Brod and Taylor, makers of the folding proofer, have collected a concise group of tips on how to control the sourness of sourdough breads at this link. It is well organized and easy to understand. The material is from a class by King Arthur Flour featuring Debra Wink.
Paul
Very helpful.
Thanks for sharing this, Paul.
Paul, thanks very much for posting! We've just updated the article with a wonderful graph after receiving permission to include it from Debra Wink. She was a great teacher and has been very generous with her time and input for that article :)
We've just posted a second part to that article. It takes one sourdough recipe and, using Debra Wink's concepts, pushes it in two different directions, one mild and one sour. It's at this link