Like, how does it get doughy and stretchy, even before kneading. The building blocks of bread and other baked goods at the start are near identical
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> The building blocks of bread and other baked goods at the start are near identical
This is the key thing here. Other baked goods contain:
– a different amount of water
– a lot more fat
A typical bread dough is:
– 1 part flour and between 0.5 and 1 parts water
(plus very small optional quantities of other things like salt, yeast, seeds, herbs, oil, etc. which we will ignore)
Consider a typical sponge cake recipe:
– 1 part flour, 1 part butter, 1 part sugar, 1 part egg
So where bread is between half and 3/4 flour, this cake is only 1/4 flour, with more water (in the eggs and butter), fat, and sugar. Of course the texture is different!
Or a typical short pastry:
– 3 parts flour, 2 parts fat, 1 or less parts water
So far, far more fat than in any bread, and far less water.
This is all important because of what makes bread like that. Bread is made of two structural components: starch and gluten*. When you get flour wet, the water is absorbed by the starch and turns into a stiff paste, and the water lets the gluten get stringy and stretchy. That combination of thickness and stretchiness makes it “doughy”. Then when its cooked that starch sets into a hard crystal structure which keeps all the air that you put inside by fermenting it or heating it (and which was trapped by the elastic gluten).
* oversimplification, there are two proteins that make up gluten, other structural proteins, non glutenous flours, etc
If you put not enough water in, it is crumbly instead as too much of the water is absorbed by the starch and there’s not enough to make a paste, and not enough to hydrate the gluten and get it elastic. This is good for e.g. pastry if you want it to stay crumbly!
If you put too much fat in, it gets between all the gluten molecules and stops them from sticking together and making long stretchy strands. This is good in both cakes and pastries as you don’t necessarily want them to be chewy.
If you put *too much* water in, it’s sloppy and more like flour soup, because the starch can’t make the water thick enough for the gluten to hold it together.
So in pastry, you normally have not enough water + too much fat. This means you are preventing gluten from being formed, preventing gluten from attaching to other glutens, and underhydrating the starch so it stays crumbly.
In cakes you usually have too much fat *and* too much water. This means there’s too much stuff between the gluten molecules for it to get stretchy and the starch isn’t enough to hold the liquid all together. This is why cakes have to have some sort of other structural component to help the starch hold them together when they are heated (usually eggs, which set into a solid when heated just like bread’s starch gel does).
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