Microstructure, physicochemical properties and in vitro digestibility of starches from different Indian lentil (Lens culinaris) cultivars

Starches isolated from four Lens culinaris cultivars were evaluated for their physicochemical, structural, thermal, pasting and in vitro digestibility characteristics. Amylose content of the L. culinaris starches from different cultivars varied from 30.6% to 33.9% and the degrees of crystallinity were 27.5-33.1%, with X-ray diffraction pattern of the C-type. Lens culinaris starch granules were oval to spherical shaped with a smooth surface and mean particle diameter of 15.9-17.4 μm. The transition temperatures and enthalpy of gelatinization (ΔH_gel) ranged between 60.2-61.3, 67.6-68.7, 74.5-75.6 °C and 8.36-8.52 J/g, respectively. The amounts of rapidly digesting, slowly digesting and resistant starch contents of L. culinaris starches ranged from 56.0 to 65.5%, 5.1% to 9.2%, and 29.4% to 34.8%, respectively. Digestibility and ΔH_gel showed a statistically significant correlation with amylose content, relative crystallinity and particle diameter. All the four starches exhibited nearly identical pasting temperatures but differed significantly (P < .05) with respect to peak, breakdown, final and setback viscosity.