Significantly improved co-extraction of hesperidin and narirutin from mandarin peel, a food processing by-product, based on statistical predictive models

Mandarin peel (MP) from food processing contains useful ingredients such as flavonoids, thus valorization strategies for MP are expected to be the first step in realizing a sustainable society. This study designed the co-extraction of two flavonoids (hesperidin and narirutin) from MP based on a multiple regression model with extraction temperature, time, and solid loading as the major variables. Numerical optimization determined that the optimal condition to maximize the extraction of both flavonoids was 60.0 °C, 100.9 min, and 95.7 g/L. Under this condition, the experimental results showed that the recovery of hesperidin and narirutin achieved 31.9 and 14.8 mg/g-biomass, respectively, which were in over 90% agreement with the predicted values. Total flavonoid content of MP extract was 81.9 mg/g-biomass, and antioxidant activity (ABTS EC 50 : 2.8 μg/mL) was similar to ascorbic acid. Previous studies have reported the identification of major flavonoids in MP, however, this is the first to achieve maximum recovery of two targeted flavonoids. In particular, the innovation of this study was the optimization of co-extraction, which demonstrated the high potential of MP extract as a natural antioxidant. • Mandarin peel (MP), a food processing residue, utilized for flavonoids production. • Optimal condition for efficient flavonoid recovery: 60 °C, 101 min, and 96 g MP/L. • The optimized process produced 31.9 mg hesperidin and 14.8 mg narirutin per 1 g MP. • Antioxidant activity (ABTS IC 50 ) of MP extract was similar to that of ascorbic acid. • This study supports and improves waste MP management in a biorefinery approach.