Skip to main content is like a fitness tracker for your sourdough starter is like a fitness tracker for your sourdough starter


It can monitor the temperature, humidity, and rise of your culture

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The device attaches to the lid of a regular Ball jar.
The device attaches to the lid of a regular Ball jar.
Image: Twilio

Baking sourdough can be a tricky business. Unlike other breads, where you can reliably use off-the-shelf dried yeast for a consistent result, sourdough uses a sourdough starter, which most people make themselves using a combination of flour and water. There are a ton of variables to getting it right, so why not use a DIY piece of tech to take some of the guesswork out?

That’s the aim of Sourd.Io, a DIY project put together by Twilio’s Christine Sunu. The device is designed to be installed into the top of a Ball jar, and it can measure the humidity and temperature of your starter and track its rise over time. That’s important because it should help you understand when your starter is at its most potent (aka, it’s reached the peak of its rise), and ready for baking. It can even generate alerts when your starter is ready for baking.

It’s a neat little project, and it nicely highlights how incredibly nerdy it’s possible to get about an otherwise very traditional form of bread baking. At its core, baking is just chemistry, which means that sourdough is exactly the kind of thing that people like Silicon Valley tech bros can obsess over.

Although it’s easy (and, dare I say it, fun) to obsess over the data, you can also safely ignore a lot of the numbers if that’s not your thing. Check out our guide on how to make a sourdough starter, which is completely free of any mention of hydration levels or humidity. If you want to know whether a starter is ready to bake with, then the easiest way is to take a spoon of it and put it into a glass of room-temperature water. If it floats, it’s fine; if it sinks, it’s not ready. It’ll never be quite as easy as using off-the-shelf yeast, but then again, actually getting your hands on yeast at the moment can be a challenge.

If you’d like to take a more scientific approach, however, then you can read full instructions for how to build the Sourd.Io project here. Unfortunately, for the time being, the device’s internet connectivity will only work in the US because it relies on Twilio’s Narrowband tech, but Sunu says she’s planning a second version that will connect with Super SIM and should work globally.