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- Effects of hemicellulose-derived saccharides on behavior of Lactobacilli under simulated gastrointestinal conditionsPublication . Gullón, Patricia; Gullón, Beatriz; Cardelle-Cobas, Alejandra; Alonso, José Luis; Pintado, Manuela; Gomes, Ana MariaFour types of purified xylooligosaccharides (XOS) from several lignocellulosic materials, showing different structural features (including chain length, branching, and linkage types), obtained from different feedstocks (Eucalyptus globuluswood, rice husks,wheat bran or barley wastes), were assessed (using fructooligosaccharides as reference substrate) for their effects on the growth of six different probiotic Lactobacillus strains in basal MRS media and survival in different simulated gastrointestinal tract (GIT) conditions. The hydrophobicity of bacterial cells, which measures their potential for epithelial adhesion, was also evaluated. Improved growth of Lactobacillus strains was observed for media containing XOS as the single source of carbohydrate, confirming their role as prebiotics. These oligosaccharides also led to improvement in the resistance of the target Lactobacillus to the simulated GIT environment. The enhancement of the survival rates depended on the type of oligosaccharide. This is the first comparative study of the effects in lactobacilli involving four types of XOS obtained from different lignocellulosic materials. The obtained results show that these oligosaccharides manufactured from alternative sources could be interesting prebiotic substrates with different structures in comparison with the available commercially and with interesting potential towards the development of synbiotic products.
- Structural features and assessment of prebiotic activity of refined arabinoxylooligosaccharides from wheat branPublication . Gullón, Beatriz; Gullón, Patrícia; Tavaria, Freni; Pintado, Manuela; Gomes, Ana M. P.; Alonso, José Luis; Parajó, Juan CarlosWheat bran (WB) samples were subjected to two stage processing (aqueous extraction and hydrothermal treatment) to assess their potential as a raw material for the manufacture of xylan-derived prebiotics. The liquid phase from the second stage, containing hemicellulose- derived soluble arabinoxylooligosaccharides (AXOS), was refined by consecutive steps of membrane filtration and ion exchange. The purified AXOS were characterised by matrixassisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF-MS) and chromatographic techniques. The most complex saccharide identified was made up of 19 pentoses. Human faecal slurry cultures were used to assess the bifidogenic activity of AXOS and their effects on the production of Short Chain Fatty Acids (SCFA) and lactic acid. The results were compared with data obtained using fructooligosaccharides (FOS), which are accepted as the gold standard of a prebiotic ingredient. The stimulatory effects reached by AXOS upon the bifidobacterial population were of the same order as those obtained with FOS. Higher SCFA production was observed with AXOS in comparison with FOS.