Comparison of microwave-assisted techniques for the extraction of antioxidants from Citrus paradisi Macf. biowastes

Microwave-assisted extraction (MAE) and solvent-free microwave extraction and Soxhlet extraction were applied to Ray Ruby grapefruit leaves (Citrus paradisi Macf.) to compare extract efficiency. Face centered composite designs were constructed via response surface methodology. Effects of factors of MAE were investigated on total phenolic content (TPC) and naringin content (NC). The optimized conditions were established as 1.4 kWL^-1 for microwave power density, 20.00 gL^-1 for solid/solvent ratio, 218.180 s for extraction time, while responses were calculated as 14.210 mg of gallic acid equivalent per g of the dried leaf (mg GAE g^-1DL) and 13.198 mg of naringin per g of dried leaf (mg Ng^-1DL) for TPC and NC, respectively. SFME and classical Soxhlet methods were also conducted for comparison reasons.