Tapioca

Like cornstarch tapioca is a “pure starch” which means that compared to wheat flour it has no protein, bran or germ in it and as such packs more of a thickening punch. Tapioca comes in “pearls”, in granules (pieces of pearls) and in flour form. All can be used as thickeners, though the smaller the pieces the more readily they dissolve and the faster they act. Tapioca flour, my preference, dissolves almost instantaneously and because it gels at a lower temperature than cornstarch you can see the results immediately if the mixture is above 140 or so degrees Fahrenheit. Like other starch gels, however it also “un-thickens” when overcooked.

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Air

Please excuse the lack of a photo, I’ve been busy today. Air is a thickener we commonly take for granted, but bubbles slow the flow of water as well as any other type of thickener. Where would our egg white foams be without it? Of course the trouble with bubble thickening is that bubbles pop. […]

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Fat

Melted fats or liquid oils make very effective thickeners in watery mediums. Oil and water won’t dissolve in each other, so when you combine them the result is a mutual disaffection that runs all the way down to the molecular level. Cooks can force the two to mix by a liberal application of the whip, which has the effect of breaking up large blobs of fat into many smaller ones. The thing is that no matter how small the blobs get they’re still many times larger than water molecules, and so do a very effective job at slowing down their flow.

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Cornstarch (Corn Flour)

Cornstarch is, obviously, a starch thickener which means it thickens much the same way wheat flour does: with tangles of long-chain sugars that slow down the flow of the water around them. However there are several important differences between wheat flour and corn starch. One of those is particle size. Cornstarch is milled much finer than wheat flour, which means when those particles come in contact with hot water, they begin to shed starch molecules much faster. So cornstarch thickening happens faster than wheat flour thickening, but then also “un-thickens” that much faster.

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Wheat Flour

Plain wheat flour is a go-to thickener in the kitchen, especially where sauces care concerned. In combination with butter or oil it becomes a roux, which is the basis of classic béchamel. White flour, most bakers know, is the ground endosperm of a wheat berry, the endosperm being the energy storehouse of the seed. Moisten the seed and enzymes in the endosperm go about breaking down the long chain starches that are stored there into simple sugars. These sugars fuel the sprout (contained in the germ) as it grows.

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Gelatin

Gelatin is a protein, one that’s derived from a very interesting material called collagen. If you were to think of an animal’s body like a machine, where the bones and joints are the moving parts and the muscles are the motors, collagen is the rope and cabling that connects it all together. In fact collagen molecules are constructed very much like rope: three long protein molecules (individually known as gelatins) woven around each other to form a tight triple-helix. They’re very strong, the perfect material for making things like tendons and other so-called “connective” tissues.

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A Thickener Primer

Most of the time, when we’re talking about thickening in the kitchen, we mean the thickening of watery substances: broth, juice, milk, thin syrups, that sort of thing. Thickening is necessary if we want those substances to have much texture other than…watery. The obvious question here is: why can’t water itself have a more interesting texture? Does it have to be so, well, watery? And what makes it that way? The answer is that water flows because its molecules are so incredibly small. They’re made up of just three atoms: two hydrogens and one oxygen if I recall correctly. Dihydrogen monoxide.

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