Checking the internal temperature is the most reliable way to ensure your sourdough bread is fully baked. Aim for an internal temperature of 205-210°F (96-99°C).
While the 'knock test' (tapping the bottom of the loaf and listening for a hollow sound) can provide a general indication of doneness, it's not always accurate, especially with sourdough. Factors like loaf size, hydration level, and oven variations can affect the sound. The most accurate method is to use an instant-read thermometer. Insert the thermometer into the center of the loaf from the bottom. If the internal temperature reaches 205-210°F (96-99°C), the bread is fully baked. If the temperature is lower, continue baking for a few more minutes and check again. The starches have gelatinized and the bread is set at this temperature.
If your sourdough crust is browning too quickly before the internal temperature reaches the target, tent the loaf loosely with aluminum foil to prevent burning while allowing the inside to finish baking.