Rheological behavior of dietary fibre in simulated small intestinal conditions

Abstract

Rheological properties of water-soluble dietary fibre (DF), including yellow mustard mucilage (YMM), soluble flaxseed gum (SFG), fenugreek gum (FG) and oat gum (OG) were studied following a simulated gastric and small intestinal digestion. Experimentally obtained steady shear flow curves of FG, SFG and OG were fitted to the Cross model. Based on the values of the Huggins constant, small intestinal fluid at 37 °C is a good solvent for SFG and FG and a theta solvent for OG. The degree of space occupancy at critical overlap concentration (c*[η]) for OG and FG were lower than expected from “normal” concentration-dependency. This departure was attributed to intermolecular associations of these DF in simulated small intestinal conditions. Apparent viscosities (at 60 s−1) of simulated small intestinal digesta containing oat β-glucan at concentrations expected in the small intestine after consumption of a meal that meets from 0.5 to 3 times the value of the European Food Safety Authority (2011) health claim on reduction of post-prandial glycemic responses were determined and were used as benchmarks. Concentrations of YMM, SFG and FG that resulted in apparent viscosities close to the benchmark apparent viscosities in simulated small intestinal conditions were found. In the majority of cases, these concentrations were different for each DF.