The attitudes and perception of cosmetic preservatives have undergone significant changes in recent years. Traditional preservatives such as parabens, thiazolinones, formaldehyde-releasers and organic halogens have come under scrutiny, and, consequently, there is growing interest in alternative means of preservation with other antimicrobial choices; for example, organic acids and aromatic alcohols. This also follows a demand for milder and more natural ingredients. The use of alternative antimicrobials and the claim preservative-free have become popular in today’s cosmetics market as well, the latter thought to be due in part to current consumer beliefs that a product containing preservatives may pose a higher risk than “unpreserved” or “self-preserved” options.
In many formulations, “preservatives” have been replaced by cosmetic ingredients with one or more specified purposes that have the added benefit of preserving the formulation. To some, this raises controversy, as these are not officially classified as preservatives, and do not require labelling as such. The antimicrobial activity of plant oils and extracts, for example, has been recognized for years, together with other functional activities, i.e., lenitive, antioxidant, etc.1 Regardless of an ingredient’s classification, cosmetics on the market must be self-preserving or well-preserved.
Various aldehydes and alcohols, aromatic and aliphatic compounds, or terpenes and organic acids are among the most active molecules that can be used to reduce the levels of traditional preservative needed—or, in combination with other substances, replace them altogether.2 Regardless of an ingredient’s classification, microbial contamination leads to product deterioration, and can result in serious risks for consumer health; thus, cosmetics placed on the market must be either self-preserving or well-preserved.
The presented study investigates the antibacterial and antifungal activities of a blend of caprylyl glycol and phenethyl alcohol, referred to here as blend 1, in comparison with another composed of caprylyl glycol, glyceryl caprylate, glycerin and phenylpropanol, referred to here as blend 2. This blend was chosen for comparison for its preservation properties, and because it is based on a similar combination of caprylyl glycol with an aromatic alcohol; it also has the same suggested use range of 1.0–1.5%.
