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Preventing Microbial Contamination

Open Cosmetics

Preventing Microbial Contamination of Anhydrous Products

Even products that are made without water (“anhydrous”) need protection from microbial contamination. A natural multifunctional active ingredient may be a safe alternative to traditional preservatives.

Bacteria, yeasts, and molds are ubiquitous in nature, which means they are virtually everywhere – ready to grow and cause problems. Cosmetic products provide a wide spectrum of physical and chemical requirements for microbial growth. Perhaps one of the most important requirements for microbial growth is water. It may seem logical to believe that the exclusion of water from product formulation would mean that the use of a preservative system would be unnecessary, but this is not always the case.

Anhydrous, meaning “without water,” products still need a preservative system as a means to protect the product from contamination by consumer use. Consider the use of an anhydrous lip balm being applied to the lips. The product is susceptible to contamination by its environment after opening and then is further exposed to contamination each time the lip balm comes in contact with the mouth area. The repeated exposure to sources of contamination creates a breeding ground for bacteria. Failure to properly preserve the lip balm could result in an infection or other health hazard to the consumer.

As a consumer uses a product, it is inevitable that the product will be exposed to contamination at some point during use. While it seems there’s a high demand for “preservative–free” products in the industry, is it really possible to develop adequately preserved products without the use of traditional preservatives?


A properly preserved formulation is the only way to protect consumers from microbial harm. Luckily, cosmetic formulators have different options to maintain product integrity in lieu of traditional preservatives by using natural multifunctional active ingredients.

What are natural multifunctional active ingredients? Nature provides us with exceptional ingredients that are able to provide desirable benefits such as moisturization and skin conditioning, as well as upholding product integrity. These ingredients provide a solution to the consumer demand of natural, effective, and safe alternatives to traditional preservatives.

Natural multifunctional active ingredients are designed to work in combination to provide full spectrum protection against microbial contamination as a means to keep the product and the consumer safe from contamination.

It is critical to evaluate the ingredients in the formula and determine whether they are oil soluble or water soluble when selecting natural multifunctional actives as preservative systems. When formulating an anhydrous product, such as a lip balm or waterproof mascara, the ingredients are likely all pigments, waxes, and oils that are oil soluble. In this case, an oil soluble natural multifunctional active will be ideal.

An effective oil soluble multifunctional active available on the market is Sambucus nigra fruit extract, a product that capitalizes on the antioxidant and antimicrobial power of the natural super–fruit, elderberry. This product can be incorporated into anhydrous formulations at use levels of 1.0 to 5.0% and will deliver both skin conditioning benefits as well as protection from harmful microbial growth. Sambucus nigra fruit extract is a breakthrough oil soluble, natural multifunctional active perfect for formulators looking to move away from traditional preservatives.

Table 1 (next page) shows the ingredient list for an anhydrous lip balm formulated with the oil soluble natural multifunctional active Sambucus nigra fruit extract.

Castor Oil

The formulating process for this lip balm is as follows:

  1. Combine ingredients 1–4, 6–8, and 11. Heat to 70°C (158°F) while constantly mixing.
  2. In a separate container, combine castor (Ricinus communis) seed oil and iron oxide and mix until well dispersed. If necessary, add heat, but do not exceed 70°C (158°F). Once well dispersed, add to main container and mix thoroughly.
  3. Cool mixture to 60°C (140°F). At temperature, add elderberry (Sambucas nigra) fruit extract and fragrance individually.
  4. Pour mixture into your container of choice then cool to room temperature
Table. Anyhydrous Lip Balm Formula

The finished product ingredient declaration, assuming fragrance at 1% or less, would be:

Jojoba (Simmondia chinensis) seed oil, octyldodecanol, castor (Ricinus communis) seed oil, sorbitan olivate, beeswax, microcrystalline wax, ethylhexyl palmitate, elderberry (Sambucas nigra) Fruit Extract, coconut (Cocos nucifera) fruit extract, hydrogenated olive oil, olive (Olea europaea) fruit oil, olive (Olea europaea) oil unsaponifiables, silica dimethyl silylate, butylene glycol, gamma aminobutyric acid, caprylyl glycol, phenoxyethanol, hexylene glycol, sodium hyaluronate, fragrance, iron oxide.


Formulator Sample Shop® is a supplier of specialty ingredients for the personal care and cosmetic industries, offering a wide range of products to meet the needs of both formulators and manufacturers.

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