I've made fresh red cabbage (not canned or frozen) a few times. Back when I was still living with my parents, it always turned out fine. Now that I'm living on my own, I'm still using the same recipe, with one minor adaptation, which is leaving out the chunks of apple my mother always wanted me to add. I've never been a fan of those chunks, and I prefer eating mine with apple sauce, added after cooking.
But now, when I cook the red cabbage, it suddenly (and always) turns blue. The taste is still pretty much the same, it's just a colour difference. Still, I'm wondering what causes it, and if there's anything I can change to get it to look red again?