Have you ever fermented Prickly Pear fruits before? If not make sure you follow instructions before you do. I'll try to find them and edit this post. Just wanted the warning out sooner than later.
"In addition, prickly pears must be boiled for half an hour or more before adding to your fermentation, or they will become a bubbling, foaming, slimy, and difficult-to-clean mess. If you can press or otherwise extract the juice, it can be boiled on its own"