Colonial Terms, Methods and Formulas for Leavening Bread

Levain - sourdough- a French term for dough raised with wild yeast .  An ancient method of capturing naturally occurring yeasts in the environment. Grain and water combined and left alone will quickly attract natural yeast and bacteria strains.  The levain is built over a series of days (and years) by the addition and subtraction of flour and water to become “young and strong” and have the ability to make a dough rise.  If the levain is left without care for its health then it becomes “old and weak” and will be overly acidic and rancidly sour. 
A portion of the levain is used as the chef or starter for making a batch of bread and another portion of the levain is used to continue the strain of yeast for subsequent batches of levain by adding more flour and water and consistently refreshing the sourdough to keep the yeast and bacteria vigorous.
Sourdough was the most commonly used method of making household or village bread and the essential knowledge of how to construct this loaf was passed down through the generations by practice.  " To this end, take the amount of flour as you want, it is mixed with water hot, work somewhat the mixture very soft… As soon as the dough has contracted a rather sour smell…We repeat once again this operation and we get a leaven own to be used. "
      The basic formula for sourdough bread is:
2 cups sourdough + 3 cups water + 6 cups flour + 1 level tablespoon salt = sourdough bread

Leaven- old dough- The English often used the term leaven to mean unbaked yeasted dough left over from previous batches.   This dough had been mixed with salt, which slows down the yeast activity, but it will continue to ripen and sour.  It is useable to raise subsequent batches of bread by adding the old dough to flour and water and using it as a chef to make a sponge.  A sponge is made by mixing a portion of the flour to be used in the dough, a majority of the water and yeast (ale or old dough). A sponge is different from a sourdough levain in that a sponge is much moister, like a thick pancake batter.
“Always keep by you two or more pounds of dough of your last baking, well covered in flour, to make leaven to serve from one-baking day to another; the more leaven is put to flour, the lighter and spungier the bread will be: the fresher the leaven, the bread will be less sour.”
    Basic formula for leaven bread is:
1 cup old dough + 1 ½ cups flour + 1 ¼ cups water = leaven
Let rest until risen or let rise overnight, then add;
4 cups flour + 1 cup water + 2 ½ teaspoons of salt =  leavened bread dough

Barm- ale yeast- During the initial process of fermentation a foam forms on top of beer.  This foam contains yeasts that are converting the sugars in malted grains into alcohol and carbon dioxide.  The yeast captured from the foamy top of the beer, or the yeast taken from the bottom of the barrel after fermentation is complete, is called barm or ale yeast. 
This form of live, liquid yeast can be stored in containers for future use in a cool, dark place for subsequent batches of beer or bread.  Many period recipes distinguish between “ale yeast” and “good ale yeast” and  “new ale yeast”
3 depending on the amount of leavening needed.  To reproduce this sort of yeast without brewing beer, I suggest buying dry brewers yeast and dry malt extract from a homebrew supplier.  A package of brewers yeast, 1 cup of dry malt and 2 quarts of warm water left overnight will produce a vigorous barm that can be used cup for cup in place of ale yeast in period recipes.  Another suggestion is to use 2 to 3 scant teaspoons of dry bakers yeast  or 1 to 1 ½ ounces of fresh yeast to  2 cups of warm water to replicate ale yeast. 4
Basic formula for barm bread is:
1 cup barm + 2 cups water  + 6 cups flour + 1 level tablespoon salt = barm bread

1 Parmentier, AA, Le Parfait Boulanger, Paris. 1778.
2Glasse, Hannah, The Art of Cookery Made Plain and Easy. Hamden, Conn.: Archon, 1971. (1796 edit.) pg. 353.
3 Smith , Eliza, The Compleat Housewife. London, 1727.  Various recipes on pgs. 176.
4 Hess, Karen. Martha Washington’s Booke of Cookery, New York, Columbia University. 1981 pg. 115.
5Hoffman, Kathryn and Kay Moss, The Backcountry Housewife, Gastonia, Schiele Museum. 2001 pg. 56.
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