Optimization of cosmetic preservation: water activity reduction. (14th October 2014)

• Record Type: Journal Article
• Authors: Kerdudo, A.; Fontaine‐Vive, F.; Dingas, A.; Faure, C.; Fernandez, X.
• Is Part Of: International journal of cosmetic science. Volume 37:Number 1(2015:Feb.)
• Page Start: 31
• Page End: 40
• Publication Date: 2014-10-14
• Subjects: Cosmetics -- Periodicals; 668.5505
• DOI: 10.1111/ics.12164
• Languages: English
• ISSNs: 0142-5463

Abstract

<abstract abstract-type="main" id="ics12164-abs-0001"> <title>Synopsis</title> <sec id="ics12164-sec-0001" sec-type="section"> <title>Objective</title> <p>Preservation of cosmetics is a prerequisite for industrialization, and among the proposed solutions, self‐preserved cosmetics are of great interest. One key influencing parameter in self‐preservation is water activity; its reduction can help to fight against microbial growth in cosmetic products. This work presents a study on the influence of humectants on water activity and its consequence on the preservation of cosmetic formulations.</p> </sec> <sec id="ics12164-sec-0002" sec-type="section"> <title>Methods</title> <p>First, water–humectants mixtures were considered. The influence of glycol and glycerin content, glycol chemical structure, glycerin purity and formulation process on the water activity of the binary mixture was studied. Molecular modelling was performed for a better understanding of the impact of glycol chemistry. Then, the results were applied to five different cosmetic formulations to get optimized products. Challenge test on five strains was carried out in that sense.</p> </sec> <sec id="ics12164-sec-0003" sec-type="section"> <title>Results</title> <p>We showed that the higher the humectants concentration, the lower the water activity. Glycol chemical structure also influenced water activity: propan‐1, 2‐diol was more efficient than propan‐1, 3‐diol, certainly because of a better stabilization in water of propan‐1, 2‐diol as shown by DFT calculation. A drop by drop introduction of glycol in water favoured a<sub>w</sub> reduction. The best water activity loss was 6.6% and was reached on the cream formulation whose preservation was improved as evidenced by challenge test.</p> </sec> <sec id="ics12164-sec-0004" sec-type="section"> <title>Conclusion</title> <p>Fabrication process as well as humectants concentration were shown to influence water activity. The hydroxyl group positions as well as the presence of an alkyl group on the glycol carbon chain impacted water binding as suggested by DFT calculation. Reducing a<sub>w</sub> improved the preservation of a cosmetic cream, inhibiting or slowing down the growth of bacteria and fungi.</p> </sec> </abstract>