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

• Published in: Food research international Vol. 89; no. Pt 1; pp. 408 - 414
• Main Authors: Kim, Jae He, Varankovich, Natallia V., Stone, Andrea K., Nickerson, Michael T.
• Format: Journal Article
• Language: English
• Published: Canada Elsevier Ltd 01.11.2016
• Subjects: Canola protein; Fractal analysis; Gelation; Rheology; Thermal transitions; Canola protein; Rheology; Thermal transitions; Gelation; Fractal analysis
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2016.08.018

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°C and 87.1°C, respectively. Rheological testing determined the gelation temperature (Tgel) to be ~87–90°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, NaCl (0.1 and 0.5M), urea (0.1, 0.5, 1 and 5M) and 2-β-mercaptoethanol (0.1 and 2%), was performed. Samples with NaCl and urea (0.1–1M) had similar temperature profiles and Tgel values to CPI alone whereas no gel was formed with the addition of 5M urea and 2-β-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. [Display omitted] •Canola protein isolate (CPI) solutions at 5, 7 & 9% formed heat-set gels at pH7.0.•Gelation temperature was independent of protein concentration.•NaCl addition at 0.1 and 0.5M did not affect gel formation.•Hydrophobic interactions and hydrogen bonds stabilize canola protein isolate gels.•The fractal dimension indicates CPI grows by cluster-cluster aggregation.