Leavening strength for butter rolls
About a month ago I began a new sourdough culture, been making simple white or a mix of white + whole-wheat breads from it, and quite pleased so far. Great flavor and leavening capability. So far, my breads are flour, water, salt, and the starter only, nothing else.
For something different, I decided to try Hamelman's Soft Butter Rolls, which calls for a lot of new things -- sugar, butter, eggs, dry milk. It is a baker's yeast recipe. Well, because I was in the experimentation mood, I did three little changes.. I added a small amount of molasses (half the percentage as the sugar), split the flour 50/50 with white+whole wheat, and instead of the baker's yeast I prefermented 20% of the flour with my starter. So, no baker's yeast. The sourdough pre-ferment had nearly tripled after 12 hours and had not both risen+fallen,it appeared at its peak when I used it.
So, I mixed everything in my stand mixer, got moderate gluten development I'd say. It could windowpane but would break if stretched too much. Bulk fermented for 90 mins. Shaped into 3 oz rounds, gently flattened into discs, and put them into KA hamburger bun pans to rise, covered with plastic. Hamelman's recipe says to wait until fully risen.
5 hours later, nothing. Absolutely zero rise at all. Heh.
I baked 'em anyway and they expanded by maybe 15%, but basically I made hockey pucks.. which while tasting good, more resembles a cake than a bread.
My question is, is it normal for a bread with a lot of extra heavier things (like eggs, milk, butter, syrupy stuff), to require the use of baker's yeast to achieve a good leavening? I was a bit perplexed at this because my starter has no problems at all raising and getting nice big open crumb structures for regular types of bread. Or maybe the small bit of molasses killed the natural yeast in my pre-ferment?
Next time, I will add the baker's yeast according to the recipe, and drop the molasses. :-)