Interactions between β-lactoglobulin and sucrose stearate at the air-water interface

摘要

We have studied the change of spread β-lg films with time by monitoring the changes in the mean area per molecule and the dilatational modulus. Film change proceeds at a slow rate. Cross-linking of protein molecules at the interface has been considered as a possible explanation. The effect of the addition of Suc18 to the protein monolayer at molar ratios (sur-factant:protein) of up to ca. 2.3 has been studied. Addition of Suc18 at a 1:1 molar ratio has been found to lead to a higher change (denaturation) rate of protein molecules. Film ageing is also reflected on the dynamic properties. The dilatational modulus decreases with time as a result of irreversible changes in the conformation of protein molecules at the interface. The addition of Suc18 shifts the modulus-time curve to lower values.