Oat protein in vitro digestion is not influenced by pectin in dispersion or gel systems

The in-vitro digestion of oat protein isolate (OPI) was studied in the presence of increasing concentrations (0.5, 1.0, 1.5 % w/w) of low methoxy pectin (LMP). The in-vitro digestion of OPI was further studied upon incorporation within a calcium LMP network. The OPI and pectin, as well as the calcium - pectin and OPI gels were characterized using rheology, mechanical properties and microstructure. The in vitro digestion of the OPI was performed using the static INFOGEST protocol, and the digestion was analysed based on degree of protein hydrolysis and amino acid composition. Both the rheology and mechanical properties, as well as results obtained upon digestion indicate no or little interaction between pectin and OPI at neutral pH values. The OPI - pectin dispersions show higher than expected viscosities, suggesting phase separated system. The addition of OPI in calcium pectin network has small impact on small deformation but diminish the mechanical strength, as compared to calcium pectin gels. The presence of pectin, as dispersion or gel, does not alter the protein hydrolysis nor the amino acid composition of the supernatant obtained after gastric and intestinal digestion phase; thereby providing opportunities for oat protein - dietary fibre formulations that preserve protein digestion integrity while offering potential prebiotic effects. • Oat protein in vitro digestion is similar with or without being in a pectin gel. • Oat protein in vitro digestion is unaffected by the presence of pectin dispersion. • Oat proteins act as inactive filler in calcium pectin gels. • Oat protein decreases the strength of hybrid calcium pectin protein gels.