Optimization of Ultrasound-assisted Anthocyanin Extraction from Black Rice Bran for Simultaneous Coloring, UV Protection, and Antioxidant Silk Finishes

This study examined the use of ultrasound to extract anthocyanin from agricultural byproduct black rice bran as a natural colorant and a multifunctional finishing agent for silk fabrics, taking into account the various health advantages linked to anthocyanins. The study employed response surface methodology to identify the optimal extraction process that would yield the highest extraction efficiency for total anthocyanin content. The optimal conditions were 30 Hz ultrasonic power, a liquor-to-material ratio of 21, 60°C an ultrasound temperature, and 30 minutes of an ultrasound time, yielding 173.25 mg/L anthocyanin. Silk fabrics were dyed in a reddish purple tone, and the mordant dyeing method produced a 34% higher color strength value than direct dyeing while displaying good colorfastness (grade ≥ 4) to washing and crocking. The dyed silks also provided excellent UV protection (UPF > 40+) and antioxidant activity, with a DPPH scavenging rate over 80%. Anthocyanins derived from black rice bran could thus be used as a bioactive functional colorant in medical and health-related textiles.