Non-conventional starches isolated from agronomic-improved beans (Phaseolus vulgaris L.): A study of their structure and physicochemical properties.

Abstract

Non-conventional starch sources are promising alternative food ingredients. Different bean varieties with agronomic improvements are constantly being developed and cultivated in the North-western Argentinean region (NOA) to increase yields and obtain high-quality seeds. However, the main attributes of their starches have not been studied. In this work, starches from 4 agronomic-improved bean cultivars were isolated and their structure and physicochemical properties were evaluated. High-purity starches were obtained, as their low protein and ash contents showed. Starch granules presented smooth surfaces with spherical to oval shapes, with a marked "maltese cross" and heterogeneous sizes. Their amylose content revealed a mean value of 318 g.kg-1 and all presented resistant > slowly digestible > rapidly digestible starch fractions. Their FTIR spectra were almost similar and the X-ray diffraction analysis showed a CA- type pattern in all cases despite their different sources. Among thermal properties, Escarlata´ starch showed the lowest gelatinization peak temperature (69.5 °C) and Anahí´ starch the highest (71.3 °C). Starch´s pasting temperatures varied from 74.6 to 76.9 °C, whereas peak viscosity and final viscosity had a similar tendency, being Leales B30 < Anahí < Escarlata < Cegro 99/11-2 and Leales B30 < Anahí = Escarlata < Cegro 99/11-2, respectively. This study provides a basis for a better understanding of the characteristics of agronomic-improved NOA bean starches, enabling their use in product formulation as an alternative to starches from conventional sources. This article is protected by copyright. All rights reserved.