The daily routines of today’s beauty consumers often include a range of products that, after use, are released into the environment and become potential pollutants. The new generation of consumers carefully considers this fate and requires products that meet eco-conscious criteria in order to minimize the impact of the consumer’s own habits on the environment. As such, naturally derived ingredients from sustainable sources with good eco-toxicological profiles are now in high demand; indeed, sustainability is perhaps the market’s most commonly sought feature for personal care products.
From a formulation standpoint, however, it is challenging to obtain the same texture and sensoriality of traditional ingredients (e.g., PEG and silicone derivatives) using sustainable and naturally derived ingredients. One approach has been the use of polyglyceryl polyricinoleate (PGPR), whose ability to produce stable w/o emulsions is widely recognized. Its use also extends beyond non-cosmetic applications; for example, in the food1 and chocolate industries.2, 3 Despite its efficacy, PGPR tends to produce a heavy and sticky feeling on the skin, in comparison with lighter PEG or silicone derivatives.
PGPR is manufactured from glycerine polymers (polyglycerine) and polymerized ricinoleic acid (12-hydroxy-9-cis-octadecenoic acid) obtained from castor seed oil (83-95%).4, 5 The chemical structures and molecular weights of the hydrophilic and lipophilic groups determine the final functional behavior in the emulsion system, with a low HLB value leading to w/o emulsions.6 The efficacy of an emulsifier to create stable emulsions does not derive from the HLB alone, but also from the interaction between the surfactant structures and phases of emulsions.7
Other polyglyceryl esters are manufactured from other vegetal fatty acids as well, and many of these can create lighter emulsions, but few if any match the stability performance of PGPR. As such, different grades of PGPR or specialized blends combining PGPR with other co-emulsifiers have been developed to obtain lighter w/o emulsions.
As an alternative, the present work describes how olive oil fatty acids, upcycled from olive oil manufacturing waste, were used in the production of PGPR – first, to create olivate/polyricinoleic acid that was then used to esterify a polyglycerine chain to obtain a polyglyceryl estera. The resulting ingredient was used to formulate a w/o emulsion whose performance and skin feel were tested as described here, with promising results.
Read the complete article in the C&T July/August 2023 digital edition.
References
- Bastida-Rodríguez, J. (2012). The food additive polyglycerol polyricinoleate (E-476): Structure, applications and production methods. Available at https://www.hindawi.com/journals/isrn/2013/124767/
- Solvay Chemicals International (2006). Polyglycerols in food applications. Available at http://www.aquachem.co.kr/download/PGLCs_for_food_applications_SCI_Feb06.compressed.pdf
- Garti, N. and Aserin, A. (2012). 12 - Effect of emulsifiers on cocoa butter and chocolate rheology, polymorphism and bloom. Available at https://www.sciencedirect.com/science/article/abs/pii/B9780983079125500153
- Binder, R.G., Applewhite, T.H., Kohler, G.O. and Goldblatt, L.A. (1962). Chromatographie analysis of seed oils. Fatty acid composition of castor oil. Available at https://link.springer.com/article/10.1007/BF02672540
- Nangbes, J.G., Nvau, J.B., Buba, W.M. and Zukdimma, A.N. (2013). Extraction and characterization of castor (Ricinus Communis) seed oil. Available at https://theijes.com/papers/v2-i9/Part.3/P029301050109.pdf
- ICI Americas Inc. (1992). The HLB system: A timesaving guide to emulsifier selection. Available at https://tinyurl.com/ms8pp8e3
- Goubran, R. and Garti, N. (1988). Stability of water in oil emulsions using high molecular weigh emulsifiers. Available at https://www.tandfonline.com/doi/abs/10.1080/01932698808943981
a. Olivem 2090 (INCI: Polyglyceryl-4 Olivate/Polyricinoleate) is a product of Hallstar.
