Nature of protein-protein interactions during the gelation of canola protein isolate networks

The nature of interactions involved during the gelation of a canola protein isolate was investigated using rheology and fractal imaging at neutral pH as a function of protein concentration (5.0-9.0% w/w). The onset of denaturation and the denaturation temperature by differential scanning calorimetry for canola protein isolate (CPI; 98.2% protein) was 78.6 degrees C and 87.1 degrees C, respectively. Rheological testing determined the gelation temperature (T-gel) to be-87-90 degrees C for all concentrations. The log % strain at break increased from 1.70 to 1.80 as CPI concentration increased from 5.0 to 7.0% (w/w). Rheological testing of CPI in the presence of destabilizing agents, NaCI (0.1 and 0.5 M), urea (0.1, 0.5,1 and 5 M) and 2-beta-mercaptoethanol (0.1 and 2%), was performed. Samples with NaCI and urea (0.1-1 M) had similar temperature profiles and T-gel values to CPI alone whereas no gel was formed with the addition of 5 M urea and 2-beta-mercaptoethanol reduced the strength of the gel network. Fractal dimension and lacunarity was analyzed using CLSM imaging. The fractal dimension value for all CPI concentrations was -1.5. The lacunarity of the gel decreased from 0.62 to 0.41 as the concentration of CPI increased from 5 to 7% (w/ w). Mechanistic understanding of CPI aggregation and network formation will enable the food industry to better tailor food structure when CPI is present as ingredient. (C) 2016 Elsevier Ltd. All rights reserved.