Rheological and microstructural properties of Bambara groundnut protein gels

• Published in: Food science & technology Vol. 123; p. 109070
• Main Authors: Ruzengwe, Faith Matiza, Amonsou, Eric O., Kudanga, Tukayi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2020
• Subjects: Bambara protein isolate; Gel; Rheological properties; Bambara protein isolate; BPI; Gel; Rheological properties
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2020.109070

The increasing demand for plant proteins has stimulated the search for alternative and novel protein sources for various food applications. Rheological and microstructural properties of Bambara protein isolate (BPI) gels, prepared under varying pH and salt conditions, were investigated and optimised using response surface methodology. BPI gels showed G’> G″ over a frequency range of 0–100 rad s−1. Although BPI gels displayed the characteristics of weak gels, slightly acidic conditions (pH 5.59–6) coupled with low NaCI concentration (0.5 mol/L) promoted the formation of more rigid gels. At slightly acidic conditions, NaCl had a stabilising effect on the protein structure as demonstrated by the increase in denaturation temperature and enthalpy of denaturation with increasing NaCl concentration. In addition, an increase in α helix and β turns contents and disappearance of random coils were observed when 0.5 mol/L NaCl was added at pH 6. Gels with the highest strength had the lowest water holding capacity and thiol content, suggesting participation of more disulphide linkages during network formation. Microscopy images of gels prepared at the slightly acidic pH in the presence of NaCl showed porous homogeneous aggregates. The BPI gels have potential application for the improvement of food texture. •Bambara protein isolate gel properties were affected by NaCl concentration and pH.•Optimum conditions for the highest gel strength were pH 6 and 0.5 M NaCl.•The gel had a higher content of α helix, followed by β sheets and β turns.•Disulphide bonds contributed to the strength of the gel.•Gels with the highest strength were composed of compact large aggregated structures.