Isolation and Partial Characterization of Starches from Dry Beans (<i>Phaseolus vulgaris</i>) and Chickpeas (<i>Cicer arietinum</i>), Grown in Sonora, Mexico

Abstract

Abstract For a better understanding of the carbohydrate components of Mexican dry legumes, in an attempt to suggest alternative processing, starches from dry beans ( Phaseolus vulgaris var. pinto ) and chickpeas ( Cicer arietinum var. surutato ) were isolated through sedimentation procedure. They were further characterized in their: physical characteristics of shape and size by light and Scanning Electron Microscopy (SEM); chemical characteristics by proximate analyses and amylose contents; functional characteristics of gelatinization temperature, viscosity and thermal properties by Differential Scanning Calorimetry (DSC); and nutritional characteristics, % digestibility. Starch in these two legumes was firstly isolated at over 85% recovery, with an amylose content of 52.4% and 46.5% for dry beans and chickpeas, respectively. SEM and light microscopy showed starch granules with a predominantly oval shape and size in the range of 20–25μ, for both legumes. Higher gelatinization temperatures were found for dry beans than for chickpeas. Similarly, fusion enthalpies and maximum gelatinization temperature were also higher for beans, as shown by DSC. However, chickpea starch gave a slightly higher % digestibility than bean starch. These results suggested that the difference in the amylose content, in both legumes, determine the starch granule structure, their intermolecular organization and their physical and functional characteristics.