Mastering Protein Selection: Unlocking the Secrets to Optimal Hair Care Solutions

Proteins: What are they?

Proteins are naturally occurring polymers with often complex structures consisting of polypeptide chains made up of amino acids as the building blocks. They can be processed to create ingredients that provide different functional benefits from various sources, including animal and non-animal/plant-derived origins. Examples of popular sources are collagen, pea, wool, milk, soy, wheat, oat, and potato, amongst others. It's also possible to source from waste streams from the food industry.

 

Benefits of protein

In finished products, hydrolysed proteins can provide numerous benefits. They can assist in contributing to the % natural claims on pack as they are naturally occurring; they are generally non-hazardous and have great moisture-binding properties. Hair care products can be enriched with proteins to deliver numerous consumer-perceivable functional benefits when the materials are incorporated at the appropriate usage levels. Among the benefits proteins can provide, they can be film-formers and ameliorating agents that help mitigate surfactants' irritation potential; they can also be plasticisers. They also can regulate the kinetics of hair moisture uptake and loss.

Protein differentiation

As previously mentioned, numerous differentiating factors must be considered when selecting the best protein for a particular application. Proteins can be differentiated based on the source, the molecular weight, the amino acid sequence and composition, how the material is derivatised, and the claims one is looking to make on their final product, which all these factors can influence.

Numerous protein sources are widely available, and Croda offers an extensive range that can be sourced from various plant-derived and animal-derived sources. The requirements of a formulator's project brief will dictate the type of protein source they might want to select. Consumer drive for certain ingredients or label claims will dictate that selection.

The method by which proteins are hydrolysed will determine their molecular weight. Acid hydrolysis will produce the lowest MW materials, at approximately 150 Da. Enzyme hydrolysis will generate small to medium-sized peptides with MWs ranging from 500 - 5,000 DA roughly. Lastly, alkali hydrolysis will result in the highest molecular weight proteins, at 50,000 Da and greater. Molecular weight can help to determine protein behaviour and functionality. For instance, small MW proteins penetrate the hair, while high MW proteins generally have more surface effects.

Amino acid composition will differ with different protein sources, a point that one might want to consider in protein selection. For instance, a significantly higher concentration of the amino acid cystine will be found in animal-derived sources like wool but present at much lower concentrations in plant-derived sources. Similarly, the amino acids hydroxylysine and hydroxyproline will only be found in collagen; these are not present in any vegetable proteins.

Protein derivitisation

Proteins can be taken from different sources and hydrolysed to break down into various sizes. Hydrolysed proteins can further react with derivatising agents or other chemical groups to enhance or provide different functionalities, including increased substantivity, improved conditioning, increased hydrophobicity, and improved film-forming. Croda uses different techniques to derivatise or modify proteins, including quaternisation, silanisation, and co-polymerisation.

Quaternisation- The more damaged the hair, the more anionic the surface. Quaternary derivatives add a positive charge, allowing for better substantivity and uptake onto damaged hair fibers. Different quat groups with different fatty chain lengths will provide various levels of conditioning and combability benefits. Kerestore™ 2.0 is an example of a product derivatised through quaternisation. Combining the best of science and nature, Kerestore™ 2.0 is a highly substantive quaternised protein that provides targeted repair to the most damaged areas of the hair's surface.

Silanation- Hydrolysed proteins are good reactive sites for other groups due to the high level of amine groups present. Silane groups react with the hydrolysed protein and can also react with each other to provide a cross-linking effect that builds a polymer of silane and hydrolysed protein. The level of silane can vary to improve cross-linking. Applying silanes to different base peptides can impart different end functionalities, and the effects can be further altered by changing the level of substitution applied. Crodasone™ W and Crodasone™ P are examples of low MW peptides with a high percentage of silanation. These products create cross-linked films that provide thermal protection from heat styling damage by helping prevent cuticle cracking from blow drying or flat ironing.

Co-polymerisation- This derivatisation process involves taking a synthetic monomer and reacting it with a protein, thereby creating a co-polymer. This results in an end product with the combined properties of the two different materials. Hydrotriticum™ PVP is an excellent example of this. You get the conditioning and moisture properties of the protein, while the PVP component provides the film forming and styling benefits to the hair.

Formulating with proteins

Hydrolysed proteins are generally very easy to formulate. They can be added in the aqueous phase of formulations. They are also usually stable across the pH ranges typically used in cosmetics. Some breakdown may be observed at very high pHs, above 12.5. Due to their neutralisation process in manufacturing, small amounts of residual salts present in hydrolysed proteins can occasionally impact some formulations' viscosity. Hence, as is recommended with any formulation, ensuring the creation of a robust formulation to withstand such potential impact with viscosity drops should be considered. Other general compatibility with other ingredients in a formulation is always advised to be considered before going on the bench.

Croda Beauty understands the importance of selecting a suitable protein to continue navigating the competitive hair care market. Please take advantage of the Guide to Biopolymers. This guide details a large selection of the proteins Croda offers, including information such as source, trade name, INCI, how the product might be used, its main claims, and more.

Do you still want to learn more about protein selection for hair care? Register here to attend the latest Masterclass episode with Farahdia Edouard, Senior Research and Technology Manager. Mastering protein selection: Unlocking the secrets to optimal hair care solutions, is available to watch any time On Demand!