Extraction of phenolics from pomegranate residues: Selectivity induced by the methods
Résumé
Pomegranate industrial residues are rich in highly valuable phenolics, especially the bioactive punicalagin (PU) and ellagic acid (EA). The effect of extraction conditions on the recovery of polyphenols was investigated with special insight at the selectivity for EA and PU, along with the monitoring of sugar extraction. Macerations in ethanol and/or water, extractions by scCO2:ethanol mixtures and pressurized ethanol were compared on the basis of yields, kinetics and extract composition. High extraction yields up to 61g/100gresidue were obtained because of significant extraction of sugars even
with CO2-based solvents. The TPC and sugar extraction yields were sensitive to the solvent polarity and pressure. Thirty-two phenolics were identified in most extracts whereas in scCO2:EtOH extracts purity of EA with respect to other phenolics was maximal, thus highlighting the selectivity of this technique. For the first time, extracts of high purity in EA and devoid of PU were produced in only one step.
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