Article by: Perry Romanowski

One of the most common type of questions we get asked here on Chemists Corner is about natural preservatives.  On the one hand this is great because it demonstrates that people understand they should be using preservatives when formulating cosmetics.  On the other hand it is troubling that some formulators (or the marketing people they answer to) have lost faith in standard, proven effective & safe, preservatives.  

But there is certainly a desire to have formulation preservative strategies that stay away from using traditional preservatives such as parabens, formaldehyde donors, and organic biocides. We’ll look at some natural preservation options below.

Hurdle strategy of cosmetic preservation

In the old days of formulating if you had a microbial problem you could simply put in parabens and formaldehyde donor ingredients and that would be effective most of the time. If you had a particularly persistent problem you could also include something like Kathon. As a natural formulator those ingredients are generally frowned on and not allowed. This means you’ll need some alternative cosmetic preservatives. But even before choosing a new preservative you can employ hurdle strategy for reducing the preservative need.

Hurdle technology – The idea behind hurdle technology comes from the food industry. This strategy involves finding different materials and factors that inhibit microbial growth on their own but at high levels. By combining these factors you can reduce the amount of any of them while still killing off more and more microbes. The idea is that you make it more and more difficult for microbes to grow and thus have a preserved product. Some of the factors involved in hurdle technology include

  • Low pH – Most bacteria grow best at a pH level of 6.5 – 7.0.  Fungi grow better at pH levels from 5.0 – 6.0. So, if you keep your pH below 5.0 you help preserve your products.
  • Heat – Use of heat during production can reduce the initial microbial count and help preserve your product.
  • Reduce water – If you use a lower level of water activity or include ingredients that can tie up water in your system microbes can’t grow. With a water activity level below 0.87 most organisms won’t grow.
  • Anhydrous – of course you could just make an anhydrous formula. This limits your options but it also reduces the amount of preservative you need.
  • Chelating agents – These ingredients can help boost the effect of your preservative. Standard cosmetics would use EDTA but for natural formulators you can try an ingredient like phytic acid extracted from rice bran.
  • Antioxidants – These will help prevent rancidity and will also slightly inhibit microbial growth. Antioxidants are more relevant in food products than cosmetics.
  • Emulsion type – Products that are Water-in-Oil emulsions require less preservatives than the typical oil-in-water emulsion. This is because it is more difficult for microbial colonies to establish themselves.
  • Packaging – You can use single use or air tight packaging which will make it difficult for microbes to grow. This would reduce your need for a preservative.

Natural preservatives

While hurdle technology will help, it is not usually enough to preserve your products. You still need a preservative. If you don’t want to use standard products here are some options.

Phenoxyethanol – This ingredient is not approved by COSMOS but it is a common preservative for natural formulators. It is a solvent for fragrances and has a light rose odor. It is effective against some bacteria and fungi. Also good against pseudomonas.  It has a wide pH range and is effective from pH 3 – 10.

Phenethyl Alcohol – This ingredient is approved by COSMOS and works similarly to phenoxyethanol. It has a stronger odor however.

Organic acids and their salts – There are a wide range of organic acids that are effective as preservatives. These include

  • Benzoic acid
  • Sodium benzoate
  • Sorbic acid
  • Potassium Sorbate
  • Dehydroacetic Acid
  • Salicylic acid

These ingredients are mostly approved by the COSMOS standard and are effective against fungi and to some extent bacteria. They only work at lower pH however so if you use them you need to formulate below pH 5.0

Benzyl Alcohol – This material is effective against a broad spectrum of microbes. While it can be found in nature most of the benzyl alcohol used commercially is synthetically produced. One drawback is that it is a known allergen. There are also some compatibility issues with benzyl alcohol and nonionic surfactants.

Natural preservative boosters

Less effective ingredients that can help boost the efficacy of alternative preservatives include

The following ingredients can help disrupt growth by interfering with the microbial cell membranes.

  • Caprylyl Alcohol
  • Caprylic Acid
  • Gluconolactone
  • Glyceryl Caprylate
  • Ethylhexyglycerin

Other fragrance components have some preservative boosting activity

  • Levulinic Acid
  • p-Anisic Acid

There are also some enzymatic systems that have been successfully employed in natural cosmetic formulations.

  • Glucose Oxidase
  • Lactoperoxidase

Finally, there are some natural ingredients that have some antimicrobial functionality. They are not broad spectrum effective so should not be used as the sole preservative system.

  • Tea tree oil
  • Rosemary
  • Cinnamon
  • Aspen bark extract
  • Grapefruit seed extract
  • Honeysuckle extract

If you are formulating natural cosmetics and need a preservative system, your best strategy would be to use some of the suggestions above.  Admittedly, preserving products using only natural ingredients is difficult. Be sure to test everything you make multiple times until you are certain your preservative system will be adequate.  And as always, make the products in as clean an environment as possible.

About the Author

Perry Romanowski

Perry has been formulating cosmetic products and inventing solutions to solve consumer problems since the early 1990’s. Additionally, he has written and edited numerous articles and books, taught continuing education classes for industry scientists, and developed successful websites. His latest book is Beginning Cosmetic Chemistry 3rd Edition published by Allured.

5 comments

  1. Celine Leilani

    Hello Perry, I have a burning question that I constantly get conflicting answers with. Clay, as we know is notorious to preserve when mixed with water i.e such as a pre-made clay mask, however even if a clay was mixed let’s say with oils only does this still not activate all those microorganisms that clay naturally has occurring within it. I mean mixing oils only or honey or eo’ s would surely not create a moist environment still for the clay too start breeding bacteria? I would love an answer for this. I have been looking at creating a wet mask with oils and or waxes only, for me I still feel a preservative is required yet many fight me on this saying no. Any ideas? Can bacteria breed from that microbe filled clay been moist from oils only?

    1. Perry Romanowski

      For microbes to grow, they need food and water. In an oil environment like you’ve explained there would not be enough water for the bacteria to breed. I would agree that a preservative is still needed however, because moisture can get into the product and then microbes can grow.

  2. Marleen Maras

    Hello Perry, I hope you can help me with this question: A company selling natural products in UK is selling a day cream on their webshop that has these ingredients: Water (Aqua), Shea Butter (Butyrospermum Parkii), Apricot Kernel Oil (Prunus Armeniaca), Emulsifying Wax, Glycerine (Vegetable Glycerine), Vitamin E (Tocopherol Acetate), Rose Essential Oil (Rose Centifolia), Vanilla Extract (Vanilla Planifolia), Geranium Essential Oil (Pelargonium Graveolens), Lemon Essential Oil (Citrus Limonum) I have 2 questions please: 1. Is it possible to have a good preserved cream with only glycerin as preservative? 2. Is it possible that this cream passed and got the approval of a safety assessor? Many thanks in advance for your help! Marleen

    1. Perry Romanowski

      1. No. Glycerin is not a suitable preservative in this formula.
      2. Possibly. I don’t know who the safety assessor was or how they validated the product.

      With a quick look at the ingredient list I would guess that this product is not adequately preserved.

  3. Jini

    Thanks for all the great info Perry! I truly enjoy reading your blogs!

    Incase someone is having a hard time finding a good “natural” preservative alternative Optiphen ND is a pretty good choice if someone would like to stay away from parabens and formaldehyde. Its INCI name is Phenoxyethanol, Benzoic Acid and Dehydroacetic Acid. Some of its ingredients you mention on this articule.

    Hope this helps someone!

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