Characterization of Natural Moisturizers by Hygroscopicity

Effects of hygroscopic moisturizers are evaluated by means of dynamic hygroscopicity and unfrozen water (UFW) value measured by DSC. The Natural Moiturizing Factors (NMF) evaluated are Na PCA, L-Proline, Na lactate, Glycerin, Na hyaluronate, partially hydrolyzed chitin and Na polyglutamate. NMF moisturizers are classified into four types of groups by their hygroscopic profiles and water holding capacities. L-Proline showed desirable features as a moisturizer which has relatively consistent water retention with the excellent water holding capacity regardless of humidity change. UFW are measured by DSC and showed good correlation to the hygroscopicity of NMF moisturizers. UFW measurement can be done within one hour, while it will take several weeks to finish conventinal hygroscopicity measurement. Thus UFW measurement by DSC is found to be useful method to predict potential hygroscopicity.