Effect of different heat-treatment times and applied shear on secondary structure, molecular weight distribution, solubility and rheological properties of pea protein isolate as investigated by capillary rheometry

A capillary rheometer study was carried out to expose a pea protein isolate to defined shear rates in a range of 250-3000 s(-1) and heat-treatment times of 0.5, 5 and 20 min at 130 degrees C, and to determine the effect on secondary structure, molecular weight distribution, water solubility and viscosity. Heat treatment caused the formation of shear sensitive protein aggregates, likely consisting of beta-turn structures or anti-parallel beta-sheets as determined via Fourier Transform Infrared Spectroscopy (FTIR). Protein aggregation caused a reduction in water solubility. Molecular weight distribution of the protein was altered, with longer heat-treatment time affecting more proteins, as revealed by SDS-PAGE. The protein isolate featured shear thinning behaviour, and no significant difference in viscosity was found for the three different heat-treatment times. This knowledge helps to understand heat and shear induced structural changes on a pea protein isolate. (C) 2017 Elsevier Ltd. All rights reserved.