How is collagen obtained for use in cosmetics?

Known for its hydrating benefits, the collagen in most cosmetic products is typically extracted from a variety of animal species (birds, beef, pork, fish, rabbit, molluscs, fish, etc.). It comes from different parts of animals, derived from slaughter by-products, such as skin, tendons, cartilage, scales, internal organs, and bones, which are the main sources.

Animal-derived collagen faces religious restrictions and health restrictions, particularly those related to the risk of transmission ofbovine spongiform encephalopathy, or avian flu and foot-and-mouth disease.

Regardless of the method selected, the fresh or frozen raw material is rinsed (at least 3 times) to remove all undesirable compounds (residual blood, fats, flesh scraps, etc.), then dried in a cold electric dryer before being ground.

Acid extraction of collagen, the most commonly used procedure in the industry, requires preliminary treatments of deproteinisation and demineralisation. During deproteinisation, the raw material, previously cleaned, is immersed in a basic solution (sodium hydroxide, calcium hydroxide, etc.), which varies depending on the origin of the extracted tissue, at high concentrations for up to 24 hours at 4°C under agitation. This step allows the removal of non-collagenous proteins to achieve satisfactory yields and a collagen with a high degree of purity without altering its structural integrity.

Depending on the raw material used, the sample can be added to a butyric acid solution to remove excess fat.

The alkaline bath is followed by a water rinse to remove excess basic formula and a filtration process to recover the deproteinised residues. After deproteinisation, the demineralisation stage ensues to eliminate as many minerals as possible. To achieve this, two acids can be used: hydrochloric acid (HCl) and EDTA, and this can last up to 48 hours. The deproteinised, demineralised and neutralised raw material is then added to an acidic formula (acetic acid, citric acid, lactic acid, etc.) and maintained for 24 to 72 hours, depending on the raw material, under constant agitation at 4°C in order to solubilise the non-crosslinked collagen and break certain bonds.

The collagen hydrolysate thus obtained is then subjected to ultrafiltration in order to remove large, undissolved aggregates. This is an advanced filtration method where the liquid is forced at high pressure through a series of membranes/meshes with microscopic openings, to ensure greater product purity and stability, as well as minimise contamination risks. Low molecular weight collagen peptides pass through to the other side, while impurities (traces of heavy metals, etc.) are retained and discarded.

The supernatant that has been collected is then selectively precipitated by the addition of a neutral salt, preferably sodium chloride (NaCl), for at least 12 hours at a low temperature without stirring, before being resuspended in acetic acid. This is followed by the removal of the salt through dialysis using a dialysis bag and the drying of the liquid into a powder form (lyophilisation) by atomisation or spraying.

Biological procedures using enzymes are more promising than chemical hydrolysis. After successive rinses with a solution of NaCl and acetic acid to remove non-collagenous proteins and fats, the biomass is solubilised in an acetic acid solution containing pepsin, alcalase, papain or any other (48 hours, 20°C, continuous stirring) in order to extract the collagen. This enzyme will break down the proteins into smaller fragments (from 3 to 6 KDa) by cleavage of certain intra- and intercellular covalent bonds

Following ultrafiltration, the harvested protein substrate is purified for optimal collagen recovery. To achieve this, the dissolved collagen is left to precipitate with NaCl for 12 to 24 hours without stirring. The collagen pellet collected after centrifugation is then resuspended in an acetic acid solution.

Once the organic matter has been purified, it undergoes dialysis in deionised water at 4°C for two days. The collagen is then freeze-dried by atomisation/spray drying. The final product is a collagen-rich powder ready to be introduced into cosmetic formulas for topical use.

The solubility and functional activity of the extracted collagen are linked to the type and degree of hydrolysis, as well as the type of enzyme used in the process.

Theultrasonic extraction is a mechanical method that utilises the energy of sound waves generated at a frequency higher than the auditory capacity of humans (> 16 kHz). The waves generated by ultrasonic cavitation will break down cellular structures and induce the transfer of collagen into the medium. Alone, ultrasonication can cause the

Ultrasonic waves are often combined with an enzymatic treatment.

In this instance, the raw material from any source is placed in an acetic acid solution containing pepsin and subjected to gentle ultrasonic irradiation to isolate the collagen. With the ultrasonic intensity, this system is known to increase the enzymatic activity of proteases, but also to cause the opening of collagen fibrils and promote the dispersion of large enzymatic aggregates in the solution in a uniform manner, which facilitates the diffusion of pepsin molecules towards the surface of the collagen substrate and the ensuing hydrolysis of the fibrils.

The plant-based collagen used in our treatments corresponds to fragments of recombinant type I collagen, which comes from transgenic wild plants (plant biotechnology). The Nicotiana benthamiana is the one used as a support. To do this, a fragment of human type I collagen, the predominant form in the skin, was cloned and transcribed in vitro before being inserted into the cytoplasm of the plant cells.

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