Name: To Purify Yeast for Bread or Cakes
Ingredients: yeast from a public brewery; cold water; brown sugar; warm milk or other liquid

Why it works: Sugar and milk are a kitchen classic. They rank in the top 18% of all ingredient pairs, and cooks put them together in 77,875 recipes. Both carry 2-nonenal, which smells fatty, green. The science ↓

To Purify Yeast for Bread or Cakes

Ingredients

yeast from a public brewery
cold water
brown sugar
warm milk or other liquid

Directions

Purify the yeast

Mix the yeast with a large quantity of cold water.
Let it sit in a cool place overnight.
Drain off the water and stir the yeast with fresh water.
Let it stand for several hours until the water can be poured clear from it.
Change the water daily in winter and twice daily in hot weather.

Revive the yeast

If the yeast ferments less freely, stir in a small portion of brown sugar and warm milk 15-20 minutes before using.

Recipe from a historical cookbook (Internet Archive).

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.

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.

Sugar + milktop 18% of all pairs

Smell alikelow

Cooked together77,875 recipes

Shared aroma: 2-nonenal (fatty, green).

Sugar and milk barely smell alike, yet cooks put them together in 77,875 recipes: they work on texture and structure more than aroma.

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

What each ingredient does

Yeast: Provides the fermentation that makes the dough rise.
Brown sugar: Feeds the yeast, giving it sugar to ferment and encouraging more active fermentation.
Warm milk or other liquid: Moistens the yeast and warms it, helping it become active again.

“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.