2.3.8. Light stability of total anthocyanin and antioxidant activity Purple-colored mulberry fruit extracts were covered and placed under normal fluorescent lights (220 V, 50 Hz and 0.37 A) at about 18 in. distance at room temperature. The samples were tested for anthocyanin and its antioxidant activity at 0, 1, 2, 3, 6 and 10 h.