by Jeff Potter
Error Tolerances in Measuring
Measuring out too much (or not enough) butter when making mashed potatoes won’t lead to disaster. But with baking, the error tolerance in measurement—the amount you can be off by and still have acceptably good results—is much smaller.
How can you learn what measurements are important? Besides trying lots of experiments and keeping detailed notes, you can look at differences between recipes. (Look back at Picking a Recipe in Chapter 1 for a discussion of comparing recipes.) By looking at the differences, you can also see what doesn’t matter so much.
Consider the ingredients for the following two pie dough recipes.
Joy of Cooking (8″ / 20 cm pie)
Martha Stewart’s Pies & Tarts (10″ / 25 cm pie)
100%
240g
flour
100%
300g
flour
60%
145g
shortening (Crisco)
–
–
(no shortening)
11.25%
27g
butter
76%
227g
butter
25%
59g
water
19.7%
59g
water
0.8%
2g
salt
2%
6g
salt
–
–
(no sugar)
2%
6g
sugar
The numbers in the first column are "baker’s percentages," which normalize the quantities to the quantity of flour by weight; the second column gives the gram weights for one pie’s worth of dough.
Just comparing these two recipes, you can see that the ratio of flour to fats ranges from 1:0.71 to 1:0.76, and that a higher percentage of water is called for in the Joy of Cooking version.
However, butter isn’t the same thing as shortening; butter is about 15–17% water, whereas shortening is only fat. With this in mind, look at the recipes again: the Martha Stewart version has 76g of butter (per 100g of flour), for about 62g of fat; the pie dough with shortening has 60g of fat per 100g of flour. The quantity of water is also roughly equal between the two once the water present in the butter is factored in.
You won’t always find the ratios of ingredients between different recipes to be so close, but comparing recipes is a great way to learn more about cooking and a good way to determine which recipe to use when trying something new.
Note
There are two broad types of pie doughs: flaky and mealy. Working the fat into the flour until it is pea sized and using a bit more water will result in a flakier dough well suited to prebaked pie shells; working it until it has a cornmeal-like texture will result in a more water-resistant, mealy, crumbly dough, which makes it better suited for uses where it is filled with ingredients when baked.
Simple Pie Dough
Measure and combine all the ingredients for either the Joy of Cooking or the Martha Stewart recipe into a mixing bowl or the bowl of a food processor, cutting the butter into small cubes (½″ / 1 cm). You should preferably use pastry flour, but AP flour is okay. Chill in the freezer for 15 to 30 minutes. Chilling the ingredients prevents the butter from melting, which would allow the water in the butter to interact with the gluten in the flour, resulting in a less flaky, more bread-like dough.
Pulse the ingredients in a food processor in one-to two-second bursts. Continue pulsing the dough until the ingredients are combined into a coarse sand-like or small pebble-like consistency. If you do not have a food processor, use a pastry blender, a couple of knives, or your fingers to crumble the fats into the flour. Make sure if you use your hands not to let the temperature of the dough rise much above room temperature.
Once the dough is at a coarse sand- or pebble-like consistency, dump the dough out onto a floured cutting board and press it into a round disc. Using a rolling pin, roll the dough out into a sheet, then fold it over on itself and roll it out again, repeating until the dough has been compressed and has enough structure that it can be transferred to a pie tin.
Prebaked Pie Shell
Some pies, such as lemon meringue pie (see Lemon Meringue Pie in Chapter 6), call for the pie shell to be prebaked. To prebake a pie shell (also called blind baking), roll out the dough and transfer it to your pie tin or mold. You’ll need to bake the pie with pie weights (no need to be fancy—beans or rice work perfectly); otherwise, the pie dough will slide down the edges and lose its shape. Once it’s baked enough to hold its shape, remove the pie weights so that the pie shell has a chance to crisp up and brown.
Set oven to 425°F / 220°C. Bake pie shell with pie weights for 15 minutes (use parchment paper to separate the pie weights from the dough, so that you can pick up the paper and remove the weights). Remove pie weights and bake for another 10 to 15 minutes, until shell is golden brown.
Note
I hate the taste of uncooked flour; it burns the back of the mouth. If you’re not sure whether your pie dough is done, err on the side of leaving it in longer.
When prebaking—also called "blind baking"—a pie shell, make sure to fill the shell with weights. Otherwise, the sides will collapse. Line the pie shell with a piece of parchment paper or foil and fill it with dried beans or rice.
Martin Lersch on Chemistry in the Kitchen
PHOTO USED BY PERMISSION OF MARTIN LERSCH
Martin Lersch blogs about food and molecular gastronomy at http://blog.khymos.org, which includes the excellent collection of recipes, "Texture: A hydrocolloid recipe collection," which demonstrates many uses of food additives. (We’ll cover food additives and molecular gastronomy in Chapter 6.)
I see from your online bio that you have a PhD in organometallic chemistry. How did you get interested in chemistry in cooking?
My whole food interest is in no way related to my studies or my work, apart from chemistry. It was when I was a student at the University of Oslo, almost 10 years ago, that I found On Food and Cooking by Harold McGee in the faculty library. It was very interesting.
