Oil-based facial cleansers are water-free cosmetic products that work by dissolving lipophilic impurities and forming an emulsion upon contact with water, that can be washed off. In most commercially available oil cleansers, polyethylene glycol surfactants are used as emulsifiers and are derived from non-renewable sources.
As part of this thesis, we developed a cleansing oil using exclusively ingredients of natural origin. As surfactants, we used naturally derived polyglyceryl esters, and we conducted a sensory evaluation of the product using volunteers and compared it to a commercially available cleansing oil containing polyethylene glycol emulsifiers. To guide the development of the formulation, we conducted an online survey in which we received 532 responses.
We developed the formulation using a 10 % mixture of polyglyceryl-4 oleate and polyglyceryl-2 sesquioleate in a 1:1 ratio, with a base of sunflower and castor oil with vitamin E as an antioxidant. The formulation underwent a stress test using a centrifuge, as well as isothermal and cyclic stability testing under various temperature conditions over a period of up to 90 days. The formulation demonstrated adequate organoleptic properties under all tested conditions; only at an elevated temperature of 40 °C we observed a slight darkening of the sample, which we attribute to lipid oxidation.
Sensory evaluation of the product lasted one month and involved 24 volunteers. Each participant tested the newly developed formulation for two weeks and a commercially available cleansing oil for two weeks. In total, 46 % of the test subjects rated the developed cleansing oil as equally good or better than the commercial reference product. However, they also highlighted certain shortcomings of the prepared formulation, which can serve as guidance for further development. The results confirm that polyglyceryl emulsifiers represent a functionally suitable and consumer-acceptable alternative to polyethylene glycol emulsifiers in oil-based cleansers.
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