Challenges in the Preservatives Market
Preservatives in cosmetics are one of the leading topics generating controversy. Numerous blogs, social media groups, and influencers discuss their effects, although the information they provide does not always come from reliable sources.
The dynamic beauty industry requires cosmetic manufacturers to introduce modern solutions, which presents a significant challenge for both formulators and marketing teams. Creating products that appeal equally to every consumer group is impossible due to financial constraints and differences in how individual raw materials are perceived. Preservatives are just one element of this complex issue, but it is a broad topic that generates particularly strong emotions. Microbiological protection of cosmetic products is essential, but consumer expectations also need to be taken into account when developing a formulation — after all, the product is created for them. As the beauty industry continues to evolve, manufacturers face a number of challenges related to preservatives, including:
the poor reputation of preservatives listed in Annex V,
the balance between preservative naturalness and efficacy,
the high cost of alternative solutions.
Resistance to conventional preservatives
A great many myths have accumulated around cosmetic ingredients listed in Annex V of the EU Cosmetics Regulation. It is worth remembering that if an ingredient is permitted for use at a specified concentration, this means that, based on current knowledge, it is considered safe. This did not, however, save parabens, which have almost disappeared from cosmetic formulations. Other examples include isothiazolinones, phenoxyethanol, and DMDM hydantoin — ingredients that were widely used just a few years ago but are now increasingly being replaced by alternative preservation systems. Fortunately, potassium sorbate and sodium benzoate, which are widely used in the food industry, as well as dehydroacetic acid and the arginine derivative ethyl lauroyl arginate HCl, are still viewed more positively.
The negative perception of preservatives is primarily rooted in their synthetic origin and occasional cases of skin irritation or sensitization. Manufacturers use the absence of these substances from a formulation as a marketing tool, resulting in the widespread use of claims such as “paraben-free” or “formaldehyde donor-free.” It is worth remembering that such claims may only be used in specific circumstances where the absence of a particular ingredient represents a genuine benefit, for example in products intended for very young children.
Cosmetic manufacturers are not indifferent to consumers' criticism of cosmetic ingredients and continue to demand new alternatives from raw material suppliers.
Additional options
Other substances not listed in Annex V can also inhibit the proliferation of microorganisms, opening up possibilities for developing cosmetic products without ingredients that are negatively perceived by consumers. The industry's demand for alternative preservatives is strong, and suppliers' portfolios are therefore expanding systematically. A characteristic feature of many new raw materials, compared with conventional preservation systems, is their multifunctionality.
Until recently, many of these substances were used as so-called “preservation boosters” because they supported the activity of the main preservative (from Annex V) and made it possible to reduce its concentration. However, research into alternative solutions has shown that using the right combination of boosters can provide cosmetics with effective microbiological protection while completely eliminating conventional preservatives.
The leading ingredients include various alcohols and their derivatives, as well as sugars:
phenethyl alcohol
glycols: pentylene glycol, hexylene glycol, heptylene glycol, caprylyl glycol, decylene glycol, propanediol
ethylhexylglycerin
methylheptylglycerin
esters: glyceryl caprylate or glyceryl undecylenate
o-cymen-5-ol
phenylpropanol
xylitol and anhydroxylitol, xylityl sesquicaprylate
maltitol with Polyquaternium-80
In addition to the above, there are other interesting alternatives:
hydroxyacetophenone (piceol)
hinokitiol
caprylhydroxamic acid
levulinic acid and sodium levulinate
anisic acid and sodium anisate
lysine
Some manufacturers are able to preserve a product using phenethyl alcohol alone, but its efficacy depends on many factors, including the concentration of the substance, other ingredients in the formulation, pH, and packaging type. It is worth noting that this is not an inexpensive solution, although it does offer significant advantages such as natural origin and a pleasant fragrance often described as violet-like. Phenethyl alcohol is a constituent of essential oils from rose and geranium.
Glycols are becoming increasingly common in cosmetic formulations and are successfully replacing glycerin and propylene glycol because they offer similar properties: they moisturize and soften the skin and prevent cosmetic products from drying out, while avoiding a sticky skin feel. They can also act as solvents for highly polar active ingredients, such as hydroxyacetophenone, resveratrol, and certain fragrance compositions.
Ethylhexylglycerin, like methylheptylglycerin, when used at concentrations above those required for a microstatic effect, can function as an active ingredient with moisturizing and emollient properties. It also reduces whitening of emulsions on the skin and works particularly well in deodorants without disrupting the normal skin microbiome.
Glyceryl caprylate and glyceryl undecylenate, in addition to their preservative properties, condition the skin and hair and provide refatting, moisturizing, and emollient effects. They can also support the emulsification of the oil phase.
O-cymen-5-ol is an interesting and effective alternative to conventional preservatives. It offers a number of advantages: it is active not only against bacteria and fungi but also against viruses, provides additional antioxidant protection, soothes redness and inflammation, and helps prevent the worsening of acne, making it a useful ingredient in this type of cosmetic formulation.
