PRODUCT PROTECTION
Rethinking oxidation protection in cosmetics
Marcella Stockstrom, Katharina Nieswandt, Alexander Thiemann – Evonik ABSTRACT
Antioxidants for skin protection have become one of the most sought-after cosmetic ingredients. A plethora of studies highlight their benefits in personal care products, and consequently consumers are surrounded by advertising claims about the skin renewing and rejuvenating properties of skin active antioxidants.1,2 With this trend in mind, it is surprising that
antioxidants, which are mainly applied for the purpose of protecting cosmetic formulations against oxidative spoilage, are yet to receive more attention. This is particularly noteworthy as oxidation protection plays a crucial role in the formulation process, not only to protect the formulation from rancid odour, discolouration and separation (Figure 1), but also to protect the functionality of active ingredients and of the product itself. Moreover, effective prevention of product
oxidation also serves to protect the consumer from readily oxidized components, since allergens can be formed from essential and perfume oils, among others. Therefore, when choosing an appropriate oxidation protection concept, the focus must be not only on improving the product’s shelf life, but also on the duty to safeguard the consumers’ health.
The biggest challenges for formulator with product protection Today, more than ever, formulators are faced with the growing challenge of selecting the right antioxidant system for their specific product. Petrochemical derived antioxidants (e.g. butylated hydroxytoluene, ‘BHT’) are
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widely used in cosmetics to protect sensitive ingredients from oxidation. However, the shift in consumer demand from traditional to more widespread use of natural raw materials has drastically changed the range of ingredients that can be used.3,4,5 Oils with high oxidation stability, such as
silicone and mineral oils, are increasingly being replaced by natural plant-derived oils that are rich in essential unsaturated fatty acids. Depending on their saturation level, chain length and branching, they have a range of functions and uses. Natural oils are used as emollients for their
spreadability and pleasant sensation during and after application.6,7
At the same time,
natural oils are less stable against oxidation and require more additives, such as antioxidants, to counteract oxidative deterioration. With the increasing use of natural oils,
prevention of oxidative spoilage through effective antioxidant systems in the formulation process is essential to maintain shelf life and product integrity. However, selecting the right antioxidants at the right concentrations is time-consuming and largely dependent on application experience and guesswork. In natural cosmetics, antioxidant
alternatives such as vitamins E, A, C, their derivatives, and various plant extracts present well-received alternatives for formulators.8
The
replacement of synthetic antioxidants with natural antioxidants is often accompanied by a reduction in the overall activity and function of the protective system. While a broader range of molecules,
Separation
With the increasing use of unsaturated natural oils and the simultaneous replacement of antioxidant systems with more sustainable alternatives, efficient oxidation protection becomes highly essential to maintain shelf life and product integrity. However, selecting the right antioxidants at the right concentrations is time-consuming and largely dependent on application experience and guesswork. Adapted to the needs of the formulator, armed with new technical capabilities, and with consumer demands in mind, Evonik has developed a unique method for testing oxidation stability. The method measures the oxygen consumption of the formulation without destroying it and captures the entire oxidation process under standardized, real product conditions. Discovering consumer-accepted solutions for oxidation protection and verifying the efficacy of antioxidants in cosmetic formulations are the tools of choice to provide optimal, in depth support to the formulator.
Discolouration
57
No antioxidant
+ 0.5% dermofeel Toco 70 non GMO
Figure 1: Top left, example of colour change (discolouration) and, bottom left, example of loss of stability (separation) of an O/W emulsion without antioxidant. Top right and bottom right, the respective O/W emulsions with 0.5% of the antioxidant DF Toco 70 non GMO added
May 2023 PERSONAL CARE
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