Improvement of preservative systems

Dr Carsten Dietz – Cosphatec, Germany

“Nowadays it must be hard to be a preservative. Every formulator needs you but no one wants you.” says Dr Carsten Dietz, technical expert in sustainable preserving systems. Over the past decade, preservatives have been the subject of much controversial discussion and thus came to the attention of the public: many magazines and rating sites started talking about this contentious topic. The story of preservation is an old one and still holds many pitfalls. On one hand consumers would like to have a long shelf life for the cosmetic products they purchase, but on the other many have negative feelings towards preservatives. This makes it difficult sometimes for formulators to find the right choice which must agree with what they stand for, their marketing strategy and their brand image. The good news is that there are several solutions already in existence, and this article will introduce you to suitable options and also to the challenges one might face during the process. Before diving into the world of preservatives, the question as to what is considered a preservative needs to be addressed first: From a microbiological point of view,

the answer is easy. All substances that avoid bacteria, yeasts and moulds growing are considered preservatives. This includes oils and salt, among other substances, that have been used to preserve food for centuries. In the field of cosmetics, the answer is not

so simple and may be different from country to country or differ within regionally responsible authorities. In the EU, cosmetic manufacturers need to follow the European Cosmetic Regulation. Based on this regulation, each substance that has only one function and which is to preserve, is listed as a preservative. All substances that have several additional

functions conducive to preserving – including a strong antimicrobial efficiency – are not categorised as preservatives. In China it happens to be much more

complicated, because authorities defined strict rules that each cosmetic product has to contain at least one listed preservative. This can be very challenging, as more and more brands are exporting their products to other countries. The difficulty lies within the different countries. Some countries simply do not want to use listed preservatives, whereas others even banned them or, as the example in China showed, some countries made it a requirement to include listed preservatives. CH3 C HO C O Figure 1: Zinc salt of lactic acid. Still, the most important thing is to

ensure suitable antimicrobial protection of a cosmetic product. When looking for a suitable antimicrobial, other aspects such as packaging solutions and good manufacturing practice need to be considered, too. This article focuses on the aspect of the suitable ingredient for such preserving systems. Finally, each formulator and/or company

needs to find raw materials that fit their products and also their brand. Unfortunately, the “one and only” preservative does not exist. Each formulation is unique, and the most

suitable antimicrobial system should be selected individually, case by case. In general, it is always recommended to combine at least two different antimicrobials that have a different mode of action. By combing two to three antimicrobials, the smart combination will show – in best case scenario – a synergetic effect which the formulation will benefit even more from. As is generally known, specific

preservatives were listed including a regulated microbial Anti- oxidative Anti-

inflam- matory


Anti- odour

maximum allowed application concentration, because some of them exhibited proven negative side effects. Whereas for other listed preservatives there may be indicators of negative side effects, but those were never proven to be related. In my opinion, it is always smart to choose ingredients – preferably not listed – that have many positive side effects, a good reputation on typical rating platforms like, for example, and no or as few negative side effects as possible. Often, such substances are called multifunctionals.

To improve preserving systems the usage of multifunctionals is strongly recommended For a better understanding of the so called multifunctionals, they can be explained using two products as an example, so the additional benefits – as well as protecting the product – can be explained. Furthermore, a short overview of frequently used strategies and typical combinations will be given afterwards.

Anti- acne

Anti- Aging

pigmen- tation

Anti- Zinc Lactate Moisturising Antimicrobial Figure 2: Versatile functions of zinc lactate. July 2021 PERSONAL CARE Exfoliation Suncare O- Zn2+ O- C O CH3 C C


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