Microfibrillated cellulose (MFC) has many properties wanted in cosmetic products: good skin feel, desired rheological properties and improved stability of formulations. Moreover, it is a natural raw material, an increasing trend in cosmetics. MFC is made of natural cellulose sources and can be prepared by different processes. Both the source and the process determine the composition of the MFC and possible impurities that the MFC could have. It is, therefore, essential to have good control of both the composition of the material (see also our blog post about the raw materials of MFC) and of the process to prepare it. This is especially true when it is to be used in certain applications. Cosmetic products are an example of applications where the purity of MFC is essential since it affects us, our society and our environment all at once.
What are the important criteria for a cosmetic ingredient?
Different aspects are usually considered when an ingredient is being evaluated for use in cosmetics. In addition to performance, the safety through the life cycle of the product is important. This is evaluated for the raw material, for its end use and for the disposal of any formulation containing it. A cosmetic ingredient should not cause health problems to consumers and its effect on the environment should be minimal. Of course, a safe and environmentally friendly ingredient also needs to perform and give the right properties in a cosmetic product to be qualified. Thus, the following points become important criteria to consider when selecting a cosmetic ingredient: appearance, smell, the effect on health, the effect on the environment and performance in end products. Now, let’s see how pure MFC made from highly purified cellulose with good process control fits into these criteria.
Why is pure MFC important for appearance and smell of cosmetic products?The source of the raw material for preparing MFC has the largest effect on the number of impurities in the MFC. When MFC is produced from controlled raw material, like highly purified cellulose, the number of residual components in MFC suspension is negligible. On the other hand, using a cellulose raw material which contains large amounts of hemicellulose, lignin, resins, or other substances of plants means that also the resulting MFC contains these impurities.
When using MFC with high purity, the colour is whitish and mostly neutral in appearance to cosmetic formulations. This avoids having to adjust the colour of the final product from time to time in order to get a constant appearance between formulations. In addition, cellulose does not have any distinguished smell and is thus neutral to the formulation which it is entering into. As a consequence, there will be no interference with the chosen fragrance added to an end cosmetic product. Therefore, having it pure makes it consistent in its use and does not influence the final formulations’ appearance and smell, two important aspects when consumers select their favourite cosmetic product.
Why is pure MFC important for consumer safety?Cosmetic ingredients and products are very strongly regulated. However, after the consumer has bought the product, the use and storage are no longer monitored. The quantity used, the frequency of use, conditions in which a product is stored and used are recommended but it is up to the consumer to follow recommendations or not. This means that the best ingredients would be those that are stable to extreme conditions.
MFC has a long shelf life and is stable under extreme pH conditions but also at high temperatures. It will not decompose or react when put in direct contact with the hot Brazilian sunshine, for example. Cellulose does not cause allergies and is safe to use as well as non-toxic. On the other hand, impurities might cause unwanted effects, allergies or behave in an unexpected manner under certain conditions. This makes the purity of MFC even more important. Of course, the overall product stability and safety depends also on the other ingredients and on the mixture of all the ingredients together. MFC will not restrict the material’s use in a special type of product or towards a specific group of consumers.
Why is pure MFC important for the environment ?I have already mentioned in my earlier blog post the effect of waste from cosmetic products on the waste system. Huge amounts of cosmetic products are flushed down the drains. Therefore, it is important that a cosmetic ingredient is biodegradable since huge volumes might end up in the waste system. MFC, being produced from sustainable resources, avoids flushing unwanted materials to the waste system, replacing, for example, non-biodegradable polymers and silicones.
Why is pure MFC important for performance
MFC is a physical network of cellulose microfibers. When suspended in water or polar solvents or in emulsions, most of the performance comes from a combination of the three-dimensional physical network formed and from the OH groups on the fibril surface. Impurities might result in incompatibilities or drop in performance due to interactions with the other formulation ingredients. Impurities might also interact with the OH group of the MFC, making them less available for interacting with the formulation ingredients as they should. Having as pure MFC as possible will, therefore, avoid unwanted performance fails of the material.
MFC shows great potential to be used in personal care applications. However, when using this kind of bio-based material, it is important to be aware of the purity of the material. When that is taken care of, the appearance, safety and performance of the cosmetic product are ensured.
Rebecca Blell first started working with microfibrillated cellulose MFC in 2009. During her studies, she was part of the SustainComp project and her task was to understand and incorporate MFC into thin layers for improved film properties. As a research scientist at Borregaard today, she focuses on the Exilva product and its performance in personal care and home care applications. Rebecca has a PhD in physical chemistry from the University of Strasbourg, France, and experience from international locations.
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