New Year, New Bread

About this lesson

People all over the world keep sourdough starters – and over 500 have shared theirs with us, as part of the global citizen science Sourdough Project. Now that we know which microbes make your starters unique, we have a new challenge for you: we’d like you all to bake the exact same recipe, and send us a picture of the result. Because you’ll all be baking from the same recipe, any differences in the bubbles or crumb will be directly attributed to the microbes in your specific starter. “Share the loaf”, and help us to solve the mystery of bread!

View New Year, New Bread on


The Shell Sourdough Recipe

How to participate

Step 1
Step 1

Step 1

Bake bread using the Shell Sourdough Recipe. When the bread is cool, place a ½ inch thick slice on a clean, black piece of fabric with a ruler one finger-width below the bottom crust.

Step 2
Step 2

Step 2

Hold your phone 6 inches above the bread, and take a “head on” picture of your slice. (Use the HDR photo setting, and make sure the flash is turned off.)

Step 3
Step 3

Step 3

Upload your picture to our SciStarter project page.

Step 4
Step 4

Step 4

Optional: Remove the crust from your slice, spread a dollop of acrylic paint evenly across a waterproof surface, and use the spongy middle part of the bread to create a print of your sourdough. (It may take a few tries to get the “perfect print”.) When you are happy with your print, take a picture and upload it to our SciStarter project page.

Materials list

to bake the bread

  • 1 large, non-reactive, container (glass or plastic) with a lid or cover
  • ¾ cup (360 g) sourdough starter
  • 6 cups (720 g) unbleached, all-purpose flour
  • 3 cups (720 g) water*
  • 1 heaping tablespoon (17 g) salt
  • 1 dough scraper
  • 2 banneton brotforms 9” in diameter (budget version: mixing bowls)
  • 2 linen towels to line the bowls (can also use paper towels)
  • rice flour for dusting
  • 1 bread lame (budget version: sharp serrated knife)
  • 2 Dutch ovens (budget version: 2 baking sheets)
  • 6 clay tiles (budget version: 1 loaf pan filled with water)
  • cooling racks

Materials list #2

to share your images

  • A piece of clean, black fabric
  • Camera or camera-phone
  • A plate or other flat, waterproof surface (i.e. laminated placemat) at least as wide as your slice of bread
  • Tempera or acrylic paint
  • A spoon or paper towel tube
  • Plain, smooth white paper (standard copy paper, or multipurpose craft paper for paint/markers will be fine)

About the research

The Dunn lab wants to learn the microbial mysteries behind bread. We have already collected over 500 sourdough starters from participants in 17 countries, as part of the global citizen science Sourdough Project.

By growing the bacteria and yeasts that live in each starter, and sequencing their DNA, we have learned a lot about how where you live, and what you feed your starter, affects the microbes that make your sourdough unique.

Here’s where you come in: now that we know which microbes make each starter special, we want to figure out how those differences affect your bread. Because you’ll all be baking from the same recipe, we can use software to measure the crumb texture and air bubbles in each slice, and connect any differences back to the microbes that we identified in your specific starter.

We’d also like to create a “quilt” of bread prints from around the world. Baking is an art, after all!

About the scientists

Erin McKenney

Dr. Erin McKenney is a microbial ecologist in the Department of Applied Ecology at North Carolina State University.

Anne Madden

Dr. Anne Madden is a microbiologist in the Department of Applied Ecology at North Carolina State University.

Lea Shell

Lea Shell, M.Ed. is a Digital Learning Specialist for the North Carolina Museum of Natural Sciences.