November 12, 2012 - 8:24pm
sponge vs. poolish
I am interested in getting opinions on the differering flavors of a sponge vs. that of a poolish. In my bread baking books the authors talk about a sponge (at a 64% hydration and a fermenting temp of 40- 55F) which is supposedly more acidic than a poolish (at a 100% hydration and a fermenting temp of 55-70 F. Both preferments I let develop for 14 hrs. I a NOT expecting a real serious sour, like a sour dough. I am, however, expecting a very subtle sour flavor. I have tried both preferments numerous times but I can not taste a bit of difference. Any idea why? thank you
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64% hydration seems a bit low to be a "sponge." A preferment at this level of hydration is more similar to a biga or a pate fermentee. A lower hydration preferment will build up more acidity than a poolish, but I would describe the flavor more as a pleasant complexity than a sourness. A poolish, on the other hand, contributes a fragrant quality to the bread.
You said that you are developing these pre-ferments for 14 hours at 40-55 and 55-70 degrees F. What formula are you using? Depending on the yeast content, you may not be letting these preferments develop for long enough. The baguette formula I use calls for a ~66% hydration preferment to develop for 12-16 hours at around 72 degrees F. Do you determine when the preferments are ready based on time or based on appearance?
Two things.
1. 64% hydration is sponge territory.
2. Wetter always creates more acidity.
I link to this article often but here it is again: http://www.bakerconnection.com/artisanbaker/article_04.htm
I determine the ripeness of my preferments by how they look. 1st I check to see an increase in volume, usually at least doubled. 2nd, I look for bubbles. The top is always covered with bubbles, some of which are popping. 3rd, I have tried various amounts of yeast. So, for example, my sponge is 125 gm. of unbleached A.P. flour, 30 gm. of W.W. flour, 100 gm. of water and 1/8th tsp. of dry yeast. Lately,I have tried increasing the yeast amount to 1/4 tsp. I think that I'd agree with your description of the bread made with poolish as fragrant, though I call it "faintly nutty". I don't know how I'd describe the bread made with the sponge but the flavor is MUCH less complex than the poolish.
It sounds like you've been doing everything right, so maybe it's a matter of personal preference. Have you tried combining the two methods to see if you like the flavor better? I believe the formula for Acme's baguettes in Maggie Glezer's Artisan Baking uses a both a stiffer pre-ferment and a poolish to improve keeping quality as well as flavor.
Pre-ferments while providing flavour are more applicable for improving dough characteristics. There are flavour differences with each type of pre-ferment but they are quite subtle. What percent of flour is being pre-fermented? And how good are your senses? You won't get any sourness with yeasted pre-ferments unless it's very, very overmature.
there seems to be a conflict of opinion. Y.Y. posts, " A lower hydration preferment will build up more acidity than a poolish".
mwilson, however, says in his post, "Wetter (preferment) always creates more acidity". Now I'm really confused.
Before we go further, I'm defining a sponge as at or near 64% hydration and a poolish as 100% hydration (at least that is what Daniel T. DiMuzio says in his text book for professional bakers).
In answer to mwilson, I am prefermenting about 40% of the total flour in my loaf.
On the subject of overmatured preferments, I've never tried that. Is it ok to use an overmatured preferment? If yes how far can that be pushed?
I'm thinking of a "sponge" in terms of Peter Reinhart's usage in BBA, which is a higher hydration, fast pre-ferment. The book I reference most often, Hamelman's Bread, doesn't seem to use the term at all. Both authors are American. Yet another case of nomenclature ambiguity in the diverse world of bread :-). My understanding has been that the hallmark of stiffer pre-ferments is their ability to build up acidity, while the major contribution of wetter poolish-like preferments is their protease activity, which is not to say that a poolish does not contribute acidity as well. Any biochemists here on TFL who could provide a more scientific explanation?
As you're concluding, both develop acidity. A stiff pre-ferment is the one of choice where boosting strength / elasticity is concerned because protease activity is greatly reduced in drier environments.
Acidity tightens gluten and protease works against this benefit. But generally speaking acidity builds up more quickly in wetter environments.
On page 69 of Daniel T. DiMuzio's book "Bread Baking: an artisans perspective, he writes, and I quote, "The hydration level of sponges... is usually 60-63%, and they can be fermented 5-24 hrs. Their dry consistancy, compared to a poolish, makes for a much slower development of yeast activity and a much lower risk of over-fermentation. IT ALSO YIELDS A HIGHER LEVEL OF ACIDITY THAN DOES A POOLISH, MAKING FOR A MORE NOTICEABLE FLAVOR ENHANCEMENT AND DOUGH STRENGTH".
I am just a beginner but he seems quite clear on the subject of drier vs. wetter and a drier sponge producing greater acidity than a wet poolish
I disagree with DiMuzio's writing. This and his description of sourdough fermentation.
But more to the point I do agree with the second part of the text you capitalized. That is to say that a sponge will do more to boost flavour and dough strength than will a poolish. But all other things being equal wetter fermentation will cause a quicker drop in pH and a faster increase in acidity (TTA).
I ran a quick and crude experiment (I'm no scientist) today which confirms this.
Mix1: 50ml water 50g flour, 1g instant yeast
Mix2: 100ml water, 50g flour, 1g instant yeast
Both mixtures measured with a starting pH of 5.7.
After 7 hours of fermentation Mix1 smelt acidic more so than the wetter Mix2 which smelt yeasty but pH tells a different story. Mix1 dropped to only 5.6 whereas the wetter Mix2 dropped to 5.4,
And the real test, taste: Wetter Mix2 tasted more acidic (fizzy - which denotes lactic acid).
Thank you all for your comments regarding acidity in a sponge. I truly appreciate your thoughts and your time. Signing off now on this post.