Impact of high pressure treatment on functional, rheological, pasting, and structural properties of lentil starch dispersions.

Lentil starch (LS) dispersions (flour to water 1:4w/w) were subjected to high pressure (HP) treatment at 0.1, 400, 500 and 600MPa for 10min, followed by evaluation on the functional, particle size, rheological, pasting, and structural properties of post-process samples. Water holding capacity of pressurized starch increased with the pressure intensity due to increase in damaged starch. The amount of resistant starch increased from 5 to 6.8% after pressure treatment at 600MPa. An increase in starch granule particle size (196-207μm) was obvious after HP treatment. The lentil starch was completely gelatinized after pressure treatment at 600MPa for 10min as evidenced from differential scanning calorimetry, rheometry, X-ray diffraction (XRD) and scanning electron microscopy observation. The elastic modulus, G' of lentil starch gel was less frequency dependent, and higher in magnitude at high pressure (>500MPa) than at lower pressure range (≤400MPa). XRD analysis revealed the disappearance of two diffraction peak intensities at 14.86° and 22.82° at 600MPa for 10min, which confirms the transformation of crystalline to amorphous region of lentil starch. Pasting properties were significantly influenced by the pressure treatment especially at 600MPa, resulting in a considerable decrease in peak viscosity, breakdown and final viscosity, and an increase in peak time. It can be inferred that the functional properties of pressure-treated LS are mainly based on the structural destruction of granules.