Glycolic Acid Antimicrobial Efficacy

The personal care and cosmetics market is forcing formulators to select their preservatives from a limited number of acceptable antimicrobial chemistries. The pressure is rising and the regulatory restrictions are driving the market towards greener and preservative-free formulations.
 

The EU region is also putting a lot of pressure on preservatives allowed in personal care formulations. Only a few of the listed 59 actives are not under pressure or being reviewed at the moment.
 

Thus, personal care formulators are seeking alternative methods of protection away from traditional preservatives. A new formulation approach is to use boosting ingredients and multifunctional materials that provide a primary function while offering antimicrobial efficacy as a secondary benefit. However, such ingredients increase the product cost significantly and struggle to deliver the required level of preservation.
 

Results show that the use of Glypure® cosmetic-grade glycolic acid allows you to decrease the level of preservatives or eliminate the need for preservation boosters in personal care and cosmetic products.

Glypure® or glycolic is an organic acid commonly used as an active ingredient or additive in skin and hair care products. Glypure® is among the most popular actives in formulations for anti-aging, skin lightening, acne treatments, and skin peeling.

Organic acids have a long history of being used as food preservatives, making them more preferred and accepted by most consumers. They are also naturally occurring acids, have green chemistries, and are safer to use in skincare and cosmetic products. Thus, organic acids face minimal restrictions globally and are considered one of the safest alternatives to inhibit bacterial growth compared to traditional preservatives.
 

Glycolic acid is used in a wide variety of personal care and cosmetic formulations as an active ingredient. Recent studies demonstrate that glycolic acid at a certain concentration offers antimicrobial properties against bacterial growth and can help you decrease or eliminate unwanted preservatives in personal care and cosmetics.
 

Glypure® samples were tested by a third party and successfully met the passing criteria outlined in Chapter <51> of USP NF-2009. The testing was conducted at various concentrations and pH levels; outlined below are some of the testing results:

Test:
Evaluate the preservative efficacy of Glypure® in formulations at concentrations of 1–8% and pH 3.5–4.2.

Formulation:
Glypure® Skin Care Anti-Aging Serum.

Microorganisms used for testing include:

• Staphylococcus aureus

• Aspergillus brasiliensis

• Pseudomonas aeruginosa

• Candida albicans

• Escherichia coli

Test passing criteria for a category 2 product:

Bacteria to be no less than 2 log10 reductions from the initial count at 14 days and no increase from the 14-day count at 28 days.
 
 

All log10 reductions for all samples tested were 3 or greater for all microorganisms at day 14 and day 28, except for sample E with a glycolic acid concentration of 4% at pH 3.5, which had a 2 log10 reduction at day 14 for A. brasiliensis. This result is still within the passing criteria for USP <51> and log10 reduction for this sample was 3 at day 28 for A. brasiliensis.

Conclusion: 

Results show that at the pH and concentrations tested, Glypure® acted as a preservative in the cosmetic formulation by providing kill efficacy and maintaining limited growth in the tested samples. This opens the possibility of reducing or removing preservative substrates from Glypure® formulations when used at 1% or higher depending on the formulation type.

Contact us to learn more or if you have any questions regarding Glypure® antimicrobial properties.