EFFECT OF ADDITION OF α‐, β‐, AND κ‐CASEIN, AND Na‐CASEINATE ON VISCOELASTIC PROPERTIES OF SKIM MILK CURD

Creep compliance was used to determine the effects of the addition of α‐, β‐, and κ‐casein, and Na‐caseinate on the viscoelastic properties of skim milk curd. The results of all measurements can be represented by a six‐element mechanical model. Addition of α‐ and β‐casein, and Na‐caseinate (1.80g/L) to raw skim milk reduced the instantaneous modulus of rigidity and final viscosity of the curd, while κ‐casein addition at the same level increased both viscoelastic parameters. Shielding of κ‐casein and depletion of serum Ca++ ions by α‐ and β‐casein is thought to have caused the reduction of curd rigidity and viscosity. Subsequent experiments indicated that the addition of β‐casein before and after rennet hydrolysis produced different curd strength with the latter producing a stronger curd.