Molecular weight changes of arabinoxylans of wheat and rye incurred by the digestion processes in the upper gastrointestinal tract of pigs

Twenty cannulated-pigs were fed wheat flour (WFL), wheat whole grain (WWG), wheat aleurone flour (WAF) and rye aleurone flour (RAF) differing by their arabinoxylans (AX) proportions. After ileal collection of digesta (0800–1800), the soluble phase was extracted. The weight average molecular weight (MWw) of the ileal soluble phase and of the dietary water extracts were determined by high-performance size exclusion chromatography.The MWw value of the ileal soluble phase of digesta after feeding the RAF diet was reduced by approximately 25% compared with the dietary water extract whereas no difference was found between the water extract and the ileal soluble phase when the wheat based diets were fed. The viscosity of the ileal phase is the highest after feeding the RAF diet. In conclusion, the MWw of AX from wheat diets is not changed during passage of the upper intestinal tract of pigs, whereas that of AX from RAF diet is reduced by 25%.