How much potato starch to used instead of mashed potato in bread?
Molly Yeh recently said she substitutes potato flour (starch?) for mashed potato in making bread when she doesn't have time to make the mashed. As I regularly make Refrigerator Potato Bread (J Beard), this is a great tip. But I can't find (from Molly on fb or her website) what ratio of potato starch to use for 1 cup mashed.
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From the National Institute of Health, "In general terms fresh potatoes contain ~20% dry matter (DM) of which 60–80% is starch, with 70–80% of this starch as amylopectin"
I would take 20% of the total weight of the mashed potatoes, then multiple by 60% (on the conservative end), which would give you a conservative estimate of how much potato starch (by weight ) to use. Then you could probably adjust as needed.
USDA lists 1 cup of mashed potatoes as ~210g, so using the estimates above, 20% x 210g x60% = 25.2g starch in 1 cup of mashed potatoes
2 TB potato starch is 17.4g. This leads to:
2TBx25.2g/17.4g = 2.889TB or 3TB of potato starch, to start
I’ll use these measures the next time I make the potato bread. Will report on the results (and hope James Beard is not rolling in his grave)…
It tasted good but yes was a little different in texture than the original version - in fact, a lighter crumb.
I think I will make it this way a couple more times and then decide if I’ll put this version in regular rotation