Dextran modulates physical properties of rennet-induced milk gels

Abstract

Physical properties of rennet-induced milk gels as core intermediates of cheese production are mainly affected by milk composition, type and amount of coagulation enzyme and starter culture activity. We investigated model systems of reconstituted milk and dextran, which triggers effects on milk gels similar to exopolysaccharides from lactic acid bacteria. Furthermore, clotting activity (0.02 or 0.04 IMCU mL−1) and milk pH adjusted prior to renneting (6.5–5.7) were studied. A lower pH at renneting resulted in an earlier gelation onset, a higher gelation velocity and gel stiffness. The addition of dextran stabilised the gels especially at higher pH, and microstructural analysis revealed larger, more interconnected protein aggregates. However, at pH 5.7, a reverse effect was observed, indicating a destabilisation of the casein network. The current study indicates that altering milk pH and addition of polysaccharides gives the potential to change textural properties of cheese by affecting rennet-induced gelation.