Disruptive tech and company collaborations lead to cleaner biosurfactants for cosmetic formulas

12 Dec 2023 --- Biosurfactants, marine surfactants and marine-derived microbes are at the cutting edge of cosmetic formulation. Personal Care Insights learns more from Sasol Chemicals and two scientific studies published in MDPI and ScienceDirect.

“Surfactants are critical ingredients in daily cosmetic products such as creams, lotions, shampoos, shower gels and color cosmetics, but are often derived from non-renewable or less sustainable resources.” Edwin Habers, business segment manager of personal care, health and wellness at Sasol Chemicals, tells us.

By leveraging disruptive technology and industry partnerships, Sasol Chemicals launched its biosurfactants brand Carinex in October, showcasing mildness, multifunctional properties and improved sustainability such as a reduced product carbon footprint. 

“As one of the world’s largest manufacturers of surfactants, Sasol Chemicals is dedicated to developing ingredients with advanced properties that simultaneously meet our customers’ sustainability goals,” Habers says.

Biosurfactants for cosmetics
Commercial biosurfactants have been around for several decades. However, the primary barriers to widespread adoption of the technology in personal care are production costs, the performance of raw material quality and the purity and scalability of production. 

“Only recently have significant technological improvements of the downstream process, which involves separating and purifying biosurfactants out of the fermentation broth, come to fruition. Thanks to these improvements, the production of biosurfactants has become economically available and scalable,” Habers explains.

The first group within Sasol Chemicals’ biosurfactant personal care brand Carinex’s product portfolio is Carinex SL. These biosurfactants use sophorolipids derived from locally sourced, natural, palm-free oils and sugars — a sustainable solution that does not compromise on performance.Sasol Chemicals launched a biosurfactant range in October (Credit SurfactGreen). 

These multifunctional surfactants combine foaming and very mild cleansing action with skin and scalp care properties and can be leveraged in anti-acne and anti-dandruff formulations. These are suitable for micellar water, make-up remover concepts, daily face care routines, and treating dry and sensitive skin. 

Habers’ notes: “They can be used in combination with classical surfactant systems and sulfate-free alternatives to achieve innovative and non-irritating shampoo, shower gel and hand foam concepts suitable for sensitive users of daily personal care products and power users like professional hairdressers or medical staff who frequently come in contact with these formulations throughout the day.” 

The materials are compatible with cationic surfactants and feature synergistic properties with cationic conditioning polymers that can be used in 2-in-1 conditioning shampoo concepts, for example. In leave-on formulations, Carinex SL can be combined with co-components to be used as effective emulsifiers for lotions and creams in sun care routines.

Marine surfactants derived from marine-based feedstocks or produced by marine-derived microbes are not part of Sasol Chemicals’ current cosmetic ingredient portfolio, but the company believes partnerships are the key to unlocking and accelerating sustainable innovation. 

“We’re eager to see how our current and potential future partnerships result in additional sustainable solutions as long as they fit our five requirements,” says Habers. Sasol Chemicals’ criteria for developing surfactants and biosurfactants are high performance, biodegradability, reduced carbon footprint, affordability and scalability. 

Saponins-rich plant extract
A recent study published in MDPI observed the effects of saponins-rich plant extract phospholipid monolayers and liposomes on personal care formulations, among others. The Langmuir monolayer technique was used to study the interactions of model phospholipid membranes with saponins.

The area isotherms were determined for the 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayer with the addition of various concentrations of licorice saponins extracts and subjected to qualitative as well as quantitative analysis. 

The findings indicate that saponins interact with the phospholipid membrane formed by DPPE molecules and that the stability of the mixed monolayer strongly depends on the presence of impurities in saponins. The plant saponins biosurfactant-rich extract mainly interacts with the hydrophilic part of liposomes.Better emulsification can be achieved by customizing the oil-water interface, a ScienceDirect study found (Credit Skintegra).

The effects of licorice concentrations and their impurities on the surface properties of a lipid DPPE film were investigated using a model membrane. The researchers analyzed a crude extract (GgC) and a purified extract (GgP). 

They concluded that the GgP extract demonstrated better surface activities in the two-dimensional lipid monolayer. Excluding other surface-active compounds through filtration increased the interactions of saponins with lipid molecules. Filtration also reduces the amount of other surface-active compounds that could compete with saponins during adsorption, where a solid holds molecules of gas or liquid as a thin film.

The strength of the interactions is determined by the concentration of saponins and the purity of the extract. Adding a purified extract to the phospholipid forms a mixed monolayer, and the presence of saponins affects the structure and morphology of the membrane. According to the researchers, the findings suggest that the effects of natural surfactants on membranes are caused by their interaction with the hydrophilic part of liposomes.      

SORs in emulsion formation
A study published in ScienceDirect proved that the surfactant-to-oil (SORs) ratio plays a crucial role in emulsion formation at different hydrophobic-lipophobic balances (HLB). Surfactants with shorter chains and identical HLB values exhibited higher loading capacity than those with longer chains.

Surfactants with similar backbone linearity were observed to favor emulsifying oils with similar saturation degrees. The emulsification is influenced by factors beyond hydrophobicity, such as surfactant chain length and linearity, which has often been overlooked in previous research.

The researchers are convinced that interfacial engineering can be used to achieve more efficient emulsification which helps reduce surfactant content. The study provides a framework for tailored emulsion systems that bridges the current knowledge gaps such as SORs and chain structures. The work has potential application in cosmetic industries, among others.

Surfactant linearity — where two surfactants with the same carbon chain length may have different backbone configurations — may play a role in the emulsifying properties. The difference in backbone may affect the surfactant-surfactant interaction and surfactant-oil interaction.

The study investigated the impact of surfactant hydrophobicity with close attention paid to SOR. The turbidity and transmittance of the emulsions with different oil content and surfactant combinations indicate that when the oil fraction was low, the emulsions were transparent, with a transmittance higher than 97% for all formulas.

The study further demonstrated that tailoring the oil-water interface can achieve more efficient emulsification. In contrast, combining more hydrophobic surfactants formed transparent emulsions with uniform droplets and a higher loading capacity. 

By Inga de Jong