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Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/58731
Title: The structure and composition of galacto-oligosaccharides affects their resistance to ileal digestion and prebiotic properties in rats
Authors: Hernández-Hernández, Oswaldo; Marín-Manzano, M. Carmen; Rubio, Luis A.; Moreno, F. Javier; Sanz, M Luz; Clemente, Alfonso
Issue Date: 24-Oct-2012
Abstract: A detailed study was performed to compare the in vivo ileal digestibility and modulatory effects in fecal microbiota of novel galacto-oligosaccharides (GOS) derived from lactulose [GOS-Lu; degree of polymerization (DP) $2, 14.0% trisaccharides] and commercial GOS derived from lactose (GOS-La; DP $3, 35.1% trisaccharides) in growing rats (5 wk old). Rats were fed either a control diet or diets containing 1% (wt:wt) of GOS-Lu or GOS-La for 14 d. Quantitative analysis of carbohydrates from dietary and ileal samples demonstrated that the trisaccharide fraction of GOS-Lu was significantly more resistant to gut digestion than that from GOS-La, as indicated by their ileal digestibility rates of 12.5 6 2.6% and 52.9 6 2.7%, respectively, whereas the disaccharide fraction of GOS-Lu was fully resistant to the extreme environment of the upper digestive tract. The low ileal digestibility of GOS-Lu was due to the great resistance of galactosyl-fructoses to mammalian digestive enzymes, highlighting the key role played by the monomer type and linkage involved in the oligosaccharide chain. The partial digestion of GOS-La trisaccharides showed that glycosidic linkages (1/6) and (1/2) between galactose and glucose monomers were significantly more resistant to in vivo gastrointestinal digestion than the linkage (1/4) between galactose units. The absence of GOS-La and GOS-Lu digestion-resistant oligosaccharides in fecal samples indicated that they were readily fermented within the large intestine, enabling both types of GOS to have a potential prebiotic function. Indeed, compared with controls, the GOS-Lu group had significantly more bifidobacteria in fecal samples after 14 d of treatment. The number of Eubacterium rectale also was greater in the GOS-Lu and GOS-La groups than in controls. These novel data support a direct relationship between patterns of resistance to digestion and prebiotic properties of GOS.
URI: http://hdl.handle.net/10261/58731
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