OIL-IN-WATER CREAM STABILITY 227 320 310 29O 280 - 270 - I [ I I •-]'" - I [ I I I -- I I --r' '• ' I I I z 4 i 8 lO l:Z 14 nu,• Figure $. Time dependence of the consistency as a function of cream prepared with U.K.-sourced glyceryl monostearate with ([2]) and without (+) added stearic acid. 1o -' g- o- 7- 6- 4 - 0 2 4 8 8 10 12 14 1• 111dE (dM) Figure 9. Time dependence of the extent of bleed as a function of cream prepared with U.K.-sourced glyceryl monostearate with ([2]) and without (+) added stearic acid.

228 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS EVALUATIONS OF GLYCERYL MONOSTEARATE SOURCED FROM NON-U.S. MANUFACTURING PLANTS Glyceryl monostearate samples sourced from inventory supplies of manufacturing plants located in Canada, Germany, Greece, South Africa, and Spain were obtained. Analyt- ical and thermal analysis results were compared to those previously obtained for U.S. and U.K. samples. Five cream batches (20 kg each) were prepared. Each of the cream bases contained glyceryl monostearate supplied from one of the above-mentioned plant sources. As shown in Table IV, there appeared to be a rank correlation between the bleed poten- tial of the cream and the acid value of the glyceryl monostearate raw material. The creams containing glyceryl monostearate with very low acid values of about 1 or less exhibited the most initial bleed. Those with acid values of 2-3.5 showed slight initial bleed, and those with acid values of about 5 and greater did not exhibit bleed. Initial higher penetrometer results, which are indicative of softer cream consistency, were ob- tained for creams containing glyceryl monostearate, having lower acid values. Thermal analysis and variable temperature x-ray diffraction measurements accurately classified and predicted the probable effects that each glyceryl monostearate source would have on the consistency and bleed propensity of the finished cream. All of the multi-sourced glyceryl monostearate cream bases developed firmer consistency and diminished bleed potential after 7 days of bulk storage at 24 ø ___ 3øC. CONCLUSIONS Glyceryl monostearate was identified as the key excipient influencing the gel structure, consistency, and bleed properties of the oil-in-water emulsion-type cream base. Acid value, which is a measure of the free fatty acids in the glyceryl monostearate, was found to be an important indicator of raw material quality. Creams prepared using glyceryl monostearate with low acid value (1-3.5) had soft consistency and exhibited liquid bleed separation initially after manufacture. Creams containing glyceryl mono- stearate with higher acid value (5- 15) had satisfactory firm consistency without bleed. Table IV Influence of Glyceryl Monostearates Sourced From Various Countries on the Consistency and the Propensity for the Occurrence of Bleed in Cream Base Observation on wire-mesh test for bleed After 7 days Sourced Acid X-ray Initial storage at from value type penetrometer Initial 24 + 3øC Germany 0.85 2 298 Bleed Slight bleed U.K. 1. ! 2 317 Bleed Slight bleed Greece 2.0 2 297 Slight bleed No bleed Spain 3.5 2 293 Slight bleed No bleed U.S. 5. ! ! 285 No bleed No bleed Canada 10.0 1 266 No bleed No bleed South Africa 14.9 ! 284 No bleed No bleed