54 FORMULATING FOR MILDNESS
Biomimetic emulsifier with cashmere touch
Audrey Manière, Aurélie Trunet, Camille Olive, Carine Bezivin – IFF/Lucas Meyer Cosmetics, France Estelle Loing - IFF/Lucas Meyer Cosmetics, Canada
Most personal care products are emulsions which can be defined as stabilised fluid systems of liquids that do not normally like to mix, like oil and water. The peacekeeper in such systems is called an emulsifier. Emulsifiers combine a water-loving head holding to the water phase and a fat-loving tail that clings to the oil phase. Oil-in-water (o/w) emulsifiers keep oil drops packed in water, while water-in-oil (w/o) emulsifiers rather retain water drops in oils. Classic emulsifiers are typically synthetic petroleum and hydrocarbon derivatives such as PEG compounds, alkoxylated amides, silicone derivatives, and ethoxylated fatty alcohol. They present the advantages of being performant, rather inexpensive, easy to work with and readily available. On the downside, some can cause skin irritation and allergies. This happens because they keep their emulsifying properties while penetrating the skin. Lipids can thus be washed away from the stratum corneum altering the multilamellar structure of the latter and compromising the barrier function of the skin. The current trend in skin care is for natural, gentle and safe products, obtained in a sustainable manner. With the help of the Internet, end users (especially Millennials) are now better informed and take the time to read product labels in order to identify potential harmful ingredients. Formulators should keep this in mind when choosing an emulsifier. What is
the point of formulating with the most natural actives, if the ingredient list ends with chemical names of bad reputation? But, are there alternatives to classic petrochemical emulsifiers and how do their performances compare?
Phospholipid-based emulsifiers offer great natural alternatives. Phospholipids generally consist of a hydrophilic phosphate head and two hydrophobic fatty acid tails joined together by a glycerol molecule. In an aqueous environment, phospholipids spontaneously arrange in bilayers in which hydrophobic tails line up against each other, while hydrophilic heads face water molecules on both sides. All living cells are surrounded by such a phospholipid bi-layer that protects them and regulates what goes in and out. For cosmetic applications, lecithin is the main natural source of phospholipids. Lecithin can be extracted from various vegetal sources including soy beans, rapeseed, cottonseed and sunflower seed, among others. Hydrogenation of lecithin greatly improves its stability against heat and oxidation and adds thickening properties.1
Hydrogenated lecithin has
multifunctional properties that make it very attractive for skin care formulations. As a technical ingredient it provides excellent emulsifying properties, plus a very soft and comfortable skin-feel. As an active ingredient, it has the ability to improve skin hydration and protect the skin barrier.1 With Biophilic™ H, IFF/Lucas Meyer
O/W Lamellar emulsion Lamellar network
Cosmetics has optimised the O/W emulsifying and viscosity enhancing properties of hydrogenated lecithin by combining it with a fatty acid (palmitic acid) and a fatty alcohol (C12-16 Alcohols). The combination increases the emulsifying and sensory properties of phospholipids and stabilises the emulsion once formed. Biophilic H also constitutes an efficient delivery system that facilitates skin absorption of hydrophilic molecules. Finally, Biophilic H acts as an active ingredient that moisturises the skin, protects the skin barrier, improves skin smoothness and preserves the skin brightness balance.
Technical characteristics Biophilic H is a patented combination of fatty amphiphiles (Palmitic acid and C12-16 Alcohols) and hydrogenated phospholipids.
Biocompatibility Phospholipids are amphiphilic molecules naturally present in all living cells making them efficient emulsifiers with great skin compatibility. They easily penetrate the skin. Hydrogenation improves phospholipids stability against oxidation and prevents discoloration and odour development. Hydrogenated phospholipids additionally are gentle to the human skin. When tested against other emulsifiers, hydrogenated phospholipids were the only ones to display absolutely no irritation potential.2
Hydrogenated
phospholipids are considered highly compatible even with sensitive skin.
Lamellar structure
Phospholipid bilayer
droplet Oil
Freeze-fracture TEM Showing lamellar structure (red arrows)
Figure 1: Promotion of lamellar structures. PERSONAL CARE EUROPE
Composed of saturated molecules (acid, alcohol and phospholipids), Biophilic H (now referred to as ‘the biomimetic emulsifier’) naturally forms a lamellar gel network in the continuous phase that entraps and stabilises the dispersed phase (Fig 1, middle and right panels). This lamellar gel is a bi-layered structure that not only thickens the water phase, but also mimics the stratum corneum three- dimensional structure thus facilitating the
April 2018
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