Yup, many anthocyanins turn blue at pH 8 and above. Some also turn green. A few drips of wine in alkaline water and there you go! You can test it by slowly adding lemon juice or vinegar and watch the color go back the other direction to reddish hues.
kjhvm t1_jdul13s wrote
Reply to comment by missmimi1011 in Filled my glass with tap water that looks light blue after drinking a glass of red wine by missmimi1011
Yup, many anthocyanins turn blue at pH 8 and above. Some also turn green. A few drips of wine in alkaline water and there you go! You can test it by slowly adding lemon juice or vinegar and watch the color go back the other direction to reddish hues.