RESUMEN
Bilberries are known to have one of the most complex xyloglucan structures described in the plant kingdom until now. To characterise this structure, xyloglucans were enzymatically degraded and the oligosaccharides obtained were analysed. More than 20 different building blocks were found to make up the xyloglucan polymer. Bilberry xyloglucan was of XXXG-type, but some XXG-type oligomers were present, as well. The building blocks contain galactose-xylose (L) and fucose-galactose-xylose (F) side chains. In both side chains, the galactose units can be acetylated. In addition, beta-xylose-alpha-xylose (U) side chains were shown. This U chain was present in three building blocks described before (XUXG, XLUG and XUFG) and four novel blocks that have not been described in the literature previously: XUG, XUUG, XLUG and XXUG.
Asunto(s)
Glucanos/química , Vaccinium myrtillus/química , Xilanos/química , Xilosa/química , Secuencia de Carbohidratos , Electroforesis Capilar , Glucanos/análisis , Espectroscopía de Resonancia Magnética , Oligosacáridos/química , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Xilanos/análisisRESUMEN
Different separation (HPAEC, RP-HPLC, CE) and identification (MALDI-TOF-MS, ESI-MS(n)) techniques were compared to analyse oligosaccharides obtained after incubation of xyloglucan with endo-glucanase. It was possible to analyse xyloglucan oligosaccharides with each technique. Several techniques, including off line (HPAEC-MALDI-TOF-MS) or online (CE-ESI-MS(n), RP-HPLC-ESI-MS(n)) connection provided complementary information on xyloglucan structure. Online CE-MS and RP-HPLC-MS are described for the first time in xyloglucan analysis. Advantages and disadvantages of the techniques for different purposes such as structural characterisation of oligosaccharides or oligosaccharide profiling are discussed. Black currant xyloglucans had a rather simple XXXG-type structure with galactose and fucose containing side chains.
Asunto(s)
Cromatografía Liquida/métodos , Electroforesis Capilar/métodos , Glucanos/química , Espectrometría de Masas/métodos , Xilanos/química , Secuencia de Carbohidratos , Cromatografía Liquida/instrumentación , Electroforesis Capilar/instrumentación , Glucanos/análisis , Espectrometría de Masas/instrumentación , Datos de Secuencia Molecular , Reproducibilidad de los Resultados , Espectrometría de Masa por Ionización de Electrospray/métodos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Xilanos/análisisRESUMEN
The effect of high-pressure processing (HPP) on cell wall polysaccharides in berries was investigated. HPP decreased the degree of methyl esterification (DM), probably by activation of pectin methyl esterase (PME), and improved the extractability of pectins. When commercial enzyme mixtures were added to mashed berries, a synergistic effect was observed between treatment with commercial enzymes and HPP. Compared to treatment at atmospheric pressure, pectic polysaccharides were degraded to a larger extent when HPP was used. In contrast, hemicelluloses were hardly affected by the added enzymes when HPP was included, although they were degraded during similar treatment at atmospheric pressure. Additionally, the activity of rhamnose-releasing enzymes present in minor quantities might be enhanced after HPP, resulting in a decrease of rhamnose in the polymeric cell wall material. These results exploring the effect of HPP at representative conditions clearly point out the potential of HPP for polysaccharide modification.