INTRODUCTION – Preserving Botanical Formulations
Preservatives are needed in cosmetic products for two reason. Firstly, to protect it from spoilage and; secondly to protect the consumer from being infected by a contaminated product.
Preserving botanical formulations naturally can be quite a challenge. Since the demonisation, bans and restrictions on some commonly used preservatives, scientists have had to think creatively about how they preserve cosmetics. As a result there has been growing interest in preservative free and self-preserving methods.
Self preserving cosmetics normally refers to products that have anti-microbial agents that are not listed under the Annex VI of the EU Directive. These types of ingredients are normally classified as skin conditioning agents or fragrance materials. They also refer to strategies used to create a series of hurdles which limit growth of pathogenic or product spoiling organisms.
Inventors of new preservative blends have to think outside the box when coming up with new and effective blends of antimicrobial ingredients that will satisfy buyer demands as well as be practical and easy to use.
Formulators also have to think more carefully about how they include these preservatives as some can compromise the formula i.e. cause destabilisation (separation or thinning of emulsions), change in colour, pH or scent. Many preservatives are based on blends of organic acids or alcohols which require a lower pH to be effective. This will obviously have a bearing on the other ingredients in the formula.
The following post is a basic guide to strategies that can be employed to preserving botanical formulations. A combination of using preservativesaccepted by most organic standards as well as the hurdle approach are normally enough to make something that is safe and virtuous to use and sell!
Why is preservation important and why should we care about germs?
A preservative can be defined as ‘A chemical agent that will either kill or inhibit the growth of microorganisms’
As stated above preservatives are used to protect the product from spoilage and also to protect the consumer from infection. There have been a documented cases of product contamination leading to serious illness and death. In the 1950’s there was a case of newborn babies contracting tetanus from contaminated talc. Similarly, in the 1960’s severe eye infections were linked to the inappropriate preservation of eye drops (1). For these reasons pathogens of concern, especially for the eye area include Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa and other Pseudomonas species also Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. These are thought to be the main pathogens likely to contaminate cosmetic products and cause harm.(2)
The cosmetic product is the perfect breeding ground for bacteria and fungi as S. Holm states;
”The nutritional requirements of most saprophytic non-fastidious spoilage contaminants are likely to be well met in almost all pharmaceuticals and cosmetics, since many ingredients are easily biodegradable, and even the trace residues of nonspecific chemical contaminants present in most commercial ingredients are likely to provide ample nutrients to permit growth. For example, even standard distilled and demineralized water contains sufficient trace nutrients to permit ample growth of pseudomonads and related species (Favero et al., 1971). It is usually the physicochemical [characteristics] parameters of the formulation which are the determining factors as growth will or will not take place’’(3)
USING THE HURDLE APPROACH
Hurdle technology or the hurdle approach has been used in the food industry since the 1970’s, and describes the use of different strategies to limit the things needed to support microbial growth. So what do microbes need to multiply to unsafe levels?
For growth, micro organisms need the following to thrive:
– Source of energy (food)
– Source of nitrogen
– Vitamins & related growth factors
– Minerals/heavy metals
Hurdle technology provides a number of challenges (hurdles) that the microbes are not able to overcome (jump over). This includes:
• Good manufacturing practice (GMP),
• pH control
• type of emulsion
• using multi-functional antimicrobial ingredients
• water activity and water content
The idea is that by creating a difficult environment for the organism to survive, you will eventually cause it to becoming inactive and unable to multiply/grow. These hurdles can mean that less or even no preservative is needed. (4)
In Preserving Botanical Formulations Naturally – Part 2 we will take a closer look at the hurdle approach.