“The recipe calls for cake flour. Can I just use all-purpose flour because that’s what I have at the moment?”
“What is pastry flour? I can’t find it at the store.”
These questions may sound familiar to you if you are new to baking. At first, this can be overwhelming because oh my God, there are too many flour types out there! Fret not, because once you understand the basic concept behind the categorization of flour, you’re gonna feel like a baking genius. Seriously.
To make it simple, flour can be divided to three categories based on its protein content:-
- Low protein content (<8%): cake flour and pastry flour.
- Medium protein content (9-12%): all purpose flour.
- High protein content (>13%): bread flour.
Don’t worry, you don’t have to memorize that. The first thing that you need to remember is this:
The higher the protein content is, the more gluten is formed.
Gluten is a protein in flour that contributes to the chewy texture of the bread. You see, this is why bread flour has the highest protein content. Bread needs gluten to get that chewiness.
On the other hand, we don’t want our cakes and pastries to be chewy, do we? We want them to be tender and crumbly. This is the very reason why we use low protein flour to make cakes and pastries. Too much gluten is a no-no.
The other important key that you need to remember is this:
Gluten is activated by water and pressure, and is hindered by fats.
When making pastries, the first step that we do is to coat the flour with butter. This first step is very critical. By rubbing the flour and butter together, it creates a fat coating around the flour to hinder the gluten formation before the dough is later mixed with water. Many recipes also warn about not mixing the dough too much as this will promote gluten formation.
Whereas when making bread, the flour is directly mixed water. Hence, gluten is activated. Bread-making requires a lot of (but not too much, it will be too hard!) pressure from the kneading process, which also contributes to activate gluten.
Wait, so that means we need to keep all the cake flour, pastry flour, and bread flour at our kitchen since the protein content in each flour is so crucial? No. Good news! Here is where the all-purpose flour play an important part. We can substitute cake flour and pastry flour with all-purpose flour. The key is to reduce the protein content in all-purpose flour by replacing some part of it with corn starch.
To substitute 125gr (1 cup) of cake flour, take 125gr (1 cup) of all-purpose flour, take away back 2 tablespoons of the all-purpose flour, then replace with 2 tablespoons of corn starch.
125gr (1 cup) of cake flour = 125gr (1 cup) of all purpose flour – 2 tablespoons of all purpose flour + 2 tablespoon of corn starch.
To substitute pastry flour, use this golden ratio of 7 parts of all-purpose flour : 1 part of corn starch. In other words, to substitute 80gr of pastry flour, use 70gr all-purpose flour and 10gr of corn starch.
Of course, these formulas are not really absolute. You can refer to other sources if you like.
I couldn’t find any reliable substitution for bread flour. I think it is best to follow the recipe when bread flour is specifically mentioned. There is no harm to use all-purpose flour to make bread if that’s all what you have. I have tried it before. The bread still raised well and was chewy, but there was definitely a difference in the texture. The bread was more cake-like.
So after all this (simple, hopefully) explanation, we can conclude that: instead of buying all types of flour, we can save some cost by just having some all-purpose flour, bread flour and corn starch ready in our kitchen.
I hope that my explanation here is simple enough to understand. If you are a baking geek or would like to know more about the baking science behind it, you can have a further reads on these references below.
- What is high gluten flour? by Joe Pastry (link)
- How do I choose the right kind of flour? by PastryChefOnline (link)
- What’s the difference? by The Kitchn (link)
- BakeWise by Shirley O. Corriher (link)