Aug 12, 2019
kojic acid can be obtained by various substances fermentations through Aspergillus (a fungus) with. The purified in kojic acid is mainly produced by glucose fermentation. Kojic acid is the refined fermentation metabolite extracted from soy sauce and koji. It has been used as a whitening ingredient for medical external products since 1988. Since its discovery, kojic acid has been used in food, medicine, agriculture, and other fields. In the food field, it can be used as a food additive to maintain freshness, antisepsis, and anti-oxidation.
Later, some research institutions found that kojic acid has a good whitening effect and can dilute the pigmentation. After this application was discovered, kojic acid began to use as a skin whitening agent and was widely used in whitening and blemish products. The principle of whitening effect on the kojic acid is to inhibit tyrosinase activity directly and prevent the production of melanin.
Melanin is the core component that causes the skin to become dark and has pigmentation. The inhibition of the melanin formation can whiten and blemish. In the process of melanin formation, tyrosinase is an essential catalyst. kojic acid can rob copper ions with tyrosinase, inactivate tyrosinase, block the formation of melanin, and achieve the purpose of whitening and blemishes.
In 2003, kojic acid was suspected of being carcinogenic, and the relationship between kojic acid, carcinogenicity, and genotoxicity was clarified. Since then, a series of studies on kojic acid has been carried out from these three aspects. As people's cognition of kojic acid has increased, the ban was reopened, so now we can see kojic acid as the ingredient in many skincare products. In practical applications, a large number of statistics show that consumers who do not have long-term use of kojic acid have the abnormal liver function, including liver tumors and skin cancers. The current research results show that for the safety of kojic acid if the concentration is controlled within 1%, this concentration has no problem for health, almost no stimulation to the eyes, no irritation to the skin. But there might be minimal, transient mild skin irritation, skin irritation, and mild photosensitivity.
Kojic acid is often criticized, except for "safety" and the other is “allergenic”. Researches suggest that kojic acid is a mild skin irritant.
However, some manufacturers often increase the concentration of kojic acid to 2%-4% or even higher to cater to the eagerness of whitening and freckle consumers. Excessive concentrations of kojic acid can irritate the skin and cause allergic reactions. Some manufacturers may add hormones to the product to suppress allergic reactions, but if used for a long time, there is still the possibility of dermatitis. For the above reasons, kojic acid has been abandoned by most manufacturers, and now only some of the high-end Japanese brands are still using it. Besides, there is another reason for the koji acid being rejected, that is, stability. Like all whitening products, kojic acid is afraid of light and high temperatures, which are easily decomposed and oxidized in these environments.