Starter Ripening - sharing lessons learned
I now believe that starters do behave in different ways when the flour fed to them is changed. I have been experiencing failures with liquid-levain-based recipes, and in the midst of all the frustration , i wondered at the reason behind such failures, particularly with Whole Wheat levain (Hamelman's Book-Levains section).
I Feed my All White starter with All Purpose Flour (10.5 Protein), which behaves in a different way than Bread flour (>11.5 Protein) does. When you judge that a liquid starter is fully ripen by watching its receding level, then you must consider the time during which a starter recedes, as Higher protein flours expand higher and take longer to recede than Lower Protein flours. For instance, if you have a bread flour based liquid starter, then you know that it takes 3-4-5 or 6 hours for it to triple or quadruple in size before it begins to recede, at wich point you know that your yeasts are in full swing. However, with lower protein flour based liquid starters, receding level of the starter does not indicate full ripness, as such flour based starters collapse earlier due to their weakness.
I have observed that liquid starters are more prone to increased bacterial activity than Stiffer starters are, and therefore, by refreshing a starter many times before full ripness you're reducing the yeasts population in the starter culture, and ultimately encouraging other less potent strains of yeast and bacterias to multiply, resulting in a final dough which does not expand.
The best indicator for a ripe sourdough starter (regadless of the type of flour used) is the smell. When a starter ferments and expands and just begins to recede or collapse, smell it. If it smells vinegary or alcoholish, then it is fully ripe, if not, then it needs more time to ripen. If the same starter smells cheese like, then your refreshing regime has caused the culture population to de-stabilize and the ideal (Wild-yeast to lactobacillus bacterial) balance has been thrown off balance.
Stiff levains on the other hand, are mostly immune to such imbalances, as the movement of bacteria (which naturally outnumber wildyeasts 1000:1) is restricted, and thus their activity is kept at bay, while yeasts have ample supply of food in comparision with thinner starters.
Just thought of sharing these lessons with my fellow TFL'ers.