Eco-design emulsions: Replacing unsustainable ingredients while balancing sensory richness

02 May 2024 --- New research highlights efficacious, eco-friendly switches for commonly used synthetic cosmetic ingredients. Demonstrated in three skin care products crafted using an “eco-design” approach, the ingredients are shown to have little impact on sensorial properties and overall product excellence.

The topic of preserving efficacy and sensorial performance in eco-friendly formulations was prevalent at the recent In-cosmetics Global trade show in Paris, France, highlighting the direction in which the cosmetics industry is heading. The new study tackles the difficulties formulators encounter in striking this balance.

“Conventional high-performance ingredients, such as synthetic acrylic polymers, texturizing microplastics and silicone emollients, whose ecological impacts are not negligible, should be replaced by natural-origin and biodegradable ingredients or synthetic substitutes derived from green chemistry principles while safeguarding product excellence,” underscore the authors.

Dual challenge
Researchers followed an “eco-design” approach to formulate three cosmetic products sold in the pharmaceutical sales channel. They replaced the items’ eco-damaging ingredients with eco-friendly alternatives.

The final three products were an acne-prone skin serum, eye contour gel-cream and body butter, made with skin care ingredients from the Italian supplier Unifarco.

Synthetic texturizers, such as PMMA and nylon-12, which are considered microplastics with a toxicity profile for the marine fauna, were switched out with “natural organic and inorganic raw materials.”

The researchers swapped synthetic dimethicone for plant-based alternatives.Meanwhile, non-biodegradable acrylic rheological modifiers — “whose persistence in the environment is problematic” — were replaced with associations of polysaccharides.

Additionally, the silicon emollients and film-forming polymers — “whose impact is determined by their chemical synthesis, which requires the consumption of many energy resources and determines significant CO2 emissions” — were replaced with plant-based emollients and a biodegradable elastomer.

Acrylic rheological modifiers, which were in the original formulas, were replaced with polysaccharidic raw materials: Sclerotium gum and xanthan gum, sphingomonas ferment extract, succynoglycan and carrageenan.

Dimethicone alternatives
The researchers also ditched synthetic dimethicone, which softens the skin, in favor of a blend of plant-based emollients. These included undecane and tridecane (natural hydrocarbons), C15-19 alkanes (long-chain fatty alcohols from plants) and ethyl olivate (an olive oil derivative).

Triheptanoin, a triglyceride from caprylic acid, was also used as a dimethicone substitute. Palm/kernel alkanes, derived from palm or palm kernel oil, were another plant-based alternative.

Other dimethicone switches included coco-caprylate/caprate (from coconut oil), C9-12 alkane (a medium-chain fatty alcohol), dilinoleic acid/butanediol copolymer (a plant-based wax) and castor oil/IPDI copolymer (a film-forming agent derived from castor oil).

In February, Personal Care Insights connected with AAK to discuss the supplier’s new fair trade plant-based dimethicone alternative based on shea kernels sourced from West Africa.

Performance results
With these three products, researchers performed a double-blind sensory test using instrumental techniques like rheological and texture analyses. Their aim was to assess the feasibility of substituting environmentally friendly ingredients for traditional “high-impact” ingredients in skin care emulsions.

The study affirms cosmetic companies can innovate responsibly by implementing eco-design principles.Rheological analyses can be used objectively and scientifically to support marketing claims of application and sensorial properties, the authors suggest.

“The replacement of the rheological modifiers in the three formulas highlighted how the use of polysaccharides resulted in a decrease in the elastic properties together with a reduction in cohesiveness and adhesiveness,” they report.

“On the other hand, the replacement of silicone emollients is highly appreciated in terms of sensory properties as they give a light, flowing, and silky texture to products, with different naturally derived emollients causing different interactions with the skin, which are difficult to detect with instrumental characterization, having an impact on the after-feel phase of the product after application.”

The researchers stress the importance of choosing raw materials carefully when minimizing the environmental impact of rinse-off and leave-on cosmetics. A “careful adjustment” is required when switching from conventional to environmentally friendly ingredients to maintain product stability and customer satisfaction, they suggest.

“The differences recorded were limited and not so marked, being inevitably due to the specificity of the raw materials used and the intrinsic performances of the selected polysaccharides,” note the researchers.

Eco-design principles
The study affirms cosmetic companies can innovate responsibly throughout the product life cycle by implementing eco-design principles. When using this method, environmental effects must be taken into account, from the procurement of raw materials to the final disposal of the product.

“With rinse-off cosmetics, water usage and the downstream effects on aquatic ecosystems are crucial concerns. On the other hand, for leave-on products, the upstream phase and raw material sourcing hold greater environmental significance, underscoring the importance of sustainable ingredient selection,” details the paper.

The research further emphasizes the importance of life cycle assessments in impartially assessing the sustainability of products. The protocol provides a systematic way to choose environmentally friendly ingredients that closely resemble the performance of synthetic counterparts, even though exact replication of the original formulas may not always be possible.

By Venya Patel

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