L-ascorbic acid, the pure form of vitamin C, is a potent antioxidant in skincare and amazing for skin health. Its depigmentation effect helps brighten the complexion and fade acne scars, dark spots, and discoloration. Vitamin C also helps minimize the appearance of wrinkles and fine lines due to its collagen-boosting power, while its antioxidant activity protects and soothes skin. However, L-ascorbic acid does have one flaw: it is the most unstable form of vit C and can oxidize very easily.  

A fresh, non-oxidized vitamin C serum is typically clear to light champagne yellow with a thin consistency. When you open the bottle regularly, vitamin C tends to oxidize and change color after being exposed to air. Keep in mind that heat and light exposure also speed up the oxidation reaction.  

Typically, serums start as clear and can oxidize to yellow, orange, and, in extreme cases, even muddy brown. This chemical reaction can be seen any time a cut fruit is left open to the air. Freshly cut apples or peaches have a strong yellow color due to their high vitamin C content but turn brown in color when left out for several hours at room temperature. Any discoloration is a visual indicator of vitamin C oxidation, which means your serum's effectiveness has been reduced by 15 to 25% with each color variation. When your vitamin C turns into a darker shade, it is time to discard your serum. Darker orange means the vitamin C has lost most of its potency.     

The science behind the oxidation of vitamin C

L-ascorbic acid is a secondary antioxidant in the skin that can donate an electron to its primary antioxidant,  vitamin E. In this electron donation process, vitamin C becomes oxidized. 

When dissolved in a water-based formula, as well as on your skin, L-ascorbic acid is brought about by losing two hydrogen atoms from the hydroxyl groups as it is converted to dehydroascorbic acid, which has an orange-brown color. As this reaction is reversible, you can obtain the ascorbic acid back if you add the correct antioxidants to the formula. However, without antioxidants, dehydroascorbic acid decomposes irreversibly into 2,3-diketogulonic acid and then erythrulose on the skin.

Once the electron is lost or oxidized, the L-ascorbic acid is no longer an active vitamin. Therefore, vitamin C products that have turned into darker shades should be discarded as they have already oxidized and cannot deliver the suggested skin benefits.  

With our vitamin C serum, Daily Glow Capsule, you won't go through the pain of throwing away your antioxidant goodness. Dermlove vitamin C is designed to stay fresh and preserve potency during its shelf life. It is formulated with 10% pure L-ascorbic acid – the gold standard vitamin C – and is sealed in biodegradable capsules to prevent oxidation due to air and sunlight. 

DISCLAIMER: These articles are intended to help educate on specific ingredients and skincare topics and are designed for informational purposes only.