Effects of pH and ionic strength on the rheology and microstructure of a pressure-induced whey protein gel

Effect of heat-induced formation of rice bran protein fibrils on morphological structure and physicochemical properties in solutions and gels

“…There apparently was a mesh-like geometric property of the gel network; However, the photomicrographs at the same magnification (10,000×) revealed that the dimensions of the mesh-like structure decreased with an increased pH value. The result of RBP gel is similar to a whey protein gel in high pressure (32).…”

Structuring dairy systems through high pressure processing

“…2A, D and G) or thick strands (Fig. 2B), which made them prone to water release (He et al, 2010). At higher pH (pH = 8) or low ionic strength (nearly zero), the electrostatic repulsion between proteins was enhanced, which slowed the phase separation; thus gels with small microscopic structures were obtained.…”

“…2C and E) and less likely to exudate. Higher pH and higher ionic strength led to harder gels (He et al, 2010). Similarly, WPC (733 g/kg protein) solutions (132 g/L) pressurised to 400 MPa at 25°C for 30 min did not form a gel at pH 3 or 4, but formed large aggregates at pH 5, porous gels at pH 6 or 7, and gels without apparent porosity at pH 9 (Van Camp et al, 1997).…”

“…SEM images (bar represents 4 mm) of the microstructure of pressure-induced WPI (0.2 g/mL) gel samples prepared in acetate buffer (pH 5.0), sodium phosphate buffer (pH 6.0), Tris-HCl buffer (pH 8.0), or in distilled water (pH 5.0, 6.8, or 8.0). Each solution was treated at 800 MPa and 30°C for 10 min (He et al, 2010(He et al, ). et al, 2003.…”

High pressure effects on the structural functionality of condensed globular-protein matrices

“…Pressure induced network morphologies can be manipulated in relation to electrostatic repulsion of polymer segments, which when minimised (at pH of about 5 or ionic strength of 0.2) results in a two phase system with large pores that are prone to water release [27]. Replacing water with skim milk increases the mechanical strength of the composite gel due to the presence of casein that contributes by itself or by interacting with the unfolded whey protein molecules, and the stabilising effect of calcium ions [61].…”