The color of anthocyanins changes with different PH value. Generally, acidic water is red, alkaline water is blue. Anthocyanin pigments are widely exist in all deep red, purple or blue fruits and vegetables, such as black goji, Mulberry, BlackBerry and purple sweet potatoes, blueberries, black rice, black beans and other plant tissues.
Here is the vedio for anthocyanidin powder 25% which is extract from Black rice.