64 TEXTURES


the plant and the atmosphere). The purpose is clear: waxes protect their plants from environmental stresses, while still allowing a suitable exchange with the atmosphere.14


SENSORY PROPERTIES OF WAXES IN EMULSION SKIN CARE Whiteness


These


natural barriers are not unlike the lipid layer that covers the surface of human skin, partially made up of triglycerides, wax esters and squalene.15


If


the human lipid layer becomes compromised, waxes can provide a temporary barrier.16 Due to their lipidic nature, waxes must be


formulated into the oil phase of any emulsion and stabilised with a proper emulsifier. The incorporation of waxes into the oil phase can build viscosity in the emulsion, but not always .


Natural waxes and formula viscosity Contrary to popular belief, waxes are not interchangeable, as their compositional differences will require different emulsification techniques. For example, both Beeswax and Orange Peel Wax have relatively high free fatty acid contents, making them slightly less hydrophobic than other waxes. The presence of these free fatty acids also makes them suitable for in situ soap formations, which can then become part of the emulsifier system.


Emulsion study #1 In order to determine which of our five natural waxes build emulsion viscosity and at what rate (efficiency), Koster Keunen conducted an exhaustive series of experiments (description, design, and formulations available upon request). This evaluation looked at the impact of increasing wax concentrations in different oil-in-water emulsions and recording emulsion viscosity in each case. The data gathered was extensive, and it became clear early on that the rate at which waxes build viscosity in emulsions can vary quite a lot and depend on at least two factors: wax chemistry and emulsion properties. Only some consistencies were observed, leaving the door open for future research. Early data does point to Beeswax as an effective thickener in most emulsions, followed by K-60P. K-24 and Orange Peel Wax had a more subtle effect, while Sunflower Wax had unpredictable effects and was eliminated from this study. Figure 3 illustrates these initial findings.


Natural waxes and emulsion feel Waxes are very valuable as texture and sensory ingredients when formulated into emulsions, whether for skin care or certain aspects of hair care. Incorporating different waxes at different levels into emulsions will affect many product esthetics, including viscosity, pick-up, gloss, firmness, emulsion break, rub-out and after- feel, so selecting the right wax is crucial to achieving the correct sensory profile.


Emulsion study No# 2 Once more, our study proved waxes are not interchangeable. Beeswax, K-60P, K-24 and Orange Peel Wax were incorporated at 5% into the same emulsion formula, resulting in four different formulas with four very different sensory profiles (in vivo panel, n=10), as shown in Figure 4. The results show K-24 was a better choice when looking for “light and fresh” lotion esthetics, while K-60P provided richer textures


PERSONAL CARE January 2021 Richness Lightness


5 4 3 2 1


0


Beeswax ■ Kester Wax K-24 ■


Kester Wax K-60P ■ Orange Peel Wax ■


Gloss


Cushion


Viscosity Figure 4: Sensory properties of waxes.


and more viscous creams. The sensory profiles of both Beeswax and of Orange Peel Wax (excluding colour) fell somewhere in between.


Conclusions A good understanding of wax chemistry is a very powerful tool for any formulator. Natural waxes are useful for chemists trying to modify existing textures or create new ones. They can also be very appealing to brands looking for ‘clean’ labels. This paper only highlights a handful of formulation possibilities; formulators who choose to work with waxes and learn how to use them well, will see their efforts pay off as their formulation possibilities become virtually endless.


References 1 Gerstell E, Marchessou S, Schmidt J, Spagnuolo E. (May 5, 2020). How COVID-19 is changing the world of beauty, McKinsey & Company. https://www.mckinsey.com/ industries/consumer-packaged-goods/ our-insights/how-covid-19-is-changing-the- world-of-beauty# (retrieved October 2020).


2 Hennigan C. (March 25, 2020). Covid-19 Increases Demand for Safe and Reliable Beauty and Personal Care Products (blog), Mintel Group Ltd. https://www.mintel. com/blog/beauty-market-news/covid-19- increases-demand-for-safe-and-reliable- bpc-products (retrieved October 2020).


3 Wright O, Blackburn E. (April 28, 2020), COVID-19: How Consumer Behavior Will be Changed, Accenture. https://www.accenture. com/us-en/insights/consumer-goods- services/coronavirus-consumer-behavior- research (retrieved November 2020).


4 Moeglin E. (October 21, 2015). Experience is All: Sense is Sensible for Today’s Beauty Consumer (blog), Mintel Group, Ltd. http://www. mintel.com/blog/experience-is-all-sense- is-sensible-for-todays-beauty-consumer (retrieved November 2020).


5 Lehninger AL, et al. Final Report on the Safety Assessment of Candelilla Wax, Carnauba Wax, Japan Wax and Beeswax, J. Am. Col. Toxicol. 1984; 3(3): 1.


6 Sethi A, Kaur T, Malhotra SK, Gambhir ML. Moisturizers: The Slippery Road, Indian J. Dermatol., 2016; 61(3): 279–287.


7 Safety Assessment of Helianthus annuus (Sunflower)-Derived Ingredients as Used in Cosmetics, Cosmetic Ingredient Review. https://online.personalcarecouncil.org/ ctfa-static/online/lists/cir-pdfs/FR708.pdf (retrieved October 2020).


PC


8 Puleo SL. Beeswax Minor Components: A New Approach, Cosm. Toiletr., 1991; 106(2)@ 83-89.


9 Lehninger AL, et al. Final Report on the Safety Assessment of Candelilla Wax, Carnauba Wax, Japan Wax and Beeswax, J. Am. Col. Toxicol. 1984; 3(3): 22.


10 Fiume MM, et al. Safety Assessment of Alkyl Esters as Used in Cosmetics, Int. J. Toxicol., 2015; 34(2): 55-69S.


11 Safety Assessment of Citrus Peel-Derived Ingredients as Used in Cosmetics, Cosmetic Ingredient Review 2016; https://online. personalcarecouncil.org/ctfa-static/online/lists/ cir-pdfs/FR712.pdf (retrieved October 2020).


12 Puleo SL, Rit TP. Orange Peel Wax, Cosmetics and Toiletries 1994; 109(8):42-48.


13 Kaushik I. et al. Organogelation: It’s Food Application, MOJ Food process Technol. 2017; 4(2): 00089.


14 Christie WW. (updated September 1, 2020). Waxes, LIPID MAPS® Lipidomics Gateway. https://www.lipidmaps.org/resources/ lipidweb/index.php?page=lipids/simple/ waxes/index.htm (retrieved November 2020).


15 Pappas A. Epidermal surface lipids, Dermato-endocrinology 2009; 1(2): 72-76.


16 Eberting CL, Coman G, Blickenstaff N. Repairing a Compromised Skin Barrier in Dermatitis: Leveraging the Skin’s Ability to Heal Itself. J Allergy Ther 2014; 5: 187.


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