Whey Protein/Arabic Gum Gels Formed by Chemical or Physical Gelation Process

Abstract

Whey proteins (WP) gelation process with addition of Arabic gum (AG) was studied. Two different driving processes were employed to induce gelation: (1) heating of 12% whey protein isolate (WPI) solutions (w/w) or (2) acidification of previous thermal denatured WPI solutions (5% w/w) with glucono-δ-lactone (GDL). Protein concentrations were different because they were minimal to form gel in these two processes, but denaturation conditions were the same (90°C/30 min). Water-holding capacity and mechanical properties of the gels were evaluated. The BST equation was used to evaluate the nonlinear part of the stress-strain data. Cold-set gels were weaker than heat-set gels at the pH range near the isoelectric point (pI) of the main whey proteins, but heated gels were more deformable (did not exhibit rupture point) and showed greater elasticity modulus. However, gels formed by heating far from the pI (pH 6.7 or 3.5) showed more fragile structure, indicating that, in these mixed gels, there are prevailing biopolymers interactions. Cold-set and heat-set gels at pH near or below the WP pI showed strain-weakening behavior, but heated gels at neutral pH showed strong strain-hardening behavior. Such results suggest that differences in stress-strain curve at the nonlinear part of the data could be correlated to structure particularities obtained from different gelation processes.

Cold‐set whey protein gels induced by calcium or sodium salt addition

“…Therefore, the fine‐stranded structure could be more able to absorb the energy given to the system during compression. On the other hand, the particulate or disordered gels show a trend to dissipate this energy of compression by the rupture at lower deformations due to the presence of more points for crack initiation (irregular structure) (Valim et al. , 2009).…”

Heat‐induced gels of soy protein and κ‐carrageenan at different pH values

“…This fragility could be attributed to the particulate structure of the gels formed at acid pH values, which are more susceptible to rupture during compression processes (Valim et al, 2009). To the contrary of gels containing soy proteins and j-CR, heat-induced gels from whey protein containing gum Arabic presented greater rigidity and deformability for systems gelled at a pH values around the pI of the whey proteins, although similarly, acidification caused an increase in the elasticity modulus (Valim et al, 2009). This difference could be attributed to the fact that in this work the acidification stage prior to heating was maintained above the pI characteristic of the soy protein fractions.…”

“…However, depending on the pH and biopolymer concentrations, the mixed systems (Li et al, 2009) can present highly complex rheological behaviour. Recently these complex systems have received much attention in the literature due to the differentiated texture properties that can be obtained for a single formulation condition by just varying the gelling process conditions, such as heat or acid induced gelling (Valim et al, 2009), addition of polysaccharides with different molecular structures or the use of different acidification conditions de Jong et al, 2009).…”

An assessment of the texture of acidified sodium caseinate gels with added inulin using response surface methodology

“…1974). The BST model was originally proposed to provide a good fit for the data of elastomers, including natural and synthetic rubber obtained in various deformation fields up to the point of rupture, and has been used to describe the behaviour of several viscoelastic food gel systems including whey protein/arabic gum (Valim et al. 2009), agarose (McEvoy et al.…”