What is a sourdough starter?

Flour and water full of wild microbes

What does the float test check?

If a spoonful has enough gas to float

How long can a starter be kept alive?

For generations with regular feeding

Sourdough Starter Quiz: Wild Yeast and Lactic Acid Bacteria

This sourdough starter quiz peeks into a bubbly jar on the counter. Play 10 interactive questions on wild yeasts and lactic acid bacteria, how flour and water capture microbes, feeding schedules, why starters smell sour, hooch on top, the float test, San Francisco sourdough and Lactobacillus sanfranciscensis, and starters kept alive for generations.

Start Sourdough Starter Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

What
What is a sourdough starter?
Yeast
Which microbes make the dough rise?
LAB
Which microbes give sourdough its tang?
Feed
What does feeding a starter mean?
Hooch
What is the liquid that can form on a hungry starter?
Float
What does the float test check?
Sour
Why does a starter smell sour?
SF
Which city is famous for sourdough bread?
Bug
Which bacterium is named after that city?
Old
How long can a starter be kept alive?

Explanations: answer key for all 10 questions

Q1: What is a sourdough starter?
Answer: Flour and water full of wild microbes
It leavens bread naturally.
Q2: Which microbes make the dough rise?
Answer: Wild yeasts
They release carbon dioxide.
Q3: Which microbes give sourdough its tang?
Answer: Lactic acid bacteria
They make lactic and acetic acids.
Q4: What does feeding a starter mean?
Answer: Adding fresh flour and water
Microbes need fresh food.
Q5: What is the liquid that can form on a hungry starter?
Answer: Hooch
It contains alcohol.
Q6: What does the float test check?
Answer: If a spoonful has enough gas to float
It is a rough guide.
Q7: Why does a starter smell sour?
Answer: Acids made by bacteria
Aroma varies with care.
Q8: Which city is famous for sourdough bread?
Answer: San Francisco
Gold Rush miners loved it.
Q9: Which bacterium is named after that city?
Answer: Lactobacillus sanfranciscensis
It has since been renamed in a new genus.
Q10: How long can a starter be kept alive?
Answer: For generations with regular feeding
Some are family heirlooms.

A Living Jar of Microbes

A sourdough starter is a simple mix of flour and water that becomes home to wild yeasts and lactic acid bacteria. The microbes come from flour, the air and even hands. Yeasts release carbon dioxide that makes dough rise, while bacteria make lactic and acetic acids that give sourdough its tang.

Starters must be fed with fresh flour and water to keep their microbes active. A hungry starter may form a layer of grey liquid called hooch, which contains alcohol. Some bakers use the float test, dropping a spoonful in water to see if it holds enough gas to float, as a rough sign it is ready.

San Francisco is famous for sourdough, loved by Gold Rush miners, and a bacterium was named Lactobacillus sanfranciscensis after the city before being moved to a new genus. With regular feeding, starters can be kept alive for generations as family heirlooms.

What This Quiz Teaches

Baking fans will enjoy these questions.

What a starter is
Which microbes live in it
How to feed it
What hooch is
Why San Francisco matters

Did You Know?

Rye flour often speeds up a new starter.
Cooler kitchens slow fermentation.
Starters can be dried for travel.
Discard can make pancakes.
Starters can be named by their owners.