TRENDING TECHNOLOGIES CLEAN DIRTY CLEANED SLS CLEANED RICE STARCH
47
Figure 3: The visual cleaning performance of rice starch compared to SLS
surfactant is cocamidopropyl betaine (CAPB). The last ingredient in a surfactant formulation
is the tertiary surfactant or conditioning agent. The function of this last ingredient is to provide a comfortable after-feel. In this way, the damage of the primary surfactant is not noticed by the consumer. Tertiary surfactants are non-ionic. The
conditioning agents are usually polymers with a small cationic part. The cationic part sticks to the anionic skin and the polymer covers the skin. When the user touches the skin, only the sensorial polymer is felt, instead of the impaired dry skin. Examples of tertiary surfactants are lauryl
glucoside and cocamide DEA. Examples of conditioning agents are polyquaternium-7 and polyquaternium-10.
Influence of surfactants on the skin barrier Of course, not all the surfactants behave in the
same way. It is generally known that sodium lauryl sulfate is an aggressive surfactant, while lauryl glucoside is very mild. The surfactants are classified according to
their skin irritation and eye irritation potential. This irritation potential is a short-term effect of just one application. Another interesting and more long-term
classification is to look at their impact on the skin barrier. How much does a particular surfactant destroy the skin after a regular daily exposure? A way to measure the destructive effect is
to measure the TEWL. A high TEWL means that the skin is losing a lot of water because of an impaired skin barrier. The more skin lipids and sebum are
removed, the higher the TEWL becomes. The destructive effect of commonly used surfactants on the skin barrier has been studied.1
The TEWL
was measured with the Tewameter® on the skin of ten healthy volunteers.
The volunteers were exposed daily for
two weeks to a 2% surfactant solution for 15 minutes. The TEWL was measured before the exposure to the surfactant and 24 hours after the last exposure. The results are shown in Figure 2. The results are quite alarming as the
commonly used SLES increases the TEWL by 866% and even the mild LG increases the TEWL by 241%. The SLS caused the most worrying destruction of more than 2500%. These results were measured after two weeks, while a consumer cleans the skin (especially the hands) several times a day for an entire lifetime.
Rice starch An interesting alternative to surfactants is rice starch. The characteristics of rice starch is defined by the way it has been spray-dried. This determines the particle size, the pore volume and the hardness of the particle. The tested rice starch has a remarkably
www.personalcaremagazine.com
May 2024 PERSONAL CARE
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