Details

Autor(en) / Beteiligte

• Katsampa, Photene
• Valsamedou, Evdokea
• Grigorakis, Spyros
• Makris, Dimitris P.

Titel

A green ultrasound-assisted extraction process for the recovery of antioxidant polyphenols and pigments from onion solid wastes using Box–Behnken experimental design and kinetics

Ist Teil von

• Industrial crops and products, 2015-12, Vol.77, p.535-543

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2015

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• [Display omitted] •Polyphenol extraction from two onion solid wastes.•Use of water/glycerol and optimization based on experimental design and kinetics.•Process assessment using kinetic parameters and antioxidant tests.•Liquid chromatography-diode array-mass spectroscopy characterisation of major polyphenols. Onion solid wastes (OSW) were used as raw material to produce polyphenol- and pigment-enriched extracts with antioxidant activity, using ultrasound-assisted solid-liquid extraction. The extraction medium used was free from conventional volatile organic solvents, and it was composed of water and glycerol. Glycerol concentration (Cgl) and liquid-to-solid ratio (RL/S) were first optimised employing Box–Behnken experimental design and then extraction efficiency was further assessed through kinetics. The optimal conditions were found to be Cgl=90% (w/v) and RL/S=90mLg−1, and under these conditions the extraction of total polyphenols and total pigments was shown to obey first-order kinetics. Maximal effective diffusion (De) values were 9.28×10−11 and 13.22×10−11m2s−1, for total polyphenols and total pigments, respectively, while the corresponding activation energies (Ea) were 31.52 and 12.11kJ mol−1. The reducing power (PR) increased as a response to increasing extraction temperature and the extract obtained at 80°C had PR value of 490μmol ascorbic acid equivalents per g of dry weight. Liquid chromatography-diode array-mass spectrometry analysis of this extract showed that the major polyphenols tentatively identified were quercetin 4′-O-glucoside and quercetin, accompanied by other quercetin glycosides, cyaniding 3-O-glucoside and a series of quercetin degradation and oxidation products.