Sodium Caseinate and -Carrageenan Interactions in Acid Gels: Effect of Polysaccharide Dissolution Temperature and Sucrose Addition

The influence of polysaccharide annealing temperature on interactions in acid-induced sodium caseinate (CAS), -carrageenan (CAR), and sucrose gels were studied. Gels were formed by glucone--lactone (GDL) addition to mixed systems leading to a slow acidification towards the protein isoelectric point. The system properties were a result of phase separation between the biopolymers, simultaneously with gelation, resulting in a heterogeneous network with particulate structure. The results showed that gels with an increased whiteness index and water entrapped were obtained at higher caseinate concentration. Increasing caseinate and carrageenan concentration resulted in more brittle and elastic gels, whereas stress in rupture behaviour depended on the relative concentration of biopolymers. The depletion-flocculation phenomenon became evident at higher biopolymer concentration, resulting in network weakening and lower water release, although this effect was reduced with sucrose addition.