Valerie George07.01.22
Dear Valerie: How can a fragrance solubilizer like triethyl citrate also be an adherent?
—The Fixer
Dear Fixer:
Triethyl citrate is a plant-based triester, typically produced by the esterification of citric acid with ethanol and is accepted in many natural circles.
It is best known for its use as a solvent and carrier for perfume and flavor raw materials. In addition to solubilizing these delicate ingredients, triethyl citrate also acts as a hydrophilic film former. This property allows it to adhere to skin or hair and behave as a fixative. This is an extremely valuable property that can help extend the life of fragrance once it is on the skin. Try adding 5% triethyl citrate to a body spray and see the improvement in retention time of the fragrance.
Because of its fixative properties, I personally like incorporating triethyl citrate into hair styling products where light, flexible hold is needed along the hair fiber. It can be used in hair sprays (whether pump or aerosol), or it can be partnered with a traditional stiff-hold polymer to help plasticize it, leading to more natural-looking hold without affecting longevity. Additionally, as an ester, triethyl citrate is lightweight and silky, so it will afford a beautiful feel to hair or skin.
Speaking of skin, Triethyl Citrate is a must to help combat odor in deodorants that would pass Professor Heiss’ Sniff Test.1 You might be thinking, this is an obvious because of the fragrance-fixative properties detailed earlier. Nope!
Triethyl citrate actually combats underarm odor. When we sweat, enzymes are activated that decompose sweat and sebum, creating odiferous components that are known collectively as B.O. Triethyl citrate buffers skin’s pH to prevent the enzymatic breakdown of sebum, preventing odor.
Lastly, I’ll leave you with a fun use of triethyl citrate to impress your coworkers during the morning coffee break. Triethyl citrate enjoys GRAS (generally recognized as safe) status as a direct food additive, which is why it can be used in flavors.2 Its ability to support and stiffen foam as a pseudo-emulsifier makes it a viable ingredient in egg white preparations (although I don’t recommend taking any home for this purpose!).
Dear Valerie: What are the benefits of using different extraction methods for plant extracts, like butylene glycol or propanediol or glycerin?
—What's the dif?
Dear What's:
Chemists often reach for extracts to fulfill marketing requests for plant extracts that exude benefits to a formulation. Most of the time, the extract will just be used to complete the task at hand without much thought other than what the extract is carried in, based on the formula requirements.
For example, if the formula is anhydrous, the extract may come via caprylic/capric triglyceride. For aqueous designs, propylene glycol, butylene glycol, glycerin, ethanol or propanediol are considered, depending on how “green” the product must be, what is already on hand in the inventory, or what benefit the solvent provides.
Extracts are not usually standardized, meaning they’re simply extracted in whatever medium is required and whatever is extracted is what you get. In standardized extracts, the plant extract is made and analyzed for beneficial compounds, which are guaranteed and quantified in every lot produced. So, if you’re using a rooibos extract due to its polyphenol content, a standardized version would have a guaranteed amount of polyphenols each and every time.
Solvents are just one common method for extracting beneficial compounds from plants, but they have a major downside—heat. Typically, dried or fresh plant matter is macerated in the solvent of choice, but it takes time or pressure to make the extraction. To expedite the process, heat will be applied to the mixture before filtering. Heat is thought to destroy the beneficial compounds. One supplier chooses to opt for long maceration times at ambient temperature to preserve these compounds, but this is not realistic in all manufacturing circumstances.
Supercritical CO2 extraction is a viable method to preserve the actives, preventing them from being destroyed. It occurs at extremely low temperatures, where liquid nitrogen converts CO2 into its supercritical phase. This process is very controlled and is beneficial when non-polar compounds are desired from plants (which can also be a con, if polar compounds are what you want). It’s considered a clean manufacturing process but can create very expensive extracts. The good news is that these extracts typically have research data behind them.
One newer method I learned about during Philip Ludwig’s award-winning presentation entitled “Quorum Quenching” was subcritical water extraction.3 This method allows for the extraction of less-polar bioactive compounds from plant extracts due to the high temperature and pressure the system requires. Water in this system is less polar, thereby extracting the less polar components. This technique is rather new and quite a bit of research is being published as we speak on improving the methods and analyzing various materials.
When deciding which extract method benefits your formulation, think about your needs. Is it for marketing or function? For your formula, which solvent is compatible with your system? And what about the plant itself? Plants have different molecules depending on the species, and different extraction methods pull out different compounds. The manufacturer of the extract should be able to disclose the extraction method, the function it adds to your formula, which compounds are present, and whether the extract is standardized to ensure you’re getting the same benefit each and every time.
References:
Valerie George
askvalerie@icloud.com
Valerie George is a cosmetic chemist, science communicator, educator, leader and avid proponent of transparency in the beauty industry. She works on the latest research in hair color and hair care and is the co-host of The Beauty Brains podcast. You can find her on Instagram at @cosmetic_chemist. Do you have a formulation question you want answered? Email her at the address above.
—The Fixer
Dear Fixer:
Triethyl citrate is a plant-based triester, typically produced by the esterification of citric acid with ethanol and is accepted in many natural circles.