So I started looking for more information, but at that time there wasn’t really very much out there. At university, they often have students visiting from high schools, so at one point I was given the opportunity to talk about everyday chemistry; I think the title was something like "Everyday Chemistry in the Kitchen." Then I put up a web page, and when I finished my PhD many years later, the page had grown, so I figured I would continue. I moved everything to http://khymos.org and started blogging.
The whole time, it’s only been a hobby. I’ve always liked cooking. Every chemist should actually be a decent cook, because chemists, at least organic chemists, are very used to following recipes. It’s what they do every day at the lab. I often tease my colleagues, especially if they claim that they can’t bring a cake to the office for a meeting, I say, "Well, as a chemist, you should be able to follow a recipe!" As a chemist, I’ve always had, in a way, curiosity. I bring that curiosity back home into the kitchen and wonder, "Why does the recipe tell me to do this or that?" That’s really the case.
How has your science background impacted the way that you think about cooking?
I think about cooking from a chemical perspective. What you do in cooking is actually a lot of chemical and physical changes. Perhaps the most important thing is temperature, because many changes in the kitchen are due to temperature variations. Searing meat and sous vide are also good places to start. With sous vide, people gradually arrive at the whole concept themselves. If you ask them how they would prepare a good steak, many people would say you should take it out of the refrigerator ahead of time, so you temper the meat. While you temper it, why not just put it in the sink—you could use lukewarm water? Then if you take that further, why not actually temper the meat at the desired core temperature? Most people will say that’s a good idea, then I say that’s sous vide. It becomes ob
vious for people that that’s actually a good idea.
I’m very fascinated by the hydrocolloids. One of the reasons I spent so much time putting the recipes together was that when I bought hydrocolloids, maybe one or two recipes would be included, but I found them not to be very illustrative. Everyone is familiar with gelatin, less so with pectin, but all the rest are largely unfamiliar. People don’t know how they work, how you should disperse them and hydrate them, or their properties. The idea was to collect recipes that illustrate as many of the ways to use them as possible. You can read a couple of the recipes and then can go into the kitchen and do your own stuff. That’s what I hope it will enable people to do.
Note
See Buying Food Additives in Chapter 6 for an explanation of colloids.
I think it’s a fantastic recipe collection, having used it myself for exactly the purpose that you describe. Out of curiosity, is there a favorite hydrocolloid of yours?
No, I haven’t even tried them all—I don’t have all of them in my kitchen.
Really?
I think the reason is more lack of time. With a full-time job, children, family... there’s simply not enough time. It’s a lot easier to skip the practical part and concentrate on the theory.
Is there a particular recipe from which you’ve learned the most or found interesting or unexpected in some way?
It’s hard to think of one recipe. When talking about molecular gastronomy, it’s easy to focus too much on the fancy applications like using liquid nitrogen or hydrocolloids. It’s important to emphasize that this is not what molecular gastronomy is about, although many people think that; many people associate molecular gastronomy with foams and alginate.
I always try to include basic things to get down to earth. One thing that comes to mind is bread. It is really fascinating the great variety that you can achieve by using only water, flour, and salt. With the flour and water, you already have the wild yeast present, so you have everything set up for a sourdough. Then it depends on how you prepare your starter, the ratios involved, how you proof your dough, and how you bake it. Of course, this is not something new; bakers know this. But from a scientific viewpoint, it’s very interesting to think about that. The no-knead bread illustrates a lot of chemistry; you’re probably familiar with that?
I am, but go on.
Glutamine and gliadin, the two proteins that make gluten, can combine all by themselves once you have a dough that is wet enough. The typical hydration for no-knead bread would be somewhere in the 75% to 77% range. You bake the bread in a preheated pot, where you simulate a steam oven. Moist air is a much better heat conductor than dry air, and the moisture condenses on the surface of the bread. It enhances the crust formation and helps the gelatinization of the starch. It also prevents the crust from drying out and limiting the rise of the bread, so you get a much better oven spring this way. Once you remove the lid, everything is set for the Maillard reaction as the crust dries out. So there is a lot about both the way you make dough and the way you bake the bread that exemplifies basic chemistry and physics.
Bread—No-Knead Method
Weight
Volume
Baker’s %
Ingredient
390g
3 to 3¼ cups
100%
All-purpose white flour
300g
1¼ cups
77%
Water
7g
1 teaspoon
1.8%
Salt
~2g
½ teaspoon
–
Fresh yeast (a pea-sized lump); you can substitute 1 teaspoon (5g) instant yeast
Mix everything until the flour is completely moistened. This should take only about 30 seconds. Cover and let rest at room temperature for 20 hours.
Place a medium-sized cast iron pot in your oven and preheat both to 450°F / 230°C. While the oven is heating, transfer the dough onto a floured surface and fold three or four times. Leave for 15 minutes. Shape rapidly into a boule—a round loaf—and place on a generously floured cloth towel. Proof until doubled in size. Dump into the preheated cast iron pot and bake with the lid on for 30 minutes. Take the lid off and bake until the crust has a dark golden color, about 15 minutes.
