Rheological Studies on Gelling Behavior of Soy Protein Isolates

Abstract

The gelling behavior of soy protein isolate (SPI) dispersions with solid contents 0.8-8.8% was studied by a dynamic fluid rheometer. Strain sweep and frequency sweep measurements showed the dispersions were stable and predominantly elastic at room temperature. Elasticity increased sharply when dispersions were heated. Cooling set was found for dispersions of higher solid contents. For solids contents < 3%, cooling set was not as pronounced; and cooling could result in reduced elasticity when the prior heating was milder. Results suggest SPI changed from an aqueous dispersion to a dispersion consisting of particles embedded in heat-soluble protein sol matrix upon heat treatment, and further underwent a transition into a gel consisting of particles embedded in heat-formed protein gel matrix. Thermoreversibility of elasticity was determined by solids content.

Dynamic rheological and thermal study of the heat-induced gelation of tomato-seed proteins

“…(Renkema et al, 2001). Similar profiles were also obtained for egg white, soy protein isolate, whey protein, wheat gluten, pea protein isolates and chickpea protein isolates by other researchers (Ould Eleya and Gunasekaran, 2004;Hua et al, 2005;Khatkar et al, 1995;Attenburrow et al, 1990;Bryant and McClements, 2000;Fitzsimons et al, 2007;Shand et al, 2007;O'Kane et al, 2004;Zhang et al, 2007;Hsu, 1999). As seen in Fig.…”

“…Disulphide bridges and sulfhydryl groups are thought to be important for the cross linking of proteins (Attenburrow et al, 1990;Hsu, 1999;Gosal and Ross-Murphy, 2000;Cordobes et al, 2004;Havea et al, 2004;Fitzsimons et al, 2007). More cross-links are created with increase in intermolecular interactions, which causes the increased formation of soluble aggregates during the heat-induced gelation of protein (Shand et al, 2007).…”

Thermal behaviour of lyophilized egg yolk and egg yolk fractions

“…Obviously the kind of material is determinant in power law exponent values, but according to Scanlan and Winter (1991) the range of values also depends on polymer stoichiometry, molecular weight and concentration, and Michon et al (1993) reported that this range also depends on the experimental conditions. According to results reported for soy protein gel (Hsu, 1999) and for gelatin, whey protein and starch gels (Hsu et al, 2000), low values of D corresponds with a more heterogeneous gel while homogeneous gels shows high values. This is in accordance with results shown in Table 4: the D range of values was 0.10-0.23, much lower than those reported by other authors, due to the fact that egg yolk and egg yolk fractions make a heterogeneous gel.…”

High pressure gelation of soy proteins: Effect of concentration, pH and additives

“…This protein unfolding can lead to the reversible or irreversible gelation of the product, with repercussions on the viscoelastic characteristics of the protein solution (Ahmed et al, 2003). Many articles have addressed the thermal gelation of soy proteins (Babajimopoulos et al, 1983;Hsu, 1999;Hua et al, 2005;O'Kane et al, 2004;Renkema et al, 2001;Renkema and van Vliet, 2004); and most look into textural characteristics of self-supporting gels. Some others have focused on high pressure induced gel formation of soy proteins (Apichartsrangkoon and Ledward, 2002;Apichartsrangkoon, 2003;Maltais et al, 2005;Molina et al, 2002) and even the combination of HP and temperature (Domoulin et al, 1998;Molina and Ledward, 2003).…”