When an accomplished baker sits down to write a new sourdough formula, why does he or she choose a liquid starter, or choose a firm starter?
Susan from San Diego
It's a very interesting question! There's probably not a single, right answer for it, but I'll try to communicate what I've gathered at least.
In a large bakery, you typically don't keep a huge pile of preferments or starters. You could have a batch of poolish, a biga or pate fermentee of some persuasion, and then either a liquid or a firm starter. Then you would adopt any given recipe to the starters/preferments you use daily. At least over here, what kind of starters are kept seems to be a regional/cultural/traditional question, and what kind of flours you're using and what breads you're producing. In Italy, for instance, a biga is common, as flours are often weak, and the extra acidity added by a biga will strengthen gluten properties of the dough.
A liquid preferment increases protease activity in the dough, making it much more extensible than if a firm starter were used. Extensibility is good for making baguettes and laminated doughs, for instance. I would guess that it's a pro also in the US, where flours are buckier and stronger than in Europe. Dry conditions in a firm levain is said to promote acetic acid, which would infuse the dough with more sour bite than a liquid levain would, but I'm afraid my taste buds aren't refined enough to make out that difference yet...
Well... I'm not sure. Tradition and convenience probably plays a part in deciding, as does the properties of your main ingredient (flour) and what products you're making. In the homekitchen, it's very easy and quick to mix together a liquid levain, but personally, I prefer to mix and knead a firm levain so that's what I use.
Edit: If you like, you could try to probe the difference of starters by making a batch of Vermont sourdough (liquid levain) and then a batch pain au levain (firm levain) from Hamelman's "Bread".
No need to go to that much trouble, but I do appreciate your kind offer. It was good of you to respond so thoughtfully. I prefer my firm starter, too, as you may have noticed.
I was perusing Jeffrey Hamelman's Bread and couldn't determine why he chose one starter over another. There's bound to be a definitive reason. Perhaps he, or another bread book author, will see this question and satisfy my curiosity.
Thank you. I was wondering why exactly one would use/need/prefer one starter over another myself.
Another point of interest...it seems common to take a "liguid" starter (i.e. about %100 hydration or more) and build to a firm starter for the first build in many (most) recipes???? I haven't figured this out yet??? I'm sure there is a reason.
I've never counted the beasties, but maybe one has more than the other per gram. Would be interesting to know.
I prefer a firm starter because it cannot be spilled.:)
As mentioned above, firm starters help strengthen dough (helpful for high hydration or very long fermentation), while liquid starters create more extensibility (great for shaping).
In addition to these two structural considerations, your flavor profile should be highly affected by the feeding schedule of your starter. Liquid starters are supposed to produce more of the lactic acid, while firm starters produce more acetic acid; I'm sure there is a lot more going on under the hood as well.
From a labor perspective, feeding a 150% hydration starter is sooo much easier than feeding a 50% starter. Quick chopstick stir vs. kneading/squishing/resting/squishing.
On a final note, I have heard conflicting stories about yeast production in firm vs. liquidy starters. I have often heard that higher hydration leads to more yeast activity, although in Advanced Bread and Pastry (by Suas), he briefly mentions that firmer starters have more yeast (without any further explanation).
Although I keep both starters, I am currently always using my firm starter for my sourdough, as I am continually increasing the hydration level and fermentation time of it. I think there is a lot more research to be had in this area.
Hope this helps.
Danny - Sour Flourhttp://www.sourflour.org
I can tell you why I prefer to keep a firm starter... If you don't bake often enough to keep a liquid starter from generating hooch, the firm starter is the way to go. There is a lot more food for the beasties in the firm starter. And, all you have to do if a recipe calls for a liquid starter is add a little water. :-)