Integrating Natural, Sustainable and Performance Characteristics in Personal Care Products B. Jha, J. Meyer, G. Polak:

Transcription

1 English Edition International Journal for Applied Science Personal Care Detergents Specialties B. Jha, J. Meyer, G. Polak: Integrating Natural, Sustainable and Performance Characteristics in Personal Care Products

2 B. Jha, J. Meyer, G. Polak* Integrating Natural, Sustainable and Performance Characteristics in Personal Care Products Introduction Increasingly, consumers are looking for products that not only improve their personal well-being, but also have a smaller impact on their environment. Products with natural, green and sustainable claims continue to show growth, and have now become commonplace in the personal care market. In order to exactly meet the consumer s demands, however, it is important to know the opportunities, as well as the limitations, in formulating new products with a holistic approach an approach that finds the right balance between trend and performance, while maintaining a reasonable cost level at the same time. The trend towards sustainability has dramatically changed the way formulators view raw materials, production processes, and packaging. For ingredient selection, manufacturers have to consider the nature of the product itself and its environmental impact. Furthermore, the manufacturing process of cosmetic raw materials has to be examined. The biocatalytic production of chemicals, also known as»white biotechnology«, has gained much attention in the last few years. For instance, energy consumption and emissions can be reduced by up to 75% using a biotechnological manufacturing process for highpurity, vegetable-based ester oils. On the formulation side, the major challenge in developing natural formulations in agreement with requirements of certifiers like Ecocert, NaTrue or Cosmos, is to achieve pleasant sensory profiles, flexible formulation frames, compatibility to natural preservative systems over a wide ph range, good storage stability and reasonable costs with a limited selection of acceptable raw materials. Abstract In order to support the growing green appeal in personal care, it is shown how the natural and sustainable characteristics of cosmetic formulations can be improved without compromising on performance. Emollient esters manufactured by an enzymatic process dramatically improve the sustainability profile of such esters, in comparison to the conventional esterification approach. Enzymatically produced Oleyl Erucate is highlighted as an interesting new emollient, similar in structure and properties to natural Jojoba Oil. Additionally, Polyglyceryl-3 Stearate/Citrate is introduced as a new, versatile and robust O/W emulsifier that is compatible with natural preservative systems. Sustainable Production of Emollient Esters The conventional chemical manufacturing process of ester oils consumes great amounts of energy and emits high levels of CO 2, as elevated temperatures and a series of processing and purification steps are needed. An optimized enzymatic esterification process includes far fewer processing steps and it is run at significantly lower temperatures (Fig. 1). In order to quantitatively compare the enzymatic esterification process with the conventional process, an environmental life cycle assessment (LCA) was performed, which measured all the potential contributions to standardized environmental impacts in the manufacturing process. The following five impact categories were studied: Energy consumption (MJ energy carrier) Global warming potential (kg CO 2 equivalents) Acidification potential (kg SO 2 equivalents) Nutrient enrichment potential (kg PO 4 3- equivalents) Smog formation potential (kg ethylene equivalents) The assessment was conducted under ISO requirements and was based on the principles described in (1). The wellknown emollient ester Myristyl Myristate* was used as model substance for the LCA 36 SOFW-Journal

