Why does my homemade sourdough come out dense and gummy inside, and how can I tell if it's underproofed or my starter is

A dense and gummy interior is usually caused by one of two things: the loaf didn't build enough gas (underproofing) or it was sliced while still steaming hot.

Here is how you can tell the difference between a weak starter and underproofing, and how to fix it.

1. Is it the starter or the proofing?

To distinguish between the two, look at the "crumb" (the holes inside):

• Underproofed: The bread will often have a "tunnel" of large, irregular holes near the top crust, while the bottom half is tight, dense, and gummy. This happens because the yeast ran out of "oomph" before it could finish expanding the dough.
• Weak Starter: The dough will likely show very little rise throughout the entire process—from the bulk ferment to the final proof. If your dough stays flat, doesn't get puffy or bubbly, and feels heavy rather than airy, your starter is likely not active enough.

2. How to test your starter

Before your next bake, perform a float test:

1. Take a small teaspoon of your active starter (fed 4–8 hours prior).
2. Gently drop it into a glass of water.
3. If it floats, it is filled with gas and ready to bake. If it sinks, it needs more time to mature or a "strengthening" feed (use a slightly higher ratio of flour to water).

3. Quick fixes for your next loaf

• The "Poke Test": During final proofing, gently poke the dough with a floured finger. If the indent springs back immediately, it needs more time. If it springs back slowly and leaves a small indentation, it is ready for the oven.
• Check the Temperature: Yeast is highly temperature-dependent. If your kitchen is cool, the dough will take significantly longer to proof. Don't rely on the clock; rely on how the dough feels (it should look 30–50% larger and feel light/jiggly).
• Wait for the Cool-Down: Even a perfectly baked loaf will turn gummy if sliced too early. As the bread cools, the moisture inside redistributes. Slicing too soon releases steam prematurely, turning the inside texture into a paste. Wait at least 2–3 hours after it comes out of the oven before cutting.

If you’d like me to check the current consensus on hydration levels or specific temperature ranges for proofing, let me know!