Physicochemical, morpho-structural and rheological characterization of starches from three Phaseolus spp. landraces grown in Chiapas

In this study starches were isolated from Mexican bean landraces of three Phaseolus species (P. polyanthus, P. acutifolius, and P. vulgaris L.). The physicochemical, structural, morphological, and rheological properties, including yield, proximate composition, minerals, swelling power, solubility, amylose content, zeta potential, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), apparent viscosity, and viscoelastic properties were characterized. The starches of the three Phaseolus species exhibited yield, protein, and ash contents of 21.4–28.7%, 0.32–1.12%, and 0.17–0.50%, respectively. Swelling power, solubility, amylose, and zeta potential were 3.06–3.27 g/g, 0.13–0.77%, 28.51–30.99%, and − 42.03 to + 1.46 mV, respectively. The FTIR intensities showed ratios of ordered crystalline to amorphous domains from 0.702 to 0.713. All XRD results revealed that three Phaseolus species had C-type crystallinity. The majority of starch granules were oval. The rheological parameters showed that all starch gels presented shear-thinning and semi-solid viscoelastic behaviors. The native starch gels of the three Phaseolus species showed consistency indexes varying from 26.53 to 4.55 Pa sⁿ, and gel strengths ranging from 37.15 to 109.99 Pa. The present work provides information on non-conventional bean starch properties, which should be useful tool for future studies on their applications in the food and non-food industries.