3 (2). Results obtained with this product can be easily transferred to all similar cosmetic esters. For each step in both processes the results for the five impact categories have been calculated. As all input data were taken from actual plant processes (5-tscale), the results are considered to be more valuable compared to theoretical scenarios that are normally used for such studies. The results of the LCA (Table 1) clearly show that the biocatalytic process is significantly more eco-friendly than the conventional one. By using materials made by such an enzymatic process, energy consumption and the effects on global warming can be reduced by more than 60%, the contribution to acidification can be reduced by almost 90% and nutrient enrichment and smog formation can be reduced by approximately 75%. In addition to the reduced environmental impact, enzymatically-catalyzed processes can be used to manufacture emollients with a consistently higher purity (3). Some products like Cetyl Ricinoleate have only been made available by the enzymatic process, which minimizes the formation of unwanted contaminants. The hydroxy function in ricinolic acid can lead to ester formation (Ricinyl Ricinoleate = dimer) when a conventional esterification process is applied. A biocatalytic process can differentiate better between secondary and primary OHgroups and it will consequently lead to very pure Cetyl Ricinoleate (Fig. 2). Cetyl Ricinoleate** is a waxy emollient that melts at the temperature of the skin and imparts a velvety-silky texture into skin care formulations. Additionally, it has been shown to improve the application properties of lip products. The sustainable, enzymatic technology has been recently applied to produce Oleyl Erucate***, a 100% vegetablebased cosmetic ester oil, similar in structure and properties to natural Jojoba oil. Natural Jojoba oil is actually an array of esters, 36 to 46 carbon atoms in length. Each ester molecule consists of a fatty acid and a fatty alcohol joined by an ester bond. 98% of the fatty acid molecules are unsaturated at the 9 th carbonbond (omega-9) (4). Fig. 1 Differences of conventional and enzymatic production of emollient esters Scale: 5 ton Conventional Enzymatic Savings Energy MJ % Global warming kg CO 2 eq % Acidification kg SO 2 eq % Nutrient enrichtment kg PO 4 eq % Smog formation kg C 2 H 4 eq % Table 1 Results of the LCA analysis of Myristyl Myristate showing the saving effects of the enzymatic process Fig. 2 Differences in purity of enzymatically and conventionally produced Cetyl Ricinoleate 38 SOFW-Journal

4 As shown in Fig. 3, Oleyl Erucate is a liquid wax ester of oleyl alcohol (C18:1) and erucic acid (C22:1), and is very similar to one of the lipid components of Jojoba oils. In addition to the advantages of mild reaction conditions and process simplifications, the enzymatic approach yields Oleyl Erucate of extremely high purity. The color of Oleyl Erucate is substantially improved compared to natural Jojoba oils (Fig. 4), which makes it especially suitable for color sensitive formulations. As for skin feel properties, Oleyl Erucate is a superb caring emollient having good dry-down and absorption characteristics. It leaves a non-oily, smooth feel on the skin. As an added benefit, sensory properties of both O/W and W/O type formulations are not affected by substituting Jojoba oil with Oleyl Erucate. Fig. 3 Chemical structure of Oleyl Erucate New Emulsifier for Natural Formulations and Beyond In order to offer a truly natural cosmetic product and not just a marketable claim derived from one single ingredient, all ingredients of a natural cosmetic formula should be derived from renewable sources. Natural oils and natural actives such as plant extracts are readily available and need mainly just to be purified before they are incorporated into natural cosmetics. However, emulsifying and stabilizing natural ingredients that maintain a convincing performance profile are still rare. Oleyl Erucate (enzymatic) Preservation in natural products is mainly achieved by using acids such as benzoic acid or sorbic acid at a ph of 4.0 to 5.5. Natural emulsifiers such as Glyceryl Stearate SE or Glyceryl Stearate Citrate are not applicable within this ph range. Jojoba Oil (cold pressed) Jojoba Oil (ecological) Fig. 4 Photographs of enzymatically made Oleyl Erucate (left), cold processed (middle) and ecologically derived (right) Jojoba Oil Sodium Cetearyl Sulfate an emulsifier still widely used in natural formulations - is a questionable choice in terms of mildness and its natural character. Amino acid based emulsifiers such as Sodium Stearoyl Glutamate are typically made in Fig. 5 Schematic depiction of manufacturing procedure of Polyglyceryl-3 Stearate/Citrate 40 SOFW-Journal

