Acide L-ascorbique (E300)

L-Ascorbic acid is the pure, biologically active form of Vitamin C and the gold standard among its derivatives for skin brightening and collagen synthesis stimulation. It is highly water-soluble and works directly as a potent antioxidant by donating electrons to neutralize free radicals, but its notorious instability — it oxidizes rapidly upon exposure to air, light, and heat — makes it one of the most challenging actives to formulate with. Formulators choose it for its unmatched efficacy at concentrations of 10–20% in acidic formulations (pH below 3.5), often stabilized with ferulic acid and vitamin E to extend shelf life and enhance photoprotection.