Why do some bread books use such large starters?
Some books, like the recently reviewed Flour, Water, Salt, Yeast (Ken Forkish), and Nancy Silverton's Breads from the La Brea Bakery, use large starters or levains- much larger than the amount used in the main dough, so that there is a lot to throw out. For instance, in Mr. Forkish's book, the levain builds all amount to 1,000 grams, yet the main doughs only use 200-300 grams of the levain. That's a lot left over- even if one were to keep some to use for the seed of the next feeding cycle, that would only account for another 100g.
So far, I've thought of two reasons why this might be a good practice, but was hoping someone could bring some fermentation science to light and/or point out some additional thoughts. My thinking so far:
First, temperature. There is a lot of emphasis on water and dough temperature in these books, and a larger batch will be slower to cool to room temp than a smaller one. However, I have a home proofer, so I'm not sure how relevant this is to my set up.
Second, fermentation. I have a rather fuzzy idea that fermentation might proceed differently in larger batches than in smaller ones. Is this solely due to the slower loss of warmth, or is there something else going on? If ambient and dough temps were held constant, would a large batch still taste better ( or different) than a small one?