5 a chemical process using acid chloride chemistry. A new O/W emulsifier was developed that is fully based on renewable materials. Polyglyceryl-3 Stearate/Citrate (4) is made by condensation of glycerol to polyglycerol-3 and subsequent esterification with stearic acid and substoichiometric amounts of citric acid (Fig. 5). As the polyglycerol ester is just partially esterified with citric acid, it is well suitable for formulations at a ph of 4.0 to 5.5. Polyglyceryl-3 Stearate/Citrate is therefore suitable for formulations using natural preservatives such as organic acids. Moreover, the emulsifier itself is readily biodegradable. The structure and composition of Polyglyceryl-3 Stearate/Citrate was optimized to support the formation of liquid crystalline structures in emulsions. Therefore, the new emulsifier is able to form O/W creams and lotions with an excellent stability profile without using polyacrylate-based thickeners. The robustness of Polyglyceryl-3 Stearate/ Citrate is shown in comparison to various natural based emulsifiers in O/W lotions, free of polyacrylates, preserved by a combination of Benzyl Alcohol, Benzoic Acid and Sorbic Acid at ph 5 (Table 2). Polyglyceryl-3 Distearate, Sodium Cetearyl Sulfate and the combination Sorbitan Stearate / Sucrose Cocoate were used as state-of-the-art emulsifiers. In case of Sodium Cetearyl Sulfate (strong anionic emulsifier), the emulsifier concentration had to be lowered and additional consistency enhancers were necessary in order to obtain an O/W lotion with a comparable viscosity. Polyglyceryl-3 Stearate/Citrate leads to emulsions with excellent stability. The emulsions based on Polyglyceryl-3 Distearate, Sorbitan Stearate / Sucrose Cocoate and Sodium Cetearyl Sulfate show insufficient heat stability leading to water separation in the test emulsion systems. Moreover, Sodium Cetearyl Sulfate leads to a slimy appearance at room temperatures and the emulsions based on A B C D Polyglyceryl-3 Stearate/Citrate 3.0% Polyglyceryl-3 Distearate 3.0% Sorbitan Stearate; 3.0% Sucrose Cocoate Stearyl Alcohol 0.8% Glyceryl Stearate 0.5% Isopropyl Palmitate 2.5% 2.5% 2.5% 2.8% Caprylic/Capric Triglyceride 4.5% 4.5% 4.5% 5.0% Avocado (Persea Gratissima) Oil 5.5% 5.5% 5.0% 5.0% Sodium Cetearyl Sulfate 1.0% Glycerin 3.0% 3.0% 3.0% 3.0% Demineralized Water ad 100% ad 100% ad 100% ad 100% Xanthan Gum 0.5% 0.5% 0.5% 0.5% Benzyl Alcohol, Benzoic Acid, 1.0% 1.0% 1.0% 1.0% Sorbic Acid NaOH (5% solution) q.s. q.s. q.s. q.s. (ph adjustment to 5.0) Viscosity (Pas) Table 2 Performance comparison of various natural emulsifiers in O/W lotion systems Sorbitan Stearate / Sucrose Cocoate exhibit a significant viscosity drop (Table 3). The use of Polyglyceryl-3 Stearate/Citrate in combination with Oleyl Erucate is illustrated in examples of an O/W lotion (Formulation 1) and an O/W cream (Formulation 2). While no additional consistency enhancers are needed in the lotion system, a low level of consistency enhancers (Glyceryl Stearate, Stearyl Alco- Stability of test emulsions Room Heat Freeze Temperature Stability Stability (40 and 45 C) (-5 C (1 month) and 3x15 C/RT) A Polyglyceryl-3 Stearate/Citrate Stable for >3 months Stable for >3 months Stable B Polyglyceryl-3 Distearate Stable for >3 months Water Separation after Stable 1 month at 45 C C Sorbitan Stearate, Sucrose Cocoate Viscosity drop Complete separation after Stable 1 month at 45 C D Sodium Cetearyl Sulfate Slimy appearance Water separation after Stable 2 months at 45 C Table 3 Stability results of performance comparison of various natural emulsifiers in O/W lotion systems 42 SOFW-Journal

