Casein/gelatin beads: I. Cross-linker solution composition effect on cross-linking degree

The effect of the cross-linker solution composition (aqueous and organic ratio) on the cross-linking degree of hydrophilic casein/gelatin beads has been evaluated. Casein/gelatin beads with different radii have been prepared and treated over the same time with three different cross-linker solvent compositions containing d, l-glyceraldehyde at the same concentration. The cross-linking degree was studied not only comparing the results of swelling process and degradation rate, widely reported in literature as methods for the cross-linking degree evaluation, but also determining the solvent penetration rate and the d,l-glyceraldehyde reacting percentage. It has been observed, in fact, that the cross-linker solvent composition influences the penetration rate through the matrix of the cross-linker, thus controlling the homogeneity of the matrix cross-linking.