Hydration level of potato flake starter?

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shogger1 on 30 Apr 2020 at 00:29

I've had a potato flake starter for over 10 years; the lady who gave it to me said it had been going since 1976. It makes a terrific nice sandwich-style loaf and pizza crust. 

Among other things I'd like to do with it, I'd like to branch out and make some crustier breads. But I need to know the hydration percentage. I understand it's a ratio of flour to water, but does it really not include anything about the potato part?  

I feed it weekly 1 cup of warm water, 1 cup of flour, 3/4 cup of sugar, and 5 TBS of potato flakes. 

Any insight would be much appreciated. I never thought about using it for any recipe other than the one that came with it when I acquired it but now that we've been stuck at home I'd like to try new things. 

Thank you!

Hydration is usually expressed as a ratio of weight, not volume.  If you are feeding by volume your hydration is going to be a rough guess at best.  But I see plenty of people who say they just feed by eye or by feel cuz they've been doing it so long they know what their starter should look/feel like when it's 100% hydration (or whatever ratio they are using), so it certainly can be done that way.

I am guessing only, but I'd consider your potato flakes part of the "flour" for the hydration equation.  There is such a thing as potato flour, after all, and those flakes pretty much dissolve, and absorb water in the process.