Why is it that you have to gradually add and stir water in to gravy mix instead of all at once?
In: Chemistry
Gravy is made with flour which is made up of these long strands of molecules called gluten. Gluten is like Christmas lights: it can fold up and tangle upon itself and each other. Also, making it cold causes gluten to contract, and making it hot causes it to expand.
So imagine squishing Christmas lights together and forming a ball. That’s gluten getting colder. It’s more difficult to reverse this and make a long string of lights again, right? When gluten is hot, the strands are straight. If you take a bunch of straightened Christmas lights together, you can easily separate them. So that’s why when it’s hot, it moves around water easier and is liquid.
Pour cold water all at once, and you suddenly make the hot water cold and all of the gluten contracts at once, and so they get tangled with each other and form clumps. And there’s less room for anything else, like water.
But pour the water slowly, and it’s like wrapping a Christmas tree.. with the tree being water. The shape will change much slower, and you can intertwine other Christmas lights without them getting stuck together since the Christmas tree/water helps keep them apart.
Moreover, as the temperature gets colder, the gluten strands will still contract, but the water/tree will help keep them from tangling up with each other. So gravy will still usually be liquidy when it’s colder.
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