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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There are several factors
1) Time. Bread doughs typically take hours to make. Time allows the gluten “strands” to form thereby making it stretchy. For many cakes, flour is the LAST ingredient to add and after it is added, the batter is done.
2) Oil to water ratio. Gluten needs water to form strands. Oil coats the gluten and makes it difficult to form long strands. Bread starts with flour and water and with very little/no oil (or oil added after the dough is formed). Cakes start with butter (mostly oil) and sugar with very little/no additional water – sometimes just the water in the eggs and butter.
3) Mechanical action. Once flour is added to cake batter, it is stirred in and that usually completes the batter – typically stirred in “just enough” – maybe 30 seconds. Bread is kneaded to enhance the stretchiness.
4) Type of ingredient. Bread flour is different from cake or all purpose flour. It contains more gluten which enhances the stretchiness of the dough. It is usually possible to make bread out of all purpose flour, but it will be somewhat less stretchy.
Bread is made with ‘strong’ flours that have more gluten.
Gluten is made of long, stretchy protein chains.
They give the dough some elasticity and are activated and made more stretchy with kneading.
It’s the ratios of things, in part, and the specific processes in part. Bread is stretchy because the flour forms a stronger network of gluten. Cake batter isn’t stretchy in part because there’s just more liquid, so any gluten that forms isn’t able to hold together the whole dough, and in part because cake batter is used quickly after being mixed.
Gluten networks develop in flour+water combinations by having proteins in the flour mix with parts of the water but that takes time. You can speed it up significantly by moving it around a bunch (kneading it) so that more of the proteins that can become gluten come into contact with water, but you can also just let it sit for many hours for no-knead bread. If you leave your cake batter sitting for a long time, it’ll come out gummy and chewier because of that. ff you *do* experiment with doing that, make the cake from scratch and add the leavening just before baking, otherwise it’ll be gummy and chewy and also flat.
> 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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