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Subcritical (carbon dioxide plus ethanol) extraction of polyphenols from apple and peach pomaces, and determination of the antioxidant activities of the extracts

Adil, I. Hasbay
Cetin, H. I.
Yener, Meryem Esra
Bayındırlı, Alev
The effects of pressure (20-60 MPa), temperature (40-60 degrees C), ethanol concentration (14-20 wt.%) and extraction time (10-40 min) on subcritical (CO(2) + ethanol) extraction of polyphenols from apple and peach pomaces (moisture content congruent to 14%, particle size = 0.638 mm) were determined. All variables increased total phenolic contents (TPC) and antiradical efficiencies (AE) of the extracts significantly (p <= 0.05). The optimum pressure and temperature were 54.6-57 MPa and 55.7-58.4 degrees C for apple pomace, and 50.6-51 MPa and 50.9-52.3 degrees C for peach pomace. The optimum ethanol concentration and extraction time were 20% ethanol and 40 min for both pomaces. TPC of the extracts were 0.47 and 0.26 mg gallic acid equiv./g sample and AE of the extracts were 3.30 and 1.5 mg DPPH(center dot)/mg sample for apple and peach pomaces, respectively. Low TPC and AE of the extracts from peach pomace could be contributed to low concentrations of ferulic and p-coumeric acids, epicatechin, and presence of anthocyanins in peach.