The hydrophobic polysaccharides of apple pomace. (1st November 2019)

• Record Type: Journal Article
• Authors: Fernandes, Pedro A.R.; Silva, Artur M.S.; Evtuguin, Dmitry V.; Nunes, Fernando M.; Wessel, Dulcineia F.; Cardoso, Susana M.; Coimbra, Manuel A.
• Is Part Of: Carbohydrate polymers. Volume 223(2019)
• Publication Date: 2019-11-01
• Subjects: Pectic polysaccharides -- Xyloglucan -- Arabinan -- Polyphenol interaction -- NMR; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2019.115132
• Languages: English
• ISSNs: 0144-8617

Abstract

Graphical abstract: Highlights: Hydrophobic polysaccharides were isolated from apple pomace. Pectin-polyphenol-xyloglucan and arabinan-polyphenol complexes were identified. Polysaccharide-polyphenol complexes are formed during apple processing. Oxidized polyphenols are covalently bonded to polysaccharides in apple pomace. Covalently bonded polyphenols modulate polysaccharides hydrophobicity. Abstract: In this work, polysaccharides extracted with hot water from apple pomace were isolated by C18 cartridge solid-phase extraction at pH 7 (Fr7). Dialysis (12–14 kDa) of this fraction allowed to obtain 17% (w/w) of polymeric material composed by 65% of polysaccharides, mainly arabinose (58 mol%), galacturonic acid (16 mol%) and glucose (10 mol%). Folin-Ciocalteu assay showed 62 g of phloridzin equiv/kg of polyphenols. Moreover, adjusting to pH 3, it was possible to retain an additional fraction (Fr3) representing a further 4% of the polymeric material. Fr3 contained 53% of polysaccharides composed mainly by galacturonic acid (66 mol%) and polyphenols accounted for 37 g of phloridzin equiv/kg. Precipitation with ethanol and subsequent methylation and NMR spectroscopic analysis of Fr7 dialysate allowed the identification of covalently-linked pectic-polyphenol-xyloglucan and arabinan-polyphenol complexes. These structures are possibly formed as a result of polyphenol oxidation reactions during the industrial processing of apples, conferring hydrophobic characteristics to apple pomace polysaccharides.