Physicochemical Properties of Runner Bean and Their Starch, With a Comparison to Corn Starch

The growing demand for sustainable and plant-based ingredients in the food and non-food industries has driven interest in alternative starch and protein sources. Runner beans, a lesser known legume, offer a promising but underexplored source of starch with unique functional properties. This study aims to evaluate the physical, physicochemical, and functional properties of starch from two distinct varieties of runner beans (Scarlet Emperor and White Swan), which exhibit notable phenotypic differences in appearance. Corn starch was included as a reference sample for starch isolates. Scarlet Emperor starch exhibited significant differences in amylose, amylopectin, relative crystallinity, pasting, and flow properties but similar crystallinity (C-type), oil absorption capacity compared to White Swan starch. Both starches also differed significantly from the corn starch control in terms of functional, pasting, and rheological properties. Extracted starches were pure with high starch content (∼96%), high lightness value (∼94) but different amylose content, 28.38 for White Swan and 30.89% for Scarlet Emperor compared to corn starch (29.67%). Both runner bean starches were smooth, bigger, and displayed higher viscosity and firmer gels than the corn starch control. These findings suggest that runner bean starch can complement with corn starch, providing better thickening capacity in food systems.