Optimization of solvent extraction of Roselle (Hibiscus sabdariff L.) anthocyanin using response surface methodology

Anthocyanins are the largest group of water-soluble plant pigments with significant health-promoting activities, and can be used as natural colorants in food systems. The overall purpose of the current study was to optimize the methanol-water solvent extraction of Roselle anthocyanin using three independent variables: extraction time (2 to 6 h), extraction temperature (20 to 40⁰C), and Roselle petal to solvent weight ratio (2 to 6 g). According to the results, the amount of extracted anthocyanin from Roselle petals ranged from 123.85 to 270.49 mg/L. An increase in extraction time, extraction temperature, and petal: solvent ratio could significantly increase the anthocyanin extraction efficiency (P≤0.05), as the highest anthocyanin content (270.490 mg/L) was obtained in the following extraction conditions: extraction temperature of 40⁰C for 4 h and petal: solvent ratio of 6. Optimal conditions for maximum anthocyanin extraction from Roselle petals were predicted to be extraction temperature of 40⁰C, extraction time of 5.71 h, and petal: solvent ratio of 6. Under these conditions, the amount of extracted anthocyanin was 266.19 mg/L, indicating the suitability of the model prediction (R2=0.96).