My applesauce has fermented, is it safe to bake with?
It sounds like it's fermented, and more harmful bacteria or mold could definitely have grown without being visible.

So it's not safe, in that there's definitely some risk. It's hard to evaluate exactly how risky it is. It sounds like you're already routinely taking risks by eating iffy food that's not obviously rotten or moldy, so you certainly could choose to take that risk here. I'd really advise against it, though.

Remember, food poisoning isn't just about stomachaches. If you end up in the hospital, it's going to cost you a lot more than a replacement jar of applesauce.



As a side note, applesauce generally requires refrigeration. The jar you have almost certainly says "refrigerate after opening." So it may not be a good choice for an egg substitute. You might want to look into actually shelf-stable substitutes. If applesauce is working for you, flax (or chia) or mashed banana might be good options. Flax and chia are totally shelf-stable, and while bananas don't last forever you can at least buy them as you need them.