I have a concord pyment that has been fermenting for a month or so. Used Concord grape juice, clover honey, Kv1116, energizer, nutrient and pectin enzyme, plus the juice of half a lemon.
This started a super deep redish purple(Welches concord juice). It started quite high gravity(1.130 if I remember correctly), it was stirred daily for the first 5 days, at which point gravity was taken, it was air locked and hasn't been touched for weeks. I noticed today it's looking brown. Still actively fermenting and smells great.
Why is this brown? There is virtually no head space and it has been actively fermenting. No air contact at all.