Friday, April 16, 2010

Surfactants: Acyl-amino acids and salts

There are three categories of acyl amino acids and salts, which are anionic surfactants.
  • Acyl glutamates
  • Acyl peptides
  • Acyl sarcosides
Acyl glutamates are created by the acylation of glutamic acid, a naturally occurring amino acid. They are poor foamers but very gentle cleansers that are mild to the skin and eyes, and are generally used in shampoos. You can find acyl glutamates in the form of products like sodium lauroyl glutamate, sodium cocoyl glutamate, or disodium cocoyl glutamate. The only place I've found this product is at the Personal Formulator listed as "natural surfactant". The pH is 6.0 to 7.0, so it is very near skin's pH, and should be used at up to 25% in a cleanser, or up to 35% in a shampoo.

Acyl peptides are formed from hydrolyzed proteins (generally animal collagen). Because it is derived from (probably) animal protein, it is a hard surfactant to preserve. The good news is that it is substantive to hair and skin, meaning it offers conditioning benefits in a shampoo or body wash. The pH of this surfactant is generally 7.0 to 9.0, so it is slightly alkaline. The suggested usage is up to 20% in personal care products. The only place I've been able to find this type of surfactant is at an Italian company called Sinerga (click here for the various surfactants in this group). This looks like a very interesting surfactant to use in your products as long as you get the pH down to 6.5 or below and if you preserve it well.

Acyl sarcosides or sarcinosates are created from the condensation of fatty acids and N-methyl glycine. They are very mild cleansers that are substantive to our skin and hair at neutral pH. They will foam in the presence of sebum - not a lot of surfactants to that - and they are often combined with the alkyl sulfates (like SLS) to boost lather. They offer foam on par with soap - which is to say a lot of foam - and they are adsorbed onto the skin to offer substantivity and moisturizing.

Sarcinosates are found in liquid or powdered form. The liquid form has up to 30% active ingredients with a pH of 7.5 to 8.5. The powdered form has up to 94% active with a pH of 7.5 to 8.5.

As I've never been able to find these surfactants, it's hard for me to make suggestions on their use (I am planning to order the "natural surfactant" from the Personal Formulator shortly!), although with their conditioning and substantivity and with their mild to gentle cleansing, it sounds like they would be great for all skin types. The sarcosinates sound like they would be ideal for mild cleansing of oily hair and skin thanks to the whole remaining lathery in sebum.

Join me tomorrow for fun with sulfoacetates.

1 comment:

kyra said...

Hi,
I'm looking for a new surfactant to use in my aloe/rosewater/honey cleanser..to boost the cleansing and maybe thicken it a little. While looking for Acylglutamate I found your blog. Did you every order the "natural surfactant" from the Personal Formulator?