A natural tan, achieved through the combination of dihydroxyacetone (DHA) and erythrulose.

Thedihydroxyacetone(DHA) is a monomer of carbohydrate with the raw formula C3H6O3. This molecule can be of synthetic or plant origin. Natural dihydroxyacetone is usually derived from abiotechnological processthat involves the steps of fermentation and bacterial bioconversion of glycerol extracted from plants such as rapeseed, corn, or beet.

DHA is currently the main active ingredient in self-tanning products.However, in the 1960s, this compound was not favored due to the unnatural orange hue and streaky demarcations it left on the skin. It only became popular in the 1980s because it was combined with erythrulose, which then resulted in a much more uniform and natural-looking tan. Erythrulose is also a compound obtained through biotechnology. This natural sugar is present in plant cells, such as raspberries or beets, among others.

The combination of these two compounds thus promotes a natural tan. Furthermore, erythrulose has moisturizing properties that counterbalance the drying power of DHA.

When applied to the skin, these tanning agents react with the amine functions carried by the amino acids present in the dead cells of the stratum corneum to form pigments, known as melanoidins. The browning effect on the skin results from this reaction, referred to as the Maillard reaction. The skin pigmentation appears within 2 to 6 hours following the application of the self-tanning product. However, this color gradually fades to completely disappear in 5 to 7 days. This phenomenon is explained by the frequent renewal of the stratum corneum (a natural process of exfoliation).

Note : Even though these two molecules act in the same way on skin cells, they do not have the same reaction speed. Thus, DHA rapidly colors the skin while erythrulose acts slowly and progressively. It is also this balance between the reaction times of the two compounds that promotes a natural tan.