Effect of cellulose-rich fibres on faba bean protein gels is determined by the gel microstructure

Journal article, 2024

Increased consumption of plant-based foods and better utilisation of side-streams can reduce the environmental impact of food consumption. A promising crop for production of protein-rich plant-based foods is faba bean, which can serve as a local alternative to soy in cold-climate regions. This study investigated faba bean protein gelation at multiple pH values and the effect of adding a fibre-rich side-stream from protein extraction. Two different sources were used to extract the fibre (cotyledon and hull). The gels were characterised in terms of textural properties, microstructure and water mobility. Gels produced at pH 4 and 5 showed reduced fracture stress, fracture strain and water-holding capacity, but higher Young's modulus, than gels produced at pH 7. The effect of adding fibre (at fixed solids content) varied with pH. Differences observed were attributed to the gel microstructure, as light and scanning electron micrographs showed coarse, aggregated microstructure at pH 4 and 5 and a fine-stranded protein network at pH 7. Irrespective of fibre source (cotyledon/hull), addition of fibre had comparable effects on textural properties. Low-field NMR revealed differences in water mobility between gels at pH 4–5 versus pH 7, and between gels with/without added fibre, likely related to contrasting microstructures and the water-binding properties of the fibre fractions.