ADAPTED BY MARTIN LERSCH FROM JIM LAHEY’S NEW YORK TIMES RECIPE
Mill Your Own Flour
Milling flour is a lot easier than you might imagine: snag some wheat berries—which are just hulled wheat kernels, with bran, germ, and endosperm still intact—from your local health food store or co-op, run them through a mill, and you’ve got fresh flour.
Why bother? Well, for one, the taste is fresher; volatile compounds in the wheat won’t have had time to break down. Then there are the health aspects. Most commercial whole wheat flours have to heat-process the germ to prevent it from going rancid, but this heat-processing also affects some of the fats in the flour.
On the downside, freshly milled flour won’t develop gluten as well as aged flour. For a rustic loaf of bread, this is probably fine, but it’s not so good if you’re trying to make whole wheat pasta, in which the gluten helps hold the pasta together. Of course, you can always add in some gluten flour to boost the gluten levels back up.
You have a couple of options for mills. KitchenAid makes a mill attachment for its mixers. If you do spring for a KitchenAid attachment, though, be warned that it can put quite a strain on the mixer. Set it to low speed and run your grain through in two passes, doing a first pass to a coarse grind before doing a fine grind. Alternatively, take a look at K-Tec’s Kitchen Mill, which is in roughly the same price range but is designed specifically for the task.
You can run other grains, such as rice and barley, through a mill as well. Too-moist grains and higher-fat items such as almonds or cocoa nibs are a no-go, though: they’ll gum up the grinder.
Wheat berries.
First pass: coarse grind.
Second pass: fine grind.
P.S. Don’t expect to be able to mill things like cake flour. Cake flour is bleached with chlorine gas to mature it. Maturing—the process by which flour is aged—would eventually happen naturally due to oxidation, but chlorine treatment speeds it up. It also modifies the starch in the flour so that it can absorb more water during gelatinization (see Making gels: Starches in Chapter 6 for more on gelatinization of starches) and weakens the proteins in the flour, reducing the amount of gluten that can be formed. Additionally, chlorination lowers the temperature of gelatinization, so batters that include solids—nuts, fruits, chocolate chips—perform better because there’s less time for the solids to sink before the starches are able to gel up around them.
Biological Leaveners
Biologically based leaveners—primarily yeast, but also bacteria for salt-rising breads—are surely the oldest method for generating air in foods. Presumably, a prehistoric baker first discovered that a bowl of flour and water left out will begin to ferment as yeast from the surrounding environment settles in it.
Yeast
Yeast is a single-celled fungus that enzymatically breaks down sugar and other sources of carbon to release carbon dioxide, ethanol, and other compounds, giving drinks their carbonation, spirits their alcohol, and beer and bread their distinctive flavors. Even making chocolate involves yeast—the cocoa beans are fermented, which generates the precursors to the chocolate flavor.
Different strains of yeast create different flavors. Over the years we’ve "domesticated" certain strains by selective breeding—from common baker’s yeast for bread and wine (Saccharomyces cerevisiae) to those for beer (usually S. carlsbergensis, a.k.a. S. pastorianus).
Since there’s plenty of yeast literally floating around, you don’t have to directly spike your brew or seed your bread with yeast. New strains of yeast usually start out as wild hitchhikers, and sometimes they taste great. Traditionally winemakers relied on ambient yeasts present in their cellars or even on the grapes themselves (this is the origin of the traditional Eur
opean le goût de terroir approach to winemaking).
However, the "Russian roulette yeast method" might not end so well when you’re working in your kitchen: there’s a decent chance you’ll end up with a nasty and foul strain of yeast that’ll generate unpleasant-tasting sulfur and phenol compounds. This is why you should add a "starter" strain: providing a large quantity of a particular strain ensures that it will out-race any other yeasts that might be present in the environment.
Note
There’s nothing magical about the strains of yeast we use other than someone taking notice of their flavor and thinking, "Hey, this one tastes pretty good, I think I’ll hang on to it!"
Like any living critter, yeast prefers to live in a particular temperature zone, with different strains preferring different temperatures. The yeast commonly used in baking breads—aptly named baker’s yeast—does best at room temperature (55–75°F / 13–24°C). In brewing beer, ales and stouts are made with a yeast that is similar to baker’s yeast; it also thrives at room temperature. Lagers and steam beer use a bottom-fermenting yeast that prefers a cooler environment around 32–55° F / 0–13°C. Keep in mind the temperature range that the yeast you’re using likes, and remember: too hot, and it’ll die.
Yeast in beverages
Wine, beer, and traditional sodas all depend on yeast to ferment sugar into alcohol and generate carbonation. Consider the following equation:
Fermentation = Water + Carbon (usually Sugar) + Yeast + Optional Flavorings
Selecting the appropriate strain of yeast and controlling the breeding environment—providing food, storing at proper temperatures—allows for the creation of our everyday drinks:
Wine = Grape Juice[Water + Sugar] + Yeast
