Subject: 17. Are all starters the same?
No. I think starters are different, a good starter should be treasured. Fortunately, the very valuable work of Ed Wood makes it most simple to prove. All you have to do is to try the Russian or another "fast" starter from Sourdough International vs a slow starter from them. The behavior of these starters is very very different with respect to rate of leavening, and ultimate levels of acidity produced and anybody willing to spend a few $$ can verify this. I also think that starters are discernibly different with respect to flavor. In fact the classical San Francisco sourdough does have a signature flavor that no other sourdough I have tasted resembles (I do not have the SI San Francisco culture so do not know how their version of it behaves with respect to the signature flavor).
I am also skeptical of grape based starters, etc. I know Nancy Silverton and other celebrated bakers advocate this but I can see no logic in it. Grapes indeed have yeast and lactobacilli on them. The problem is these particular varieties of yeast and lactobacilli have never been recovered in any sourdough starter that has been examined from any place in the world. These organisms are undoubtedly specific to grapes as certain other lactobacilli are specific to yogurt. There are hundreds of strains of yeasts and equally large numbers of lactobacilli. These organisms develop niches where they thrive. To transplant an organism from one natural environment to another is not a formula for success. It is like taking a polar bear and putting it in the desert. There are hundreds of cheeses made based on very small differences in starter cultures and processing. These people are undoubtedly celebrated bakers but to them a yeast is yeast and a yeast on a grape is a "wild yeast" and they have no understanding of any of the nuances. I do not claim to know what exactly is resident in their starters and whether any organisms they introduce from the grape actually survive and are viable over time (years as opposed to weeks).
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