Evaluation and modelling of rheological properties of high pressure treated waxy maize starch dispersions

Samples of 10% waxy maize starch dispersions were treated at pressures from 450 to 600 MPa for 0–120 min. The rheological properties of the dispersions were studied by viscosity and low deformation viscoelastic measurements. At 450 MPa, the consistency coefficient did not exceed 7 Pa sⁿ even after a treatment time of 110 min, whereas at 550 MPa a value of 20 Pa sⁿ was reached in about 5–10 min. G′ measurements as a function of treatment times at different pressures gave almost identical results to viscosity measurement, except that at longer treatment times G′ decreased, indicating that excessive pressurisation seemed to weaken the gel structure. A sigmoidal type model was found to adequately correlate the consistency coefficient values, obtained at different holding times and processing pressures, with the F value of the process, a value representing an equivalent processing time at specified reference pressure and temperature conditions, defined analogously to the traditional thermal processing terminology.