An Optimized Accelerated Solvent Extraction Method for the Isolation of Health-promoting Compounds from Non-pungent Peppers

Peppers are known to contain many health-promoting bioactive compounds. In non-pungent peppers, phenolic acids and flavonoids may positively contribute to antioxidant activity. The present study examined the impact of different accelerated solvent extraction (ASE) conditions on total phenolic content (TPC), and antioxidant activities of non-pungent pepper samples. Direct and sequential extraction was conducted using hexane, ethyl acetate, acetone, methanol, and water at temperatures of 40, 80, 120, 160, and 200^°C under 1500 PSI pressure. The total phenolic content of the extracts was determined by Folin–Ciocalteu method and antioxidant activity of the extracts was assayed through in vitro models such as radical scavenging activity using 1, 1-diphenyl-β-picrylhydrazyl (DPPH) and ORAC assays. TPC was expressed as gallic acid equivalents (GAE) and was found to be highest at 200°C for all solvents in both the direct and sequential extractions. In direct extraction, MeOH, water, acetone, and EtOAc extracted 13.56, 12.15, 8.62, and 8.44mg/g GAE respectively, whereas the sequential extractions had 9.19, 7.50, 5.14 and 4.57mg/g GAE in MeOH, EtOAc, acetone and water, respectively. A positive correlation between DPPH and TPC was observed with a correlation coefficient (R²) of 0.742. The data indicated that total phenolics present in MeOH extracts from non-pungent peppers at high temperature likely contribute to overall antioxidant capacity. The optimized ASE method will be more efficient, rapid and reproducible to extract and isolate these compounds from peppers. This study was supported by United States Department of Agriculture grant Designing Foods for Health through the Vegetable & Fruit Improvement Center 2010-34402-20875 and State funding 2013-121277 VFIC-TX state appropriation.