Vine shoots as new source for the manufacture of prebiotic oligosaccharides

Abstract

Vine shoots were subjected to a hydrothermal treatment to cause the selective solubilisation of the hemicelluloses. The hemicelluloses solubilisation products were refined by a sequential processing with nanofiltration and ion exchange obtaining a refined product with a purity of 99%. A depth chemical and structural characterization of the purified oligosaccharide mixture from vine shoots was performed for the first time by HPLC, FTIR, HPAEC-PAD, MALDI-TOF and UPLC-DAD-ESI-MS. The characterization showed the presence of oligosaccharide mixtures with a wide polymerization degree (DP = 2-17) and a rich substitution pattern. Moreover, the thermal behaviour of the mixture was evaluated by TGA in order to obtain information about the thermal and storage conditions during its incorporation into processed functional foods. The thermal and acid stability of the obtained oligosaccharides was also evaluated corroborating their resistance to the digestive conditions. The assessment of the prebiotic activity of the digested mixture was carried out by in vitro fermentability with faecal inocula from human volunteers by the monitoring of short chain fatty acids production and the population dynamic of bifidobacteria by FISH.

Keywords: Agricultural residues; Autohydrolysis; Membrane technology; Prebiotic; Structural characterization; Xylooligosaccharides.