Cross-linking of fava bean protein and pectin: Effect of pH, concentration, and temperature

Fava bean protein isolate (FBPI) shows promise as a natural emulsion stabilizer. However, challenges such as creaming, and phase separation necessitate research on ways to increase its stability. Crosslinking through the Maillard reaction has the potential to enhance the functionality, stability, and heat resistance of the resultant conjugates by creating a chemical connection between a polysaccharide and a protein. This study aims to investigate how pH, concentration, temperature, and treatment methods impact the effectiveness of the conjugate formation. Three concentrations (10%, 5%, 3%) of FBPI and pectin solutions were prepared and subjected to pH adjustments of pH 5, 7, and 9. Ultrasound and heat treatments were administered at temperatures of 20, 30, 40, 60 and 85 °C. An altered OPA test was used to quantify the degree of graft (DG) in order to gauge the effectiveness of cross-linking. Results showed that Maillard reaction improves the stability of conjugates between FBPI and pectin. Ultrasound treatments produced the greatest DG (3.9%), outperforming heat treatment (2.21%). The reaction was strongly impacted by pH; an acidic pH (pH 5) decreased solubility and DG (3.7%), but an alkaline pH (pH 9) yielded a higher degree of graft (4.2%). Higher quantities of pectin (10%) promoted the Maillard process. At higher temperature (85°C), heat treatment showed increased DG of 2.88% from 2.21% at 40°C temperature. However, ultrasonic treatment showed decreased DG (3.97%) at 40 °C from 4.13% at 20°C, due possibly to protein denaturation. Heat treatment and ultrasound demonstrated additional effects on the DG, offering a thorough comprehension of the ideal circumstances for improved cross-linking. The outcome of this work can lead to better protein-based product functioning, stability, and texture.