I’ve been fiddling quite a bit with sourdough starters the last couple of months, killing off several trying to perfect my growing and storing processes. About two weeks ago I began to notice something strange happening. The starters were taking longer and longer to start growing. Which is to say, they didn’t bubble up nearly as fast as they did this spring. What took two days in May took five in September. Now I can’t seem to get a starter going at all. Judging from the aroma, my flour-water porridges are bringing in the right lactic acid bacteria, but as far as a yeast goes, I can’t seem to get any takers.
I can think of two possible explanations. First, that the yeast I’d been attracting is a Spring and Summer phenomenon. But then wouldn’t there be another that would be just as happy to take its place? It seems impossible that there wouldn’t be some all-weather critter around that wants a free lunch.
The other explanation is something that I’ve been hearing about for a few months but haven’t taken very seriously: that flours this year are showing elevated levels of leuconostoc bacteria, a microbe that thrives in low-acid environments and crowds out yeast cultures as they start to form. This may be my problem, since my difficulties with starters began with a new shipment of flour I received from King Arthur in August.
Fortunately, there’s something you can do about leuconostoc, as I discovered over at the inimitable Peter Reinhardt’s blog. That is, to acidify the starter mixture from the get-go by using canned pineapple juice instead of water for the first few days. The acid keeps the leuconostoc down long enough for any yeast present in either the flour or the air to get a foothold. I think I’ll try it. That Peter Reinhart, he’s one smart cookie.