If you want to start making your own sourdough, start with this DIY tracker

A sourdough starter is far more than just a substitute for store-bought yeast. For Christine Sunu, each starter is a spectacle of life: Feed it water and flour consistently, and it will become a sluggish blob that breathes, bubbles, and grows. Introduce it to a dough, and the starter will proliferate and breathe life into what would otherwise become a flat, dense loaf. Put it in the freezer, and it will hibernate in its dormant state. Ignore it, and it will die.

“It’s a really neat idea that you can have this critter that consistently makes a certain kind of bread and that potentially changes over time and grows with you,” Sunu, the designer and inventor of sourd.io — a data tracker that monitors a starter’s rise, ambient temperature, and ambient humidity in real time — told me during a recent phone call. 

Image: Christine Sunu via Twilio

is a simple enough endeavor: Mix water and flour, let it sit, and within a few days, wild yeast from the flour converted from starch and breathe out carbon dioxide.

That means each starter has a life of its own: Each is a unique culture that consumes wild yeast from the air around it. Some develop complex flavors with age; others may evolve over time and depending on how their environment changes. Some starters are generations-old family heirlooms that have survived wars and migrations. For Sunu, they’re microbiological colonies born out of historical origins and delicious scientific subjects ripe for modern, technological exploration. 

“I cannot possibly recommend attempting to capture wild yeast in your college dorm,” the long-time baker said, laughing heartily as she recalled the first time she experimented with a sourdough starter. “It was a fairly gross experience that my roommate from freshman year still makes fun of me about today.”

A lot has changed in the 15 years since then: Sunu graduated from college and went on to work at neurogenetics and biophysics labs, where she taught herself to code and program image-tracking algorithms. Her interest in making and baking has remained unwavering, however, and with new skills came the opportunity to explore old passions in different ways. 

“I like working with bread because it also has a biological component,” said Sunu, a freelance product designer and developer who also manages a community of Internet of Things (IoT) developers at the cloud communication platform Twilio. Of sourd.io, she said, “I like building things that help us monitor and learn about the small worlds around us.” 

In these days of social distancing, Sunu has been spending a lot more time with Brad the bread, who, according to an eBay seller’s packaging, descended from the mother-dough of a bakery in Egypt. Rumor has it that the mother-dough has been giving life to bread and cultures like Brad for more than 50 years, but no one knows for sure.

To keep Brad happy and alive, Sunu has spent the past few weeks cooking up sourd.io to monitor his health. To assemble the data tracker, Sunu connected a 3D-printed jar lid to a battery, a temperature/humidity sensor, an ultrasonic distance sensor used to monitor the starter’s rise over time, and a cellular board that transports the data to an internet platform.

Image: Christine Sunu via Twilio

Sunu feeds Brad as she prepares to bake and notes the starter’s vital signs: its rise, its ambient humidity, and ambient temperature. The idea, she said, is to explore the best indicator for a fully risen starter through data analysis.

So far, Brad’s growth seems to correlate with rising humidity, but Sunu says this can differ from one living culture to another.

“It’s deeply comforting right now to raise starters and make bread,” Sunu, who identifies as “a cat lady for sourdough,” told me. “I like working with hardware for a lot of the same reasons I like baking: It gives me time away from screens to work with my hands, and it gives me a chance to be precise and data-oriented. The main difference is that I can’t eat the hardware, but in this case, it might at least help me make something I can eat.”

Sunu encourages others to replicate the DIY project with her recipe, though she suspects that it might be “pretty intimidating to build” for those who don’t have experience with hardware codes. It’s not impossible, however: Makerspaces can help. But with many of their brick-and-mortar locations closed due to the pandemic, Sunu said she, like some other makers, is happy to answer questions over Twitter.

If all else fails, there’s always this nugget of delight: a time-lapse of Brad living and breathing life to its fullest. Like, literally.