Selective ultrasound-assisted aqueous extraction of polyphenols from pomegranate peels and seeds

摘要

In this study, the optimization of ultrasound-assisted aqueous extraction of polyphenols from pomegranate peels and seeds was conducted. A 10-min sonication (t_u) pretreatment (≈60 W) accelerated the extraction kinetics and intensified the polyphenol recovery from peels and seeds. Ultrasound pre-treatment permitted the selective recovery of polyphenols from peels by maintaining a constant concentration of the total soluble matter (°Brix) before and after sonication. Two different near-linear correlations were found between soluble matter and polyphenol extraction for the peels' and the seeds' extracts. Luminescence emission spectra showed significant differences between peels and seeds extracts (t_u = 10 min then diffusion for 200 min) below 450 nm and above 600 nm. Ultrasound pre-treatment enhanced the quantity of the extracted molecules from peels and seeds without affecting their diversity. The optimal ultrasound pre-treatment duration was 10 min, since it ameliorated the polyphenol extraction compared to 5 min, and gave the same yield as 20 min.