Chewed artichoke turned blue
We eat artichoke often. We pressure cook them in an old one quart aluminum pot. I have seen the cut stem (not chewed) butt turn and ooze blue from the cut stem when left in the fridge too long. In that condition the stem has a sour fermentation, but no obvious mold. I have eaten it like this thinking, I am getting extra. I like artichoke stem a lot and have bought them with long stem in Oregon, USA. The blue appears to be in the nature inherent with the thistle flower that it is.