Folliwing Dan DiMuzio's guidance (and others) re creating a more sour levain I prepared a 500g, 50% hydration levain, and then fed it every 12 hours for two and a half days. I maintained it at 55°F, in our wine closet, thoroughout. Subsequently, I used DiMuzio's Pain au Levain (firm starter: 480g, 60%) formula with two changes. 1. The aforementioned 50% hydrated levain vs. the formula's 60% levain; and, 2. I encreased the whole-wheat flour percentage to 20% vs. the formula's 10%. Yes, I knew the increased whole wheat flour content would alter the flavor, but I reasoned the whole-wheat alteration wouldn't effect the sour component of the finished bread. My objectives were threefold. Maintain the same excellent ovenspring with the stiffer levain as I've been experiencing with the 60% hydrated levain. Increase the perceived sourness in the flavor profile. Finally, I wanted to practice batard shaping and scoring, a shape I haven't made very often. Except for the batard shaping, as nearly as possible, I replicated all the mixing, bulk fementation, final proof, and baking steps I've used before baking the basic formula.
Just for fun, while the stiff levain was fermenting after its final feeding, I used the 250g of levain that would otherwise been discarded to make a single, all white flower batard.
The results of both bakes are shown in the photos.
As hoped for, the pain au levain is distinctively sour, but not to the extent of many of the commercial San Francisco sourdoughs I've tasted. The ovenspring was preserved, and I'm satisfied with my batard shaping and scoring.
The leftover starter loaf.
and its crumb--closed more than usual.