How good is your sourdough starter?

Sourdough Insights

We’re thrilled to welcome Los Angeles-based baker Guy Frenkel as a guest contributor to the Quest for Sourdough blog. Guy has been part of our journey from the very beginning, joining us at the Sourdough Institute in Saint Vith with his starter “Elizabeth”—a culture that’s as creative and expressive as the breads he bakes with it.

In his first post, Guy explores a question many sourdough bakers ask themselves: Is my starter any good? And more importantly, how can I tell?

Capturing wild yeast and bacteria and nurturing them into a thriving colony is one of the most rewarding parts of sourdough baking. Many bakers form a deep connection with their starters—naming them, feeding them daily, and treating them like living companions. But while starters may feel personal, they’re also highly variable. And not all starters perform the same.

Your starter affects everything: the crumb structure, oven spring, crust, and most importantly, the flavor of your bread. It’s the soul of your loaf. So learning how to evaluate its performance is key to improving your baking.

What makes a starter “better”?

There’s no single perfect starter. Instead, starters have qualities that can be measured and compared based on your baking goals. Guy suggests a few useful parameters to help you assess your starter’s behavior:

• Time to peak – How long does it take to reach full activity after feeding? Is it fast and energetic or slow and steady?

• Height at peak – Does it double, triple, or even quadruple in volume before collapsing?

• Time at peak – How long does it hold its peak before falling? A longer peak gives you a wider window for baking.

• Bubble structure – Are the bubbles small and uniform or large and irregular? This can influence the crumb texture of your bread.

• Smell and taste – What aromas do you notice? Sweet, sour, fruity, alcoholic? Taste it (yes, really!)—you’ll find hints of that flavor in your final loaf.

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To compare starters, Guy recommends using a consistent feeding ratio—for example, 30g starter, 45g water, and 60g flour—and observing how each one behaves.

These observations will help you understand your starter’s strengths and weaknesses, and guide you toward the kind of bread you want to bake. In future posts, Guy will explore how to influence these qualities—adjusting peak times, flavor profiles, and more.