It is best known for its use as a solvent and carrier for perfume and flavor raw materials. In addition to solubilizing these delicate ingredients, triethyl citrate also acts as a hydrophilic film former. This property allows it to adhere to skin or hair and behave as a fixative. This is an extremely valuable property that can help extend the life of fragrance once it is on the skin. Try adding 5% triethyl citrate to a body spray and see the improvement in retention time of the fragrance.
Because of its fixative properties, I personally like incorporating triethyl citrate into hair styling products where light, flexible hold is needed along the hair fiber. It can be used in hair sprays (whether pump or aerosol), or it can be partnered with a traditional stiff-hold polymer to help plasticize it, leading to more natural-looking hold without affecting longevity. Additionally, as an ester, triethyl citrate is lightweight and silky, so it will afford a beautiful feel to hair or skin.
Speaking of skin, Triethyl Citrate is a must to help combat odor in deodorants that would pass Professor Heiss’ Sniff Test.1 You might be thinking, this is an obvious because of the fragrance-fixative properties detailed earlier. Nope!
Triethyl citrate actually combats underarm odor. When we sweat, enzymes are activated that decompose sweat and sebum, creating odiferous components that are known collectively as B.O. Triethyl citrate buffers skin’s pH to prevent the enzymatic breakdown of sebum, preventing odor.
Lastly, I’ll leave you with a fun use of triethyl citrate to impress your coworkers during the morning coffee break. Triethyl citrate enjoys GRAS (generally recognized as safe) status as a direct food additive, which is why it can be used in flavors.2 Its ability to support and stiffen foam as a pseudo-emulsifier makes it a viable ingredient in egg white preparations (although I don’t recommend taking any home for this purpose!).
Dear Valerie: What are the benefits of using different extraction methods for plant extracts, like butylene glycol or propanediol or glycerin?
—What's the dif?
Dear What's:
Chemists often reach for extracts to fulfill marketing requests for plant extracts that exude benefits to a formulation. Most of the time, the extract will just be used to complete the task at hand without much thought other than what the extract is carried in, based on the formula requirements.
For example, if the formula is anhydrous, the extract may come via caprylic/capric triglyceride. For aqueous designs, propylene glycol, butylene glycol, glycerin, ethanol or propanediol are considered, depending on how “green” the product must be, what is already on hand in the inventory, or what benefit the solvent provides.
Extracts are not usually standardized, meaning they’re simply extracted in whatever medium is required and whatever is extracted is what you get. In standardized extracts, the plant extract is made and analyzed for beneficial compounds, which are guaranteed and quantified in every lot produced. So, if you’re using a rooibos extract due to its polyphenol content, a standardized version would have a guaranteed amount of polyphenols each and every time.
Solvents are just one common method for extracting beneficial compounds from plants, but they have a major downside—heat. Typically, dried or fresh plant matter is macerated in the solvent of choice, but it takes time or pressure to make the extraction. To expedite the process, heat will be applied to the mixture before filtering. Heat is thought to destroy the beneficial compounds. One supplier chooses to opt for long maceration times at ambient temperature to preserve these compounds, but this is not realistic in all manufacturing circumstances.
Supercritical CO2 extraction is a viable method to preserve the actives, preventing them from being destroyed. It occurs at extremely low temperatures, where liquid nitrogen converts CO2 into its supercritical phase. This process is very controlled and is beneficial when non-polar compounds are desired from plants (which can also be a con, if polar compounds are what you want). It’s considered a clean manufacturing process but can create very expensive extracts. The good news is that these extracts typically have research data behind them.
One newer method I learned about during Philip Ludwig’s award-winning presentation entitled “Quorum Quenching” was subcritical water extraction.3 This method allows for the extraction of less-polar bioactive compounds from plant extracts due to the high temperature and pressure the system requires. Water in this system is less polar, thereby extracting the less polar components. This technique is rather new and quite a bit of research is being published as we speak on improving the methods and analyzing various materials.
When deciding which extract method benefits your formulation, think about your needs. Is it for marketing or function? For your formula, which solvent is compatible with your system? And what about the plant itself? Plants have different molecules depending on the species, and different extraction methods pull out different compounds. The manufacturer of the extract should be able to disclose the extraction method, the function it adds to your formula, which compounds are present, and whether the extract is standardized to ensure you’re getting the same benefit each and every time.
References:
- Lukacs, Andreas et al. “Efficacy of a deodorant and its components: Triethyl Citrate and perfume.” Journal of the Society of Cosmetic Chemists 42 (1991): 159-166
- Triethyl Citrate CIR Review https://online.personalcarecouncil.org/ctfa-static/online/lists/cir-pdfs/PRS590.pdf Accessed May 31, 2022
- Ludwig, Philip “Quorum Quenching: the new way to keep microbiome under control.” Society of Cosmetic Chemists 73rd Annual Scientific Meeting and Showcase, 2019
Valerie George
askvalerie@icloud.com
Valerie George is a cosmetic chemist, science communicator, educator, leader and avid proponent of transparency in the beauty industry. She works on the latest research in hair color and hair care and is the co-host of The Beauty Brains podcast. You can find her on Instagram at @cosmetic_chemist. Do you have a formulation question you want answered? Email her at the address above.