[SciShow intro plays]

Hank: You ever want to indulge in some baked deliciousness without quite so many fats, or maybe you want to cut animal products out of your cooking? Some bakers use applesauce to replace the butter, oil, or eggs in their favorite cake recipes. So how can the carbohydrates in applesauce replace the fats and proteins in a pastry?

Baking is just chemical reactions, and so we need to understand how the ingredients work together in the first place. When flour and water come together, two of the proteins in flour, gliadin and glutenin, unravel and combine to form long strands of gluten. So if you're making and you add water to the dough to start making gluten, and then keep kneading the dough until it's full of a super stretchy gluten network, all that gluten makes a nice chewy bread. But pastry chefs try to keep gluten at bay to keep a light and airy texture in cakes and pie. How do they do that? With fats.

The fats in your pasty dough are hydrophobic, meaning the butter and oil molecules don't like binding with water. These fat molecules coat the flour proteins, so they don't interact as much with the water and form too much gluten. In other words, all that butter in pie crust helps it stay tender and flaky. So when bakers replace fats with applesauce, they're trying to achieve the same thing in a slightly different way.

See, applesauce is full of a polysaccharide called pectin, which normally holds cell walls together in some plants, including fruits like apples and berries. But pectin doesn't coat the flour proteins like the fats do, instead, it competes for the water's attention to form a jelly-like mesh of its own. That way, less water interacts with the flour molecules and less gluten is formed.

Baking with applesauce can be tricky. It has a lot of water on its own, so adding too much applesauce could also make a muffin too bready, but applesauce can replace more than just fats, it can also substitute for eggs which generally help thicken some baked goods and give them some more texture.

An uncooked egg white is basically a bunch of folded-up proteins floating in water. When you heat egg whites up, those proteins unfold and start sticking to each other, which helps keep your batter together. And when you heat up pectin, those polysaccharide molecules start binding to each other and other molecules like water to create a tangled, gummy network. Just think of like a jam or jelly, that gelatinous texture is thanks to pectin. Applesauce can give your cake some structure, just like eggs do, all while keeping it tender as well.

Thanks for asking and thanks for spending some time with us at this lovely time of the year. Right now, to celebrate the baking that we're all doing, we're selling SciShow aprons. So that's a thing, you can get them at dftba.com. We've also got some other SciShow stuff if you just wanna represent your love of SciShow, or if you know somebody who would like to represent their love of SciShow, maybe you want to pick them up something... for this... time of the year when we tend to give gifts.