whole wheat levain scent
I began a starter from scratch several months ago using Hamelman's procedure, and maintain it at 125% hydration and primarily AP white flour. I do spike it with some whole rye from time to time. I've never once had any bad scents with it, except for a bit of the wet-paint smell if I have neglected it for too long. Using this starter, I have made many white-flour and whole-rye levains from it, all without issue. However, whenever I have made a 100% whole-wheat levain, the levain smells cheesy / a bit sulfury when it is ripened. In the past I went ahead with it anyway, and the resulting final dough did not smell chessy, the bread was tasty, etc. But it always kind of bugged me about how the levain smelled. So I've sorta been avoiding making whole-wheat levains because of it.
This week, I decided to see if I could somehow train my starter to do better with whole-wheat flour. So this past Monday, I began feeding it 25% whole wheat, 75% white flour, every 12 hours, all week. I detected a little bit of the cheesy scent during the first couple days (nowhere near as strong as the 100% whole wheat levain scent), but after 2-3 feedings, even that small amount of cheesy scent disappeared. Yay, I thought. I kept feeding it the whole-wheat/white flour mix all week.
This morning I took a small portion of the starter, and fermented a new 100% whole-wheat levain. The result? Darn cheesy smell again! Sulfury and pungent.
Any ideas? My next thought was to branch off the starter and try to maintain a 100% whole-wheat starter, with the understanding that I'll get the cheesy scent, but maybe after feeding it enough times entirely with whole-wheat flour, it might do better over time.
Or, is this a normal scent for a whole-wheat levain? I don't have any off-scents at all when making up white-flour or whole-rye flour levains.