Gluten and Starches: A Thread

Wheat gluten has received a lot of attention in the past few years due to all the discussions around people who are gluten-sensitive or coeliac or just afraid of it for no actual scientific reason, without much discussion of what it actually IS, what it does for your cooking, and how to work with it for best results.

The most famous (and infamous) gluten, wheat gluten, is a protein — or more precisely, a combination of two proteins, gliadin and glutenin. (Gliadin is the one that specifically gives coeliacs digestive issues, by the way.) Gluten is found in the endosperm of the wheat grain. Various amounts of other gluten also appear in grains closely related to wheat, most notably barley, spelt, and rye. Coeliacs beware supposedly "wheat-free" spelt goods, for example, because they may be wheat-free but they are not gluten-free.

Other grains have similar proteins sometimes also referred to as gluten (e.g. "corn gluten") because they also come from the endosperm of the grain and share similar properties, but chemically are completely different and are therefore, ironically, "gluten free" despite the name. Language is a messy business sometimes.

What makes gluten special (and starches, when we get to them) is its ability, when mixed with water, to form long, durable threads in your food. You may have noticed this when working with dough that if you pull it apart it doesn't just tear in two but actually has some pretty decent tensile strength and stretches out into sheets and strings. That's the gluten doing its magic. You can see this property on extra-spectacular display when you watch a skilled pizzaiolo hand-tossing pizza dough.

. . . And that stretchiness is precisely what gluten is "for", giving pizza, bread, and baked goods that chewy springy texture that makes them oh so wonderful to eat. But like so many things, more is not always better. So the first word of wisdom is to pick the right flour for the task.

Flour Choice

By it's very name, "all purpose flour" is the workhorse of the kitchen and can make anything from basic pizza to cookies relatively well. And if a recipe calls for all-purpose flour, that's the one you should use; it's been optimized that way.

Professional bakers and baking aficionados, however, often take things to the next step by using flours specific to purpose, and the gluten content of the types of wheat used for each is the primary differentiator, roughly from highest to lowest:

• Semolina Pasta Flour - 13%+ - very dense

• Bread Flour - 13-14% - chewy and firm

• Pizza Flour / 00 Flour - 12-13%- stretchy and rubbery

• All-Purpose Flour - around 12%

• Pastry Flour - 9-10% - meant to be more delicate and crumbly

• Cake Flour - 7.5-9% - extremely soft and crumbly

For those of you who have tried various gluten-free baked goods, you'll probably have noticed that the GF version of foods near the bottom of that list are consistently quite good (I even make a case that some rice flour shortbread can be much more delicate and tasty than the wheat flour kind), whereas GF breads are hit and miss, and a good GF pizza dough is sort of the holy grail. That's because pizza crust really depends on that strength and stretchiness that almost no other chemical can provide, and without it gets bready or even cakey. Similarly, if you try using cake flour for pizza, you're going to have a mess.

And on the flip side, using bread flour for cake, even without kneading or mixing it too much, is generally going to give you a cake that's heavy and awful.

And using all-purpose flour in a recipe that specifically calls for bread flour or cake flour is risky at best. If you don't want to buy the special stuff, it's better to find a recipe optimized for all-purpose instead.

. . . all of which which brings us to our second subtopic.

Kneading: How to empower your gluten

Unlike starches, gluten is a little lazy and requires some intense physical stimulation to do its thing. Beginner bakers often skip or underperform the kneading step of breadmaking (assuming it's just glorified mixing, and that the dough looks mixed enough) and wind up with sad, cakey bread. That's because the kneading process is required to get those gliadin proteins to splice the glutenin threads together to make the long protein ropes in the dough and hold it all together.

Good recipes usually tell you a specific target texture instead of or in addition to a number of minutes, because that's really what you're going for.

And just like choosing the right flour, you don't want to under OR OVER-knead your dough, or you're going to wind up with the wrong end product. In several cooking classed I've taken, I've been reprimanded for over-mixing and over-kneading, so that's my own fatal flaw.

Shortening: How to disempower your gluten

In addition to using low-gluten flour and batter or dough which is not kneaded, there's another way cakes and pastries can be made extra-crumbly: the shortening process. You may be thinking, "Hey, shortening, I've heard of that. Like Crisco, right?" And you're not wrong. It's also the reason for the names of shortbread, shortcakes, and so on.

