What's the purpose of a short sponge?
A lot of recipes for rich or sweet doughs will call for poolish-like sponges that ferment for only 30-60 minutes or so before being added to the dough. I absolutely cannot figure out what benefit this would bring over simply punching down the dough after the first bulk rise and letting it to rise twice (or bulk rising in the fridge). I can't imagine that such a short amount of time would allow for much enzyme activity in the sponge, or at least nothing that a longer rise couldn't accomplish. According to some books and online sources, the sponge supposedly "increases acidity in the final dough", I guess like a sourdough starter, but that makes even less sense to me; don't yeast perform alcoholic fermentation and not lactic/acetic acid fermentation? To be honest, I find indirect commerically-yeasted doughs to be very annoying and would prefer to just extend the bulk/proof over dealing with a sponge.
rim shot...
i think it helps to make a quick sponge to get a bigger volume of active yeast to mix into your final dough. instead of having a little bit of yeast in a dryer environment, you get it feed in a wet environment where they can better multiply and then you have more material to mix into the final dough, so it mixes more evenly and they're ready to work. i agree, it's not enough time for enzyme activity to make much flavor.
it may also give the yeast something to do while you autolyse the flour. =)
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But actually, thanks for your input. So you're saying that it's used to multiply the yeast population and give greater rise to the dough? I guess that makes sense considering that rich/sweet doughs require more yeast to power through all the fat and sugar. Still, I don't understand why so many sources tout the supposed flavor and textural benefits of a sponge. Oh well, my breads have been coming out fine without one so I guess I don't need to worry about it too much.
and the type of yeast used. This is what makes many of the differences.
The yeast available for baking has changed over the years and the older the recipe, the more likely you will run into directions for older types of yeast. The short sponge is one way of testing the yeast before using (and perhaps wasting) any valuable ingredients. If the yeast is good, then the recipe is "good to go." If the yeast is bad or damaged from high temps or moisture, rancid etc., then it can be discarded and different yeast used.
Some of these older types of yeast are still in use and it never hurts to know where the recipes are coming from including what time in history. A quickly copied recipe can exclude the fine details such as type of yeast, type of flour and temperatures. Too much was left to the experience of the cook or baker who held a successful method secret. When the yeast was modernized, often the recipe method was not.
It is important to know what type of yeast one is using so unnecessary steps can be skipped or added. Words like: Active, Dry, Instant, Fast, Rapid, Fresh, Brewer's are just some of the clues to type of yeast. More in the yeast FAQ's above in the site tool bar. Many packages will include specific directions, others may not.
Have fun and stay safe, Mini
Ahh, so basically sponges are akin to blooming the yeast in that they both were necessary precautions in "the olden days" when yeast was less reliable. That makes more sense when you consider that old or dead yeast probably did produce loaves with inferior texture and, to a lesser extent, taste. My, how Amazon and the ability to buy 1 lb blocks of SAF on demand have changed everything...