adding a teaspoon or so of balsamic vinegar. Dice the bacon and combine the two, and optionally add some blue (or other) cheese. Quantity of ingredients is really down to personal preference, so experiment!
- You can strip the stem and thicker veins from hardy greens such as Swiss chard by grabbing the stalk with one hand and the green leaf portion with the other hand, and pulling the stalk out.
Poached pears are easy, tasty, and quick. And, at least compared to most desserts, they’re relatively healthy, or at least until the vanilla ice cream and caramel sauce are added. Much of our enjoyment of fruit comes from not just their flavor but also their texture. Consider an apple that’s lacking in crispiness or a banana that’s been bruised and become mushy: without their customary texture, their appeal is lost. But this isn’t always the case. Poaching fruits such as pears causes similar changes in the structure of the fruit’s flesh, breaking down cell walls and affecting the bonds between neighboring cells to create a softer texture that’s infused with the flavor of the poaching liquid.
In a shallow saucepan or frying pan, place:
- 2 medium (350g) pears, sliced lengthwise (longitudinally) into eighths or twelfths, and core removed
- 1 cup (240ml) red wine
- ¼ teaspoon ground pepper
Set the pan over low to medium heat, bringing the wine to a simmer and then poaching the pears for 5 to 10 minutes, until soft. Flip them halfway through, so that both sides of the slices spend some time facedown in the liquid. Remove the pears and discard the liquid. (You can also reduce the liquid down into a syrup.)
Notes
- Fun chemistry fact: the boiling point of wine is lower than that of water. The exact temperature depends upon the sugar and alcohol levels, and as the wine simmers, the ratios shift. It’ll start somewhere around 194°F / 90°C. It’s doubtful that this will actually help you avoid overcooking the pears, though.
- Pears are one of those fruits that are underripe until you look away and then go rotten before you can look back. To encourage them to ripen, you can keep underripe pears in a paper bag so the plant tissue will be exposed to the ethylene gas they give off. I find I can get away with poaching pears that are a little more underripe than I might want to eat fresh, but your pears should be at least a little soft.
- Try serving this with caramel sauce (see
Caramel Sauce
) and vanilla ice cream. Or try poaching other fruits, like fresh figs, and using other liquids. Figs poached in port or a honey/water syrup with a small amount of lemon juice and lemon zest added after poaching are sweet and tasty. - You don’t need to actually measure out the ingredients. As long as the pears have enough liquid to poach in, they’ll turn out great. Add freshly ground pepper to suit your tastes.Note
Don’t use preground pepper. Preground pepper quickly loses its complex aromatic flavors — well before it makes it into your hands — leaving it with just a hot spicy kick but none of the subtlety of peppercorns.