We've found powdered buttermilk to be an acceptable substitute for fresh in baking applications. Does it also work in nonbaked goods?
We’ve long substituted powdered buttermilk for fresh buttermilk in baking recipes, but when we recently tried to use it in nonbaked goods, we ran into problems: It made for watery coleslaw, loose mashed potatoes, and fried chicken with a coating that didn’t adhere properly. And curiously, when we added more powder to the same amount of water, the mixture didn’t noticeably thicken.
That’s because when fresh milk is inoculated with bacteria to create buttermilk, the proteins in the milk form a soft gel that thickens its consistency (some manufacturers also add thickeners). But when buttermilk is dried to make powdered buttermilk, the protein gel is disrupted, so reconstituted buttermilk ends up being thinner than its fresh counterpart.
There’s no way to thicken reconstituted buttermilk, but you can still substitute it for the real thing in coleslaw and mashed potatoes: Decreasing the amount of water by 25 percent while using the full amount of powder recommended on the package will yield the same tangy flavor without introducing a lot of excess moisture. But because the more concentrated formulation isn’t actually thicker, it won’t help breading cling, so it is unsuitable for fried chicken.
In sum, except in recipes where buttermilk’s viscosity is key, such as fried chicken, the powdered kind will work fine as long as you use 25 percent less water than recommended to reconstitute the powder.