Hi Laura, I've noticed my whole wheat starter gets grey in color on the top layer if I neglect it too long in the refrigerator. I suspect this has to do with oxidation; the same way refrigerated dough can turn grey over time in the refrigerator. I wouldn't worry about the grey color, but I'm guessing more frequent feedings will eliminate the problem.
Barb
October 2, 2018 at 6:42pm
In reply to Hello, After I feed my starter it bubbles up and then develop… by Laura DiNatale (not verified)