Rheological properties, structure and digestibility of starches isolated from common bean (Phaseolus vulgaris L.) varieties from Europe and Asia

This study aims to explore diversity in rheological properties, structure and digestibility of starches isolated from 16 common bean (Phaseolus vulgaris L.) varieties from Europe and Asia. All common bean starches showed CA-type (closer to A-type) crystallinities. Relative crystallinity varied from 27.8% to 32.9% with a similar coefficient of variation (CV: 5.0%–6.0%) to 1045/1014 cm−1 ratio (varied from 0.429 to 0.508). A peak position shift occurred at 989 and 1014 cm−1. The peak intensity at 989, 1014 and 1045 cm−1 varied greatly and the variation followed the order: at 989 > 1014 > 1045 cm−1. A great variation was also observed for the presence of hydroxyl group and the C–O bond stretching. Rapidly digestible starch, slowly digestible starch and resistant starch contents varied from 61.5% to 73.0% (CV: 4.7%), 0.3% to 7.2% (CV: 53.7%) and 23.9% to 35.4% (CV: 11.4%), respectively. CV of storage modulus (G′) and loss tangent (tan δ) were 29.4%–39.4% and 11.9%–36.1%, respectively. G′max (maximum G′ during heating) varied from 2.52 to 10.32 kPa. These starches showed high G′. This study indicates extensive variation in starch properties among these common bean varieties, which may be useful for selecting varieties for processing, or selecting genotypes for plant breeding.