COMPARISON OF THE GELATION PROPERTIES OF BETA-LACTOGLOBULIN GENETIC VARIANT-A AND VARIANT-B

The gelation of beta-lactoglobulin genetic variants A and B (beta-Lg A and beta-Lg B) was examined with 7% protein solutions at pH 7. Both variants formed viscoelastic solid gels exhibiting low phase angles (<8 degrees) and dramatically increasing storage moduli during the cooling period as measured by small-strain dynamic theology. However, beta-Lg A had a lower gelation point (72.3 degrees C) and a higher initial gelling rate (15.4 Pa/min) than beta-Lg B (7.6 min at 80 degrees C and 2.9 Pa/min, respectively). Furthermore, the beta-Lg A gel had different viscoelastic properties than the B variant gel, as indicated by a shorter relaxation time (60 s) than that of the B variant (156 s). Thus, the subtle change in the primary structure involving two amino acid residues results in a very significant change in functionality.