First of all, I'm not a sourdough newbie. Ive been baking with it for about 6 years, and except for my first experiment, Ive started all my starters myself with only whole wheat flour and water. when I was a Peace Corps volunteer in the Republic of Georgia, I (re)introduced sourdough to a some small village bakeries and home bakers as a secondary project. It cut their costs by 80%, as the only commercial yeast was available from Russia (their enemy if you aren't up on current events). Which is pretty interesting, because 50 years ago, most people in Georgia were using sourdough exclusively and there wasn't a word for yeast in their common vernacular.
Anyways, I have a starter that´s been going for about two months now. I have it at approximately 100% hydration by weight, but I kept it fairly wet for the first couple weeks.
It has some interesting properties... It will only raise whole wheat flour. White flour gets a small rise, but not nearly enough to bake with. It is incredibly fast, doubling in volume in less than two hours in a cold room, and if you add heat to the process, it raises a 100% whole wheat loaf better than commercial yeast. And it isn't sour at all. Its not my go-to starter because of its lack of sour flavor, but it is great for making cinnamon rolls, pizza crust, and bread for my sister who likes whole wheat, but not sourdough.
Anyways, on to the big problem. A couple of weeks ago it developed a slightly off smell. Reminiscent of dirty feet and bile. Only a tiny bit, but enough to be unpleasant. I tried to make some sourdough pancakes today, but the smell of the sponge that I set out last night was too unappetizing to cook with. I made bread with it today though, and It still produces an almost entirely not sour loaf. I added some apple cider vinegar in an attempt to kill off some of the unfriendly microbes a week or so ago, but it only covered up the smell temporarily. Any ideas?
One other question... What do you guys do with your excess starter? Because I don't have as much time as I used to for baking, for the first time ever, I'm having to throw out starter.
Don't know the solution but am wondering if the bread or whatever tastes like bile ... or stinky feet. My starter's just gone totally lactic and the smell is similar to what you've described, although I would describe it more like cheese whey. I know this because when I go to a local cheese maker's farm shop there's a spot along the driveway up that has a certain smell. It clicked the other day and I realized it was similar to my starter. I asked the head cheese and he said that whey has alot of lactic acid in it. Thankfully, my bread still tastes the same, more of less on any given day, etc. The flour I'm using now has a little higher ash content - T7. Maybe that's it. Another mystery of this great tradition ... I guess. Good luck, Tony.