CHARACTERIZATION OF THE VARIATION IN THE PHYSICAL-PROPERTIES OF COMMERCIAL CREAMS USING THERMOGRAVIMETRIC ANALYSIS AND RHEOLOGY

A study was conducted to compare the physical properties of Aqueous Cr eam BP obtained from different manufacturers. The samples were studied using thermogravimetric analysis (TGA) and stress scan rheology as co mplimentary techniques. TGA studies showed two main peaks in the first derivative curves, corresponding to free and lamellar water. The prof iles for creams obtained from different manufacturers showed marked va riations between the samples, although the total water content was sim ilar in all cases. Similarly, stress scans also showed marked differen ces between the creams, although no clear correlation between the ther mogravimetric and rheological data was observed under the conditions u sed in the study. Three batches of cream from one manufacturer were th en examined. Differences in the rheological properties were again obse rved, but less marked differences were seen in the TGA profiles. The s tudy indicates that while the chemical composition of commercial aqueo us cream may be controlled, considerable variations in the physical pr operties of these systems may be observed, both between different manu facturers and between batches from the same manufacturer. The implicat ions of the poor correlation between stress scan rheological and therm ogravimetric analysis data are discussed in terms of the use of these two methods in the quality control of creams. (C) 1997 Elsevier Scienc e B.V.