Extraction, characterization, physicochemical and rheological properties of two different varieties of chickpea starch

Abstract

The variations in physiochemical, rheological, morphological, and thermal properties of extracted starches of two chickpea varieties (PDG-5 and BG-1076) were evaluated. Both the varieties resulted in starch yields 28.2–31.2 g/100 g. Amylose content was 30.2–31.2%. Morphological study by scanning electron microscopy of starches of both the varieties of chickpea revealed the presence of oval, spherical shaped granules with smooth surfaced, with mean granular length of 2 to 30 μm and width of 3 to 10 μm. Rheological properties of extracted starches at selected concentration (1–5%) were evaluated in flow viscometry and dynamic oscillatory mode to assess flow properties in terms of shear stress, shear rate, apparent viscosity, elastic, and viscous modulus. Fourier transform infrared spectroscopy showed the presence of polysaccharides bands. X-ray diffraction patterns showed that extracted starches are mixture of both A- and B-type crystal. Thermal and pasting properties of chickpea starches were determined using differential scanning calorimeter (DSC) and rapid visco analyzer, respectively. Onset (T0), peak (Tp), end (Tc) temperature, enthalpy of gelatinization (ΔH), peak height index, and gelatinization temperature range were measured by DSC. DSC thermograms revealed that T0, Tp, and Tc values of chickpeas were ranged from 65.6°C to 66.5°C, 69.6°C to 71.1°C, and 75.6°C to 76.2°C, respectively, whereas the corresponding enthalpy values varied between 14.8 and 15.6 J/g. The viscosity values at the peak, hold, final, breakdown, and setback viscosity for PDG-5 variety were 2,562, 2,200, 3,646, 852, and 1,456 cP, respectively, and the corresponding values for BG 1076 were 4,848, 3,416, 6,384, 1,452, and 2,978 cP. It was observed that starches from BG-1076 variety with low swelling power had higher solubility and pasting temperature.