Effect of extrusion-cooking conditions on the pasting properties of extruded white and red bean seeds

Abstract

The extrusion-cooking technique may be used to convert the common bean into functional food products. There is still insufficient information on the properties of extruded beans. The aim of this work was to investigate the effect of extrusioncooking conditions on the pasting properties of two cultivars of the common bean (Aura and Toska) available on the Polish market. The bean was extruded using a twin-screw extruder at variable screws speeds and different amounts of water were added directly to the barrel. The pasting properties of the obtained extrudates were measured using a Micro Visco-Amylo-Graph. The extruded beans revealed more stable viscosity characteristics than the unprocessed ones. The addition of increased amounts of water to the processed material raised the peak viscosity of both extruded bean varieties. A higher screws speed during bean processing resulted in a higher peak viscosity only in the case of the Aura cultivar. However, the decreasing value of the cold paste viscosity was observed at higher speeds. This may indicate the negative effect of the extruder's screws speed on the gel formation ability of the extruded bean. The results showed that the extrusion-cooking process reduced the retrogradation tendency of bean paste due to starch degradation occurring during processing. K e y w o r d s: common bean, extrusion-cooking, pasting properties

Use of Legumes in Extrusion Cooking: A Review

“…However, the presence of constituents other than starch, such as proteins, lipids, and fibers, negatively influences the peak viscosity [54] of legume flours, both raw and extruded, as recently reported in beans [55]. Indeed, in legume flours the starch granules are surrounded by a protein matrix, which limits their hydration and swelling [55]. In addition, high screw speed has a negative effect on gelatinization, lowering the initial viscosity and raising the peak viscosity of extruded flours [55].…”

“…Instead, if the peak viscosity of extruded flour is similar to that of not extruded flour, then starch is still able to swell upon heating (i.e., to gelatinize), indicating that during extrusion only partial gelatinization occurred [53]. However, the presence of constituents other than starch, such as proteins, lipids, and fibers, negatively influences the peak viscosity [54] of legume flours, both raw and extruded, as recently reported in beans [55]. Indeed, in legume flours the starch granules are surrounded by a protein matrix, which limits their hydration and swelling [55].…”

“…Indeed, in legume flours the starch granules are surrounded by a protein matrix, which limits their hydration and swelling [55]. In addition, high screw speed has a negative effect on gelatinization, lowering the initial viscosity and raising the peak viscosity of extruded flours [55].…”

“…Finally, the increase in viscosity at the end of the cooling phase of the MVA analysis is due to the retrogradation of gelatinized starch. Unprocessed flours show a higher degree of retrogradation than extruded ones, which have undergone a relevant thermal and mechanical degradation [53,55]. Therefore, extruded legume flours could be profitably added to bakery products, which could help delaying starch retrogradation.…”

Influence of extrusion cooking on physicochemical properties and starch digestion kinetics of Sphenostylis stenocarpa, Cajanus cajan, and Vigna subterranean grains

“…reduction in relative molecular weight of starch polysaccharide chains resulting from shearing of glycosidic bonds in amylopectin and amylose chains during the cooking process [ 32 , 33 ]. The combination of high temperature and moisture employed in extrusion cooking, also disrupts intragranular hydrogen bonds allowing for association of water with free hydroxyl groups and resulting in modified functional and rheological properties [ 34 ].…”