Phenylpropanol is a fragrance ingredient found, among other sources, in strawberries and in hyacinth and narcissus flowers. It has a broad spectrum of antimicrobial activity and a wide effective pH range, which has led to its use in many types of formulations. Its use may also make it possible to omit a separate fragrance composition.
One of the directions in the development of new “preservatives” involves xylitol derivatives. Xylitol itself can inhibit microbial proliferation and, like most sugars, also has moisturizing properties. A rather unusual system is the combination of maltitol and Polyquaternium-80, which has a pleasant caramel-like scent and conditions the skin, while offering low use levels, high efficacy, and natural origin.
Hydroxyacetophenone, although obtained synthetically, occurs naturally in a variety of plants, including white spruce, and has antioxidant and soothing properties. It is most commonly used in combination with pentylene glycol or hexylene glycol.
Another booster discovered in coniferous trees is hinokitiol, which has a characteristic cypress-like scent and proven antibacterial and antiviral activity. Due to its terpenoid structure, it may also exhibit anti-inflammatory properties.
An interesting and effective alternative is caprylhydroxamic acid, which has chelating as well as moisturizing properties. It is particularly well suited to natural formulations as an ingredient that inhibits the proliferation of mould and fungi, but it requires additional support against bacteria, for example from caprylyl glycol.
Levulinates and anisates are becoming increasingly popular, and both manufacturers and consumers are becoming more familiar with them. In cleansing products, they can be used together, whereas emulsions require additional wetting or emulsifying agents, such as glyceryl caprylate. Anisic acid has a delicate fragrance and can therefore serve as the only perfuming substance in a formulation.
Among the simple alternatives to conventional preservatives is a rather surprising ingredient: poly-epsilon-lysine. It is an amino acid and can therefore serve as a structural and nourishing component for the skin, while also providing conditioning benefits for the hair.
Natural preservative blends
The substances described above can be used individually or in combination with complementary ingredients, but this is not the only solution offered by raw material suppliers. An increasing number of blends based on plant extracts are available that can effectively inhibit microbial proliferation. These are typically multifunctional blends based on citrus extracts, garlic ferment, or radish ferment. Examples of the INCI compositions of such raw materials include:
Pentylene Glycol, Glycerin, Citrus Aurantium Amara Fruit Extract, Citrus Reticulata Fruit Extract, Citrus Aurantium Sinensis Peel Extract
Camellia Sinensis Leaf Extract, Yeast Ferment Extract, Glycerin, Allium Sativum Bulb Extract, Water
Glycerin, Citrus Reticulata Fruit Extract, Citrus Aurantium Amara Fruit Extract, Citrus Sinensis Peel Extract, Ascorbic Acid, Citric Acid, Lactic Acid, Water
Benzyl Alcohol, Glycerin, Citrus Reticulata Fruit Extract, Citrus Aurantium Amara Fruit Extract, Citrus Sinensis Peel Extract, Tocopherol, Ascorbic Acid, Citric Acid, Lactic Acid, Aqua
Leuconostoc/Radish Root Ferment Filtrate
Their undeniable advantage is their high level of natural origin, as well as additional properties, such as supporting the care of skin affected by seborrheic dermatitis.
Conclusion
Replacing phenoxyethanol or isothiazolinones in long-established formulations requires both financial and time investment because alternative raw materials are considerably more expensive than conventional preservatives. Until recently, the cost contribution of MIT + MCIT as a preservative system could amount to just one grosz per kilogram of shampoo, whereas developing a natural shampoo may require an ingredient that increases the cost by, for example, PLN 1–5 per kilogram.
Furthermore, changing the preservative system often causes undesirable changes, such as thinning of the formulation or altered sensory properties during application. These changes need to be corrected, which also increases the cost of the product.
Naturally, a series of additional tests must also be performed, including microbiological testing, preservative efficacy testing, stability testing, and compatibility testing between the formulation and packaging.
Some preservation systems need to be supplemented with an additional raw material because they are not sufficiently effective on their own. Others have to be used at relatively high concentrations (e.g. 4–5%), while several of the ingredients mentioned above have a distinctive scent that may not always fit the concept of the product.
All of these factors make reformulation a difficult, laborious, and costly process, which often makes it more practical to develop a completely new product from scratch.
The beauty industry requires flexibility and the ability to respond quickly to consumer needs, which is reflected in the ever-growing number of cosmetic raw materials available on the market. To maintain strong interest in a product brand, formulations must continually evolve through the implementation of modern solutions, including alternative preservation systems.
Many companies have already introduced some of the ingredients described above, but for a large number of manufacturers, alternative preservation remains a challenge that they will have to address in the future.
Zuzanna Fedyczak for "Chemia i Biznes - Rynek kosmetyczny i chemii gospodarczej "1/2022 page 40
