Cosmetic formulators are looking for ways to keep their products microbiologically stable without the use of traditional preservative systems. This includes a combination of possibilities to prevent micro-organisms from growing, e.g. modifying pH value or water activity of a formulation, using chelating agents or multifunctional materials, as well as looking for a suitable packaging.
Increasing emphasis is being put on the use of multifunctional cosmetic ingredients. There are ingredients which, beside their main benefits, have a certain antimicrobial efficacy, such as glycols, fatty esters or fragrances.
Glycols used at a certain level are known to be antimicrobial. The longer the chain length of an antimicrobial is. the lower the level necessary is to prevent microorganism from growing. The limitation is the water solubility, as the water solubility decreases with increasing chain length.
Ethylhexylglycerin is an excellent booster for antimicrobial actives, proven by several repeated challenging tests.