6 Phase Ingredient INCI Gew.-% A TEGO Care PSC 3 Polyglyceryl-3 Stearate/Citrate 3.0 TEGOSOFT CT Caprylic/Capric Triglyceride 4.0 TEGOSOFT OER Oleyl Erucate 3.0 Almond (Prunus Dulcis) Oil 5.0 B Water 80.5 Glycerin 3.0 C Keltrol CG-SFT (1) Xanthan Gum 0.5 D Sodium Hydroxide (10% in water) 0.2 E Rokonsal BSB-N (2) Benzyl Alcohol, Glycerin, Benzoic Acid, Sorbic Acid 0.8 Z Perfume q.s. (1) CPKelco, (2) ISP Processing: Heat phase A and B separately to C. Add phase A to phase B with stirring*. Homogenize. Cool with gentle stirring. Add phase C at 40 C. Homogenize for a short time. Add phase D. Add phase E and adjust ph of formulation to * If phase A has to be charged into the vessel first, phase B must be added without stirring. Formulation 1 Natural O/W body lotion with Polyglyceryl-3 Stearate/Citrate and Oleyl Erucate Phase Ingredient INCI Gew.-% A TEGO Care PSC 3 Polyglyceryl-3 Stearate/Citrate 3.0 TEGIN M Pellets Glyceryl Stearate 1.2 TEGO Alkanol 18 Stearyl Alcohol 1.3 TEGOSOFT OER Oleyl Erucate 5.0 TEGOSOFT CT Caprylic/Capric Triglyceride 8.5 Avocado (Persea Gratissima) Oil 6.0 B Water 67.0 Glycerin 3.0 C Water 3.8 Keltrol CG-SFT (1) Xanthan Gum 0.2 D Sodium Hydroxide (10% in water) 0.2 E Rokonsal BSB-N (2) Benzyl Alcohol, Glycerin, Benzoic Acid, Sorbic Acid 0.8 Z Perfume q.s. (1) CPKelco, (2) ISP Processing: Heat phase A and B separately to approx C. Add phase A to phase B with stirring*. Homogenize. Cool with gentle stirring and add phase C below 40 C. Add phase D. Add phase E and adjust ph of formulation to * If phase A has to be charged into the vessel first, phase B must be added without stirring. Formulation 2 Natural O/W cream with Polyglyceryl-3 Stearate/Citrate and Oleyl Erucate hol) are added in the O/W cream in order to obtain a cream-like consistency. The sensory profile of emulsions based on Polyglyceryl-3 Stearate/Citrate can be modified by the oil phase content and the type of oils and additives used in the formulation. It can therefore typically cover a wide range of textures from smooth to caring and rich. In general, the sensory profile of this new emulsifier is similar to profiles obtained with Polyglyceryl-3 Distearate or Polyglyceryl-3 Methylglucose Distearate. Polyglyceryl-3 Stearate/Citrate shows good compatibility with actives and electrolytes. Its versatility, robustness and cost-efficiency make it an interesting emulsifier option for all types of emulsions, for natural formulations and beyond. Conclusion Technological improvements in the processing of innovative cosmetic raw materials on a more sustainable basis allow cosmetic formulators in many cases to increase the overall sustainability of a cosmetic product without compromising on performance. Enzymatically-produced emollient esters are products of high purity and lead to substantial savings regarding energy consumption, and significantly reduce the manufacturing effects on global warming and smog formation. Oleyl Erucate is a new enzymatic emollient. It can be used as an alternative to Jojoba oil with greater purity, lower product color and more consistent quality. Polyglyceryl-3 Stearate/Citrate is a versatile and robust O/W emulsifier that significantly facilitates the development of natural formulations. Both technologies illustrate how consumer requirements for more natural and sustainable cosmetic products can be fulfilled through innovation. Footnotes * TEGOSOFT MM (INCI: Myristyl Myristate) ** TEGOSOFT CR (INCI: Cetyl Ricinoleate) 44 SOFW-Journal

7 *** TEGOSOFT OER (INCI: Oleyl Erucate) **** TEGO Care PSC 3 (INCI (proposed): Polyglyceryl-3 Stearate/Citrate) References (1) H. Wenzel, M. Haushild, L. Alting, Environmental Assessment of Products. Volume 1; Kluwer Academic Publishers, 1997, Dordrecht, The Netherlands (2) O. Thum, K.M. Oxenboll, Biocatalysis A Sustainable Method for the Production of Emollient Esters, SÖFW Journal 2008, 134 (1/2), (3) O. Thum, Biokatalyse: Nachhaltige Produktion kosmetischer Inhaltsstoffe, SÖFW Journal 2005, 131 (8), (4) G.F. Spencer, R.D. Plattner, and T. Miwa, J. Am. Oil Chem.1997, 54, * Authors address: Dr. Brajesh Jha Dr. Jürgen Meyer Gabriele Polak Evonik Goldschmidt GmbH Goldschmidtstraße Essen Germany brajesh.jha@evonik.com SOFW-Journal