by Tim Hall on Wed Sep 04, 2013 12:42 pm
Scoop the mold out and keep the applesauce relatively sealed to keep molds spores out. You didn't do anything "wrong." It's just a part of the natural cycle of things, molds being fermentative too.
What happened is this: Molds grow very fast, especially on the surface of things where there's plenty of oxygen. They're growing fast enough to compete with the bacteria in the whey. You simply had some mold spores drop on your applesauce and not enough "competition" to keep it at bay.
FYI the bacteria from the whey will grow in your applesauce, but it's also a good environment for yeasts. Don't be surprised if your applesauce is a little alcoholic tasting after a while.