PRESERVATIVES 77
Natural and synthetic: bridging the gap
Naama Eylon – Sharon Laboratories, Israel
This article will outline the development process of new preservative solutions by Sharon Laboratories: Sharon™ Amplify, and SharoSense™ Plus. The industry analysis that led the decision to develop two new concepts ‘less is more’ and ‘synthetic-naturals’ as well as review the product efficacy and compatibility for the personal care industry. The development project of the
preservatives Amplify Line, started from the challenges the personal care industry is facing due to the global trends in preservation. The task formulators must address is choosing a preservative solution that will guarantee product safety. The risk of contamination can be influenced by many factors: Product type, where is it stored: exposed to moisture, heat or humidity?
INCI: water content, presence of natural extracts, mud, clay, some components create a tougher-to-preserve formula
Packaging: as in general an open jar may increase the contamination risk if compared to a pump or tube The products characteristics will define the type of threat to fight: Gram-negative and positive bacteria, yeast or mold. So while the need for product safety
remains high, the formulators must also take into consideration other aspects: regulatory updates, impact on odor, color, compatibility with other ingredients or even the country’s climate. Officially there are many different preservatives to choose from, but
5000 3750 1,000,000 <10 2500 1250 200 0 S. aureus 100 Figure 1: Amplify MIC comparison. May 2019 200 E. coli P. aeruginosa 100 A. niger 100 C. albicans
100 10 0
0 Days 7 Days 14 Days 21 Days 28 Days Figure 2: Amplify challenge test. PERSONAL CARE NORTH AMERICA
A. niger C. albicans
E. aureus
E. coli P. aeruginosa
SharomixTM
professionals in R&D feel there are fewer options. Often, it is the consumer who is perceived as the cause, for wanting ‘free from everything’ product and this generates a call for ‘mild’ systems, to replace classic preservative solutions. The problem is that mild systems are in fact… mild – too mild. Many of the new preservative solutions are not strong enough to handle the antimicrobial challenge, and there is a risk for microbial contamination. When the preservative solution is not
strong enough, there are a few actions the manufacturers of finished goods would do. First – to raise the level of use, and that would probably be over 1%. Another option is add additional material: booster, preservative, extract with some antimicrobial activity. One more path is adding a chelating agent, and of course, a combination of all the above. However, those steps have implications. Higher levels of use of a preservative can raise regulatory issues as many materials are allowed for use in a specific limit (like phenoxyethanol or benzyl alcohol at 1% maximal limit). In addition, a higher level of use can cause formulation hurdles such as impact on viscosity, stability, odor and more. Further implications come from the end user angle, such as skin sensitivity, and of course, higher cost.
Taking a new approach to preservation Many personal care companies today are
Amplify (Phenoxyethanol,
Ethylhexylglycerin, cationic surfactant) Phenoxyethanol, Ethylhexylglycerin blend
dealing with tough-to-preserve products, where they wish to avoid the use of classic reliable preservatives such as parabens, formaldehyde donors and isothiazolinones. Avoiding those drives them to use combinations of a solvent such as phenoxyethanol with a booster such as ethylhexylglycerin or caprylyl glycol, just to find out this solution is not enough for broad spectrum protection against bacteria, yeast and molds and poses a risk of possible contamination. Our goal was to offer a new preservative solution that would have strong efficacy, and allow a significantly lower level of use in finished products. In order to achieve this goal, we researched the potential role of cationic catalysis in preservation. It is found that a combination of several
ingredients known to have a mild antimicrobial profile can be reinforced by the presence of cationic surfactants in a specific low ratio.
Several molecules with cationic properties
were evaluated. Among them didecyldimmonium chloride, polyquaternium- 2, polyquaternium-80, and others. An optimization project was performed
in order to evaluate the level of the cationic surfactant needed to enhance different preservative solutions. It was proven that the addition of a cationic catalyst in various ratios improved the efficacy of the preservative blend significantly, allowing the level of use in a finished product to be reduced by 50%.
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