Dielectric Characteristic of a Glycerol and a Globular Protein in Solution

Abstract

The dielectric dispersion of a glycerol (lipid) and a globular protein casein (the most abundant protein in milk) have been investigated by means of a resonance technique over the frequency range 0.1 ± 50 MHz for three concentrations and at a mean room temperature of 24 0.5 0 C.The study revealed that casein exhibited beta-dispersion and has while the glycerol did not. The dielectric parameters of the protein like the dielectric increment, relaxation frequency and relaxation time show some dependence on concentration, and the sample studied displayed more than a single relaxation time indicating that the Cole-Cole structural model is better than the single Debye model in explaining its structural properties, whereas this is not the case with the glycerol. The large values of the Cole-Cole spread parameter,α also suggest structural heterogeneity of the casein molecule in solution. The average dipole moment of 386 ± 16D when compared with other globular proteins could mean some degree of asymmetry of the electric change distribution, of the casein molecules in solution. As for the glycerol it does not exhibit any degree of asymmetry as the curve is almost parallel to the frequency axis.