Stabilization of Labile Active Ingredients in an Oil-Water Emulsion Cosmetics by Freeze-Drying

BACKGROUND: Due to the instability in oil/water emulsion, certain labile active ingredients were often not used in cosmetics. OBJECTIVE: The present study has tested the effect of freeze-drying to stabilize an oil/water cosmetic emulsion. MATERIALS AND METHODS: A preliminary freezedrying process was established at the basis of calorimetric and freeze-drying microscope studies. The stability of labile molecules in the cosmetic emulsion was evaluated at 48°C after freeze-drying. RESULTS: The accelerated stability experiment showed that the freeze-dried emulsion retained 90.1% vitamin C after 28 days at 48°C, whereas the oil-water emulsion retained only 28.3% vitamin C. The freeze-dried emulsion had significantly less oil oxidation than did the oil-water emulsion. CONCLUSION: Freeze-drying improved the stability of vitamin C and oily active ingredients in cosmetic emulsions.