Functional properties of flour from low-temperature extruded navy and pinto beans (Phaseolus vulgaris L.)

Abstract

This study assessed the feasibility of using low-temperature (85 °C) extrusion to process navy and pinto beans flours for gluten-free products. Bean flours were extruded using a twin-screw extruder and ground (250 μm particle size). Extruded (EXT) flours physical properties were compared with raw and 82 °C steam-cooked (STC) bean flours and cookies quality from EXT and STC flours also was evaluated. The EXT bean flours demonstrated better physical and functional characteristics, i.e., a significant increase in water absorption index, from 2.10 in STC to 2.73 in EXT navy flour and water solubility index, 13.33 to 25.56 (navy) and 13.35 to 21.19 (pinto) over STC bean flours. Extrusion cooking affected Hunter color “a” and “b” values significantly for navy and pinto bean flours, whereas, a mixed trend was observed for color “L” values. Extrusion decreased peak and final viscosities of navy and pinto flours when compared to raw or STC bean flours. The cookie diameter, height, and spread factor were comparable between EXT and STC flour cookies. Cookies from EXT flour scored >6 (1–9 hedonic scale) for flavor, texture, and overall acceptability which were higher than STC flour. Over seven-eighths (94/107) of the panelists could not detect beany flavor in the cookies.