If your starter shows a sign of mold that is pink or orange in color, toss it out and start over. As your starter is developing you may find a liquid on top that is referred to as “hooch.” As the yeast begins to ferment this liquid shows up if the starter has not been fed regularly enough.

How do I know if my starter has gone off?

You can tell that a sourdough starter is bad or dead if it doesn't respond to regular feedings after being unfed for a long time or if they develop any kind of mold or discoloration.

Is my sourdough starter still alive?

While sourdough is amazingly resilient, heat is fatal for a sourdough culture. You may try feeding it to see if it bubbles up, indicating it is still alive. If the temperature climbed much above 85ºF, the starter is likely dead.