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Calculating hydration when oil and water are in a formula

GabrielLeung1's picture

Calculating hydration when oil and water are in a formula

Calculating hydration is at its simplest dividing the mass of the flour by the mass of the water. But this simple definition falls apart when complex formulas with many different liquids are analyzed for their hydrations.

My question is this: How does one account for oil's affect on hydration?

Hydration can be observed in the amount of gluten that develops after flour and water have been combined and worked. Gluten forms because water unsoluble proteins within the flour bind together within the dough in an attempt to avoid the water molecules as much as possible (I think). If this is true, oil should also affect hydration because it should have the ability to attract the gluten forming proteins due to the gluten forming protein's attempt to avoid water. 

I've not found any instruction calculating hydrations when ingredients other then water add to the hydration of the dough. What I have been doing however, is adding the mass of oil to the mass of water in order to determine the hydration. With more complicated hydrating ingredients, like eggs, I have absolutely no idea how to calculate hydration.

This is the question I'd like to pose to the community: How do you calculate hydration when ingredients other then water are contributing to the hydration of a dough?

pmccool's picture

fats, including oil, are not included in the hydration calculations because they don't contribute water to the dough.  Therefore, they don't hydrate the gluten-forming proteins, which is another way of saying that they don't lead to gluten formation.  Instead, they interfere with the formation of the long gluten strands (i.e., "shortening").

As with everything else, there is an exception or two.  Butter, for instance, is not entirely fat.  There's a small percentage of water in butter, so if you want to be really scrupulous about your measurements, you'd want to factor that in.  In most breads, the amount of water contribution from the butter is negligible because the butter itself is such a small percentage of the overall dough.  Honey and other syrups are water-based solutions, so they also contribute a percentage of their weight as water to the dough.

There are a number of sources that list the water content of various foodstuffs; I think the FDA has one, for instance.  Sorry not to be able to point you to one or two, but I'm not remembering the addresses.  They have been mentioned in earlier discussions on TFL, so try searching for them.



GabrielLeung1's picture

I was making a sandwich loaf with 68% hydration and 8% vegetable oil, and the dough that had come out behaved more like 75% hydration then 68%. 

I was hoping this could be explained in forming gluten "indirectly" as I described above.

But you are right, oils are tenderizers. Back to the drawing board I suppose.