Optimization of extraction conditions of antioxidants from sunflower shells (Helianthus annuus L.) before and after enzymatic treatment

▶ The response surface methodology (RMS) is a useful statistical technique for studying the influence of the solvent polarity, temperature and time of extraction process on the antioxidant capacity and total phenolic content in extracts obtained from sunflower shells before and after cellulolytic and pectolytic enzymes addition. ▶ Methanol concentration has a greater impact on antioxidant capacity of sunflower shells without enzyme-treated and TPC in all studied shell samples, whereas the extraction temperature is mostly effective independent variable on antioxidant capacity of the enzyme-treated shells. ▶ The proposed ferric-reducing antioxidant power (FRAP) method is relatively simple, precise and convenient for the determination of antioxidant capacities of shells, and along with RSM can be employed to optimization of extraction parameters for obtaining shell extracts with high antioxidant capacity and phenolic compounds content. ▶ The significant correlation between total phenolic content and antioxidant capacity of the studied extracts of sunflower shells was observed (r = 0.9275). ▶ Antioxidant capacity and total phenolic content depend strongly on the extraction conditions (solvent polarity, temperature, time), but are in general independent on the addition of enzymes solutions.