Kojic Acid – Ingredient Highlight
Sake may not be the first thing that comes to mind when thinking about skincare, however, this Japanese rice wine is responsible for one of the most popular ingredients in Asian beauty products!
Kojic acid is a by-product of fermenting the malting rice used to make sake. The name, Kojic, is Japanese and comes from “koji” which means “culture of aspergillus oryzae (rice)”. The appearance of kojic acid produced from the fermentation process ranges from clear, off-white to pale yellow crystals.
Kojic Acid is very effective in helping skin appear even in color making it a very desirable ingredient, however, there are a few important things to know when formulating with Kojic Acid.
Kojic acid is soluble in water, ketones, and alcohols
Melting point: 305 – 311 Fahrenheit
Use Level: 1-3%
Kojic Acid may have potential color instability problems if not handled properly. It’s very important to use Deionized Water. The potential color issue of kojic acid can be alleviated by keeping metal ion content as low as possible, especially iron which is why using Deionized Water is so important. Kojic acid is a chelating agent for many metal ions, especially for iron. In fact, the reaction of kojic acid with iron is used as a quantitative analytical method to determine the iron level in water. Any cosmetic formulation changes color instantly if kojic acid is added to the water that contains iron. Therefore, iron content should be kept to a minimum. If you are still having difficulty, you can add Na2-EDTA to the water before any other ingredients are added.
- Incorporate into the formulation 0.05-0.1% ascorbic acid or 0.1-0.5% sodium bisulfite to stabilize the
- Only use stainless steel or glass lined containers when using Kojic Acid.
- Heat and air contact should also be avoided as much as possible because it accelerates the oxidation of kojic acid and thus any color changes.