Akademik Veri Yönetim Sistemi
WASTE AND BIOMASS VALORIZATION, cilt.11, sa.5, ss.2101-2110, 2020 (SCI-Expanded)
Pistachio (Pistacia vera L.) hull is the largest by-product of pistachio industry which is accumulated every year at harvest time and can lead to environmental pollution. This study investigated the microwave-assisted ethanol-water binary solvent extraction of phenolic compounds from pistachio hull. The effect of different ethanol/water ratios was investigated on the changes in extraction yield, total phenolic content and antioxidant activity. The obtained results indicated relationships between the tested parameters, i.e. ethanol concentration and extraction yield. The maximum yield was obtained with 50% ethanol (32.9 g dry extract/100 g dry matter). Total phenolic content of the extracts was found in the range of 21.3-39.3 mg/g extract as gallic acid equivalent. Antioxidant activity was determined by using three different tests. Using the DPPH test, the best antioxidant activity with the lowest IC50 value (0.70 mg/mL) was obtained for 40% ethanol and the least antioxidant activity was obtained for 100% ethanol with the highest IC50 value of 2.73 mg/mL. Using the beta -carotene bleaching assay, the pistachio hull extracts showed antioxidant activity at 5000 mg/L in the range of 44-97%. The ORAC test showed that 50% ethanol extract had the highest antioxidant activity (260.9 mu mol Trolox equivalents/g extract). Using HPLC assay, the gallic acid was the main phenolic compound of hull extracts which ranged between 1.18 and 19.83 mg/g crude extract. These findings propose that pistachio hull extracts can be a valuable source of bioactive compounds.