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Liquid Yeast

Homemade liquid yeast for bread, made by fermenting a cooked mixture of potatoes, flour and water, or hops, flour and water, with lively yeast.

From an old cookbook · modernised transcription
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Why it works: Flour and sugar are a kitchen classic. They rank in the top 15% of all ingredient pairs, and cooks put them together in 92,116 recipes. Both carry phenylacetaldehyde, which smells hawthorne, honey. The science ↓

Liquid Yeast

Ingredients

Directions

Make raw potato yeast

  1. Raw Potato Yeast: Mix one fourth of a cup of flour, the same of white sugar, and a teaspoonful of salt to a paste with a little water.

  2. Grate three medium-size fresh and sound potatoes as rapidly as possible into the paste.

  3. Mix all quickly together with a silver spoon.

  4. Pour three pints of boiling water slowly over the mixture, stirring well at the same time.

  5. If the mixture is not thickened to the consistency of starch, turn it into a granite-ware kettle and boil up for a minute, stirring well to keep it from sticking and burning.

  6. If it becomes too much thickened, add a little more boiling water.

  7. Strain the mixture through a fine colander into an earthen bread bowl, and let it cool.

  8. When lukewarm, add one cup of good, lively yeast.

  9. Cover with a napkin and keep in a moderately warm place for several hours, or until it ceases to ferment.

  10. As it begins to ferment, stir it well occasionally.

  11. When well fermented, turn into a clean glass or earthen jar.

  12. The next morning cover closely and put in the cellar or refrigerator, not in contact with the ice.

  13. Reserve enough for the first baking in a smaller jar so the larger portion need not be opened so soon.

  14. Always shake the yeast before using.

Make hop yeast

  1. Raw Potato Yeast No. 2: Make as the preceding, but boil one fourth of a cup of loose hops tied in a clean muslin bag in the water for five minutes before pouring it into the potato and flour mixture.

  2. Hop Yeast: Put half a cup of loose hops into a granite-ware kettle, pour over it a quart of boiling water, and simmer about five minutes.

  3. Meanwhile stir to a smooth paste in a tin basin or another saucepan a cup of flour and a little cold water.

  4. Line a colander with a thin cloth and strain the boiling hop infusion through it onto the flour paste, stirring continually.

  5. Boil this thin starch a few minutes until it thickens, stirring constantly so no lumps form.

  6. Turn it into a large earthen bowl, add a tablespoonful of salt and two of white sugar.

  7. When cooled to blood heat, add one half cup of lively yeast, stirring all well together.

  8. Cover the bowl with a napkin and let it stand in a moderately warm place twenty-four hours, or until it ceases to ferment, beating back occasionally as it rises.

  9. Put into a wide-mouthed glass or earthen jar previously scalded and dried, cover closely, and set in a cool place.

Make boiled potato yeast

  1. Boiled Potato Yeast: Peel four large potatoes and boil them in two quarts of cold water.

  2. Tie two loose handfuls of hops securely in a piece of muslin and boil in the water with the potatoes.

  3. When the potatoes are tender, remove them with a perforated skimmer, leaving the water boiling.

  4. Mash the potatoes and work in four tablespoons of flour and two of sugar.

  5. Pour the boiling hop infusion over this mixture gradually, stirring constantly to form a smooth paste, and set aside to cool.

  6. When lukewarm, add a gill of lively yeast and proceed as in the preceding recipe.

  7. Boiled Potato Yeast No. 2: To one teacupful of very smoothly mashed, mealy potato, add three teaspoonfuls of white sugar, one teaspoonful of salt, and one cup of lively yeast, or one cake of Yeast Foam dissolved in a very little water.

  8. The potatoes should be warm but not hot enough to destroy the yeast.

  9. Allow this to stand until light, when it is ready for use.

Nutrition, whole recipe (rough)

665Calories
17 gProtein
1 gFat
145 gCarbs

Counts 4 of 7 ingredients. The other 3 aren't in our nutrition table and add nothing above, so the real totals are higher.

What these numbers assume: 4 portions
IngredientPortion assumedkcal
Flour1 cup (125g) all-purpose455
Potato1 medium (173g) baked161
Sugar1 tbsp (12.5g) granulated49
Salt1 tsp (6g)0
Waternot in our table0
Hopnot in our table0
Cakenot in our table0

One typical portion per ingredient; the recipe's quantities are not counted. A rough guide only, not for medical or dietary planning.

By E. E. Kellogg. Recipe from a historical cookbook (Project Gutenberg).

Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures. See the original page.

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.

  1. Flour + sugartop 15% of all pairs
    Smell alikemoderate
    Cooked together92,116 recipes

    Shared aroma: phenylacetaldehyde (hawthorne, honey).

  2. Flour + potatotop 15% of all pairs
    Smell alikemoderate
    Cooked together5,355 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Sugar + potatotop 30% of all pairs
    Smell alikelow
    Cooked together3,032 recipes

    Shared aroma: beta-damascenone (apple, rose).

  4. Flour + hopstop 32% of all pairs
    Smell alikelow
    Cooked together10 recipes

    Shared aroma: eugenol (clove, spicy).

  5. Hops + potatotop 39% of all pairs
    Smell alikelow
    Cooked together3 recipes

    Shared aroma: myrcene (balsamic, herbaceous).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Potatoes
Their starch thickens the mixture and gives the yeast a food source to ferment.
Flour
Forms a starch paste that thickens the liquid and feeds the yeast.
White sugar
Provides readily fermentable sugar that the yeast consumes to produce gas.
Lively yeast
Ferments the starch and sugars, producing the gas that leavens bread.
Hops
Add bitterness and aroma and help preserve the yeast.

The step that matters

Add the yeast only when the mixture is lukewarm. Yeast cells are killed by heat, so adding yeast to boiling or very hot liquid stops fermentation. Cooling to lukewarm keeps the yeast alive and active.

Swap the potato

How well each one fits the dish's main ingredients (flour, sugar, hops):

  1. Mustardfits better
  2. Arrowrootfits better
  3. Parsnipfits better
  4. Potatothe original

Fit is the average pairing score against flour, sugar, hops. Candidates are from the same food group and used in at least 100 recipes.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.

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