I've tried several times to make a biga, but the ingredients don't come together. When I first mix it, it resembles tiny balls but goes no further than that.  I am using King Arthur bread flour, recently purchased, and Fleischmann’s instant yeast.  The water is at room temperature. My question is, could the yeast be old and  should I use spring water as opposed to tap water?  Any help you can give me would be greatly appreciated.

-- Karla

A biga is one form of pre-ferment, a dough or batter made beforehand and used in bread dough.  There are two major kinds of pre-ferments, firm or dry, and wet or sponge, depending on the ratio of water to flour.  Pre-ferments enhance the taste of bread by extending the fermentation time, creating more complex flavors and enhancing the texture of the final product.

The following bakers percentages, as given by Peter Reinhart in The Bread Baker's Apprentice: Mastering the Art of Extraordinary Bread, show the degree of hydration between two firm and one wet pre-ferments.

The firm pre-ferments are blended and then kneaded for a few minutes before being coated with oil and left to rest at room temperature, while the wetter one, the Poolish, is mixed just long enough to blend well.  It is not necessary to remove all of the lumps.  In all cases, the bowl should be covered during resting. For the Pâte Fermentée, resting time is about one hour, or until it has risen to about 1 ½ times its original volume.  The usual instruction for a wet pre-ferment is to allow it to rest until it bubbles up and then collapses back down to its original volume.

The equivalent measures for home baking are:

If you use traditional rise instead of instant yeast, increase the amount used by about one third.  Each of these mixtures gives enough pre-ferment to use in making two 1 pound loaves.  Once they are finished resting, they can be refrigerated for up to a few days before use.

Because the dry pre-ferments have approximately the same hydration as the dough for French bread, they should have about the same consistency and will rise like bread dough.  The Poolish will be about the consistency of pancake batter and will become bubbly.  If they fail to act in this way, then the yeast may indeed be too old.   Yeast becomes weaker with age and should be used or discarded before the expiry date on the package.  Yeast should be stored in a cool, dry place.

Saccharomyces cerevisiae, the strain of yeast used for making bread, is tolerant of temperatures up to about 110°F (43°C), but best performance for making a pre-ferment is up to about 80°F (27°C).  Warmer than that will speed up the yeast, reducing the benefits of making a pre-ferment in the first place.

As to the question of using bottled or spring water in place of tap water, unless the tap water where you live is particularly hard or soft, don’t waste the money.  If you are worried about chlorine or fluorides in your water, you needn’t be.  There isn’t enough to significantly harm the yeast. If you want, though, you can either let it stand overnight in an open container or boil it and then allow it to cool completely.  Either method will drive off these chemicals.

Anyone who likes making homemade, artisan-style breads should try using a pre-ferment and see the difference it makes.