This is a post by Nitesh Rajput
Cosmetic products become easily contaminated by bacteria and fungi. Containing water, oils, peptides, and carbohydrates, cosmetics are a very good medium for growth of microbes. All these factors contribute to the fact that cosmetic products need preservation to prevent microbial growth, spoiling of the cosmetic product and potential skin infections.
Need for cosmetic preservatives
The need to control microbial activity is inherent in two major facets of personal care. The first area is that of antimicrobial care where the product helps to retard the growth of topical pathogens, or eliminates them. The second is in the area of preservatives that retard the growth of microbes in personal care product formulations.
Cosmetic preservatives have potent antimicrobial properties preventing personal care products effectively from spoiling and prolonging substantially the shelf-life. Some of these agents also have stabilizing effects able to preserve the function of various active ingredients including anti-oxidants (vitamins), emulsifiers and surfactants.
Among the most effective natural preservatives are essential oils and various herbs such as rosemary, clove, thyme, cinnamon, tea tree and lavender,neem, grape seed etc. which are more organism specific than their synthetic counterparts. This means they may be effective against one organism but not another. They must be carefully blended to create a synergistic effect against a range of organisms.
The subject of natural preservatives is one that probably has more academic interest than practical or economic virtue because cosmetic preservatives have to fight a broad range of microbes. However, natural preservatives do give a wonderful marketing angle.
The preservative activity can be boosted by operating at as low a pH as possible. Natural acidity could be obtained from one of the many of the alpha hydroxy acids (AHAs) which are obtained from citrus species, where the major components are citric and malic acids.
Antioxidants such as natural tocopherol and ascorbic acid will further aid in preservation, as well as reducing the potential rancidity.
Why are preservatives necessary?
Most cosmetic products contain water and nutrients for microorganisms to grow and flourish. It has been amply demonstrated that inadequately preserved cosmetics can be hazardous to human health. Cosmetics with contaminants are not only unappealing to the eye and smell bad, but they may also be pathogenic resulting in the need for medical attention. Skin infections can result from contaminated body products, especially when applied to cracked dry skin.
Cosmetics are often stored in the bathroom where the environment is warm and moist. Our skin carries an abundance of microorganisms in addition to tap water which in turn is not sterile. Often times this water is introduced into products in either accidentally or even on purpose. The most carefully prepared products may become contaminated under these circumstances.
What to look for when choosing a Preservative
Ideally, when looking for a suitable preservative for cosmetics there are many things to be considered and to look for:
1. What ingredients are you using? Are they oil soluble or water-soluble?
2. What will the final pH of your product be?
3. Non-sensitizing: It should not have any allergic or sensitizing tendencies.
4. Broad Spectrum Activity. It should be active against both gram positive and gram negative bacteria.
5. Long lasting: it should continue to work under normal conditions and even less favorable conditions.
6. Rapid action: if your cosmetic should become contaminated the preservative should act quickly to re-sterilize it.
7. What sort of packaging are you using?
8. Non-toxic and Non-irritating
9. It should be compatible with all the ingredients in the formula
10. Stability: It should be chemically stable to heat or not undergo disintegration during storage.
Potential Natural Cosmetic Preservatives
Here is a brief list of materials that could be used as possible “natural” preservatives.
Salt (sodium chloride)
Bee Propolis - The propolis is effective in protecting the hive offering both antibacterial and antifungal properties.
Grapefruit Seed Extract
Alpha tocopherol (also known as vitamin E)
Grapfruit Seed Extract
Essential Oils (various)
For more see this article about alternative cosmetic preservatives