Effect of chemical modification of sodium caseinate on diffusivity of aroma compounds in aqueous solutions

The concentration profiles obtained from a gel were used to measure diffusion of volatiles in water and in aqueous solutions of sodium caseinate glycosylated or not. The physicochemical interactions between solutes and substrates were studied by exponential dilution. As the aroma retention by sodium caseinate increased, the diffusion coefficient decreased. Chemical modification of sodium caseinate affected both the activity and the diffusion coefficients of the volatiles. These variations were interpreted in terms of a relation between the change in structure and the different physicochemical properties of the proteins. The glucosylated and galactosylated proteins exhibited the highest viscosity and induced a decrease in the diffusion coefficients, contrary to lactosylated and maltosylated proteins. The cause of increased viscosity is the variation of the quantity of bound water between the two types of substituted proteins.