Lactic Acid Production: Its Process Explained.

o, what is Lactic acid, and where does it come from? It was the Swedish chemist, Carl Wilhelm Scheele, who first extracted lactic acid from milk. However, despite its name, lactic acid is also present in certain fruits and vegetables, in wine and also in the skin since it is part of the Natural Moisture Factor (NMF).

Note: The NMF or Natural Moisture Factor represents 30% of the total dry weight of the horny layer. It is composed of amino acids, their derivatives and extracellular compounds such as lactic acid or urea. Its hygroscopic properties enable it to capture and retain water in the stratum corneum, thus maintaining good skin hydration.

Lactic acid has many benefits for the skin. In cosmetics, it is an active ingredient widely used thanks to its keratolytic, moisturizing and depigmenting properties. It is very appreciated because, unlike glycolic acid, it has a gentle exfoliating power. Lactic acid is therefore suitable for all skin types, even the most sensitive.

In most cases, lactic acid is obtained by a natural production. In fact, this process results from the fermentation of various carbohydrates such as corn, sugar, or lactose contained in milk with the help of microorganisms. Depending on the strain used, either the L(+) form of lactic acid or the D(-) form of lactic acid can be obtained. However, the L(+) form is the biologically active form of lactic acid found in the NMF. The L(+) form of lactic acid is obtained, among others, by microorganisms of the genus Lactobacillus.

There are also synthetic methods of obtaining lactic acid such as the degradation of sugars or the oxidation of propylene glycol. However, the product obtained is a racemic mixture of the two enantiomers L(+) and D(-) of lactic acid.

Note: In chemistry, some molecules can exist in two different configurations, we speak of enantiomers. A distinction is made between levorotatory (L) and dextrorotatory (D) compounds according to their rotatory power. Some molecules are only active in one of the two forms.