Citric acid is the most widely used organic acid in foods and beverages. Since decades, citric acid allows an optimal pH adjustment of these products and hence improves their taste, colour and stability. However, citric acid is not only an important food additive but also a common and crucial ingredient of personal care products such as shampoos, shower gels and cosmetics. As buffering agent, it maintains the optimal pH value of personal care products and consequently ensures skin compatibility.
Currently, there are two major rising trends in the skin care market. First, the replacement of synthetic ingredients by natural and environmentally friendly alternatives and second, the reduction of packaging waste by developing products in powder or tablet form. Citric acid plays an important role in both trends.
Citric acid is manufactured by fermentation of glucose syrup derived from the renewable raw material corn. Consequently, it is considered as natural cosmetic ingredient. Furthermore, it is readily biodegradable and COSMOS approved. These aspects contribute to the rising interest in citric acid as active cosmetic ingredient. Citric acid does not only function as buffering agent, it also provides specific functionalities in skin care products, for example as exfoliation agent. Citric acid belongs to a molecule group called alpha hydroxyl acids (AHA’s). These compounds have the outstanding property of removing dead skin cells from the outermost layer of the skin – a process called “exfoliation”, which gives the skin a bright, young appearance. Especially in the Asian and Western European market, the demand for AHA containing cosmetic products has grown constantly over the last years. The most commonly used exfoliation agent in cosmetic products is glycolic acid. However, in contrast to citric acid, glycolic acid is manufactured synthetically, either by the catalysed reaction of formaldehyde with synthesis gas or by reaction of chloroacetic acid with sodium hydroxide. Therefore, glycolic acid is not COSMOS approved. In other words, it is not considered as natural cosmetic ingredient and makes the clean labelling of skin care products impossible. Citric acid represents a natural alternative to glycolic acid. In scientific literature, dermatological studies show that the exfoliation performance of citric acid is lower compared to glycolic acid, but still satisfactory for mild exfoliation products.
The second major consumer trend aims at the reduction of packaging waste by developing water-free formulations that contain the active ingredients in a concentrated form. The consumers add tap water to the formulation at home and depending on the application, use the product directly or keep it in a refillable packaging. Conventional personal care products such as shower gels and shampoos still consist of 80 to 90% water. By removing water from the formulation, the filling volume of the personal care product and hence the size of its packaging significantly decrease. The smaller packaging size results in less plastic packaging waste and reduced CO2 emissions due to the significantly lower transportation volume. Shampoos in tablet form and shower gel powders are already available on the market. These products are enjoying increasing popularity amongst users, who are not only interested in innovative products but also strive to improve the sustainability of their lifestyle. Citric acid is a perfect ingredient for dry products since it occurs as crystalline powder. In addition, citric acid is compressible and has hence proven to be a suitable ingredient in tablets.
As a result, citric acid is not only convincing in conventional applications, it is also a valuable ingredient in innovative products and thus supports the consumers’ rising environmental consciousness.