The reason why cookies, shortbreads, cakes, and so on, almost always include plentiful quantities of butter, oil, shortening, lard, or other fats/oils is not just for flavour. All lipids have the side-effect of "shortening" the gluten molecules so they only form short little bundles instead of long ropes. It would be incredibly off-putting if your sugar cookie or muffin stretched like a pizza crust when you bit into it.

The shortening process is also the secret behind flaky pastry like pie crusts, croissants, and phyllo dough: they're a hybrid, where the dough is mixed and kneaded to form strong long gluten threads in general, but then rolled out thin and layered with chilled butter in between to shorted the gluten on the vertical axis. The gluten WANTS to grab its friends in the next layer down, but can't because of the thin layer of butter in between.

Generally your recipes will take care of the proper ratios of fat/oil to flour to make the texture work, so you don't need to worry about that, but because we all love butter and olive oil and so on, it's a key food chemistry concept to understand to make sure you're not short-circuiting (no pun intended) an otherwise good recipe:

• Be mindful of the timing of adding olive oil to your pizza dough. Even if the recipe doesn't specify it, I tend to add it only after kneading, to make sure all those stretchy gluten ropes are safely formed already.

• Innocently adding unspecified butter or olive oil to a bread recipe "for flavour" may actually ruin the bread.

• Tampering with the butter/oil/shortening quantity, temperature, and directions in recipes that DO call for it can also mess things up, especially tricky things like the croissant dough I mentioned above.

• Gluten-free flours require no shortening process, which is one reason rice flour cookies can be so deliciously delicate. It's almost like rice flour was the better person for the job in the first place, but alas, western culture is addicted to wheat.

Starches

It's useful to piggyback on our discussion of gluten and discuss starches at the same time. Starches are the other chemicals plentiful in the endosperm of grain seeds, and primarily function to nourish the embryo as the seed germinates. Not only do they contain a lot of energy, but also, kind of like gluten, they tend to form long-stringy mega-molecules that hold things together.

This makes starchy flours and even purified corn/wheat/rice starch perfect for thickening sauces, soups, stews, and so on. Starches are also the foundation for the dredges and batters that make fried food so crispy and tasty, not to mention tasty batters for pancakes, waffles, and crêpes.

Starches also have the magical ability to make oil and water get along with each other, a reason most cheese fondue recipes have a pinch of flour in them to keep the cheese itself from separating and helping it blend with the wine. This principle also makes starch terrific for sticking things together: most deep fry recipes (e.g. fish & chips) call for dredging your protein in dry flour, then the wet batter, sometimes multiple times. Without that step, you've probably experienced watching all your precious batter falling off in the oil. Dredging in flour or starch helps the wets stick to the dries and the dries stick to the wets.

Some other helpful hints for working with flours more generally (wheat or no) and other starches:

• Starches experience a process similar to gluten with regard to shortening. If your mashed potatoes are too gluey and not stiff and starchy, are you sure you didn't add too much butter in there too soon? Or used high fat cream when the recipe called for regular milk? You're unintentionally shortening your potato starch.

• A little corn starch is a great way to rescue a broken sauce, or to make a soup or stew less greasy if it has separated. But beware: when starch gets hot, it clumps! So what you need to do first (especially for a pot of soup or stew) is to make a little slurry of corn starch and COLD water in a separate little cup, stir it all up, and then add it a little at a time to your main dish. I wish someone had shown me that long before I learned it. It's a little less necessary for whole flours but still helps. Nobody loves lumpy gravy.

• Adding extra starch to a batter can make it extra light and/or crispy. You'll notice a lot of tempura, fish & chips, and cornbread recipes call for a little spoon of corn starch in addition to the flour for exactly that reason. It's kind of a cheat for lowering the gluten percentage of the flour. It can also make gluten-free flours more resilient.

I hope this food chemistry insight gives you the courage to take another crack at that one bread recipe that never turned out right, or to take your Thanksgiving mashed potatoes and gravy to the next level. Enjoy!

References

• G Is for Gluten. Kansas Wheat Board.

• 10 Types of Flour. Savory Experiments.

• McGee, Harold. On Food and Cooking. Scribner, 1984-2004, revised.