Sauerkraut and Middle School Chemistry

I chose to put some red cabbage in my sauerkraut because Paul has always said that red sauerkraut is so much better than green. However, when I noticed that the sauerkraut is beginning to turn red instead of purple, I realized that it is also useful as an indicator of how far the fermentation has progressed. As I learned in middle school science class, red cabbage juice changes colors depending on pH. So as the sauerkraut gets more acidic, it turns brighter red and eventually pink.